DC Systems, Energy conversion & Storage Matchmaking Event de faculteit/Afdelinge… · Efficient Energy Conversion DC systems, Energy conversion & Storage COMMUNICATION IN WIRELESS

DC Systems, Energy conversion & Storage

Matchmaking Event

24th April 2019

High Voltage DC Materials and Components High Voltage DC Diagnostics and Monitoring

High Voltage DC Systems DC Grids and Storage for Smart Cities

Electromechanics and Electric Mobility Efficient Energy Conversion

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DC Systems, Energy Conversion & Storage

Master’s Thesis Proposal

Efficient Energy Conversion DC systems, Energy conversion & Storage

COMMUNICATION IN WIRELESS CHARGING: E-BIKE

Type of project: MSc thesis

Scope:

To research the used communication methods in wireless charging. Design and development of the communication system for the e-bike wireless charging station.

Problem definition:

Since charging cables for the e-bikes are not standardized yet, bulky cables need to be carried by the cyclists in each charging station. Wireless charging for e-bikes would just consist of a fixed receiver installed on the bike, that makes its use more convenient. In this system, the process is started when the e-bike is parked on a special tile that works as a power source. On the other hand, the e-bike’s double kickstand picks up the transferred power and charges the battery. Moreover, having the communication between the transmitter and receiver would allow the user to request either the start, stop or pause of the charging process. Through the communication, the receiver could also ask the transmitter for a specific voltage level while the charging process is running.

Methodology:

Firstly, a literature research must be executed on the available standards and communication methods in wireless charging. Then, the research will narrow on the communication through the power line for the e-bike wireless charging system. After the phases of analysis and design, the laboratory implementation would work as proof of concept.

Research Objectives:

Research and compare the communication methods used in wireless charging.

Design and implement the communication through the power line for the e-bike wireless charging setup.

Contact details:

PhD student: Francesca Grazian ([email protected])

Supervisor: Dr. Peter van Duijsen ([email protected]) Prof. Pavol Bauer ([email protected])

mailto:[email protected]



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DIGITAL CONTROL OF A S IC-BASED INVERTER FOR WIRELESS CHARGING OF EVS


Scope:

To programme the digital control of a SiC-based inverter such that it can work together with an analog controller for guaranteeing soft switching operating in the EV wireless charging system.

Problem definition:

International standards limit the EVs wireless charging technology. As an example, the operating frequency of the transferred magnetic field must be between 81.38-90 kHz, which means that it is also the operating range of the inverter at the transmitter side. Within that band, the soft switching of the inverter must also be ensured which can be done by detecting the zero-crossing of the current. This control would be easy in case all the circuit parameters do not change. However, the equivalent load is changing while the battery is charging and also the coupling between the coils is not fixed but the user has some freedom to park the car. Therefore, the optimum operating frequency varies over the process and the control must adapt to these different conditions ensuring a minimum target efficiency of the power transfer and safety of the operation.

Methodology:

First, a literature research must be executed on the characteristic of EVs wireless charging, focusing on the control strategies used. Then, the analog and the digital functions of the control strategies must be identified separately and the approach for integrating them together must be found. After the first phase of analysis and design, the concept can be validate developing a laboratory prototype.


Understand and identify the challenges of the control in EVs wireless charging.

Integrate the analog and the digital controllers to have soft switching operation in the allowed frequency range.

Realize a controller that can stand the possible operating conditions (coupling and load).

Contact details:


Supervisor: Dr. Thiago Batista Soeiro ([email protected]) Prof. Pavol Bauer ([email protected])

[1] LAUNCHPAD TMS320F28069M EVAL BRD, from TI website

[1]




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INVERTER TOPOLOGIES FOR AN E-BIKE WIRELESS CHARGING SYSTEM

Type of project: Extra Project/ SIP 2

Scope:

Comparison between inverter topologies for an e-bike wireless charging system in terms of complexity, stress on the components, power density and cost.

Problem definition:

Since charging cables for the e-bikes are not standardized yet, bulky cables need to be carried by the cyclists in each charging station. Wireless charging for e-bikes would just consist of a fixed receiver installed on the bike, that makes its use more convenient. In this system, the process is started when the e-bike is parked on a special tile that works as a power source. On the other hand, the e-bike’s double kickstand picks up the transferred power and charges the battery.

Several power electronics topologies can be used for the inverter and they have different characteristics and operations. However, to enhance the power transfer, the power factor must be as close as possible to 1, and the soft switching operation is privileged.

Methodology:

First, the project is carried out though simulations for understanding the characteristics and the operation of the different topologies. Finally, lab-work as a proof of concept is executed.


Understand the operation of different inverter topologies.

Compare the topologies in terms of complexity, stress on the components, power density and cost.

Evaluate the suitability of the topologies for e-bike wireless charging system.

Contact details:


Supervisor: Dr. Peter van Duijsen ([email protected]) Prof. Pavol Bauer ([email protected])




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WIFI COMMUNICATION FOR EV WIRELESS CHARGING

Type of project: Extra Project/ SIP 2

Scope:

To evaluate the feasibility of the Wi-Fi as a communication method for EV wireless charging in terms of communication speed, energy consumption, accuracy and interaction with multiple devices.

Problem definition:

The communication between transmitter and receiver in EVs wireless charging can allow different features such as supporting to the user in the coils’ alignment, the compatibility check of the systems, and requesting either the start, stop or pause of the charging process. Moreover, through the communication, the receiver can ask the transmitter for specific voltage levels while the charging process is running. In this project, the use of Wi-Fi (Sub-1 GHz) is evaluated for EVs wireless charging.

Methodology:

The (short) first phase is understanding the different wireless communication protocols (Bluetooth, Wi-Fi, ZigBee etc.). Then, the project is dedicated to familiarizing with TI Launchpad development Kits and programming them such that they can communicate through Wi-Fi (Sub-1 GHz). Therefore, the project is mainly taking place in the laboratory.


Understanding the operation of TI Launchpad development Kits for Wi-Fi communication.

Characterize this communication in terms of speed, energy consumption, accuracy and space range.

Evaluate the scenario in which multiple devices are interacting together. What would happen to the charging process?

Contact details:


Supervisor: Dr. Thiago Batista Soeiro ([email protected]) Prof. Pavol Bauer ([email protected])




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SOLID-STATE CIRCUIT BREAKER – AUXILIARY POWER SUPPLY DESIGN


Scope:

The two main challenges of meshed low voltage DC grids today are the flexible control of power flow and short-circuit protection. The conventional approach to deal with both problems is to incorporate galvanically isolated DC-DC converters with integrated short-circuit protection, which are rated for the full power rating of the grid. In the previous research, partially rated power flow control converter was proposed in combination with a solid-state short circuit breaker (sscb). This thesis builds on these results.

Problem definition:

The sscb is required to operate during all abnormal states of the grid reliably. The crucial part is supplying the auxiliary power to the sscb during faults. The aux. power supply for sscb poses an exciting design challenge. Besides the extreme operational conditions, the power supply needs to be very efficient across a wide input voltage range.

Methodology:

In the first phase, the student will get familiar with the design requirements of the sscb for lvdc system. Based on the literature review of the available solutions for the auxiliary power the student selects the best fit for the application. Then proceeds with the design of the prototype power supply.


Choose appropriate topology for the sscb aux. power supply

Design the pcb and integration with the existing sscb

Experimental verification

Contact details:

PhD student: P.Purgat ([email protected] )

Supervisor: dr. Z. Qin([email protected]) prof. P. Bauer ([email protected])




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SOLID STATE CIRCUIT BREAKER – AVALANCHE TESTING

Type of project: MSc thesis / Extra Project

Scope:

The two main challenges of meshed low voltage DC grids today are the flexible control of power flow and reliable short circuit protection. In LVDC systems the application of the solid state circuit breaker (SSCB) proves beneficial in terms of cost and system efficiency. The corner stone technology of the SSCB are MOSFETs. One of the dominant failure causes in MOSFETs are the failures in avalanche mode.

Problem definition:

The most severe operating conditions the SSCB has to sustain is the opening of highly inductive circuits. Therefore, to benchmark the reliability of the designed SSCB it is necessary to validate that it can survive the avalanche mode ratings.

Methodology:

In the first phase, the student will get familiar with the design requirements of avalanche testing circuits and compare different avalanche testing methods. In the second phase the testing circuit is designed and testing plan developed. In the final stage, the avalanche testing is executed.


Choose appropriate avalanche testing method

Design the avalanche testing circuit

Execute the reliability test

Contact details:

PhD student: P.Purgat ([email protected] )

Supervisor: dr. Z. Qin([email protected]) prof. P. Bauer ([email protected])




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DEVELOPPING SAFER AND MORE RELIABLE SOLAR INVERTERS


Scope:

To study, design and construct a transformer-less single-phase photovoltaic inverter which features low common-mode noise emission.

Problem definition:

Currently, transformer-less photovoltaic (PV) inverters are widely found in the energy market because of the inherent benefits in cost reduction and power efficiency enhancements when compared to galvanic isolated versions. In such circuit concept lower impedance from the high voltage potentials to the ground exists. Therefore, Common-Mode (CM) voltages can reduce life-time of the PV panels as leakage current can flow through its stray capacitances to the ground degrading the insulation materials. Additionally, it can generate a health hazard for personal involved in the maintenance of the PV system as the leakage current can flow through their body.

Methodology:

To study, simulate, design, construct and test a power electronics inverter using computational tools and TU Delft’s laboratory facilities.


Literature review of transformer-less PV inverter with low CM voltage emission

Benchmark suitable inverter solutions using multi-objective design approach

Design and construct a single-phase PV inverter solution with Low CM emission

Test the constructed prototype

Contact details:

Supervisor:

Dr. Ir. Thiago Batista Soeiro, [email protected]

Prof. Dr. Eng. Pavol Bauer, [email protected]

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Source: https://www.fleetcarma.com/ everything-need-know-electric-cars/

Existing AC-DC Converter and TI

DSP Control Board

DIMENSIONING ULTRA COMPACT AND EFFICIENCY POWER ELECTRONICS FEATURING SOFT-SWITCHING FOR ELECTRIC VEHICLE CHARGERS


Scope:

Study, design and implementation of a grid interface circuit or AC-DC converter featuring Triangular Current Modulation (TCM) for two power stage charging of Electric Vehicles (EV).

Problem definition:

The Electric Vehicle (EV) charging market is very dynamic. The so called AC-type chargers can be found confined within the vehicle or on-board. This must be able to withstand the harsh environment with ambient temperature of above 75 oC. Therefore, compact and high-efficiency power electronics (and implementing electrolytic-less capacitors) in the power range of 6 kW .. 12 kW is desired. The operation of the grid-connected power stage with triangular current modulation and phase-shift interleaving has become standard in high compact and high efficiency systems. The required large current ripples across the magnetics allows the operation of the bridge-legs of the circuit with Zero-Voltage Switching (ZVS), leading to the utilization of smaller passives and cooling systems. Unfortunately, variable switching frequency operation is required and means to limit the frequency range are necessary in a digital implementation with the latest microcontrollers available in the market. The addition of passive networks and/or the use of modified TCM algorithms have shown promising results.

Methodology:

To study, simulate, implement a narrow frequency range triangular current modulation in a TI DSP. The functionality of the developed software will be tested in an existing AC-DC power converter.


Literature review in high efficiency and ultra-compact power AC-DC conversion systems;

Investigation and proposal of TCM techniques narrowing switching frequency range;

Implementation of a developed TCM modulation in an existing TI DSP control board;

Test the developed software in an existing prototype.

Contact details:

Supervisor:





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DIMENSIONING ULTRA COMPACT AND EFFICIENCY POWER ELECTRONICS BASED ON SINGLE PHASE DIRECT ON-BOARD EV CHARGERS


Scope:

Study, design and implementation of a single-phase grid interface circuit or AC-DC converter featuring electrolytic less direct power stage charging of Electric Vehicles (EV).

Problem definition:

The Electric Vehicle (EV) charging market is very dynamic. The so called AC-type chargers can be found confined within the vehicle or on-board. This must be able to withstand the harsh environment with ambient temperature of above 75 oC. Therefore, compact and high-efficiency power electronics and implementing electrolytic-less capacitors in the power range of 6 kW .. 12 kW is desired. The operation of the grid-connected power stage with advanced modulation and control schemes can make this technology a reality. As the life-time of the power converter in high temperature environments is typically limited by the usage of the electrolytic capacitor technology, a more reliable system is finally obtained.

Methodology:

To study, simulate, implement a direct power conversion isolated AC-DC circuit for EV charging applications. Means to implement modulation and control schemes which can eliminate the requirement of electrolytic capacitors within the AC-DC and DC-DC converter stages of state-of-art solutions will be investigated.


Literature review in high efficiency and ultra-compact power AC-DC conversion systems;

Investigation and proposal of modulation and control techniques allowing DC electrolytic-less direct power conversion.

Implementation of a modulation and control strategy for the studied circuit in an existing TI DSP control board;

Contact details:

Supervisor:



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Source: https://www.fleetcarma.com/ everything-need-know-electric-cars/

Eletrolytic-less

Capacitor



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DIRECT MEDIUM VOLTAGE CONNECTED FAST ELECTRIC VEHICLE CHARGER


Scope:

Study, design and simulate a medium voltage direct-connected isolated AC-DC converter for promoting DC-type charging of Electric Vehicles (EV) using modular multilevel topologies.

Problem definition:

The Electric Vehicle (EV) charging market is very dynamic. In the future, more often DC-type chargers placed “off-board” with higher power capability will be employed than the currently intrinsic “on-board” AC-type chargers supplied by the car manufacturers. Connections to medium-voltage (MV) level AC grid becomes economically sensible for EV chargers with power capabilities of several 100 kW than today’s most used 380 V .. 480 V AC grid. Due to safety reasons the EV battery charger will be galvanically isolated from this grid and the most compact way is achieved by using high frequency transformers. This circuit will also demand for high power efficiency, low cost and to be able to deliver power to a wide range of battery voltages, i.e. 300 .. 1kV. Both Grid-to-Vehicle and Vehicle-to-Grid power flows will be facilitated by the charger.

Methodology:

To study, design and simulate the EV charger concept using computational tools such as MATLAB.


Literature review and proposal of suited modular power electronics for DC-type EV chargers;

Benchmark the proposed circuits;

Design and simulate an advantageous DC-type EV charger concept directly connected to the MV AC grid.

Contact details:

Supervisor:


Aditya Shekhar, [email protected]


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MICRO-INVERTER USING MODULAR MULTILEVEL CONVERTER IN SOLAR APPLICATION


Scope:

To investigate the benefits of modular multilevel converter employing low voltage SMD Si-Mosfets.

Problem definition:

Up to 5 kW PV installations micro-inverters are common alternatives for the typical string solar inverters. The main drawback of the technology is the slight higher initial cost, however a more efficient energy generation can be achieved because each one of the PV modules are operated optimally at the maximum power point. The modular multilevel converter can be used employing low voltage rated Si Mosfets which displays excellent loss performance. Power efficiency above 97% is possible yielding to much lower total cost of ownership than string inverters. Additionally, the system can be designed with redundancy for improved reliability (no single point of failure). Conductive electromagnetic interference which is a typical problem in solar applications can be dealt within the modular cell.

Methodology:

To study, simulate, design, construct and test a power electronics inverter using computational tools and TU Delft’s laboratory facilities.


Literature review of transformer-less PV inverters: String and Micro-inverter technologies

Propose innovative solutions to conductive EMI

Benchmark suitable inverter solutions using multi-objective design approach

Design and construct a single-phase PV inverter solution using modular power electronics


Contact details:

Supervisor:




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FAST ELECTRIC VEHICLE CHARGER: DESIGNING ELECTROMAGNETIC COMPATIBILITY MULTI-STAGE PASSIVE FILTERS


Scope:

Develop analytical models for calculating the grid-tied converter conductive electromagnetic noise generation and optimize the multi-stage AC-filter design for compliance with international grid codes.

Problem definition:

The Electric Vehicle (EV) charging market is very dynamic and is rapidly growing. Compliance with international grid-codes and safety standards becomes necessary for market penetration due to the connection to the AC grid. The necessary AC-filter becomes the critical element or limiting factor for both cost and maximum achievable power density. Basic LCL filters cascade with higher frequency order low pass filters are the state of art solution. In this case simple, reliable and robust passive and/or active damping techniques are implemented for damping circuit oscillations. In order to increase the power density by reducing its filter size, higher-order basic filters such as the LLCL filter, the LCLCL filter, and the LCCLL filter have been proposed. Additionally, incorporation of passive and tuneable notches filters or high frequency linear shunt active filters have been proposed. All of those can improve power density but one may have to compromise on efficiency and accept higher cost. Additionally, problems with oscillations can become more severe and more complicated to be actively attenuated.

Methodology:

To study, derive analytical models, propose design guidelines for passive filters and simulate AC filter structures for grid- tied power converter of an EV charger. All to be implemented in MATLAB.


Literature review of multi-order AC filters for fast EV chargers;

To derive analytical models in the frequency domain in MATLAB;

To verify models with circuit simulation and propose simple design guidelines.

Contact details:

Supervisor:



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Compliance:

IEEE519 + CISPR class B

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FAST ELECTRIC VEHICLE CHARGER: PARALLEL MODULAR GRID-TIED CONVERTER


Scope:

Study, design and simulate parallel PWM interleaved grid-tied converters for fast electric vehicle charging infrastructure.

Problem definition:

The use of interphase transformers (IPTs) in order to implement parallel modular multilevel rectifiers presents several advantages over conventional single unit rectifier systems, namely better loss distribution among semiconductors (or current evenly shared between modular circuits allowing reduction of conduction and switching losses) and reduction of high frequency harmonics proportional to the number of employed parallel circuits in both input voltages and output currents (or reduction of generated common- and differential-mode voltages and lower RMS current across ac and dc-link capacitors). Additionally, when compared to conventional modular converters using uncoupled inductors and interleaving PWM techniques, lower circulating current between the parallel circuits is typically achieved for the same total ac filter magnetic volume. Therefore, low weight/high power density electronics can be achieved by implementing multistate switching cells-based multilevel rectifiers (MLMSRs) comprising the concepts of IPTs.

Methodology:

To study, model, design and simulate high power MLMSRs. All to be implemented in MATLAB.


Literature review of modular high power fast EV chargers;

To derive analytical models to evaluate power rectifiers in MATLAB;

To verify models with circuit simulation and propose simple design guidelines.

Contact details:

Supervisor:



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PLANNING THE FUTURE DC-GRIDS: FAST ELECTRIC VEHICLE CHARGER


Scope:

Study, design and implementation of isolated DC-DC converter for promoting DC-type charging of Electric Vehicles (EV) to be used in future DC grids.

Problem definition:

The Electric Vehicle (EV) charging market is very dynamic. In the future, more often DC-type chargers placed “off-board” with higher power capability will be employed than the currently intrinsic “on-board” AC-type chargers supplied by the car manufacturers. Additionally, DC-distribution grids may be available bringing a cost advantages for all DC-loads, such as the EV batteries. Due to safety reasons the EV battery charger will be galvanically isolated from this grid. This circuit will also demand for high power efficiency, low cost and to be able to deliver power to a wide range of battery voltages, i.e. 300 .. 1kV. Both Grid-to-Vehicle and Vehicle-to-Grid power flows will be facilitated by the charger.

Methodology:

To study, simulate, design and test an isolated bidirectional DC-DC converter for charging EVs using computational tools and TU Delft’s laboratory facilities.


Literature review and proposal of suited power electronics circuits for DC-type EV chargers;

Benchmark the proposed circuits;

Simulate, design and construct an advantageous DC-type EV charger concept.

Contact details:

Supervisor:





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FUTURE RELIABLE AND EFFICIENT POINT-TO-POINT DC DISTRIBUTION GRIDS


Scope:

To study, analyse, design and construct a Modularized DC-DC based Multilevel Converter.

Problem definition:

The development of DC grids has the economic benefit of better utilization of the installed power converter and distribution/transmission components. Connection of DC-grids with different voltage levels can be implemented by wide voltage gain power electronic circuits based on the modular multi-level converters and/or by implementing high-frequency galvanic isolation transformers. This can achieve both power and voltage scalability by usage of Power Electronic Building Blocks (PEBBs).

Methodology:

To study, simulate, benchmark and design down-scaled modular DC-DC converter for DC-grids using computational tools and TU Delft laboratory facilities.


Literature review of DC-DC modular multilevel converter

Benchmark suitable power converter solutions

Design, construct and test a down-scaled in power and voltage prototype

Contact details:

Supervisor:




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DEVELOPPING ADVANCED ELECTRIC VEHICLE TRACTION SYSTEM USING PARALLEL CONNECTION OF SI AND SIC BASED SEMICONDUCTORS


Scope:

To optimize the utilization of parallel Si IGBTs and SiC MOSFETs in Electric Vehicle traction systems.

Problem definition:

Power electronic converters are the future of transportation. Many countries have announced banning future sale of passenger vehicles powered by fossil fuels within the next 20-30 years. Presently all major automotive companies are developing their own hybrid or full electric vehicle (HEV/EV) technologies. The power inverter used in the electric traction system must be able to cope with the load profile of the vehicle, which critically requires a high power intake when the EV is accelerating, e.g. during few tens of seconds. On the other hand, the longer operating times occurs during cruise speeds which constitutes a partial load operation. The utilization of parallel Si IGBT and SiC Mosfet constitutes a good compromise between power efficiency performance and cost. Moreover, the high current capability of the Si IGBT and low switching losses of the SiC MOSFETs ensures a better utilization of the cooling system. The sizing of the semiconductor chip areas is an optimization problem.

Methodology:

To study, simulate, design, construct and test an Electric Vehicle traction system.


Literature review of EV Traction System;

Optimize the usage of SiC Mosfet and Si IGBT chip areas according to the power;

Benchmark, design and construct a downscaled EV traction system


Contact details:

Supervisor:


Dr. Jianning Dong, [email protected]


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DEVELOPPING INTELLIGENT GATE DRIVERS WITH ULTRA-FAST SHORT-CIRCUIT DETECTION FOR HIGH PERFORMANCE SEMICONDUCTOR TECHNOLOGY


Scope:

To design and construct a high-side gate driver for Silicon Carbide (SiC) MOSFETS with high voltage isolation and common-mode noise rejection featuring ultra-fast short-circuit detection.

Problem definition:

Silicon Carbide (SiC) based Metal-Oxide Semiconductor-Field-Effect Transistors (MOSFETS) are widely praised as the future of high-end power converters due to their improved performance over conventional Silicon (Si)- based devices. To unlock the full potential of the SiC technology high-speed gate driver circuitry are necessary to reduce the time of the commutation dynamics of the MOSFET and thus reduce the energy dissipated during each switching action. This operational benefit results in an increment of the Electromagnetic Interference (EMI) caused by the consequent high dV/dt and di/dt of the switching mechanism. More importantly, EMI issues can degrade the breakdown capability of the insulation materials and cause instability and unexpected behaviour of the control circuitry. Finally, ultra-fast short-circuit detection and the respective corrective action must be implemented in order to protect both the power converter and their connected sensitive loads. In today’s commercial available SiC MOSFETS a short-circuit action can lead to over-current in the excess of 10x the rated value within 10µs, which implied that the detection circuitry + the reaction time to a short-circuit event must be ideally within < 1 µs.

Methodology:

To study, simulate, design, construct and test an intelligent gate driver using computational tools.


Literature review of high-voltage gate drivers and fast short-circuit detection

Design and construct an intelligent gate driver


Contact details:

Supervisor:



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High-Voltage High-Side Gate Driver Concept

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Wireless Power Transfer

Gate Driver Based on the LLC Resonant DC/DC Converter

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FLEXIBLE AND FUTURE TROLLEY BUS GRIDS


Scope: Today’s trolley grids have a rather one-dimensional objective: supply power for traction. But they can have much more functionality with integrated storage and distributed generation.

Problem definition: A lot of energy is wasted during braking operation of the trolley bus fleet which needs to be recovered using properly sized, positioned and operated storage integrated shared trolley grid.

Methodology: Model the energy consumption of an fleet of electric buses in presence of different charging infrastructure and determine proper size of the shared storage integrated trolley grid. Show that the designed system can simultaneous improve the efficiency and voltage profile of the supply.


Determine the power/energy consumption pattern of ‘n’ number of trolley buses sharing the

trolley grid sections.

Estimate the proper shared grid integrated storage to recover braking energy.

Simulate the voltage profile of the trolley grid with moving buses to show that storage

integration can also improve the power quality. Suggest the best location of the storage

elements on the trolley grid.

Motivated student can also look into PV-integration (remember that trolley grid has uni-

directional power flow, so if solar panels generate excess energy, this cannot be sinked to the

main grid).

Contact details:

PhD student: <A. Shekhar, [email protected] >

Supervisors: <Gautham Ram Chandra Mouli; Pavol Bauer>


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DRIVE INTEGRATED CHARGING FOR ELECTRIC VEHICLES


Scope: Currently the role of dedicated on-board EV charger and motor-drive converter are decoupled. A combined converter designed to fulfil both requirements can provide some advantages like lighter design, fast-charging and vehicle to grid functionality.

Problem definition: Incorporating the twin functionality of grid connected charging the on-board battery and driving the EV motor within a single converter drive.

Methodology: Design and simulate the model of a bi-directional ac-dc converter system to show that it can charge the on-board battery from the grid as well as act as the motor drive for the EV.


Assess the requirements of motor-drive and grid-connected charging of on-board EV battery

charging and determine whether these can be met by a single converter.

Model the ac-dc converter to show that it can comply with both the requirements .

Determine if the proposed solution is viable as compared to conventional solution with

dedicated on-board charging separate from motor drive.

Motivated student can also try and develop a converter prototype for the same.

Contact details:




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CHARGING INFRASTRUCTURE AND ON-BOARD STORAGE SIZING FOR ELECTRIC BUSES


Overnight charging

Trolley bus

Opportunity charging

Scope: E-mobility research aims to achieve transportation electrification by developing charging infrastructure for electric vehicles (EV) while maximizing the catenary-free driving range and efficiency at minimal costs.

Problem definition: On-board storage can improve the autonomous driving range of EV but reduce the transport efficiency. On-road charging can add an interesting dimension to the economics of the EV storage sizing problem. This project studies the trade-off between on-board storage and on-road charging for optimally extending the driving range of the EV at minimum cost.

Methodology: Model the energy consumption of an fleet of electric buses in presence of different charging infrastructure and determine proper size of the on-board battery by quantifying operational and installation cost in trade-off with the objective of autonomous driving range extension.


Compare the technical implications of different methods such as overnight charging,

opportunity charging, in-motion charging and trolley systems.

Model the driving range of an electric bus based on the specification, velocity profile, on-

board storage and charging infrastructure.

Minimize the storage requirement using different charging solutions while maximizing the

driving range of the EV.

Determine the economic viability of the chosen charging scheme for a case-study with a fleet

of electric buses in a city route (for example: Arnhem)

Contact details:




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D C E & S




DEVELOP MODULAR MULTILEVEL CONVERTER BASED ANCILLARY SERVICES FOR THE DISTRIBUTION GRID


Scope: This project explores the use of modular multilevel converter (MMC) for harmonic elimination1. The concept is to be applied to mitigate the power quality issues and highlight the trade-offs and challenges therein.

Problem definition: Develop schemes to detect and mitigate medium voltage grid current and voltage harmonics by operating a MMC as STATCOM. Different harmonic detection and current injection strategies need to be implemented and compared in terms of power quality conditioning.

Methodology: Simulations as well as experimental work is desired. The student is expected to learn about the operation of the MMC and develop control techniques to comply with different grid requirements at medium voltage level.


Identifying the methodology to detect harmonics at the point of common coupling (PCC).

Determining how fast the convertor needs to react while keeping its internal balancing.

Showing the operation of MMC as STATCOM for harmonic elimination experimentally.

Compare different methods of achieving harmonic elimination using MMC and 2 level VSC.

Contact details:


Supervisors: <Thiago Batista Soeiro; Pavol Bauer>

1 E. Kontos, G. Tsolaridis, R. Teodorescu and P. Bauer, "High Order Voltage and Current Harmonic Mitigation Using the Modular Multilevel

Converter STATCOM," in IEEE ACCESS, vol. 5, pp. 16684-16692, 2017.


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D C E & S




LEARNING WITH THE LAB-SCALE MODULAR MULTILEVEL CONVERTER

Type of project: Extra Project

Scope: The available lab scaled modular multilevel converter (MMC) can be used to gain knowledge on real time digital simulator (OPAL-RT) and other hardware operation.

Problem definition: Experiment with the available lab-scaled MMC to understand the operation principles. Its operation will then be tested by applying different control strategies.

Methodology: Laboratory work is expected.


Learn and test different PWM techniques and generate the required carrier wave to switch

the submodules.

Apply simple control schemes, for instance capacitor balancing to test the proper operation

of the available lab-scale MMC.

Collaboration with Industry: No.

Contact details:

PhD student: <A. Shekhar, [email protected]>

Supervisor: <Thiago Batista Soeiro; Pavol Bauer>


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D C E & S




DEVELOP A NOVEL DYNAMIC VOLTAGE DC LINK OPERATION


Scope: It is possible to increase the dc link voltage without increasing the voltage ‘seen’ by the converter switches in a MMC. This improves the efficiency of the system without investing in higher rated components.

Problem definition: Develop a control strategy for operating the dc link with dynamic voltage while keeping the MMC energy within the rated limits to obtain efficiency and capacity improvement.

Methodology: The student is expected to prove this idea through simulations and implement it experimentally in the available lab scale converter. The fundamental equations2 will be given to the student for the implementation of this concept, for which familiarity with MATLAB is important.


Show through simulations that the energy in the MMC can be controlled such that the dc link

voltage can be dynamically raised without increasing the voltage seen by the submodule

capacitors and switches.

Define boundaries within which this concept can be applied.

Determine the achievable efficiency/capacity gains of operating the MMC with dynamic dc

link voltage.

Implement the concept in the available lab-scale MMC prototype to justify the claimed gains.

Contact details:

PhD student: <A. Shekhar, [email protected]>

Supervisor: <Thiago Batista Soeiro; Pavol Bauer>

2 Refer conference paper: “Modular Multilevel Converter Performance with Dynamic MVDC

Distribution Link Voltage Rating” in 18TH International Conference on Power Electronics and Motion Control At: Budapest, Bulgaria


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D C E & S




OUTPUT IMPEDANCE SHAPING AND EMISSION COORDINATION OF OFFSHORE WIND POWER CONVERTER WITH A PARALLEL BACK-TO-BACK STRUCTURE


Problem definition:

The concern for power quality in Offshore Wind Power Plants (OWPPs) has risen in recent years. One of the reasons is the increasing interactions between power electronic converters (PECs) and the grid, which lead to resonances and oscillations at different frequencies that might cause problems in the system operation or even the loss of system stability (yes, this happened in real OWPPs!).

The possible grid-converter interactions are determined by the different impedances in the system1: the passive ones (e.g. transformers, cables), the varying impedance of the grid and the output impedance of the wind PECs (which depends on the topology, on the filters and on the control).

Lately, the power rating of WTGs has notably grown. One of the solutions in order to deal with such power levels is to install several back-to-back (B2B) power electronic stages in parallel2. The fact that these B2B structures are so close to each other, with barely no intermediate cables in between them, offers new possibilities for coordinating their harmonic emission and their output impedance design.

The objective of this Master Thesis would be to explore such possibilities.

Methodology:

Develop theoretical small-signal model of the output impedance of the parallel B2B structure

Validate the model with Simulink simulations

Construction of the parallel set up in the lab and validation via measurements with a

frequency analyser (a student that is willing to work in the lab is needed!)

Contact details:

PhD student: Lucia Beloqui Larumbe ([email protected])

Supervisor: Dr. Zian Qin ([email protected]),

Prof. Dr. Eng. Pavol Bauer ([email protected])

1 J. Sun, "Impedance-Based Stability Criterion for Grid-Connected Inverters," in IEEE Transactions on Power Electronics, vol. 26, no. 11, pp. 3075-3078, Nov. 2011. 2J. Chivite-Zabalza, et al., "Comparison of power conversion topologies for a multi-megawatt off-shore wind turbine, based on commercial Power Electronic Building Blocks," IECON 2013




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D C E & S




DETERMINATION OF REALISTIC LIMITATIONS FOR THE VARIATION OF THE OUTPUT IMPEDANCE IN AN OFFSHORE WIND POWER CONVERTER


Problem definition:


The possible grid-converter interactions are determined by the different impedances in the system: the passive ones (e.g. transformers, cables), the varying impedance of the grid and the output impedance of the wind PECs (which depends on the topology, on the filters and on the control).

If the grid impedance varies with its operation point, it could be interesting to adapt the wind PEC output impedance in order to compensate such changes and try to dampen possible resonant points. The problem is that it is not yet so clear how many degrees of freedom there are for doing so, as any changes done in its control loops or filter design might hamper other performance requirements (e.g. LVRT capabilities).

The objective of this Master Thesis would be to explore such degrees of freedom and to establish realistic impedance variation requirements. This Thesis will provide the MSc student a holistic vision of the challenges and trade-offs when designing the control loops of a wind PEC. This Thesis falls within the immediate research of the PhD student so the possibility of publishing results is very high.

Methodology:

Find all the connection requirements offshore wind PECs need to meet and their trade-offs

Determine which are realistic degrees of freedom to vary the output impedance of the PEC

Validation through Simulink and (possibly) through measurements in a laboratory set up

Contact details:




AC

ACDC

DC

FILTER

G

POC




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D C E & S




ACTIVE POWER FILTERING IN OFFSHORE WIND FARMS

Type of project: Extra Project (15 ECTS)

Problem definition:


One of the solutions that is typically applied for steady-state harmonic problems is the so-called Active Power Filtering (APF). This technique consists in measuring the harmonic currents at a certain point in the network and using a PEC to generate exactly the same harmonic but in the opposite phase in order to achieve a cancellation effect.

This technique has been widely used in several applications, however, it is not clear its actual application in (onshore and) offshore wind farms. In these systems there are several possible configurations: at the wind PEC level, at the offshore or onshore substation, taking advantage of already existing STATCOM, at the Modular Multilevel Converter in HVDC-connected OWPPs, etc.

The objective of this extra project is to review all these possibilities. It is important that the student is critical about the actual feasibility in all the possible configurations (e.g. due to current constraints) and that the student is able to identify the pro’s and con’s of each configuration.

Methodology:

Review literature about Active Power Filtering

Review specific literature of APF being applied already in onshore and offshore wind farms

Make a report of the possible configurations and the potential of this technique in OWPPs

Contact details:







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D C E & S




IMPEDANCE MODELLING OF NEUTRAL POINT CLAMPED INVERTER

Type of project: Extra Project (15 ECTS)

Problem definition:



Lately, the power rating of WTGs has notably grown. One of the solutions for dealing with such power levels is to rise the grid-side AC voltage through the use of 3-level Neutral Point Clamped (NPC) converters. It is expected that the output impedance of the NPCs is similar to such of regular 2-level inverters. The modelling of NPC, then, should not be a burdensome task; however, there are still differences in their modulation techniques and other issues that should be carefully analysed.

The objective of this extra project is to investigate these differences and to find their impact on the output impedance. This extra project will provide the Master student deeper insight into these two types of converter topologies and their control loops.

Methodology:

Analyse the differences between 2-level inverters and 3-level NPC inverters

Determine which issues could affect the output impedance of the converter

Validation of this impedance through simulations in Simulink

Contact details:




1 J. Sun, "Impedance-Based Stability Criterion for Grid-Connected Inverters," in IEEE Transactions on Power Electronics, vol. 26, no. 11, pp. 3075-3078, Nov. 2011.




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D C E & S




IMPEDANCE MODELLING OF MODULAR MULTILEVEL CONVERTER FOR OFFSHORE WIND FARM APPLICATIONS


Problem definition:

The concern for power quality in Offshore Wind Power Plants (OWPPs) has risen in recent years. One of the reasons is the increasing interactions between power electronic converters (PECs) and the grid, which lead to resonances and oscillations at different frequencies that might cause problems in the system operation or even the loss of system stability.


In particular, the problem of loss of stability in real OWPPs has been usually reported to happen in those with HVDC connection1, in which the wind turbine PEC fell into interactions with the HVDC converter. As the typical converter in such application is the Modular Multilevel Converter (MMC) the objective of this Master Thesis would be to provide a validated model of this converter.

Methodology:

Explore the specificities of MMC design for such application

Model the converter in Simulink and calculate there its impedance in the frequency domain

Validation of this impedance through measurements in a laboratory set up with a frequency

analyser (a student that is willing to work in the lab is needed!)

Contact details:




1 C. Buchhagen, C. Rauscher, A. Menze and J. Jung, "BorWin1 - First Experiences with harmonic interactions in converter dominated grids," International ETG Congress 2015; Die Energiewende - Blueprints for the new energy age, Bonn, Germany, 2015, pp. 1-7.




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D C E & S




1A1

2A1

1An

2An

1C1

2C1

1Cn

2Cn

1B1

2B1

1Bn

2Bn

A B C

1A

1

2A

1

1A

n

2A

n A

B

C

Future: Modular Energy Storage

2xx

1xx

State-of-Art

A

B

C

Lc

CF

Lg

AC

EM

C F

ilte

r +

Pro

tect

ion

Low Freq. Tranformer

Medium Freq.

Tranformer

LLC Resonant Converter Cell

DC

Fil

ter

+ P

rote

ctio

n

PLANNING ENERGY STORAGE IN MV DISTRIBUTION GRIDS: IMPLEMENTATION OF MODULAR CASCADED H-BRIDGE CONVERTERS AND ANCILLARY SERVICE PROVSION


Scope:

Study and implementation of modular power electronics and intelligent control algorithms to integrate energy storage into medium voltage (MV) power grids and provision of ancillary grid support.

Problem definition:

The penetration of intermittent renewable energy sources like wind and solar is dramatically increasing. At the same time introduction of new types of loads like electric vehicles is resulting in an increased and unpredicted demand of electricity. This has brought about severe impacts on electrical distribution networks, which currently offer very little operational flexibility. In the future, it is expected a substantial increase in the number of Battery Energy Storage Systems (BESSs) connected to the low voltage or medium voltage distribution networks. For the medium voltage grid modular power electronics based on the cascaded H-bridge converter (CHB) constitutes a good choice. Therein, the required isolation can be shifted to the modular cells where a high frequency AC-link is created. This circuit is not only well suited for congestion management but it can also work as a STATCOM providing harmonic compensation and other ancillary grid services.

Methodology:

To study and design a power converter implementing the CHB converter and LLC resonant circuit. Evaluate the benefit of using the energy storage system for several grid ancillary service provision.


Literature review of BESSs in medium voltage grids and grid ancillary service provision market;

Benchmark the proposed BESSs against state of art solutions;

Implement the developed study in a hardware demonstrator.

Contact details:

PhD student: Marco Stecca <[email protected]>

Supervisors: Dr. Ir. Thiago Batista Soeiro <[email protected]> Prof. Dr. Ir. Pavol Bauer <[email protected]>

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D C E & S




IMPROVING SYSTEM LEVEL RELIABILITY OF STORAGE SYSTEM CONVERTERS

Type of project: Extra Project / SIP2

Scope:

Study the optimal configuration of a grid connected energy storage system in order to maximize the device reliability and availability.

Problem definition:

Battery energy storage system are becoming an effective option for grid operators to face the technical issues deriving from an increase of non-predictable renewable generation. Storage systems are interfaced with the grid through power electronic converters. Due to the high costs of these systems it is important not only to ensure high efficiency, but also to provide reliable units.

The provision of ancillary services generally requires the units to be 100% of the time available to avoid incurring in fees. It is then fundamental to design the single components, but also the system redundancy in order to reach this target.

Methodology:

The project consist on the review of the main topologies of storage system converters and on the study of the system level reliability. Moreover the student will analyse which are the grid requirement in terms of system availability for providing ancillary services. If the student is particularly interested in specific ancillary services the focus can be on these.


Review on the most common topologies for grid connected storage system converters.

Analyse the availability requirement for ancillary service provision.

Design an optimal configuration that can improve the availability of the device.

Benchmark the converter designed vs the most common commercial solutions.

Contact details:


Supervisors: Dr. Ir. Thiago Batista Soeiro <[email protected]> Dr. Ir. Laura Ramirez Elizondo <[email protected]> Prof. Dr. Ir. Pavol Bauer <[email protected]>

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D C E & S




1A1

2A1

1An

2An

1C1

2C1

1Cn

2Cn

1B1

2B1

1Bn

2Bn

A B C

1A

1

2A

1

1A

n

2A

n A

B

C

Future: Modular Energy Storage

2xx

1xx

State-of-Art

A

B

C

Lc

CF

Lg

AC

EM

C F

ilte

r +

Pro

tect

ion

Low Freq. Tranformer

Medium Freq.

Tranformer

LLC Resonant Converter Cell

DC

Fil

ter

+ P

rote

ctio

n

OPTIMIZING A TWO LEVEL CONVERTER FOR GRID CONNECTED ENERGY STORAGE


Scope:

Study and optimize a two level converter for grid connected energy storage systems.

Problem definition:

The penetration of intermittent renewable energy sources like wind and solar is dramatically increasing. At the same time introduction of new types of loads like electric vehicles is resulting in an increased and unpredicted demand of electricity. This has brought about severe impacts on electrical distribution networks, which currently offer very little operational flexibility. In the future, it is expected a substantial increase in the number of Battery Energy Storage Systems (BESSs) connected to the low voltage or medium voltage distribution networks. The interface between storage systems and the grid available in the market are several, however the most common solution for the connection to MV grids, where it is required to step up the voltage, is through a two level converter.

Methodology:

To study and optimally design a power converter implementing the two level converter. Evaluate the benefit of using the energy storage system for several grid ancillary service provision. The optimization of the converter will be linked on the ancillary services which the storage will provide.


Literature review of BESSs, ancillary service market and two level converters;

Optimize the selected topology for ancillary service provision;

Implement the developed study in a hardware demonstrator.

Contact details:


Supervisors: Dr. Ir. Thiago Batista Soeiro <[email protected]> Prof. Dr. Ir. Pavol Bauer <[email protected]>

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STUDYING COMPONENT LEVEL RELIABILITY OF STORAGE SYSTEM CONVERTERS


Scope:

Study the reliability of the main components of a grid connected energy storage system converter.

Problem definition:

Battery energy storage system are becoming an effective option for grid operators to face the technical issues deriving from an increase of non-predictable renewable generation. Storage systems are interfaced with the grid through power electronic converters. Due to the high costs of these systems it is important not only to ensure high efficiency, but also to provide reliable units so that the outages will be very rare.

The first step for realizing reliable products is to understand how the single components are subject to degradation and predict their lifetime. Once the weak points are found it is possible to highlight system level solution to mitigate the failures.

Methodology:

The project consist on the review of the main topologies of storage system converters and on the study of their components reliability. Moreover the student will analyse which are the critical components that limit the lifetime of the converters and evaluate where it could be possible to improve the design.


Review the most common topologies for grid connected storage system converters.

Analyse the reliability of the main components of the converters.

Highlight the weak points of the converters in terms of reliability.

Contact details:


Supervisors: Dr. Ir. Thiago Batista Soeiro <[email protected]> Dr. Ir. Laura Ramirez Elizondo <[email protected]> Prof. Dr. Ir. Pavol Bauer [email protected]


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D C E & S




DESIGN OF A WIDE BANDGAP SEMICONDUCTOR BASED BATTERY CHARGER


Fig 1: (a) Wide Bandgap Semiconductor characteristics, (b) interleaved boost converter

Scope: Design of a battery charger based on wide bandgap semiconductors

Problem definition: The introduction of wide bandgap semiconductors such as SiC and GaN, allows power electronic systems to be designed more efficient, smaller and lighter. Since they can be operated at much higher voltages, frequencies and temperatures. This allows new design possibilities. This thesis is about the design of a battery charger based on SiC or GaN technology.

Methodology: The methodology to arrive at a good design and control method are the following:

Literature review of wide bandgap semiconductors and battery charger topologies.

Develop simulation models of the prototype and design the control loop.

Validate the operation by building an existing laboratory prototype.

Research Objectives: The pertinent research objectives are highlighted below:

Review of possible battery charger topologies

Development of laboratory prototype

Contact details:

PhD student: Wiljan Vermeer, [email protected]

Supervisor: Gautham Ram Chandra Mouli, [email protected]



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D C E & S




PAINLESS POWER SUPPLY FOR A PACEMAKER


skin

coil

Requirement of PPG:

Ø small

Ø light

Ø efficient

Inside body Outside body

Monitor & control

Power

converter

Battery

Control & alert

coil

Pacemaker

pulse generator

(PPG)

Electrodes

Scope: Evaluating limits and design challenges of contactless powering body implants like pacemaker with minimum pain.

Problem definition: Lead-related complications have remained a clinical challenge for Pacemakers. While market-released leadless devices have addressed some of the issues, their pacer-integrated batteries cause new health risks and functional limitations, e.g. surgeries are needed for battery replacement. Inductive power transfer enables contactless powering of these bio-electronic devices; however, challenges like a comfortable Specific Absorption Rate (SAR), size, efficiency, etc., are not addressed yet.

Methodology:

Literature review on SAR quantification and coil designs for body implants

Study existing methods and analyse their advantages, disadvantages and complexity

Research Questions:

What frequency is more suitable, by considering the SAR, coil size, etc.?

What would be the good size ratio between the battery and the contactless power transfer?

What would be the most suitable converter especially the internal part, by considering reliability, heat dissipation, size, etc.?

Contact details:

PhD student: <S.Bandyopadhyay, [email protected]>

Supervisor: <Zian Qin, [email protected]>

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D C E & S




LIGHTNING IMPULSE PROPAGATION WITIN A NEW TYPE OF WINDING


Scope:

Study on the lightning voltage distribution in the next generation of transformers and reactors.

Problem definition:

Part of the factory acceptance test for extra high voltage transformers and reactors is Lightning Impulse (LI) testing. During such test, the voltage distribution along the winding depends on electrical parameters of the winding (capacitance, inductance and resistance). The later, in turn, are related to the physical dimensions of the winding and the ratings of the transformer. It is widely known that the lightning impulse voltage does not distribute linearly along the winding. The challenge lies in understanding the details of voltage distribution across the winding during the lightning impulse. As an example, a 230 kV reactor can contain up to 2000 meters of copper wire per winding. Such length in combination with very short rise-time of a lightning impulse might additionally introduce the travelling wave effect and oscillations within the winding.

Methodology:

Literature study on the transient behaviour within transformer windings.

Inventory of parameters governing the voltage distribution along the winding during LI test.

Winding model development and simulation of the LI voltage distribution.

Measurement of LI voltage distribution on a real winding and model verification.


Develop a tool/model which will help to determine the LI voltage distribution along the winding of when considering dimensions and number of turns differ.

Develop a test setup which will help to develop design criteria for this new winding type

Contact details:

Company contact: Luc Dorpmanns, [email protected]

University supervisor: Armando Rodrigo Mor, [email protected]

http://www.sgb-smit.com/

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D C E & S




DEVELOPMENT OF DESIGN RULES FOR LARGE POWER TRANSFOREMRS FILLED WITH ENVIRONMENTLY FRIENDLY LIQUIDS


Scope:

Study on the lightning impulse withstand properties of transformer insulation impregnated with environmentally friendly liquids.

Problem definition:

Due to the efficiency and durability, a modern power transformer is one of the most sustainable elements of the power system. The market demands as well as legal regulation force the increase in using environmentally friendly materials in the high voltage components. Royal SMIT Transformers considers replacing the mineral oil by the environmentally friendly liquids (esters) in the produced power transformers, reducing the environmental footprint of the produced transformers even more. On the other hand, it must be ensured that the use of new insulating liquid will not jeopardize the reliable operation of the transformer for the period of e.g. 40 years. The proposed research will be the first step to verify the latter.

Methodology:

The investigation will consist of both theoretical and practical parts:

Literature study on the breakdown phenomena and withstand capabilities of esters.

Lightning impulse testing of inter-turn insulation impregnated with different types of esters.

Statistical analysis and comparison of the obtained values with those obtained for mineral

oils (reference to the previous research, e.g. MSc thesis of A. Ionut – TU Delft, 2011


Define the withstand capabilities of cellulosic insulation impregnated with esters.

Compare the breakdown characteristics of mineral oil to the properties of esters when

considering the two liquid types as impregnating medium for high voltage transformers.

Contact details:




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D C E & S




POLARITY REVERSAL EFFECTS OF LIGHTNING IMPULSE TESTS


Scope:

Study on the effect of polarity reversal of lightning impulse test on modern transformers.

Problem definition:

Part of the factory acceptance test for extra high voltage transformers and reactors is Lightning Impulse (LI) testing. These tests are usually done with negative polarity to prevent air side flashovers. More and more request are seen for additional positive polarity lightning impulse tests. During lightning impulse tests ionisations might occur in the pressboard/insulating liquid insulation system. The electrons / space charge generated could have an influence on the withstand behaviour during test with opposite polarity. Purpose of the research is to find a practical procedure how to perform these tests with different polarities in a consecutive order.

Methodology:

Literature study on the behaviour during positive and negative LI of insulation

Inventory of effects occurring inside the insulation during LI tests

Development of a practical procedure to perform both polarity tests after each other

Measurement of LI withstand during this new developed procedure


Develop a model which will help to determine the LI behaviour inside an insulating system with opposite polarity LI tests

Develop a test setup which will help to develop the new procedure

Contact details:




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D C E & S




SUITABILITY OF SILICONE LIQUIDS INSULANTS FOR MV DC JOINT


Scope:

The research focuses on the applicability of newly developed silicone liquid insulation in the medium voltage DC joint.

Problem definition:

Lovink produces AC joints that are filled with silicone liquid. In the previous research it has been shown that the type of liquid used currently is well suitable to be used in a DC joint. However, the physical and electrical properties of the liquid change due to the ingress of moisture, the liquid solidifies. Further on, according to simulations, the interface between solid and liquid is critical for DC operation. However, the latter has not been proven by tests.

Currently, a new silicone liquid is being developed and its advantage is that the physical properties are not changed by the moisture penetrating the material. The main goal is to verify is such material is still suitable for the joint when considering the electrical stresses

Methodology:

The first step is to do a literature study on the insulating materials used in DC components. Further on, the DC field distribution in complex structures together with the governed laws is to be studied. Finally, the researcher needs to perform the DC breakdown tests on samples of silicone material.


Investigate the criticality of the interface between the solid and liquid silicone material (current type).

Propose and perform the tests to verify the suitability of the new silicone liquid for the DC application in MV joints.

Contact details:

Company contact: Lukasz Chmura, [email protected]

Company contact: Dennis Bergsma, [email protected]


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D C E & S


Electromechanics and Electric Mobility DC systems, Energy conversion & Storage


ACTIVE ACOUSTIC NOISE REDUCTION OF PERMANENT MAGNET SYNCHRONOUS

MACHINE


Scope: Reduce electromagnetic excited noise emitted from permanent magnet synchronous machine

using active control method.

Problem definition: Comfortable user experience requires electric machine to be quiet in a wide

speed range for different applications, e.g. electric vehicle and home appliances. Currently

unpleasant vibration and noise from the electric motor is reduced by auxiliary approaches such as

attenuation or absorbance. If the vibration and noise problem could be solved by active control of

electrical machines, it will save the overall cost and reduce the system size.

Methodology: Existing modelling technique will be improved and applied to investigate methods for

electromagnetic excited acoustic noise reduction. Different modulation techniques, and dv/dt filters

will be investigated. Based on the selected methods, simulations will be carried out to compare the

performance. Selected control methods will be implemented on an existing motor drive.


Acoustic noise modelling of electric machines.

Investigate and compare different approaches for noise reduction through control.

Implement active noise reduction control algorithm in an existing setup.


Contact details:

Daily Supervisor: Dr. Jianning Dong ([email protected])

Dr. Thiago Batista Soeiro ([email protected])

Supervisor: Prof. Pavol Bauer ([email protected])




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D C E & S




COMPARATIVE STUDY OF MODULATION TECHNIQUES IN ELECTRICAL DRIVES


Picture source: A. Andersson, “Electric Machine Control for Energy Efficient Electric Drive Systems,” PhD Thesis, Chalmers University, 2018.

Scope: This project aims at implementing and comparing different pulse width modulation

techniques applied in electrical drives.

Problem definition: Pulse width modulation (PWM) is commonly used to control the power

converters in electrical drives. Various modulation techniques are available, including sinusoidal

PWM (SPWM), space vector PWM (SVPWM), third harmonic injection PWM (THPWM), random PWM

(RPWM) and different types of discontinuous PWM (DPWMs). Different PWM techniques result in

different harmonic spectrum and result in different system efficiency, noise emission and loading in

power converter components. This thesis will carry out a comparative study on different PWM

techniques and analyse their performance in the electrical drive system.

Methodology: A power converter and its controller have been built. Different modulation techniques

will be first implemented in simulation. Their influence on the drive system will be simulated. C codes

will be generated through simulation blocks and deployed to the controller. Efficiency and noise will

be measured experimentally.


Implementation of different modulation techniques

Comparison different modulation techniques in the electrical drive system


Contact details:







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D C E & S




APPLYING DV/DT FILTER IN PERMANENT MAGNET SYNCHRONOUS MACHINE

DRIVE


dv/dt filter

Scope: This project aims at design a dv/dt filter for a permanent magnet synchronous machine

(PMSM) drive and adapt the machine control algorithm to consider the effect of dv/dt filter.

Problem definition: PMSM drives are widely used in modern industry, consumer electronics and

household. In the request for higher power density, high speed semiconductors (IGBT, SiC or GaN)

are employed to drive the PMSM, which results in fast rise time voltage pulses by pulse width

modulation (PWM) techniques. Unfortunately, it creates a number of problems to the drive system,

which include over voltage, parasitic earth current, harmonics, acoustic noises, and eddy current

losses. By applying the dv/dt filter between the inverter and the PMSM can help relief the problems,

however, it affects the machine dynamics. Control method, e.g. the rotor flux observer must be

adapted to consider the effect brought by the dv/dt filter.

Methodology: Dynamic models of dv/dt filter in PMSM drive will be built. Simulation will be used to

design the dv/dt filter and evaluate its effects on control. Control algorithms considering the dv/dt

filter will be implemented in an existing setup.


Design of a dv/dt filter for a PMSM drive

Dynamic modelling of dv/dt filter and the PMSM drive with it

Control algorithm of PMSM considering the dv/dt filter


Contact details:







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D C E & S




MODELLING AND CONTROL OF A MAGNETIC BEARING


Scope: This project aims at modelling and control of the magnetic bearing in a conceptual design of

wind turbine generator setup.

Problem definition: Magnetic bearings are very appealing in many rotating machinery applications

because it enables non-contact operation, does not require lubrication and provides possibility of

active rotor dynamics control. The magnetic bearing and the permanent magnet machine form a

highly dynamic system. Unbalanced force resulted from the magnets is coupled with the levitation

force of the magnetic bearings. In order to achieve stable operation of the magnetic bearing,

accurate model should be built to consider the nonlinearity and coupling. Highly dynamic control

should be implemented to ensure the system stability.

Methodology: A sliding mode controller with neural network to compensate the uncertainties has

been designed and simulated. Hardware to implement the control has been made. The work will be

extended by building more elaborative models to consider various coupling factors and tuning the

controller to make it work in the setup.


Modelling of the magnetic bearing coupled with the permanent magnet machine

Development of the control algorithm of the magnetic bearing


Contact details:


Faisal Wani ([email protected])





43

D C E & S




OPTIMIZATION OF THE PROPULSION MOTOR FOR SOLAR RACING CAR


Scope: This project aims at optimizing the propulsion motor for the solar racing car.

Problem definition: Electric motor is the key component of the solar racing car. Its weight, efficiency,

robustness and controllability are critical in the solar racing. In order to make the most out of the

power train, the electric motor should be designed considering the racing profile, dynamics and

system architecture. A multi-objective optimization of the motor is needed to consider all the

constraints and requirements, and make the racing car competitive to other teams.

Methodology: Finite element method (FEM) will be used to model the electromagnetic performance

of the motor. Different sources of losses will be considered. The thermal performance will be

simulated through FEM or thermal circuit. Both key operating points and wide range performance

will be considered. Intelligent optimization algorithm, e.g. particle swarm or genetic algorithm, will

be used to obtain the Pareto front of the optimization.


Identification of design constraints and requirements

Electromagnetic and thermal modelling of the electrical machines

Optimization of the electric motor considering the racing profiles


Contact details:





44

D C E & S




POSITION SENSORLESS CONTROL OF PERMANENT MAGNET SYNCHRONOUS

MACHINE IN WIDE SPEED RANGE


Scope: Design a position sensorless control scheme for the high-speed permanent synchronous

machine operating in a wide speed range.

Problem definition: Modern PMSMs are usually controlled by digital controllers. It is preferable to

design the motor control loops including the current loop and speed loop directly in the discrete-

time domain to obtain high dynamics and ensure stability. On the other hand, an observer/estimator

of the rotor position and speed is often used to eliminate the rotor position sensor. In many highly

dynamic applications, the PMSM is operating in large speed range. The position sensorless control

scheme should be adaptive from start-up to high-speed operation. Besides, the controller should be

robust to tolerant parameter uncertainties and disturbances. Control algorithms will be simulated

and verified in the MATLAB/Simulink first and then deployed to the TI DSP in the experimental setup.

Methodology:

Develop the mathematics model of the PMSM

Design the controller and observer based on the developed PMSM

Do the simulation and implement the control in the experimental setup


High-performance controller design including current, speed regulation and position

observer; Simulation; Laboratory prototype testing


Contact details:





45

D C E & S




SMART BI-DIRECTIONAL WIRELESS IPT SYSTEM FOR V2G APPLICATIONS


Fig 1: (a) Wireless IPT charging for smart house, (b) smart charging with V2G and V2H capability

Scope: Analysis on V2x possibilities/smart charging, resonant converter control and lab work on

existing setup to ensure high efficiencies with bi-directional power flow.

Problem definition: The possible flexibilities and potential of wireless charging makes it a prime

candidate of replacing conventional wired charging of EVs. Additionally, they can provide emergency

back-up power and ancillary services via V2H and V2G capabilities respectively. The main research

challenge in this field is to develop a robust control system to ensure bi-directional power flow and

maintain high efficiency.

Methodology: The methodology to arrive at a good design and control method are the following:

Literature review of bi-directional control for resonant converters

Develop a dynamic model of the IPT system

Design the controller in simulation and validate the operation via existing laboratory prototype


Stability analysis of a IPT system and draw guidelines

Develop a control strategy to stably control power flow in both directions

Implement bi-directional control on an laboratory prototype

Contact details:

PhD student: S. Bandyopadhyay [email protected]

Supervisor: Zian Qin, [email protected]


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D C E & S




HARDWARE-IN-LOOP SIMULATION FOR UNTROLLED/UNCONTROLLED CHARGING

OF ELCTRIC VEHICLE ON DISTRIBUTION GRID


Source: OSCD, Elaad

Scope: This project aims at developing a hardware-in-loop (HIL) simulation system for Electric vehicle

(EV) charging in distribution grid, and simulate the impact of EV charging on the grid, with and

without the smart charging algorithm.

Problem definition: HIL is a cost-effective and time efficient method to implement large-scale grid

experiments. In this system, a power amplifier, an AC charger and a battery will be connected to the

simulator to model the real charging environment. OPAL-RT will be employed as the HIL platform.

Methodology: The student is expected to set up the OPAL-RT facility and rebuild the given grid

model in the HIL system. Then operate the EV charging simulations with/without smart charging

algorithm. The target of this project is to accomplish the HIL system, and compare the impact of

controlled/uncontrolled EV charging on the distribution grid with the established HIL system.


Set up the OPAL-RT HIL simulation system

Implement the given grid model in the HIL system

Real-time simulation and compare the controlled/controlled EV charging in distribution grid

Contact details:

PhD student: Yunhe Yu, [email protected]

Supervisor: Prof. Dr. ir. Pavol Bauer, [email protected] Dr. Gautham Ram [email protected]




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D C E & S




IMPACT OF UNCONTROLLED EV CHARGING ON REAL DISTRIBUTION GRIDS

Type of project: Extra Project/SIP2

Scope: The integration of massive EVs can affect the stability of the grid, and disrupt the balance

between the supply and the demands due to increased peak demand and unpredicted charging

behaviour. The increased absolute number of EVs increases the absolute demand on power and

energy, which can lead to an overload of system assets like transformers and lines. With the growing

quantity of EV owners, the increased load peak can be much higher than the percentage of increased

EV share. That is because the newly appeared load demand from those EVs will highly possibly be

added on top of the existing peak demand. The transformer is hence under high risk of overloading

and in the end leading to its loss of life. Besides, the high penetration level of EVs can increase the

total power losses and the voltage deviation especially at the far end of the buses.

Problem definition: This project aims to simulate and analyse the impact of uncontrolled EV charging

on six real Dutch distribution grids with four different EV penetration levels.

Methodology: The student is expected to review literature on how uncontrolled charging impacts

the distribution grids. Then operate the simulation to model the grid performance with different EV

penetrations. Finally, analyse the simulation results and make comparisons on different grids and EV

penetrations levels.

Software: PowerFactory, Pyhton


Operate the uncontrolled EV charging simulation with four different EV penetrations.

Analyse the simulation results and make comparisons on different grids and EV penetrations

Contact details:






48

D C E & S




MODULAR MULTIOBJECTIVE SMART CHAGRING ALGORITHM ON DISTRIBUTION

GRID


source: Elaad

Scope: This project aims at developing a smart charging algorithm which can control the charging

process of a large amount of Electrical Vehicles (EVs) while ensuring the grid service stability and

increase the renewable energy utilisation.

Problem definition: The main goal of this project is to create an algorithm, which take varies

parameters into consideration and manage the grid according to the grid features, the energy

demand of EV users and the PV generation. With the implementation of this algorithm, the

transformer overloading, line congestion and voltage drop can be prevented and the requirement of

every EV user can be fulfilled.

Methodology: The student will first explore which platform and software are the best combination

with grid simulation and smart charging algorithm, the options are suggested but not limited with:

PowerFactory, python, MATLAB, Simulink, GAMS etc. Then the student will focus on the smart

charging development, to satisfy the EV users while ensure grid stability is the main concern. Finally

the student is going to simulated the developed algorithm with some study cases.


Explore the most suitable platform and software combination for optimization as well as simulation

Develop smart charging algorithm which including the nonlinear behaviour of the distribution grid

Verify the developed algorithm with study cases in simulation

Contact details:






49

D C E & S




COOLING SOLUTIONS FOR HIGH POWER DC CHARGERS


Scope: For this Msc. Graduation topic we wish to investigate different cooling solutions that can be

used in high-power DC charging. For some systems, the charge cable is liquid cooled to be able to

reach up to 500A charge current. Liquid cooling may be useful for other parts of the charging system.

Problem definition: High power charging solutions are complex systems that generate a lot of heat

and require a lot of space. A compact system with advanced cooling solutions will take less space on

the streets, may give better life-time and less noise.

Methodology:

Identify (sub) systems and their cooling requirements

Propose different cooling solutions

Test these solutions on an existing product


Determine the most effective cooling solutions

What is the impact on design of key components: semiconductors, magnetics, charge cables, etc.

Increase the power density while reducing noise

Contact details:

Company contact: [email protected]

University supervisor: Prof. Pavol Bauer ([email protected])


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D C E & S




PV, EV CHARGING AND BATTERY STORAGE CONTROL STRATEGIES AND METERING


Scope: For this Msc. Graduation topic we wish to investigate

a combination of systems and functions:

- DC EV charging - Battery Storage - Photo voltaic - Metering - Local DC grids - AC Grid stability (reactive power, line in-balance,

harmonic injection, etc.)

Problem definition: Soon we will see complex products that

incorporate one or more of the functions above. In the home

you will see a combination of these systems, but different

homes may have different configurations. Some may have

emphasis on battery storage, others may have a high-power

DC charger, others generate a lot of energy from PV. Each

home needs a control strategy to use these combinations

optimally, but If these systems can be ‘virtually’ shared that

could be beneficial for the individual user, as well as for the stability of the grid.

Methodology:

Define the environments we are evaluating, for instance: o A home o A residential neighbourhood o Industrial area o A province, or even a country

Determine what functions are required in these environments

Use simulations to analyse the proposed solutions


Define a control strategy, to optimally use the different systems in the defined environments

What type of products would be needed with what key requirements (power, storage capabilities, etc)

How would these products work together to form larger virtual system? o Will this help grid stability? o How will we meter and trade these functions in the different environments?

Contact details:




51

D C E & S




A BIDIRECTIONAL ISOLATED DC/DC CONVERTER FOR EV CHARGING SYSTEMS


Scope: This MSc assignment entails the design of a bidirectional isolated DC/DC converter for electric

vehicle charging applications (marked in green). This part of the power module is relatively unique to

this application and has no equivalence in, for instance solar applications because of the needed

isolation. It therefore warrants a separate investigation.

Problem definition: Long term GaN is needed to stay competitive. The prices of the devices are

expected to be on par with current conventional technologies while SiC will always be a bit more

expensive. The emphasis is on technology prototype development I.E. hardware, understanding the

week points of the technology. The sooner we can take new technologies for a spin “outside of the

lab”, the better. The prototype will not immediately be ready for large scale production.

Methodology:

- Set general requirements (420Vin +/- 20Vripple due to PFC, 200-1000Vout, 6A, .15A ripple, 2kW, Capacitive-load)

- 2 months literature study -> 1 chapter - 2 months simulating 3-5 topologies -> 1 chapter - Select 1-2 topologies for possible implementation - 2 months detailed design of these 1-2 topologies -> 1 chapter - 2 months implement, test and benchmark-> 1 chapter - 1 month write report


Compare different topologies and implement a technology prototype, utilizing GaN (and SiC diodes)

This prototype will possibly be benchmarked against other implementations

This new design should give a benefit for: 1 cost (eventually), 2 efficiency, 3 power density

Contact details:




52

D C E & S




FOREIGN CONDUCTIVE OBJECTS MODELLING FOR DYNAMIC WIRELESS CHARGING

OF EV


RegulationStage

Energy StorageSystem

Power Grid

Power Grid

Receiver

TransmitterRoad

Road

Electric Vehicle

Electric Vehicle

Road

Magnetic Flux

Scope: As an approach to mitigate the range anxiety and bulky battery packages of EVs, dynamic

inductive power transfer (IPT) for EVs charging attracts lots of attention. Conductive objects like coins

and cans are very likely to occur on the road, and performances of dynamic IPT system can be

affected if these objects placed between transmitters under roads and pick-ups on board.

Problem definition: When conductive objects are placed near or in the magnetic field produced by

dynamic IPT system, eddy current will be generated. This eddy current could lead to power loss and

change in magnetic field and electrical waveforms. Modelling should be done to evaluate if

conductive objects having limited size could affect the efficiency and modify the waveform of the

electrical variables in the dynamic IPT system.

Methodology:

Literature review of the foreign conductive objects analysis for the dynamic IPT system

Analytical analysis of the power loss caused by eddy current

Electromagnetic model of the dynamic IPT system with the presence of conductive objects


Modelling method for the evaluation of the effect of foreign conductive objects

Guideline for the design to mitigate the adverse effect of foreign conductive objects

(OPTIONAL) Method for foreign conductive objects detection

Contact details:

PhD student: Wenli Shi [email protected]

Supervisor: Dr. Jianning Dong [email protected] Prof. Pavol Bauer [email protected]


53

D C E & S




MULTI-OBJECTIVE OPTIMIZATION FOR DYNAMIC WIRELESS CHARGING OF EV


RegulationStage

Energy StorageSystem

Power Grid

Power Grid

Receiver

TransmitterRoad

Road

Electric Vehicle

Electric Vehicle

Road

Magnetic Flux

.1

4h D

D

i

.1

2h D

D

.

yx

i

Scope: Recently, dynamic inductive power transfer for EVs charging has received a great deal of

attention. This technology enables moving EVs to pick up power from transmitting devices installed

under the road. Therefore, range anxiety, one of the main technical problems of EVs, can be

significantly alleviated, and the weight and volume of batteries on board can also be reduced.

Problem definition: As a loosely-coupled power transfer system, special attention should be paid to

the power level and the efficiency of the dynamic IPT system, which depend heavily on its operation

state, including the lateral misalignment, driving speed, air gap and temperature. Also, the total cost

of the system is important to be considered. This research focuses on multi-objective optimization

that can yield low cost, high efficiency at high power density.

Methodology:

Literature review of the topologies of the coil and the compensation of dynamic IPT system

Electromagnetic model and analytical analysis of a multi-coil dynamic IPT system

Multi-objective optimization considering different operation factors


Optimal topology of the coils and compensation circuits

Guideline of the deployment of the transmitting coils under roads

Mathematic method calculating the maximum power and efficiency of dynamic IPT system

Contact details:

PhD student: Wenli Shi [email protected]

Supervisor: Dr. Jianning Dong [email protected] Prof. Pavol Bauer [email protected]


54

D C E & S



DC Grids and Storage for Smart Cities DC systems, Energy conversion & Storage

EXPERIMENTAL DESIGN AND VALIDATION OF DC DISTRIBUTION GRIDS


Scope: It is essential for the broad adoption of DC distribution grids to design an experimental set-up and verify the research done on the modelling, stability, control and management of DC distribution grids. Different projects are available to design converters or do experimental work. Problem definition: Distribution grids are subjected to changes such as the increasing participation of distributed energy resources (DER), segmentation of the grid, and increasing participation of consumers and producers. This poses significant challenges with respect to stability and control. DC distribution grids are foreseen to have advantages over ac in terms of efficiency, distribution lines, and converters . However, more theoretical and experimental work is required to research and prove these advantages. Methodology: These topics either mainly involve the design of suitable converters and/or the execution of experiments. Moreover these projects entail literature research, simulations and (microcontroller) programming. Examples of Research Objectives:

Simulation of DC distribution systems

Design of an isolated DC/DC converter

Converter (PCB) design

Programming power electronic converter’s microcontroller

Design and implementation of the communication between power electronic converters

Conduct experiments regarding the control of DC distribution grids

Contact details:

PhD student: Nils H. van der Blij ([email protected])

Supervisor: Laura Ramirez-Elizondo ([email protected]) Prof. Dr. Eng. Pavol Bauer ([email protected])

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D C E & S




MODELLING, STABILITY, CONTROL AND MANAGEMENT OF DC GRIDS


Microgrid

MicrogridNanogrid

Energy Storage System

Renewable Energy Sources

Electrical Loads

Fault Isolation Device

Microgrid

MV Grid

~

Scope: To aid the broad adoption of DC distribution grids more research is required on the modelling, stability, control and management of dc distribution grids. Many topics within these categories are available for master students. Problem definition: Distribution grids are subjected to changes such as the increasing participation of distributed energy resources (DER), segmentation of the grid (for example into microgrids), and increasing participation of prosumers. This poses significant challenges with respect to stability and control. It becomes attractive to employ DC distribution systems since they have several advantages to AC distribution systems. DC distribution grids do not require the synchronization or reactive power governance, and do not have issues with harmonic and inrush currents. Moreover, the interconnection of dc (micro)grids is significantly simpler. Furthermore, dc distribution grids are also foreseen to have advantages over ac in terms of efficiency, distribution lines, and converters. Methodology: These topics mainly involve literature research, analytical derivations, simulations and/or programming. However, design/experimental topics are also available. Examples of available topics are:

Power flow control in DC distribution grids

Transient analysis of DC distribution grids

Small-signal stability of DC distribution grids

Centralized/decentralized/distributed control of DC distribution grids

Optimal sizing and location of storage in DC distribution grids

Stochastic analysis of uncertainty in DC distribution grids

Protection of DC distribution grids

Contact details:

PhD student: Nils H. van der Blij ([email protected])

Supervisor: Laura Ramirez-Elizondo ([email protected]) Prof. Dr. Eng. Pavol Bauer ([email protected])

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D C E & S




DEVELOPMENT OF BATTERY MANAGEMENT SYSTEM FOR TESTING OF BATTERY AGING

Type of project: Extra project

Fig 1: Battery Management System

Scope: Development of a battery management system to test and validate battery aging

Problem definition:

Storage systems play a key role in sustainable energy system. However knowledge on battery aging is required for proper planning and cost analysis. This requires systems which can validate battery models on cycling and calendar aging. Especially calendar aging is something which has not been investigated in literature.

This thesis is about the design of such a battery management system, which will be used to validate existing and/or new models on battery aging. Collaboration with the industry can be involved for validation purposes. The expected result of the project is a working prototype.

Methodology:

The project consists of a literature review about the operation of a battery management system, and the development a simple battery management setup.


Short literature review about battery modelling and management.

Design a battery management system which can validate the new model.

Build a test setup and verify the results compared with the simulations.

Contact details:

PhD students: Marco Stecca, [email protected] Wiljan Vermeer, [email protected]

Supervisors: Dr. Ir. Laura Ramirez Elizondo [email protected] Dr. Ir. Gautham Ram Chandra Mouli [email protected] Prof. Pavol Bauer [email protected]






57

D C E & S




INTELLIGENT ENERGY MANAGEMENT ALGORITHM COMBINING, EV, PV, STORAGE AND HEATPUMP


Fig 1: (a)EV Smart grid (b) EMS

Scope: Design of a linear optimization algorithm used for the energy management of future buildings combining the flexibility of EV, PV, storage and heat pumps.

Problem definition: In the future distributed generation of renewable energy is needed in order to reduce carbon emissions. Unfortunately, the intermittent nature of renewable energy also poses problems in terms voltage and frequency stability in the grid. Furthermore, the increasing electrification of devices such as vehicles, cooking and heating is expected to increase the peak stress on the distribution grid up to three times the current ratings of the transformer/cables. By developing a building energy management system which maximizes the local consumption of renewable energy and minimizes the grid impact using smart control of EV, PV, storage and heat pumps, both problems can be greatly reduced or even solved. This thesis is about the development of such an algorithm using linear optimization methods.

Methodology: The methodology used in this thesis:

Literature review of distributed generation, smart charging and demand response.

Study various (linear) optimization methods and analyse their advantages, disadvantages and determine the most suited one.

Set up and solve the optimization problem and assess its effectiveness.


Literature review of all relevant aspects

Optimization problem formulation and results

Assessment of result compared to conventional buildings

Contact details:





58

D C E & S




HEAT PUMP POTENTIAL FOR DEMAND RESPONSE APPLICATIONS


Fig 1: (a) (b)

Scope: Evaluating the potential for heat pumps in demand response programs

Problem definition: Due to its intermittent nature, the increasing share of renewable energy sources in the distribution grid gives rise to voltage stability issues. Demand response programs can play a vital role in counteracting these problems by moving the flexible appliances from the high demand time to the time where there is a high production of energy. Furthermore, the replacement of the gas boiler with much more efficient heat pumps provides a huge potential of using these heat pumps for demand response applications. This thesis investigates the possibilities of using heat pumps for demand response programs as well as the impact on the future distribution grid.


Literature review of the problems which arise from distributed generation and investigation of different heat pump technologies.

Study existing optimization methods and analyse their advantages, disadvantages and complexity

Design a demand response method based on the provided flexibility of heat pumps and show its effectiveness in a simulation.


Quantification of heat pump and thermal storage dynamics

Development of optimization technique

Quantification of demand response potential of heat pumps.

Contact details:





59

D C E & S




MULTI-OBJECTIVE OPTIMIZATION METHOD FOR BATTERY SIZING


Fig 1: (a) Pareto front (b) Residential Energy Storage

Scope: Design of a multi-objective framework to be used for battery sizing

Problem definition: In the future distributed generation of renewable energy is needed in order to reduce carbon emissions. Unfortunately, the intermittent nature of renewable energy also poses problems in terms voltage and frequency stability in the grid. Residential energy storage units are expected to play a large role in mitigating these effects. However they are also very expensive, therefore a multi-objective framework can be made to optimize the effectiveness compared to cost of the system. This thesis is about developing a mathematical framework which does this, also taking into account the cost of battery aging.


Literature review of optimization methods, battery technologies and aging.

Develop mathematical models for cost and battery usage.

Set up and solve the optimization problem and assess its effectiveness.


Literature review of all relevant aspects.

Optimization problem formulation and results.

Sensitivity analysis arguing multiple optimal solutions.

Contact details:





60

D C E & S




POWER FLOW CONTROL IN LVDC GRIDS USING PARTIALLY RATED POWER FLOW CONTROL CONVERTERS


Microgrid

MicrogridNanogrid



Electrical Loads


Microgrid

MV Grid

~

Scope: Generally, future distribution grids lack the robustness and inertia of current AC systems. Therefore, additional control is necessary to ensure appropriate operation. For example, the power flow in multi-terminal dc grids needs to be controlled to achieve efficient operation. In this thesis, a partially rated power flow control converter (PFCC) will be used to achieve this goal. Problem definition: The primary goal of the thesis is the development of a control algorithm for PFCC’s in multi-terminal LVDC networks. The primary objectives of the decentralized algorithm should be able to prevent local overloads and excessive currents in distribution lines without utilizing communication. Methodology: Large-signal PFCC and LVDC grid models are available to be used in Matlab/Simulink. These models allow fast deployment of complex systems. Besides simulations, the results will be verified in a laboratory-scale microgrid. Research Objectives:

Review of decentralized power flow control algorithms in DC systems

Development of a power flow control algorithm for PFCC’s in LVDC grids

Simulations of the proposed power flow control algorithms

Experimental verification of the proposed algorithms

Contact details:

PhD student: Pavel Purgat ([email protected]) Nils van der Blij ([email protected])

Supervisor: Zian Qin ([email protected]) Pavol Bauer ([email protected])





61

D C E & S




COMPARISON OF BUILDING BLOCKS FOR LVDC GRIDS


Microgrid

MicrogridNanogrid



Electrical Loads


Microgrid

MV Grid

~

Scope: Generally, future distribution grids lack the robustness and inertia of current AC systems. Therefore, additional control is necessary to ensure appropriate operation. For example, the power flow in multi-terminal dc grids needs to be controlled to achieve efficient operation. For this end different solutions were proposed in the previous research, including the partially rated power flow control converter with integrated short circuit protection. Problem definition: The primary goal of the thesis is to compare different building blocks i.e. different power electronic solutions for the control of the LVDC grids. At TU Delft integrated cost efficient building block for LVDC grids was proposed recently. The goal is to benchmark the proposed solutions against the other existing concepts. Methodology: In the first stage of the project the student will be acquainted with the state of the art research in the LVDC systems. In the second phase using existing simulation tools different power electronic concepts for the control of LVDC grid will be compared. In the last stage, chosen scenarios will be verified in a laboratory-scale microgrid. Research Objectives:

Review of power electronic concepts for control of LVDC systems.

Simulations and comparison of the power electronic concepts.

Experimental verification of the chosen scenarios in the laboratory.

Contact details:

PhD student: Pavel Purgat ([email protected]) Nils van der Blij ([email protected])

Supervisor: Zian Qin ([email protected]) Pavol Bauer ([email protected])





62

D C E & S




POWER ELECTRONICS CONTROL FOR SEAMLESS ISLANDING TRANSITION


Scope:

Develop and test control strategies for power electronic converters to allow a seamless transition of distribution grids during unintentional islanding.

Problem definition:

Islanding operation is a situation in which a portion of electric grids continues to operate even if disconnected from the main network. Islanding can be intentional or unintentional, the second condition it is not yet allowed due to difficulties of grid operators in ensuring an acceptable level of security and power quality to the customers.

However with an increasing penetration of distribution generators (DG) and storage systems (ESS) it might be possible to operate distribution grids in islanding operation safely. The main challenges are first in detecting the fault, then in controlling the transient that arises accordingly and, if these two steps are completed successfully, in keeping the system stable balancing loads and generation.

Methodology:

The research consists on first studying the islanding operation of distribution grids, the load/generation requirements and the role of storage in this. Second the student will develop a control strategy for the power electronic converters in order to manage the transient during the island formation.


Study the grid requirements for sustaining islanding operation.

Evaluate the role of the power electronics device in the dynamic behaviour of the grid during the transition.

Design a control strategy for achieving a seamless transition after the disconnection from the main grid.

Contact details:


Supervisors: Dr. Ir. Thiago Batista Soeiro <[email protected]> Dr. Ir. Laura Ramirez Elizondo <[email protected]> Prof. Dr. Ir. Pavol Bauer [email protected]


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D C E & S




POWER ELECTRONICS FOR GRID CONNECTED ENERGY STORAGE SYSTEMS


Scope:

Study the most common AC/DC converter topologies for grid connected storage systems.

Problem definition:

Battery energy storage system are becoming an effective option for grid operators to face the technical issues deriving from an increase of non-predictable renewable generation. When connected to distribution grids storage systems can be used for performing several ancillary services, voltage control, frequency control, congestion management, etc… . The requirements in term of response speed or system availability might differ according to the functionality provided.

Since storage systems are interfaced with the grid through power electronic converters, these difference in the requirements can be reflected in the design of the conversion unit.

Methodology:

The research consists firstly on a survey on the main AC/DC converter topology and on the grid ancillary services. Later the student will evaluate the best fitting converter according to the functionality that the storage unit will provide. Through this project the student will get familiar with the most common AC/DC converters and with storage systems.


Literature review of BESSs converter topologies and grid ancillary service provision market.

Evaluate the advantages of each topology on the others.

Simulate the behaviour of the different topologies in the provision of ancillary services.

Contact details:


Supervisors: Dr. Ir. Thiago Batista Soeiro <[email protected]> Dr. Ir. Laura Ramirez Elizondo <[email protected]> Prof. Dr. Ir. Pavol Bauer <[email protected]>

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D C E & S




BATTERY MODELLING AND TESTING FOR GRID CONNECTED AND RESIDENTIAL APPLICATIONS


Scope:

Estimating the effect of calendar and cycling ageing in residential / grid connected battery modules

Problem definition:

In the future storage systems might play a key role in the distribution grid planning. For a proper integration and planning of the storage device it is necessary to have an extended knowledge about their performances and lifetime. However external conditions and the battery cycling pattern has strong influence especially in the lifetime. For this reason it is interesting to study the battery behaviour in the utilization different cases (voltage control, losses minimization, congestion management, primary frequency control). The expected result of the project is to extract detailed information about the battery performances and lifetime, when performing several grid services, to be used in grid expansion studies or for the designing of home energy management systems.

Methodology:

The research consists on first developing several battery cycling patterns compatibles to the different functionalities and then testing them on the battery banks. The main electrochemical, electrical and thermal parameters will be extracted and models will be built accordingly.


Literature review about battery performances and modelling techniques.

Create battery cycling patterns for the different applications.

Test the batteries for evaluating calendar and cycling ageing.

Build detailed models to be used for project feasibility studies and verify their fitness with the selected application.

Contact details:

PhD student: Marco Stecca [email protected] Wiljan Vermeer [email protected]

Supervisors: Dr. Ir. Laura Ramirez Elizondo [email protected] Prof. Dr. Ir. Pavol Bauer [email protected]





65

D C E & S




DEVELOPPING DISTRIBUTED CONROL SCHEME FOR POWER MANGMENT IN DC MICRO GRID


Scope: Improvement of DC network system in large scale mainly depends on the new controlling techniques. Recently, decentralized and distributed strategies have received a great deal of attention, However, these strategies are still immature and need more development to address critical issues such as voltage deviation and power error tracking.

Problem definition: Traditionally, the clustered and interconnected Micro Girds in the tertiary level are controlled via the central controlling strategy. This approach is sufficient for the small scale MGs with less complexity. However; it is not competent in the complex systems. Distributed controlling approach seems the best option in the complex system with a suitable algorithm.

Methodology:

Literature review of decentralized and distributed controlling techniques and adaptability of

their algorithm for different controlling levels in DC network

Identification of the issues in central controlling

Power flow analysis in DC network


Develop an adaptable distributed control algorithm for the power management of multiple

DCMGs

Simulation of small scale DCMG to validate the controlling algorithm

Contact details:

PhD student: Farshid Norouzi, [email protected]

Supervisor: Laura M. Ramirez-Elizondo ([email protected])




66

D C E & S



High Voltage DC Systems DC systems, Energy conversion & Storage

HIGH TEMPERATURE SUPERCONDUCTIVITY FOR DEGAUSSING


Scope: Due to their permeability, naval ships distort Earth’s magnetic field. These anomalies in the

magnetic field can be detected by sensors attached to airplanes or, even worse, magnetic mines.

Luckily, there are methods to prevent detection by making ships “magnetically invisible”. One of

these methods is to install a degaussing system, a set of coils designed to induce a magnetic field

which compensates for the distortion.

Problem definition: Nowadays, degaussing coils are made out of copper. Due to energy losses and

weight issues, however, it might be better to use a superconductive material. Moreover, the

developments in high temperature superconductivity (HTS), makes the use of superconductors a

serious option.

In a degaussing system, multiple coils are used. Due to the magnetic coupling of these coils, noise

from on-board power electronics, geometry of the ship and other reasons, a complex control system

is required. It is expected that the implementation of superconductive coils has a significant impact

on the control system.

Methodology: In this project a model should be built to simulate the effect of the use of

superconductive coils on the control system and to test control strategies. Laboratory experiments

might be needed to verify the results.


To conduct a literature review

To obtain a model of superconductive coils and a degaussing control system

To define and test an experimental test set-up

Contact details:

PhD student: Djurre Wikkerink, [email protected]

Supervisors: Prof. Rob Ross, [email protected] Dr. Armando Rodrigo Mor, [email protected]

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D C E & S



High Voltage DC Diagnostics and Monitoring DC systems, Energy conversion & Storage

MAGNETIC ANTENNA CHARACTERISATION FOR PARTIAL DISCHARGE

MEASUREMENTS


Scope: To characterize the frequency response of a new magnetic antenna developed for partial

discharge (PD) measurements in Gas Insulated Systems (GIS), using different techniques in order to

get the Bode magnitude and phase plots.

Problem definition:PD measurement plays an important role in the monitoring and diagnostic of

high voltage gas insulated systems (GIS) due to its high capabilities to detect in-service failures

related to defects in the insulation system. Partial discharges in a GIS produce electromagnetic waves

that are picked up by electric and magnetic antennas installed in the GIS enclosure. A new concept

for PD measurements in GIS has been recently developed based on a novel magnetic antenna.

Nevertheless, this novel antenna lacks a detailed electromagnetic characterization, which means that

at the moment the antenna frequency spectrum is relatively unknown.

Methodology: A profound study of the different techniques available to characterize antennas for PD

applications. These techniques should be tested and fitted by pertinent computer simulations. Using

the results from the simulation, a test or set of tests should be established and done in order to

obtain the magnetic antenna characterization.


To conduct a literature review.

To perform computer simulations of the magnetic antenna characterization.

To obtain the frequency spectrum of the magnetic antenna by experimental tests.

Contact details:

Postdocs researchers: Fabio Muñoz, [email protected]

Postdoc researcher: Luis Carlos Castro, [email protected]

Supervisor: Armando Rodrigo Mor, [email protected]



68

D C E & S




DEVELOPMENT OF A PD RECOGNITION SYSTEM FOR HVDC GIS BASED ON

MAGNETIC ANTENNAS


Scope: To develop a recognition system for partial discharges (PD) occurring in High Voltage DC

(HVDC) gas insulated system (GIS) based on a new magnetic antenna.

Problem definition:PD measurement plays an important role in the monitoring and diagnostic of

HVDC GIS due to its high capabilities to detect in-service failures related to defects in the insulation

system. PD in a GIS produce electromagnetic waves, which are commonly measured by electric

antennas installed in the GIS enclosures. At the High Voltage Lab, a new concept of PD

measurements has been developed based on magnetic antennas, having some advantages as PD

polarity detection. This new magnetic antenna measures the PD signals in the range of tens of MHz

but -unfortunately- is also able to pick up the noise and the electromagnetic disturbances that are

traveling across the GIS enclosure. Therefore, it is important to develop a recognition system capable

of discriminate noise, external disturbances and partial discharges in an HVDC GIS.

Methodology: A profound study of the clustering, denoising and discrimination techniques available

for transient pulses. Then, the techniques should be implemented and tested using computer

algorithms and real measurements in the GIS available at the High Voltage Lab.


To conduct a literature review.

To implement clustering, denoising and discrimination techniques by computer algorithms.

To check the recognition techniques by experimental tests.

Contact details:

Postdoc researcher: Fabio Muñoz, [email protected]

Postdoc researcher: Luis Carlos Castro, [email protected]




69

D C E & S




STUDY OF TRICHEL PULSES IN AIR


Scope: To numerically model negative corona (Trichel pulses) in air using COMSOL Multiphysics

software and Matlab. The aim is to control solver’s step size during the whole simulation to minimize

the simulation time.

Problem definition: High electric field around sharp points can cause local breakdown of air known

as corona discharge. If the polarity of applied voltage is negative and the dielectric medium has

electronegative gas (such as oxygen) repetitive pulses of the same magnitude is usually observed

during corona discharge. The goal of this project is to solve hydrodynamic equations of charged

particles coupled with Poisson’s equation, to model the so called Trichel pulses in 2D-axis symmetric

domain. Proper meshing, type of solver and step size taken by the solver are important parameters.

In this extra project it is expected that the model is controlled from Matlab and proper algorithm is

developed to control step size during the whole simulation in order to lower the simulation time.

Methodology: The work is simulation based and can be performed on the high end computer

available in HV laboratory. Experimental verification has to be done when a functional model is

developed.


literature review, getting use to the existing model (how is it made, boundary conditions, functionality and limitations)

Implementing and controlling the existing COMSOL model by Matlab. Identifying the most suitable meshing strategy and controlling solver’s step size to obtain shorter simulation time

Contact details:

Supervisor: < Mohamad Ghaffarian Niasar, [email protected]>

Rob Ross, [email protected], Peter Vaessen [email protected]



70

D C E & S




AGING OF HVDC TRANSFORMER’S INSULATION SYSTEM


Scope: To understand aging mechanism of oil-impregnated paper exposed to AC superimposed with

DC and pulse stress.

Problem definition: Converter transformer is an important part of a HVDC link. Any unexpected

failure of such transformer can be very costly due to the cost of transformer itself and the cost of

power interruption. Condition monitoring of such transformer is therefore very crucial. To be able to

properly interpret partial discharge measurements recorded from a converter transformer it is

necessary to understand how each dielectric component inside a converter transformer behave to

different stresses. Paper insulation inside a converter transformer is stressed by DC and distorted AC

electric field at the same time while on a conventional transformer the insulation is only stressed by

AC electric field. Partial discharge behaviour of a converter transformer is therefore different than a

conventional transformer and hence the interpretation is different.

Methodology: The work is experimental based and should be carried out in high voltage laboratory.

Lifetime of oil-impregnated paper insulation should be investigated under simultaneous DC and AC

superimposed with pulse electric stress. Evaluation of PD over lifetime and change of impulse

breakdown strength of oil-impregnated paper should be analysed.


literature review of insulation system used in HCDC converter transformer and a summary of

available tests used to ensure a proper made converter transformer

Aging of oil-impregnated paper stressed with AC superimposed with pulses, as well as DC

superimposed with pulses

Measurement of Impulse breakdown strength and PD activity of electrically aged oil-

impregnated paper

Contact details:

Supervisor: <Mohamad Ghaffarian Niasar, [email protected]>




71

D C E & S




CONTROL SYSTEM FOR ELECTROSTATIC VOLTMETER


Scope: The goal is to construct a control unit for electrostatic voltmeter to measure potential

distribution along a surface. The device will then be used to measure surface charge decay over

commonly used dielectrics.

Problem definition: Surface charges may accumulate on the surface of DC insulator and alter electric

field distribution. In gas insulated substations due to field emission from the enclosure, electric

charges are injected to SF6 and deposits on the surface of the spacer. In outdoor polymeric insulator

surface charges are formed on the insulator due to corona activity. The presence of surface charges

may decrease the breakdown strength of the insulator, leading to failure of HVDC component (in the

event of lightning impulses) and hence interrupting power transmission. Therefore understanding

how surface charges form and decay on the surface of insulator is very important for HVDC insulation

design. HV laboratory has recently bought an electrostatic voltmeter. The voltage probe must be

mounted a 2 axis CNC unit to scan the surface potential at a fix distance between the probe and the

plate. Proper rails, bearing and stepper motors, type of microcontroller, together with flexible

control algorithm (speed of scan, initial point setting) must be purchased, programmed and

constructed. The final product will be used to measure surface charge decay over commonly used

dielectric materials.

Methodology: Proper components for a 2 axis CNC control unit must be chosen and purchased. A

code must be written to control the stepper motors with the required flexibility. Final product should

be assembled and used to measure charge decay over known dielectric sample. The results of the

measurement must be compared with literature.


Purchasing the proper components for 2 axis CNC unit and development of the control code>

Assembling of the product and testing its performance by means of surface charge decay over known dielectric material and comparison with literature.

Writing the final report and user manual for the developed device.

Contact details:




72

D C E & S




DESIGN AND PROTOTYPING A SOLID STATE MARX IMPULSE GENERATOR


Traditional Marx generator Solid state monopolar pulse generator J. Rao, et. al, “All Solid-State Rectangular Sub-Microsecond Pulse Generator for Water Treatment Application”, IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 46, NO. 10, OCTOBER 2018

Scope: To design, model and prototype a 10 kV solid state Marx impulse generator.

Problem definition: TU Delft and KEMA laboratories are collaborating to create a universal high

voltage test source capable of generating arbitrary waveforms including lightning impulses. The high

current passed through the switches and the electromagnetic disturbances created during the

lightning impulse impose limitation on switch sizing and required shielding of the communication and

control system of the test generator. To identify challenges related to actual design of the high

voltage arbitrary waveform generator, in this project a solid state 10 kV impulse generator will be

designed, modelled and prototyped.

Methodology: Accurate Spice/ Simulink model of the impulse generator including the important

parasitic components will be made. This is check influence of different design parameters and to

avoid overstress of switches during operation. Based on the simulation result, 3 stages of the pulse

generator will be made and tested. At this stage isolation is created by means of 20 kV fast opt-

coupler. Upon successful achievement in the first part, synchronization method will be replaced by

fibre optics or laser pulses and the full scale test generator will be developed.


Literature review of different topology used in solid state pulse generators

Simulation of the Marx pulse generator considering parasitic parameters. Calculate voltage distribution along the stages of the generator.

Prototyping and testing the developed solid state impulse generator

Contact details:

Supervisor: Mohamad Ghaffarian Niasar, [email protected]

Tiago Batista Soeiro, [email protected]

Peter Vaessen, [email protected]




73

D C E & S




MODELLING OF CHARGE DECAY IN HVDC CABLES


Scope: To develop a model that can demonstrate charge decay and recovery voltage phenomenon

on HVDC cables.

Problem definition: Space charges can accumulate in DC cables and alter the electric field

distribution in the cable. Space charge build up and decay depends on insulation parameters,

temperature, and environment. Charge decay can happen very quick or can take many days. When

voltage is removed from a DC cable, trapped space charges can remain in the insulation for a long

time. A de-energized cable can therefore develop potential difference between conductor and the

sheath due to the available space charges. This is important from the safety point of view as such

electric potential can be lethal. In this project a finite element model and a circuit model will be

develop to demonstrate how the potential decay occurs when the voltage is removed from the cable.

The model must be validated by means of experiment.

Methodology: The work consists of development of a numerical model that can simulate charge

decay and voltage recovery phenomenon in HVDC cables. The work also involve experimental work

which will be done in high voltage laboratory.


literature review of mechanism of charge decay and voltage recovery measurement as a

diagnostic method

Development of a FEM model in COMSOL Multiphysics that simulate charge decay in HVDC

cable. Development of a circuit model that can represent voltage recovery phenomenon

Comparison of the developed model with experiment

Contact details:


Peter Vaessen [email protected], Rob Ross, [email protected]




74

D C E & S




RELIABILITY ANALYSIS OF POWER SEMICONDUCTOR SWITCHES EXPOSED TO

REPETTETIVE LARGE PULSE CURRENT


DC

MCGate

driver

Oscilloscope

Scope: Build circuitry and conduct experiment to determine reliability of IGBTs/MOSFETS exposed to

repetitive large pulse current.


voltage test source capable of generating arbitrary waveforms including lightning impulses. To

synchronize switches for lightning impulse with a front time of 1.2 𝜇𝑠, a very fast gate driver capable

of turning on the switch within 10 ns is desired. Some researchers have suggested to use different

driving voltages during turn on and steady state, others suggested to use gate-boosting circuitry to

achieve faster switch turn on and off. On the other hands, during fast impulses a large pulse current

passes through the switches. It is very important to determine reliability of the switches exposed to

such condition over long time.

Methodology: The student build circuitry of a fast gate driver as well as circuitry to test switches

exposed to large pulse current. Experiment should be carried out to identify long term reliability of

switches under large current pulses.


Literature review of existing very fast gate driver circuitry

Design test setup and perform experiment to identify long term performances of different switches

Reporting the outcome of the project

Contact details:

Supervisor: Mohamad Ghaffarian Niasar, [email protected] Tiago Batista Soeiro, [email protected]



75

D C E & S



High Voltage DC Materials and Components DC systems, Energy conversion & Storage

DESIGN OF A COAXIAL SAMPLE FOR CALIBRATION AND CHARACTERIZATION OF

SPACE CHARGE ACOUSTIC MEASUREMENTS


Scope: Design of a sample resembling a full size HVDC cable, capable of emulating trapped electric

charges at different radius of the cable’s dielectric bulk. The calibrated sample should be compatible

with the acoustic methods used at Space Charge measurements.

Problem definition: HVDC networks are widely increasing their presence in the transmission network

due to the new developments and achievements of HVDC power converters. Therefore,

measurement of the Space Charge phenomena in HVDC components is becoming more relevant. The

availability of different space charge measurement methods brings the necessity of calibration and

characterization of measurement equipment in order to reach standardized measurements. This

brings the necessity of a reliable calibrated sample to reproduce the same charge values in different

tests and equipment.

Methodology: The research involves full understanding of the acoustic methods for space charge

measurements. The student will make a design of the coaxial calibration sample and proceed to its

construction and validation tests.


Develop a design for a space charge calibration sample.

Construction and testing of the sample prototype.

Contact details:

PhD student: Guillermo Mier, [email protected]




76

D C E & S




INTEGRATED ULTRASOUN SENSOR FOR THE CALIBRATION OF PRESSURE WAVE

PROPAGATION METHODS IN SPACE CHARGE MEASUREMENTS OF HV CABLES


Scope: Design a electroacoustic sensor that will be coupled to a HV cable sample during PWP

measurements. The use of this sensor should be capable of predict the measured space charge

values at different trapped charge values.

Problem definition: HVDC networks are widely increasing their presence in the transmission network

due to the new developments and achievements of HVDC power converters. Therefore,

measurement of the Space Charge phenomena in HVDC components is becoming more relevant. One

of the challenges involving the measurement of SC in HVDC cables is the need of a HV at the inner

conductor for calibration purposes; which brings the necessity of very long cables for the

construction of terminations, as well as the incapacity of measuring SC in post-mortem tests. The

capacity to measure the propagating pressure wave at different points of the cable allows to

calibrate without the HV at the inner electrode.

Methodology: The research involves full understanding of the PWP method for space charge

measurements. Selection of the most appropriate sensor according to the electrical and mechanical

requirements. The process involves simulations and extensive laboratory work.


Selection and design of the sensor.

Validation of the design by laboratory testing.

Methodology to calibrate PWP method with the measured pressure waves.

Contact details:

PhD student: Guillermo Mier, [email protected]




77

D C E & S




30KH HIGH POWER DENSITY TRANSFORMER WITH 35 KV ISOLATION

REQUIREMENT THERMAL DESIGN INVESTIGATION


Figure 1 The proposed medium frequency transformer construction and 2D FEM thermal simulation

Scope & Problem definition: Most of recent research on power electronics have been focused on the

solid state transformer as it comprises all types of power conversion required in energy supply. SST

uses a medium frequency power transformer to replace the traditional line frequency power

transformer thus the size and weight can be reduced. The to be designed transformer is operated at

30 kHz, at 50 kW power rating and needs to handle 35 kV isolation. The biggest challenges are to

realize both isolation requirement and thermal requirement at a high power density level.

The transformer size is largely reduced when operating at medium frequency compared with

conventional power frequency transformer which provides the possibility of higher power density.

However, there is a trade-off between the high power density and thermal performance. First of all,

the exposed cooling surface is also reduced accordingly. And it is safe to assume that the dissipated

heat is proportional to the exposed cooling surface directly. Secondly with higher frequencies, effects

such as skin and proximity and hysteresis losses are significantly increased compared to operation at

50/60 Hz. Besides the design process should consider high isolation requirement. And this again

defects the transformer thermal performance and this is because firstly insulation material adds

extra losses to the system, secondly the construction of the insulation will block some cooling

surfaces and thirdly those insulation materials normally have relatively low thermal conductivity. As a

consequence, the thermal design should be carefully considered and evaluated.

Methodology:

Develop transformer losses analytical tools (core, copper and dielectric losses)

Develop analytical and 3D FEM thermal models for transformer

Optimize the thermal design according the simulation results


Develop an accurate transformer thermal analyse method Compare the different materials thermal properties

Contact details:

PhD student: Tianzhu Tang, [email protected]

Supervisor: Mohamad G Niasar, [email protected]

78

D C E & S




30KH HIGH POWER DENSITY TRANSFORMER WITH 35 KV ISOLATION

REQUIREMENT INSULATION DESIGN INVESTIGATION


Figure 2 A example of the medium frequency transformer cross section constructions

Scope: Most of recent research on power electronics have been focused on the solid state

transformer as it comprises all types of power conversion required in energy supply. SST uses a

medium frequency power transformer to replace the traditional line frequency power transformer

thus the size and weight can be reduced. The to be designed transformer is operated at 30 kHz, at 50

kW power rating and needs to handle 35 kV isolation. The biggest challenges are to realize both

isolation requirement and thermal requirement at a high power density level.

Problem definition: Current power frequency high voltage cast resin dry type transformers insulation

configuration are usually made of air and solid material that are able to achieve the desired isolation

level. In order to increase the power density, we have proposed to ground the resin cast high voltage

side windings using semiconductors and use multi-layer insulation materials construction. To verify

our concepts, the insulation performance of such design should be investigated first.

Methodology:

Develop 2D analytical and 3D FEM electrostatic models for the winding electric field

Choose different insulation materials and compare those designs

Develop experimental prototypes and test its insulation performance (lab work)


Develop an electrostatic analyse and design tool for windings

Compare the properties of different insulation materials

Evaluate the manufacture feasibility of the proposed multi-layer insulation concept

Contact details:



79

D C E & S




HIGH POWER DENSITY TRANSFORMER TESTING CIRCUIT SIMULATION


Figure 3 The LLC circuit and the voltage and current across the tranformer

Scope & Problem definition:

Most of recent research on power electronics have been focused on the solid state transformer as it

comprises all types of power conversion required in energy supply. SST uses a medium frequency

power transformer to replace the traditional line frequency power transformer thus the size and

weight can be reduced. Before diving into the transformer design, it is important to get the exact

waveform across the transformer. LLC topology is used in the converter which maintains merits as

ZVS for all primary side main switches and ZCS for secondary side diodes under wide range inputs,

and the three-level technique, which is suitable for high voltage input applications, together.

Methodology:

Using matlab simulink to simulate the circuit operation and achieve the waveform across the transformer


Modelling the circuit operation conditions

Investigate the transformer magnetizing inductance and leakage inductance’s influence on the converter

Contact details:



is1

80

D C E & S




REPLACEMENT STRATEGY FOR GAS-PRESSURIZED UNDERGROUND CABLE SYSTEMS


Scope: In this project a replacement strategy for gas pressurized underground cable based on field

measurement and health index will be developed for TenneT power system grid.

Problem definition: In order to maintain the high voltage grid reliability, TSOs like TenneT are

continuously investing in either maintenance or replacement of the components/systems.

Particularly near economic end of life the question maintain or replace is prominent. Two types of

older cable exist in the TenneT grid to data: oil pressurized cable (NL: ODK) and gas pressurized cable

(NL: UGD). Newer cables are the XLPE insulated cables.

As for UGD TenneT TSO operates HV (110 kV and 150 kV) underground cable systems grids. These

cable systems have been installed since early 70's. In order to set up an effective replacement

strategy, TenneT aims to prioritize UGD cables that feature high partial discharge levels. Such a

strategy is required, because replacing the entire UGD grid system at once is not technically nor

economically feasible.

Methodology: The work is based on field measurements and data analysis that feed into the health

index and risk index methodology for underground gas pressurized cables. The challenge is to

develop a suitable measurement of monitoring technology for prioritizing the most urgent UGD

cables.


Literature review

Study the specific characteristics of UGD cables, terminations and cable joints

Define a measurement strategy and test testing techniques

Data analysis and developing knowledge rules for the health index

Prioritizing and developing replacement strategy

Contact details:

Dr Babak Gholizad: [email protected]

Dr Armando Rodrigo Mor: [email protected]

Prof Dr Rob Ross: [email protected]




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D C E & S




DESIGN AND MODELLING OF FAST RISE TIME MARX GENERATOR


Scope: The scope of this project is to develop a finite element model and design a fast rise time Marx

generator. Fast rise time pulse generator is used to test insulation materials under high pulsed

voltages.

Problem definition: High voltage impulse generators are capable to generate impulse with a rise

time of 1.2 µs (See figure above). This impulse generators are useful to full fill the power system

standardized tests. However, in recent years, by introducing power electronics converters, the shape

and rise time of the pulses is going to change. To test insulation materials under faster rise time than

standard lightning impulse generator, reconsidering the pulse generator and design of the pulse

generator is needed.

Methodology: The work is mostly focused on the detailed design of fast rise time Marx pulse

generator on computer simulation. After the development of the model, a prototype has to build to

verify the accuracy of the constructed model and design procedure. The experimental part will be

done in a high voltage laboratory of TU Delft.


A literature review of existing Marx generator and their design

To be able to couple different physics in COMSOL Multiphysics software

Development of a FEM model that can accurately predict the electrical parameter of the pulse generator

Experimental verification of the constructed model

Contact details:

Babak Gholizad, [email protected]


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D C E & S




DESIGN OF HIGH VOLTAGE SUPERCONDUCTING TRANSFORMER

Type of project: Extra Project/ MSc Thesis

Superconducting transformer (left) and copper transformer (right) with comparable nominal power (medium voltage

traction transformer)

Source: M. Noe, EUCAS Short Course: Superconducting transformer

Scope: The scope of this project is to develop a finite element (FEM) model and design a high voltage

superconducting transformer.

Problem definition: Superconductors are materials that can conduct a stationary electrical current

without resistance. Higher current carrying capability of the superconductors provide a great

opportunity to reduce the size of the power components. The size and weight of the component

become an important factor in dense areas. Physics and working temperature of the

superconducting materials are different. Modelling the physics and behaviour of the material require

good understanding. Several numerical approaches to model the superconducting material has been

developed. Applying those numerical approaches to design a component is the goal of this project.

Methodology: The work is mostly focused on modelling and preliminary design of high voltage

superconducting transformers. Analytical design and FEM design of the transformer to predict the

losses and size of the transformer is expected.


Literature review

To be able to couple different physics in COMSOL Multiphysics software and build a physics of superconductor

Development of a FEM model that can accurately predict the electrical parameter of the transformer

Comparison between FEM and analytical design of the transformer

Contact details:

Babak Gholizad, [email protected]

Rob Ross, [email protected]



83

D C E & S




PIPE AS ALTERNATIVE FOR HV EXPORT CABLE (FEASIBILITY)

Type of project: MSc thesis (2x)

HV cable Pipe-laying vessel

Scope: Investigate the technical possibilities to use a large diameter (1 to 2m) pipe with “insulation

foam” at a higher than atmospheric pressure that positions the inner (high voltage) conductor.

Aspects to be covered are electric field calculations, breakdown strength of insulation foam, fixation

of the central conductor, transmission capacity, assembly at sea, economic considerations etc.

Problem definition: Offshore windfarm high Voltage export cable is very expensive and contributes

about 30% to the CAPEX cost of the transmission system. Future cable capacity is limited to

approximately 2-3 GW due to size and weight of the cable. An economic alternative for GW-size

export cable is sought after.

Methodology: This project includes a (short) literature study on high voltage cable and GIL

developments. Identification of suitable insulation foams and experimental study of breakdown

strength of foams under high(er) pressure. The mechanical and thermal aspects, as well as assembly

at sea and economic analysis could be subjects for the second MSc thesis

Research Objectives (both MSc ):

Literature survey

Field calculations, insulation foam breakdown experiments

Mechanical and thermal aspects

Sea assembly

Economic analysis

Collaboration with Industry: Yes, collaboration with other disciplines is essential for success

Contact details:

Supervisor: Peter Vaessen, [email protected]

Mohamad Ghaffarian Niasar, [email protected]



http://www.google.nl/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwiuwL7n54DTAhVBvBoKHWHODVsQjRwIBw&url=http://www.offshorewind.biz/2015/02/16/rte-looking-for-assistance-on-offshore-wind-connections/&psig=AFQjCNE2zzTQOWGZ6Ybhsl2n9EilQKh60A&ust=1491051833911138

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D C E & S




MODELING MULTILEVEL CONVERTER TOPOLOGIES IN PSPICE FOR DEVELOPING A

NOVEL HIGH VOLTAGE TEST SOURCE


Scope: The goal is to develop a PSPICE model of Modular Multilevel Converter (MMC) and cascaded

H-bridge with non-ideal behaviour of switches and passive components.

Problem definition: These multilevel converter topologies are studied to generate arbitrary wave

shapes for high voltage testing application. High voltage testing involves not only periodic signals

such as sinusoidal, square waveform but also non-periodic signals such as impulses. These impulses

have very short rise time (shortest: 1.2 µs). This will create large 𝑑𝑣

𝑑𝑡 and

𝑑𝑖

𝑑𝑡 stresses on switches.

Hence, it is critical to understand the behaviour of switches when subjected to these stresses.

Methodology: The main focus of the project will be on theoretical understanding and simulation

study of non-ideal behaviour of switches in the mentioned multilevel converter topology. Since the

converters are not used for power transfer application, these model need to be developed from

scratch. At the end of successful study, it might be possible to test these models on small-scale

hardware prototype.


Literature review on non-ideal component in switches (IGBTs and MOSFETs)

Model these non-idealities in PSPICE and study its dynamic performance

Implement MMC and cascaded H bridge topologies with non-ideal model of IGBT in PSPICE

Contact details:

PhD student: <Dhanashree Ganeshpure, [email protected] >


<Thiago Batista Soeiro, [email protected]>




85

D C E & S




200 KV CLASS WIRELESS POWER TRANSFER ARRAY


Scope: The goal of this project is to design a wireless power transfer array with 200 kV insulation

level capable of transferring 500 W per cell.

Problem definition: High frequency pulses and harmonics are the type of stress that are being added

to the grid following the increase penetration of power electronics. To ensure reliability of power

component it is necessary to test them under actual stress present in the grid. It is therefore

requested by number of testing companies, to design and prototype a high voltage arbitrary voltage

waveform test generator. The goal of the project is to design a power electronics based HV test

generator capable of generating 200 kV arbitrary voltage waveform. One candidate topology for such

test generator is cascaded H-bridge topology. Isolated power supply is required in cascaded H-bridge

topology with insulation clearance sufficient for the operating voltage of the test generator. Using

ferrite core/iron core transformers at 200 kV insulation level requires a complicated insulation

system which ends up into a bulky structure. In this regard, a novel idea of using wireless power

transfer with high voltage insulation clearances is being proposed for this master thesis. The goal is

to use existing knowledge in wireless power transfer, in combination with high voltage consideration

required for this project, and come up with the most suitable design.

Methodology: Existing designs for wireless power transfer will be reviewed first. The best transfer

ratio that results in the most compact design, with suitable insulation clearances must be chosen. At

least two cells should be built and tested. Mutual interaction between the cells, and insulation

performance of the array must be analysed with experiments.


Literature review of existing topologies for wireless power transfer

Design and construction of the power array based on HV requirements and desired power transfer capability. Suitable dielectric and cooling system must be chosen

Experimental verification of the concept design with at least two cells

Contact details:


Peter Vaessen [email protected]


86

D C E & S




DESIGN AND PROTOTYPING A STEP-DOWN 100-1200 V TO 12 V DC-DC

CONVERTER


DC DCDC/DC

Two stages axillary power supply https://en.wikipedia.org/wiki/HVDC_converter

Scope: To design, model and prototype a step down 100-1200 V to 12 volts DC-DC converter for

axillary power supply of MMC sub-modules.


voltage test source capable of generating arbitrary waveforms. One of the option for the final

topology to be used in the test generator is Modular Multi-level Converter (MMC) which has the

advantage of not requiring galvanic isolation. For high voltage MMC it is necessary to power each

sub-module from its own capacitor since it is not practical to power the submodules from a power

supply located at low voltage level. In this design a variable main DC power supply is aimed, thus the

sub-module axillary step-down power supply should operate over a wide range of input voltage.

Methodology: literature review and choice of the topology suitable for the requested specifications.

Design the buck converter and simulating the circuitry in Matlab Simulink. Constructing the proposed

design and report the test results.


Design and simulate a MMC axillary power supply based on the required specifications

Prototyping and testing the step-down converter

A report describing the details of the design

Contact details:


Tiago Batista [email protected]



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D C E & S




DESIGN OF MULTI-LEVEL CASCADED H-BRIDGE, CONTROLLED AND PROGRAMMED

WITH WI-FI

Type of project: Extra project/MSc thesis

H-Bridge and gate driver

DC/DC

AC/DC MC


DC/DC

AC/DC MC


DC/DC

AC/DC MC

25 kHz high current H-bridge

DC Source

3 level cascaded H-bridge converter

Scope: To design and prototype a low voltage multilevel cascaded H-bridge converter with separate

microcontroller on each stage controlled and programmed over Wi-Fi and synchronized by a master

microcontroller.


voltage test source capable of generating arbitrary waveforms. Multilevel cascaded H-Bridge

topology is one of the candidate for the final topology of this test generator. Since the final test

generator has many stages, it is convenient to avoid lots of fiber optic connections for the

communication system. Low cost low voltage motor driver, Wi Fi Arduino, isolating transformers and

DC/DC converters will be used to develop the sub-module. Each sub-module will be made with its

own Wi Fi equipped microcontroller. The goal is to code the microcontroller over Wi Fi and to

generate the desired output waveform. Synchronization of the microcontrollers is done using a

master microcontroller.

Methodology: To construct low voltage sub-module of a multilevel cascaded H-bridge using low cost

components. To develop control and communication system with Wi-Fi equipped microcontroller.


To construct sub-module of multilevel cascaded H-bridge converter

To programme the microcontroller over Wi-Fi

To control and synchronize three stages of the test generator using a master microcontroller

Contact details:


Tiago Batista [email protected]



88

D C E & S




DYNAMIC CURRENT RATING MODEL FOR HVAC AND HVDC CABLES


Scope: To develop a model for dynamic rating of HVDC cables taking into account electric field

dependency of the insulation loss and field distribution.

Problem definition: Dynamic rating is to better use the capacity of cable system without exposing it

to risk of overheating and consequence lifetime reduction. In the cable course students learn how to

evaluate cable ampacity, taking into account different losses and thermal model of the cable system

at 50 HZ AC for a constant current. In this project the existing FEM models must be rebuild using

MATLAB-COMSOL interface and controlled such that dynamic rating of power cables is possible. Field

dependency of dielectric loss and temperature dependency of field distribution must be taken into

account at the same time. This is to avoid over stressing HVDC cable insulation above the rated

stress. An easy to use software must be developed for cable ampacity calculation.

Methodology: The work is simulation based and is performed using COMSOL Multiphysics.

Experimental setup consisting of current varying heating element immersed under water will be

made to verify the accuracy of the model developed.


<literature review, to learn standard method for cable ampacity calculation

<development of a Matlab controlled COMSOL model for dynamic cable rating >

<construction of experimental setup and verification of the developed model>

Contact details:

Supervisor: < Mohamad Ghaffarian Niasar, [email protected]>




89

D C E & S




MODELLING OF A FAST ACTUATOR FOR HVDC BREAKER APPLICATION


Scope: Development of a FEM model that accurately represent operation of a Thomson coil.

Problem definition: To interrupt HVDC current three main technologies are available. In the first

technology power electronic switches are used to interrupt the current. This technology offers a very

fast operation (~1μs) however the on-state loss is rather high which makes the technology expensive

to operate. The second technology is purely mechanical. The on-state loss for this technology is

minimized but the operation time of the switch is rather high (~60ms). In the third technology a

combination of both methods are used in which the on-state operation has almost a minimal loss

while the operation time is reduced significantly (~5ms) compared to purely mechanical switch. To

achieve an ultra-fast actuation a Thomson coil can be used. The coil is connected to a capacitor bank

and the armature is connected to the breaker push-pull rod. By discharging the capacitor bank

through the coil, the armature experienced a force which moves it away from the coil. The

phenomenon involves number of physics that are coupled. Electromagnetism, heat transfer, Newton

motion laws, and solid state mechanic equations. The involved physics must be solved together in

order to accurately model the behaviour of the actuator.

Methodology: The work is mostly focused on computer simulation. After development of the model,

a small scale Thomson coil has to build to verify accuracy of the constructed model. The experimental

part will be done in high voltage laboratory of TU Delft.


Literature review of the existing HVDC circuit breaker mechanisms and understanding operation cycle of each method

To be able to couple different physics in COMSOL Multiphysics software

Development of a FEM model that can accurately predict the operation of a Thomson coil

experimental verification of the constructed model on a small scale Thomson coil

Contact details:


Peter Vaessen [email protected]


90

D C E & S




OVERHEATING ISSUE AT CABLE METALLIC SCREEN CONNECTION TO EARTH


Single core medium voltage power cable with copper wires screen

https://www.powerandcables.com

Scope: Overheating and consequently failures have occurred at medium voltage (MV) power cable

metallic screen termination. The aim of this project is to define the ampacity limit and endurance for

the screen terminations.

Problem definition: The overheating in metallic ground screen connection is due to high transition

resistance between cable metallic screen and the earthing tail, creating heat (RI2), combined with

high induced currents in the metallic screen of the cable in operation.

Methodology: The overheating in screen terminations will be simulated by applying constant and

dynamic current loading as well as over-voltages and transients. Depending on progress, a laboratory

work can be performed to validate the modeling. The simulation will be carried out in COMSOL

Multiphysics.


Literature review and define strategy- understanding of the physical and electrical phenomenon ongoing in cable screens and connections

Simulation of thermal heating in cable metallic screen connections

Perform experiment and validate the developed model

Collaboration with Industry: Yes, DNV GL

Contact details:

Company supervisor, [email protected]

University Supervisor: Peter Vaessen, [email protected]

Mohamad Ghaffarian Niasar, [email protected]




91

D C E & S




THE INFLUENCE OF HARMONICS ON THE DURABILITY OF MV JOINT INSULATION


Scope: The transition of conventional power network with centralized generation towards the grid

with high utilization of renewables is already taking place. The energy harvested by windmills and

solar panels is needs to be transferred to the existing AC grid by means of DC to AC converters. The

converters are based on the principle of high frequency switching of power electronics. This efficient

way of energy transfer has a principal drawback. The generated 50 Hz signal is contaminated with

higher harmonics.

Problem definition: Lovink produces liquid filled MV joint. To ensure a long term reliability of the

joints, a study on the behaviour of materials under the influence of the harmonics is necessary. Since

the dissipation factor is decisive regarding the dielectric heating, it is interesting to observe the

behaviour of tanδ changes when the insulation is subjected to high frequency electric field.

Methodology: The research would begin with the literature study on the influence of higher

harmonics on the condition of the electrical insulation. Further on, the practical part would focus on

stressing the sample of insulation with higher harmonics and performing periodic measurements of

tanδ.


To verify if the quality of the MV liquid/solid insulation will decrease as influenced by the higher harmonics

To determine the behaviour of tanδ for the solid/liquid insulation stressed by higher harmonics

Contact details:

Company contact: Lukasz Chmura, [email protected]

Company contact: Dennis Bergsma, [email protected]

University supervisor: Mohamad Ghaffarian Niasar, [email protected]

Time

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V(S6:4)

-40KV

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40KV

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