Smart Grid Research at The Ohio State University
Jin Wang, Mahesh Illindala [email protected]
November 28, 2016
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Renewable energy based charging facility
Vertically Integrated Research Topics
New switching devices
Circuits and control
System integration
Two Junction points
kk-1
(K)dcV
k+1=kS k+1S
kS k+1S
(K-1)dcV
Reference
Waveform
m1A
2A
21 AA kS
k+1S= k
k+1
Two Junction points
kk-1
(K)dcV
k+1
kS k+1S
(K-1)dcV
Reference
Waveform
m1A
2A
21 AA
300 kW Inverter for the Integration of Renewable Energy
Optimal PWM for Multilevel Inverters
SiC and GaN Devices
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Desired Features for Smart Grid Power Electronics
► Higher reliability
► Higher efficiency
► Lower cost
► Better stability in spite of constant
power loads
► More comprehensive system level fault detection and protection for microgrid
and dc networks
► Reduced complexity of High Voltage DC (HVDC) and Flexible AC Transmission
Devices (FACTs) with medium voltage SiC devices
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Research Project Examples and Research Platform
► SiC based Power Electronics for Utility Applications
► CERTS Microgrid
► Flexible Distributed Energy Resources
► Real-time simulation platform
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Example 1: SiC Devices for Utility High Voltage Applications
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The Need for High Voltage DC (HVDC) Systems
Source: Siemens, HVDC and Trans Bay Cable, 2005
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Evolution of Switching Devices
Dr. kamel Madjour, Silicon Carbide Market Updates, PCIM May 2014
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Trans Bay Cable Project
The world’s first IGBT based HVDC project (Yr. 2010).
Circuit topology: 200 kV DC, 600 MW, IGBT based Modular Multilevel Converter
(MMC)
In North America, four IGBT based HVDC projects have been approved or
commissioned.
Source: Siemens, HVDC and Trans Bay Cable, 2005
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Thyristor GTO, and IGBT based Solutions
Source: Siemens, HVDC Plus Basics and Principle
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The Rise of SiC Power Devices
Dr. kamel Madjour, Silicon Carbide Market Updates, PCIM May 2014
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SiC Based Medium Voltage MMC Project at OSU
►Team
• Longya Xu, Jin Wang, Fang Luo (OSU)
• Julia Zhang (Oregon State University)
• National Renewable Energy Laboratory (NREL)
• More than 10 students
►Idea
• White House Initiative to improve efficiency and reduce footprint of industrial MV drive systems
►Objective
• To build 1 MVA medium-voltage Modular Multilevel Converter and using SiCswitching devices
Compared to Si based solutions, SiC based solution will provide better
power quality and lower power loss.
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►Specifications
• Rated power of 1 MVA
• Up to 4160 V rms line-line
• Motor current up to 140 A rms
• Fundamental frequency up to 1000 Hz
►Results in the first two quarters
• Market survey of MV drives and SiC devices
• Characterization of two 1.7kV SiC devices
• Design and fabrication of gate drive board
• Design of main circuit components (capacitors, inductors)
• Design of DSP and FPGA controller boards
• Offline system simulations using MATLAB
Gate
Driver
Board
Load
Inductor
Coaxial Current
Shunt
Decoupling-
Capacitors
DC-link
Capacitor
Laminated
Bus Bar
DPT FixtureSiC Module
Vgs: 25 V/div
4 µs/div
Id: 100 A/div
Vds: 250 V/div
Hard switching waveform at 1160 V/300 A
Vds voltage overshoot is 100 VSingle Submodule Single MMC Arm
SiC Based Medium Voltage MMC Project at OSU
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Example 2: Modeling and Control of CERTS Microgrid
14Aerial View of the CERTS Microgrid
The first utility microgrid test bed with distributed energy sources and
storage devices.
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Vs
To gain a better understanding of the mechanical & electrical limiting conditions of distributed energy resources (DER)
Inverter-based DERs Synchronous
generator-based DERs
Any islanded microgrid can be subjected to its limiting conditions for overloads.
Project Objective
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Source: Datasheet of GM 8.1L engine, 8.1L, 8 cylinder – 496 cubic inches, General Motors
Mechanical torque limit, Tlim
Mechanical power limit, MPmax
Role of Fuel Map on the Mechanical Power Limit of DER
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Modeling Approach
Physics-based modeling of DERs without infringing
on confidential information of manufacturers
Modeling of essential characteristics to represent
the general behavior of DERs from a broad range of
manufacturers
Limiting conditions are not observed in scaled-down
laboratory microgrid experiments emulating engine
prime-mover by alternative means
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Synchronous Generator-based DER Model
Engine fuel map sets the
mechanical torque limit
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Mechanical power limit: Torque limit of the prime-mover Tlim
gets reflected as MPmax line on the P-f characteristics
Step load
0-80 kW
Mechanical Power Limit on the Synchronous Generator-based DER
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Mechanical torque limited at Tlim
Step load 0-80 kW
Impact of Limiting Conditions on the Synchronous Generator-based DER
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Inverter-based DER Model
Engine fuel map sets the
mechanical torque limit
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Mechanical power limit: Torque limit of the prime-mover Tlim
gets reflected as MPmax line.
Step load
0-94 kW
Impact of Limiting Conditions on the Inverter-based DER
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Step load
0-94 kW
Impact of Limiting Conditions on the Inverter-based DER
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Example 3: Flexible Distributed Energy and Storage Resources
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Energy Saving Formations in Nature
Drafting
“Formation flight of birds improves aerodynamic efficiency. Theoretically, 25 birds could have a range increase of about 70% as compared to a lone bird ..”
- Lissaman and Schollenberger, Science, 1970.
Leading
Flying Geese
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Energy Saving Formations in Nature
“Pelicans flying in a ‘V’ can glide for extended periods using the other birds’ air streams ..”
- Weimerskirch, et al., Nature, 2001.
Weimerskirch, et al., Nature, 2001.
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Flexible Distribution of EneRgy and Storage Resources (FDERS)
Adjust formation by adjusting virtual impedance of the
inverter based generation units.
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Flexible Distribution of EneRgy and Storage Resources (FDERS)
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Real-time Simulation based Hybrid Microgrid Testbed
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Why Real-time Simulation?
Why is real-time simulation important?
Provide hardware-in-the-loop functions
Hardware-in-the-loop methodologies:
Control Hardware-in-the-Loop (CHIL)
Validation of control strategies, e.g.electric machine drive speed / flux control
Power Hardware-in-the-Loop (PHIL)
Validation of both electrical equipment and associated control strategies
System-in-the-loop (SITL)
Validation of communication strategies, e.g. cyber security
http://ww.opalrt.com
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Main Grid
Transformer11
Fuse11 CB11
Converter Inverter
Local Energy
Storage (LES)
CB21 Fuse21
PVConverter Inverter
PV31CB31Fuse31
PVConverter Inverter
PV32CB32Fuse32
Converter Inverter
PHEV1
CB41
Fuse41
Converter Inverter
PHEV2
CB42
Fuse42
CB51
Fuse51
Load1(Normal)
CB52
Fuse52
Load2(Nonlinear)
CB61
Fuse61
Power
Amplifier
Real Time Simulator
Virtual Microgrid
LCL21
LCL41 LCL42
LCL32
LCL31
LCL61
208 V
Microgrid
Control Center
OPNET
Communication Server
SwitchboxVoltage, Current, Power,
Circuit breaker Status,
DSP control command
PHIL
SITL
SCADA
Overview of the OSU Hybrid Microgrid Testbed
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Features of the Testbed
Flexible and reconfigurable electric power network with real-time
simulation based Power Hardware-in-the-Loop (PHIL) unit
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Main Grid
ACDC
ACDC
ACDC
ACDC
ACDC
Transformer
Power
Amplifier
PHEV I
PHEV II PV Panel II
PV Panel I
AC Load LES
ACDC
PV Panel III
ACDC
PHEV III
PHIL based Virtual Branches
Real Hardware Branches
ACDC
ACDC
ACDC
ACDC
ACDC
Power
Amplifier
PHEV I
PHEV II PV Panel II
PV Panel I
AC Load LES
PHIL based Virtual Grid
Real Hardware Branches
ACDC
ACDC
ACDC
ACDC
ACDC
Power
Amplifier
PHEV I
PHEV II PV Panel II
PV Panel
I
AC Load LES
Real Hardware Branches
Microgrid 1
Microgrid 2
Utility
PHIL based Virtual Microgrids and the
main utility lines.
- Simulate one or several subsystems of the Mircogrid
- Simulate a scaled-down utility grid, and study the interaction between a Microgrid and the utility
grid
- Simulate one or more scaled-down Microgrids, and study the interaction between different
Microgrids
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Features of the Testbed (Cont’d)
Flexible and reconfigurable communication network with System-in-
the-Loop (SITL) unit
Low latency real-time Supervisory Control and Data Acquisition
(SCADA) system with high speed data acquisition
- Accept real network traffic
- Simulate different types of communication networks at real time
- Controllable latency, loss of packets, and cyber attack, etc.
- FPGA based Data Acquisition
- Real-time operation system dedicated for communication
Communication
Network
SimulatorReal Network
TrafficReal Network
Traffic
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Experiential Setup
Hybrid Microgrid Testbed setup
PHIL Inverter Pack FPGA based
SCADA
PHIL Real-time
Simulator
Real-time Monitoring
and Control Center
LES Unit
LANProgrammable
AC Load
The Monitoring and Control Station
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Experimental Results
The PHIL system and LES system are operating together in grid-
connected mode
The SCADA system is collecting information from the testbed and
displaying it in HMI
10 ms/div
Vgrid: 250 V/div
IPHIL: 2.5 A/div
ILES: 10 A/div
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Conclusions
► Future Smart Grids require innovation in both hardware and control
►Power electronic and especially SiC based power converters will bring new circuit functions and improved performance
►DER based Microgrid control need address interactions between of mechanical systems and electrical systems
►New control strategies can be implemented to improve system reliability
►New test platforms are needed
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To save a life, be a doctor.
To save the world, be a power
electronics engineer!
Thank you!
Questions?