Upload
others
View
15
Download
3
Embed Size (px)
Citation preview
Technology for a better society
Tokyo, 27-05-2015
1
Salvatore D'Arco Research Scientist [email protected]
HVDC grid connection
Technology for a better society
• Relevance of HVDC transmission research in Norway • Background for research on HVDC technologies • Examples of R&D focus areas and research projects at SINTEF
• R&D activities on HVDC technologies from a system perspective • R&D activities on HVDC technologies at a component level
• Joint laboratory facilities at NTNU/SINTEF
2
Outline of presentation
Technology for a better society
• Geographical location on the North Sea • Electrification of oil and gas installations • Integration of offshore wind farms • Transnational export of hydropower and balancing reserve
• Present involvement of Norwegian industry in the development of offshore
wind farms in UK and future perspectives of developments of offshore wind in Norway
• Relevance of Norwegian industry as supplier of components as cables, subsea equipment, offshore platforms
3
Relevance of HVDC technologies for Norway
Technology for a better society
• HVAC connection is the preferred option for connection of offshore wind farms relatively close to shore. Cable capacitance prevents its application for longer distances.
• Technology transition from point to point connections based on Line Commutated Converters to meshed grids (e.g. North Sea supergrid) based on Voltage Source Converters
• Recent advances in HVDC technologies • Cable technologies (higher voltage ratings) • Converter terminals (Modular Multilevel Converter) • DC breakers
• Pressure on costs due to expected lower price of energy and lower incentives
4
Background for HVDC grid connection
Technology for a better society
• Reduction of installation and operation costs • Increase conversion efficiency, reduce platform space • Alternatives to HVDC (low frequency HVAC, capacitance compensation)
• Power system protection (fault detection, fault clearance) • Interoperability of converter technologies
• Integration of offshore wind farms • Challenges in power system dominated by power electronics • Load flow analysis and market assessments in future scenarios
5
R&D on HVDC technologies from a system perspective
Technology for a better society
6
Protection and Fault Handling in Offshore HVDC grids Objectives: Establish tools and guidelines to support the design of multi-terminal offshore HVDC grids in order to maximize system availability. Focus will be on limiting the effects of failures and the risks associated to unexpected interactions between components.
• Develop models of offshore grid components for electromagnetic transient studies.
• Define guidelines to reduce the risks of unexpected interactions between components during normal and fault conditions.
• Define strategies for protection and fault handling to improve the availability of the grid in case of failures.
• Demonstrate the effectiveness of these tools with numerical simulations, and experimental tests.
• Expand the knowledge base on offshore grids by completion of two PhD degrees and a PostDoc at NTNU and at RWTH.
Technology for a better society
• Project focus on decentralized architecture not relying on communication between terminals. • Identify fault detection markers to trigger protection devices • Mechanisms to ensure protection selectivity • Impact of Fault Current Limiters on protection schemes
• Verified in simulation a protection scheme based on current derivatives and threshold limits.
7
Fault handling in MT HVDC systems
6 6.001 6.002 6.003 6.004 6.005
2
4
6
8
10
12
14
16
I dc2-
>1,P
[kA
]
Time [s]
6 6.0005 6.001 6.0015 6.002 6.0025 6.003 6.0035
-2
0
2
4
6
8
10
12
14
16
d(I dc
2->1
,P)/d
t [kA
/s]
Time [s]
9: 380km 2->18: 390km 2->17: 400km 2->11: 400km 1->32: 410km 1->3R
2 set-point
BestPaths Project
• Large energy project in FP7 (39 partners from 11 countries, 62 M€ budget)
• Objective is help to overcome the challenges of integrating renewable energies into Europe’s energy mix. It aims to develop novel network technologies to increase the pan-European transmission network capacity and electricity system flexibility.
• The project unites expert partners around five large-scale demonstrations to validate the technical feasibility, costs, impacts and benefits of the tested grid technologies.
• SINTEF Energy hosting demo 1
8
BestPaths Project, Demo 1
• Main focus is on interoperability of HVDC technologies • To investigate the electrical interactions between the HVDC link
converters and the wind turbine converters in offshore windfarms. • To de-risk the multivendor and multiterminal schemes from the point of
view of resonances, power flow and control. • To demonstrate the results in a laboratory environment using scaled
models - 4-terminal DC grid with 50 kW MMC VSC prototypes and a Real Time Digital Simulator system to emulate the AC grid.
• To extrapolate the results to a real project (East Anglia Offshore Wind 7,2 GW in the UK Round 3)
9
Technology for a better society
The Virtual Synchronous Machine (VSM) is a concept for controlling power electronic converters in order to reproduce the characteristics of traditional synchronous machines. • Introducing virtual inertia and damping to controlled power converters
Applicable in a wide range of relevant power system configurations: • Power systems with high penetration of renewables • Islanded power systems dominated by power converters • Offshore power systems (e.g. AC grids for HVDC connected offshore wind farms
and/or oil platforms) Compared to inertia emulation based on frequency derivative offers better performances since does not depend on dominant presence of physical inertia
10
Application of the Virtual Synchronous Machine concept
Technology for a better society
Offshore wind farm with multi-infeed HVDC
11
VSM-controlled
Technology for a better society
• Characterization and reliability of semiconductor devices for high power applications
• Wide band modelling of components for electromagnetic transient analysis • Subsea cable technologies for high power transmission
12
R&D on HVDC technologies at a component level
Technology for a better society
Power Cycling Reliability of Power Electronics Devices
13
Step#1: Temperature determination Step#3: Lifetime prediction according
Miner’s rule
Step#2: Cycle counting
Possibility 1calculation
Possibility 2measurement
Tvj(t)
Minima and Maxima extraction
Input data:e.g.: P(t), Q(t),
wind speed
Ciruit simulationLosses model
Thermal model Rainflow counting algorithm
Linear composition
Nf curves
Residual lifetimexy%
Wind profile
Lifetime characteristics
Technology for a better society
Power Cycling Tester with 4x modules + 4x press packs
14
Technology for a better society 15
Wide band modeling of HVDC components
Volta
ge [p
.u.]
• Advanced techniques for modeling and simulation of linear devices via rational functions.
• Wide-band transformer modeling from measurements
• Non-linear transformer core modeling • Advanced numerical modeling and
simulation of power cables
Simulation of voltage transfer in distribution transformer, validation by measurements
Characterizing transformer via frequency sweep measurements, modeling via rational functions
Technology for a better society
Renewable energy / Smartgrids laboratory
16
• 55kVA wind turbine emulator • 60 kVA 2L-VSC converters
(back-to-back or STATCOM configurations)
• in-house developed 20 kVA laboratory converters with FPGA-based control systems
• OPAL-RT multiprocessor platform • Rapid prototyping • Real-Time & Hardware-
In-the-Loop simulations
Technology for a better society
Laboratory Scale of a Multi Terminal DC Grid
17
AC
DC
ACDC
AC
DC
AC
DC
60 kVA VSC
60 kVA VSC60 kVA VSC
60 kVA VSC
55 kVA Induction gen-set
IM IGAC
AC
17 kVA Synchronous Generator
Grid model with variable load
IM SGAC
AC
Technology for a better society
Future planned developments
• National Smart Grid Laboratory & Demonstration Platform – Infrastructure project financed by RCN – Physical extension and general upgrade – Grid emulator (200 kW, >5 kHz bandwidth) – Strengthening of real time simulation computational capabilities
• Bestpaths project – Development of 3 MMC units – Addition of DC breakers
18
Technology for a better society
Technology for a better society
19