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Reference Number NIA_NGET0057
Title DC Circuit Breaker Technologies
Status Completed
Energy Categories Other Power and Storage Technologies(Electricity transmission and distribution) 100%;
Research Types Applied Research and Development 100%
Science and Technology Fields ENGINEERING AND TECHNOLOGY (Electrical and Electronic Engineering) 100%
UKERC Cross Cutting Characterisation Not Cross-cutting 100%
Principal Investigator Project Contact
No email address given
National Grid Electricity Transmission
Award Type Network Innovation Allowance
Funding Source Ofgem
Start Date 01 October 2012
End Date 01 April 2016
Duration 42 months
Total Grant Value £257,000
Industrial Sectors Power
Region London
Programme Network Innovation Allowance
Investigators Principal Investigator Project Contact , National Grid Electricity Transmission (100.000%)
Web Site
Objectives The above areas have been identified as needing to be addressed as part of the risk managed introduction of multi terminal VSC HVDC technology onto the transmission system and the future development of DC grids. In particular, if the UK plans on developing truly economical and secure DC grids, a thorough understanding of both the operation and the application of DC breakers will be required. The project will deliver reports on the results of studies and a documented set of models for use in National Grid’s internal system studies. The work forms an essential step in being able to implement the technology on the transmission system. Deliverables: - Interim 1 - Report 2. 1- Interim Report 2 - Report 2. 2- Full Report 2. 1- Interim Report 2. 2- Full Report 2. 2- Full Report 2. 3
Abstract The European Union Renewable Energy Directive has committed the UK to a target of more than 30% of electricity to be generated from renewable sources by 2020. The report “Our electricity network” by the Electricity Networks Strategy Group (ENSG) recognised that a key technology to achieve the above aims is Voltage Sourced Converter (VSC) HVDC transmission. This is well suited to multi-terminal and HVDC Grid applications being considered for onshore and offshore network integration. A major bottleneck for wide-scale HVDC use is DC circuit breaker technology. The present solutions to fault isolation on an HVDC system is to use AC breakers and de-energise the entire DC system, see Figure 1 below. For a heavily integrated DC system, such as that envisaged as giving the lowest cost in the National Grid Offshore Development Information Statement (ODIS, 2010, 2011), this would result in an unacceptable loss of simultaneous generation as stipulated by the Security and Quality of Supply Standards (SQSS) infeed loss risk limits. DC Circuit breakers, Figure 2 below, offer a better solution to isolate a smaller faulted section of the DC network quickly, which ties in better with present AC protection philosophy. However, while the major manufacturers (ABB, Siemens, and Alstom Grid) are working on solutions, no commercial DC circuit breaker exists and breaker technology is unproven at the 500kV, 2kA level proposed for future offshore networks and DC grids. Outline documents to specify future DC products still need to be developed urgently though, as lower voltage and current prototypes are being developed by manufacturers with the intention of commercialising high voltage and current products. It is essential, therefore that an adequate understanding of the possible technologies, their operational characteristics and application issues be developed. Research The method that has been proposed for this project includes;1. DC Circuit Breakers - topologies and physics1. 1 Literature of prior art DC circuit breakers reviewing operation, physical limitations, speed of operation and potential for VSC-HVDC integration. Areas covered include prior art from: - Proposals for VSC-HVDC (papers, patents etc. )- Past LCC-HVDC circuit breakers- Railways- Motor contactors/loads- AC breaker circuits As well as: - A review of methods for DC current breaking, and an indication of what could/could not be scaled up to HVDC voltage levels, to assess what might be proposed in the future by manufacturers. - Impact of AC/DC grid characteristics and proposed grid and converter topologies on faults. 1. 2 Application of technology The review will cover: - Methodologies for testing. - Specification quantities used- Identification of the range of duties (electrical, environmental etc. ) that the DC Circuit Breaker is likely to experience- Suggestion of possible tests and test circuits The work will build on the initial scoping studies undertaken in EPSRC Supergen project “Wind energy Technologies” and National Grid project “Multi-terminal VSC HVDC operation, control and ac system integration”, which involved in the University of Manchester and National Grid. The proposed work is however far more detailed than can be accommodated in either of these projects, within their timeframes and schedule of deliverables. Deliverables: - Interim Report 1. 1- Full Report 1. 1- Full Report 1. 2- First year PhD transfer report2. Detailed Evaluation of Concepts 2. 1. Simulation The initial outline studies of 1. 1 and 1. 2 will be supplemented by detailed simulation to fully evaluate candidate new and potential concepts. Initial simulations will be undertaken in an appropriate software package (such as PSCAD, EMTP or SABER). Key dynamics to be captured will be identified in order to allow reduced order simulations to be carried out in more conventional power systems software, to ensure robust modelling without excessive detail. These models will be used to determine in detail how testing can most sensibly be done to evaluate circuit breaker behaviour (both those presently proposed by manufacturers and future concepts). The goal is to build on the work of section 1 to ensure that the right tests are being proposed and that they correctly capture and predict the behaviour of the equipment in a real system. The tests proposed in section 1 will be reviewed and revised prior to synthetic testing in section 2. 2. 2. 2 Synthetics testing The study work to date will be validated by performing the tests proposed/identified in section 1 and 2. 1 on candidate circuit breaker topologies. This is to see if the right tests are being proposed, and if the test/models represent and predict the behaviour of the physical system. The most promising topologies will be evaluated in the high-voltage laboratory at Manchester, in module or sub-module form. Such systems will be a small part of the high voltage direct current breakers to be tested and so performance of each breaker can be extrapolated from the testing of a small part. Such physics-based testing will allow an evaluation to inform specifications, simulations and establish detailed device functionality. The current break rating of the sub-modules is chosen to be up to 2 kA (as appropriate depending on the level required to satisfactorily test the technology) since this level has been proposed in ODIS. A test rig comprised of a capacitor energy store, high current diodes, inductor, vacuum switch, varistors, shunts, voltage dividers and measurement system will be used to test each proposed topology, for fitness of purpose. 2. 3 Fault Current Limiters Many of the proposed topologies have a severe limit on their over-current breaking capability. The integration of fault-current limiter technology into future DC breaker topologies thus forms an important adjunct to any DC breaker study. A literature review of candidate topologies will lead to simulation of appropriate designs and an evaluation of their ability to enhance DC breaker performance.Note : Project Documents may be available via the ENA Smarter Networks Portal using the Website link above
Publications (none)
Final Report (none)
Added to Database 09/08/18