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Reference Number NIA_NGET0106
Title Control and Protection Challenges In Future Converter Dominated Power Systems
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 2013
End Date 01 October 2016
Duration 36 months
Total Grant Value £364,000
Industrial Sectors Power
Region London
Programme Network Innovation Allowance
Investigators Principal Investigator Project Contact , National Grid Electricity Transmission (100.000%)
Web Site
Objectives The innovation outputs are expected to cover following aspects: a) Environmental & Strategic: to facilitate greater percentage of renewable power generation in GB power system. b) Reliability: to ensure stable operation with different generation mixes, and fit for purpose transmission protection functions into the low carbon future. c) Connection: to contribute to avoid block on renewable connections, to avoid a hard limit on renewable power development from a system technical point of view. d) Commercial: to contribute to avoid constraining renewable power development in the low carbon future and reduce cost from billions to lower hundreds of millions of pounds per year in constrains due to system technical reasons. The project’s success can be measured against the following specific deliverables: 1) Representative and validated models of VSC and LCC converters suitable both for system stability (e.g. first swing stability) and protection performance analysis. 2) Establish confident model and studies of GB system with up to 75% NSG, applying NGET’s proposed means of improving frequency stability (optimised synthetic inertia & fast response) and steady state voltage support (in regions with absence of generation in merit)3) Describe key limiting factors of operation with even higher percentage NSG beyond 75%, such as: Synchronising torque inadequacy. LCC-HVDC converter commutation. Protection reinforcement for transmission system. Quality of Supply
Abstract The specific issues to address are as follows: Decreasing synchronising torque and first-swing stability (inertia) of the power system due to converter-interfaced sources. Potential lack of "system strength", and the effects of converters during unbalanced faults. The impact of strength-related effects and converter interfaces on protection system performance (e.g. specific issues around impulse starters, possible issues with waveform distortion on fault detection and discrimination, etc. ). How harmonics (and unbalance) will increase in future, and how they can be controlled and/or absorbed. Research Two PhD studentships are proposed for this project. Both students will initially focus on building understanding and simulation skills to enable the performance of the system under a range of future converter-dominated scenarios to be accurately characterised. Following on from this, one of the students will concentrate on the area of converter control and response of converter-interfaces to system transients, exploring ways in which converters can be made more "grid-friendly" across the range of studied scenarios. Focused on increasing synchronising torque, the other student will concentrate on the system protection aspects, examining specifically the effects of converter dominated generation systems on existing protection schemes, and the potential for novel protection schemes to address identified problems. Both students will be part of a complementary team, with requirements, constraints and solutions from each side being considered by both parties throughout the studies. They will be part of a large existing team of researchers and academics. While the envisaged activities and deliverables are as described below, these may change during the project to ensure that the end result is a holistic viewpoint consistent with the findings of both researchers and the wider team. NGET’s input to problem specifications and provision of specialist engineering support, data and validation of outputs is critical. It is envisaged that in the later stage manufacturers of converters & protection systems will be coupled For the student focusing on converters, the main activities will be: 1) Characterisation of system performance under a variety of future scenarios - with a focus on overall system and individual converter responses to a range of events under different levels of converter-penetration. 2) Investigation of incremental changes to existing "conventional" converters (i.e. dq-based inner-current-loop controlled with PLLs) which might make them capable of providing inertial responses, and/or enhanced fault ride-through and fault-current responses. 3) Investigation and demonstration of more radical non-standard converter control algorithms such as "Virtual Synchronous Machines", which could potentially provide inertia, synchronising torque, harmonic (and unbalance) mitigation, and useful fault current output, even during unbalanced faults and in networks with arbitrary impedances such as cable- connected networks (where reactive power infeed is not the correct response). This investigation could span both dynamic electrical effects at very short time steps, but also higher-level costs/benefits/constraints implied by such implementations, due to over-rating required and/or energy storage required at the DC bus or elsewhere. For the student focusing on protection, the main activities willbe: 1) Characterisation of system performance under a variety of future scenarios - with a focus on LCC and VSC responses to balanced and unbalanced system faults. This will require investigation and development of representative high resolution models of VSC and LCC type converters capable of reproducing instantaneous values (over the required time steps of interest) of currents and voltages in response to both symmetrical and unsymmetrical faults. 2) Using the developed high fidelity converter models, conduct an investigation into the performance of transmission system protection schemes under a variety of high converter penetration scenarios. 3) Investigate, develop and demonstrate alternative and novel protection methods that are resilient to wide variations in fault level, are sensitive to very low fault currents and can cater for the anticipated changes to waveform shapes and distortion levels that may arise during faults on converter-dominated systems.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 10/07/18