HVDC systems play a critical role in facilitating the objective of the GB power system moving towards low-carbon operation in the future. The ambitious plans for HVDC system development and growth, coupled with the rapidly increasing penetration of Non-Synchronous Generation (NSG), has introduced significant challenges to the operation of transmission systems, and these challenges will grow as the penetration level increases markedly in the future. One of the key challenges is the potential impact of the increasing proliferation and capacity of converter interfaces (between generation/HVDC interconnectors and the AC systems) on the reliable operation of existing AC protection systems.
This project aims to develop and use high-fidelity and representative network models, test configurations, and procedures for comprehensive testing and assessment of the impact of HVDC system and, more generally, converter-interfaced sources, on AC protection performance. The network model will be simplified but representative and configurable, in order to emulate different levels of NSG penetration, overall system strength and fault level for evaluating AC protection performance. Different control strategies will be applied to the HVDC systems (i.e. dictating the behaviour of the converter interface in response to AC system faults) to investigate the most desirable options to support dependable, secure and timely protection operation. A Synchronous Compensator (SC) model, applied at the HVDC site, will also be included in the network model to investigate how the SC with varied capacity could support the AC protection operation. The network model will be developed using the RSCAD/RTDS platform and a Hardware-in-the-Loop (HiL) test setup will be established where the RTDS simulator and physical protection relays will be interfaced using current and voltage analogue amplifies.
Test procedures and methods will be developed for comprehensive assessment of protection performance using the HiL test setup under a variety of typical converter scenarios. This way potential risks of compromised protection performance will be evaluated. To address (or at least reduce) those risks, several potential mitigating measures (e.g. improved fault current injection strategy, protection settings adjustments, installation of a SC with varied capacity, etc.) that could help maintain high performance of existing protection schemes will be identified and tested. Based on the outcomes of the tests, recommendations relating to desirable converter performance during faults and the desirable capacity of SC will be established to inform both, future revisions of grid codes, and improved design of HVDC systems.