Protection challenges in future converter dominated power systems: demonstration through simulation and hardware tests

A model of a converter source capable of providing a controllable fault response is introduced to analyse the performance of protection in future power system scenarios. Using a reduced power system model of the National Grid transmission system in Great Britain, a comprehensive set of tests of protection performance are performed to verify how protection systems may be impacted by the introduction of converter-interfaced energy sources and infeeds. Converters with a range of different types of fault response are modelled, as grid codes defining converter response to AC system fault are not completely specific at the present time. The simulated data are injected into an actual protection relay through secondary injection equipment and also to a dynamic protection relay model through simulation, and the results are analysed and compared. The initial results show that there can be a degree of negative influence on protection system performance in converter-dominated scenarios where the power system is relatively “weak”, primarily in the form of longer operating times in certain scenarios. The paper concludes with analysis of results and an overview of on-going and future work to broaden the investigations.