Distance protection issues with renewable power generators and possible solutions
Neena George, O. D. Naidu
Abstract
Global initiatives to reduce negative impact on environment and strategies to mitigate climate change issues have led to increased stress on clean and green energy. However, this change for good is accompanied by new challenges to power system engineers, especially protection engineers. Traditional protection philosophies designed for grids dominated by synchronous generators have now become inadequate to protect modern grids with high penetration of inverter-based renewable energy resources. The peculiar fault current characteristics, controlled by converter topologies, control algorithms, grid codes and fault ride through characteristics have introduced challenges to the most prominently employed distance protection. This paper analyses the impact of inverter-based resources on the performance of stepped distance protection, including Zone 1, Zone 2 and Zone 3. Extensive testing is conducted using transmission line system modelled in PSCAD, and observations are discussed. Certain insights on potential solution strategies are also provided. Further, performance of fault location function, which is an integral part of commercial distance relays, is also analysed for the renewables-integrated grid. Single-ended as well as double-ended fault location algorithms are studied, and observations are discussed.