Impact of Renewable Energy Sources on the Protection of MV Distribution Networks

Given the speed of renewable energy sources (RES) introduction in modern grids, there is an increasing need to characterize the challenges it imposes on protection systems and find suitable solutions to maintain reliability.
This paper describes the results obtained in tasks 3.4 and 3.5 of the FLEXIGRID h2020 project, in which a study of the impact of converter-based generation on feeder relays installed in MV primary substations and on fault passage indicators installed in MV secondary substations was done.
A benchmark MV distribution grid was defined and modelled in RTDS, including high penetration with PV and wind type III and IV generators. Different test cases were defined, with different fault locations, fault types, fault resistances, load conditions and neutral connections. The Spanish Grid Code was considered when defining the control of the mentioned converter-based generators. In this work, the results of testing with the traditional units and algorithms are shown, it describes the new units and algorithms implemented in the feeder relay and fault passage indicator; in the final section it exposes the results obtained with the improved protection functions and finally, the challenges faced in setting.