Practical Evaluation of Existing Line Protection Methods for Networks Connected with Inverter-Based Renewable Sources: Wayforward

Global renewable installed capacity is expected to increase by 75-90% replacing a major portion of the fossil fuel-based power plants by 2050 (as per forecasts by relevant agencies such as IEA and IRENA). Climate goals, energy security, economy are the major root causes of the shift. Renewable sources are connected to the grid through power electronic converters, unlike conventional sources. The influence of these power electronics converters poses challenges to line protection methodologies. This is due to their unique fault response characterized by limited and control-modulated fault currents. Fault response could also vary from grid to grid depending on prevailing grid codes related to renewable integration. The protection methodologies developed decades back and were created using knowledge of traditional power systems are now at risk of failing. Many practical relay failure cases have been reported due to renewable integration in our discussions with various utilities. In this paper, we evaluate the existing line protection methodologies for lines connected with renewables using experimental and field data. The major challenges and findings are presented in the paper and a way forward is also recommended for further scope of research in this domain.