Overcurrent protection assessment with high PV penetration in a distribution network

This paper investigated the potential protection issues associated to high PV penetration. Impacts of different penetration level (20%, 40% and 60%) on two different network configurations (centralized and distributed) have been modelled and analyzed using PSCAD/EMTDC software. The inverter controller response was assessed under grid faults integrating LVRT capabilities. The presence of PVs in the grid has led to identify nuisance tripping or false tripping in high penetration condition of Solar PV. Moreover, and most important presented in this research is the operational impacts study of PVs on the protection coordination which has been done for a satisfied backup and selectivity protection with a reliable and effective relay setting suggestion. In the simulation results, the most impactful fault is with the centralized case (fault3) causing the protective device to trip faster, which tends to be harmful for high penetration. The severe increase of the available short circuit current due to the proximity of PVs can impact neighbouring overcurrent protection devices, which implies a potential use of protection devices with directional capabilities. Some measures have been recommended as well to mitigate the PV impacts with an acceptable penetration level.