Renewable energy integration challenge on power system protection and its mitigation for reliable operation

Renewable energy resources are environment friendly but their integration as distributed energy resources (DERs) poses fundamental operational and governance challenges such as power system instability, reliability, power quality and protection. Protection is one of the major issues with integration of renewable energy with distribution system. Considering the high variability of generation from DERs, the current contribution from DERs are also highly dynamic and that can create bidirectional power flow, influence the protection relay operations and can introduce protection blinding to the existing protection relays. The present protection relays are unable to adjust with these dynamic changes as the fault current level varies with the DERs contributions, therefore relay pickup current settings are unable to match with the updated network conditions. Therefore, a secure protection for distribution network is a challenging issue with high penetration of DERs. This paper introduces an alternative protection scheme that can work irrespective of grid connected or islanded condition of distribution network and update its relay settings and pickup current based on the point of common coupling (PCC) information. This proposed scheme was tested in a 3-bus system and in IEEE 33-bus radial distribution network and was able to handle the protection blinding issue.