Vulnerability Assessment for Primary-Backup Overcurrent Relay Coordination Deprivation Due to Virtual Power Plant

Variable renewable energy-based distributed generations (VRE-DG) have extensively penetrated into the conventional distribution network. A virtual power plant (VPP) can group the diversified VRE-DG into one unit. The VPP operator (VPO) can control the VRE-DG operation and coordinate with the distribution system operator (DSO) for electricity trade and economic dispatch. Thus, converting consumers into prosumers. The VPP commissioning can complex or degrade the operation of the protection system. In this paper, a detailed analysis of potential susceptibility degradation of primary-backup overcurrent relay (OCR) coordination owing to VPP is provided. Protection degradation index (PDI) is introduced and a novel strategy to emend the parameters of affected OCR according to PDI is proposed to rehabilitate the coordination among primary-backup OCR. The studied VPP includes wind turbine generator (WTG), Photovoltaic (PV), and communication station-based storage batteries (CSESB). The case studies are conducted on the Tianjin distribution network (TDN) China, modified with the incorporation of VPP to show the impact of VPP on protection coordination and proficiency of the proposed strategy.