Adaptive Voltage Based Relay Setting for PV Connected Distribution System

Inverter based distributed generations (IBDGs) have gained popularity in order to reduce carbon emission from fossil fuel based power plants. The contribution of very low fault currents due to low thermal overload capability and low voltage ride through (LVRT) techniques applied to control the voltage has resulted in different voltage profile than the fault condition with conventional synchronous machines. As a result, integration of these sources in distribution grid has caused maloperation of conventional over current relays (OCRs). In this paper, the adaptive setting of the OCR has been proposed using estimated voltage considering the operation of LVRT. The validation of the method proposed is been investigated on an IEEE distribution system comprising of 12 buses, using DIgSILENT Power Factory 2018 software and results obtained are significantly better. Both the time of operation of relays is improved and coordination is maintained.