Study on Operational Characteristics of OCR with Voltage Component in a Power Distribution System with SFCL

Abstract

Recently, the power system has been changed to introduce the loop power distribution system or the distributed generations for stability and flexibility of power supply. These changes tend to influence on the capacities of protective devices and may cause the malfunctions due to excess of the devices’ capacity. So, as one of the countermeasures of reduction of the fault current, the superconducting fault current limiter (SFCL), has been noticed. However, the reduction of the fault current due to the application of the SFCL in a power distribution system may be able to cause the unexpected malfunctions of the overcurrent relay (OCR). As the OCR, one of the representative protective equipment in a power distribution system, requires the current exceeding the pickup current to be operated, the reduction of the fault current may affect to trip operation of OCR. So, this paper will deal with a trip delay caused by application of the SFCL, which is one of the unexpected malfunctions. To improve OCR’s trip delay, the OCR with voltage component is proposed and the operational characteristics of the OCR with voltage component have been analyzed using the PSCAD/EMTDC in a power distribution system.