Mobile QR Code QR CODE : The Transactions of the Korean Institute of Electrical Engineers
Title A Prevention Algorithm for Malfunction of Directional Over Current Ground Relay in Distribution System with PV System
Authors 박양권(Yang-Kwon Park) ; 이후동(Hu-Dong Lee) ; 태동현(Dong-Hyun Tae) ; 노대석(Dae-Seok Rho)
DOI https://doi.org/10.5370/KIEE.2020.69.7.1001
Page pp.1001-1009
ISSN 1975-8359
Keywords DOCGR; PV System; Power Source System; Malfunction; SLG Fault; Protective Device; Test Devices; Current Transformer; Protective Relay
Abstract In distribution system with PV system, malfunction cases of the DOCGR have been reported by an misuse of RCA(reference characteristics angle) and OPA(operation angle) at installation of CT and caused the problems including interruption and unstable power supply. Accordingly, practical countermeasures to prevent a malfunction of DOCGR in the field are being required. Therefore, this paper presents a malfunction mechanism of DOCGR in distribution system with PV system and proposes of prevention algorithm for malfunction of DOCGR to be operated only in case of SLG(single line-to-ground) fault at PV system side.
Furthermore, in order to perform a demonstration of malfunction in DOCGR, this paper presents a modeling of test devices for DOCGR which is composed of power sources, protection devices and PV system based on PSCAD/EMTDC S/W, and also implements a 2.5kW scaled test devices for characteristics of DOCGR. From the simulation and test results of malfunction characteristics of DOCGR based on the proposed modeling and test devices, it is confirmed that the malfunction of DOCGR has been occurred in case of SLG faults at both power source and PV system side if direction of CT is installed to reverse(L-K). In addition, it is found that the proposed algorithm is practical and useful tools to prevent malfunction of DOCGR without modification of wiring and position of CT when the DOCGR is operated by changing the proper setting values of RCA and OPA. And also, it can contribute to user education for preventing malfunction of DOCGR in real distribution system.