배전계통에 한류기적용을 고려한 임피던스보정 알고리즘을 활용한 과전류계전기 동작 특성 분석

초록

Recently, as the interest in renewable energy has increased and the electric power industry has developed, the distributed power generation has increased and the fault current has increased. This situation can cause the over-current which exceeds the capacity of the circuit breaker, it may lead to accidents in a power system, so it needs to replace in a larger capacity circuit breaker or to reduce the fault current. Installing a superconducting fault current limiter (SFCL) is an effective way to limit the fault current, though the trip delay of the over-current relay(OCR) occurs, also affects the protection coordination between OCRs. The correction method using the voltage component of SFCL was carried out as a previous study on this problem. However, this method is complicated because the correction factor should be changed according to the system condition. In this paper, an impedance compensation method is proposed to effectively exclude the effect of SFCL on the OCR. Unlike the correction method using the voltage component previously studied, the bus voltage was reflected, and the relay elements were calculated as impedance using this to reconstruct the characteristic equation of the OCR to decrease the influence of the SFCL. In addition, for precise correction, the impedance is divided into resistance/reactance components and compared with previous method. The results are analyzed through simulation using PSCAD/EMTDC.

키워드