A Percentage Current Differential Relay for Bus Protection Using a Compensation Algorithm Unaffected by a Remanent Flux

잔류자속에 무관한 보상 알고리즘을 적용한 모선보호용 전류차동 계전방식

This paper proposes a percentage current differential relaying algorithm for bus protection with a compensation algorithm of a CT. The compensating algorithm estimates the core flux at the start of the first saturation based on the value of the third-difference of the secondary current. It calculates the core flux and compensates distorted currents in accordance with the magnetization curve. The test results indicate that the algorithm can discriminate internal faults from external faults when the CT saturates. It can improve not only stability of the relay in the case of an external fault but sensitivity of the relay in the case of an internal fault.