A Study of the Best Suited Algorithm for Digital Protection Relay in Fluctuated Overload Condition

과부하상태의 변동을 고려한 디지털보호계전기의 최적보호알고리즘 연구

Recently, in power system, even though the needs of digital protection relay are highly increased, there are some problem in the field during apply digital protection relay. When the relay are in the fluctuated overload condition, existing algorithm calculate the trip time only with the measured current of just previous stage, and when the load current fluctuate between overload and normal condition, existing algorithm sometimes dose not make the relay trip. This thesis will study about these kinds of existing algorithm problem in digital protection relay, and will suggest the best suited algorithm for digital protection relay in fluctuated overload condition.