A New Digital Distance Relaying Algorithm Based on Fast Haar Transformation Techniques with Half a Cycle Offset Free Data

Offset이 제거된 반주기 테이터를 사용하는 고속Haar 변환에 기초한 디지털 거리계전 알고리

A very fast algorithm, using fast Haar transformation with half a cycle dc-offset free data, to extract the power frequency components and to detect faults in power systems is proposed. For the speed-up, two important techniques are used. First, according to the symmetric characteristics of sine and cosine functions, fundamental frequency components are calculated with only half a cycle sample data. For using these characteristics, post-fault de-offset components must be removed beforehand. Therefore, secondly, a newly designed digital filter is used to remove exponentially decaying dc-offset from the post-fault signal. In accordance with series simulations, transmission line faults can be detected in around half a cycle after faults.