A NEW ALGORITHM FOR HIGH RESISTANCE EARTH FAULTS DETECTION USING PHASE COMPARISION TECHNIQUE

Abstract

Distance relaying is one of the main schemes in the protection of overhead transmission lines. Recently digital relaying techniques provided many algorithms that present higher performance and better accuracy than the conv ntional electromagnetic and solid state rnlays. The problems associated with distance relaying !nakc any proposed scheme very difficult in hardware and softw rc. This thesis outlines the problems associated with the effect of high resistance earth faults on distance relay measuremen and presents a new digital relayi11g technique to overcome these problems. The main feutures of the technique is the avoidance of using complex mathc e•tical analysis. The proposed relaying scheme solves the relay problems by using a phase comparison technique itl il digital form. The outlined technique was npplicd to 400 KM line and used the restricted reactance characteristic to overcome the problems of the effect of l1igh resistance on the distance relay measurments during earth faults. A suggested arrangment for tl1e relay hardware has been introduced.