ANN based distance protection of long transmission lines by considering the effect of fault resistance

Distance relays are widely used for protection of transmission lines. Traditionally used electromechanical distance relays for protection of transmission lines are prone to effects of fault resistance. Each fault condition corresponds to a particular pattern. So use of a pattern recognizer can improve the relay performance. This paper presents a new approach, known as artificial neural network (ANN) to overcome the effect of fault resistance on relay mal-operation. In this paper effect of fault resistance for single line to ground type of fault is considered. The scheme utilizes the magnitudes of resistance and reactance as inputs. Once trained with a large number of patterns corresponding to various conditions, it can classify unknown patterns.