A fault detection and classification using new distance relay

This paper describes a new distance relay for fault-detection and classification in transmission lines using wavelet transform. The coefficient of discrete approximation of the wavelet transform with Haar wavelet is taken as an index for transmission line fault detection and selection of faulty-phase. The abrupt direct offset (DC) component of the current in a power system can be found and used to be a fault detection indicator. The apparent impedance has been calculated and then compared with the setting impedance using the same technique of wavelet . A simulated fault signals using Matlab is used to verify the algorithm of relay. The relay tested practically using lab T.L. The simulated result and the practical results agrees. This technique will detect the fault and gives a trip signal during the first- half cycle after the initiation of the fault.