The use of S-Transform for distance relay´s power swing detection

This paper presents an intelligent approach for detecting power swing for distance relay operation. The proposed scheme uses time-frequency transform known S-Transform for feature extraction. It is based on S-Transform analysis on the active power measured at distance relay point in transmission line. The proposed scheme overcomes the traditional relay scheme drawback, by detecting and discriminating the unstable from stable swing occurring in the system. To ascertain validity of the proposed scheme, simulations were carried out with the IEEE 39 bus system. Test results show that the proposed scheme can reliably be used for detecting unstable swing from stable swing.