A Robust STFT Based Algorithm for Detection of Symmetrical Fault during Power Swing

Effective power swing blocking (PSB) schemes are a crucial component of any power system protection technology. Distance relays act as the primary protection element of the long distance transmission lines. Its operation is based on the impedance trajectory at the relay location. However, apart from faults, there exist multiple power system events that are nonhazardous in nature but has similar impedance trajectories to faults. In order to prevent false triggering of distance relays in such cases, various PSB schemes have been proposed for proper detection and prevention. In the present work a robust STFT based algorithm for detection of symmetrical fault in existance of power swing is proposed. The input attribute of the algorithm is the three phase instantaneous power at the relay location. The 39 bus New England power system model has been utilized as the test environment. Further five diverse power system events simulated in MATLAB-SIMULINK platform have been employed to validate the efficacy of the proposed algorithm.