Differential Power-Based Symmetrical Fault Detection During Power Swing

Distance relays are blocked during power swing to ensure reliability of the power system. However, if a fault occurs during a power swing, it should be detected and the unblocking function should be invoked to clear the fault as soon as possible. Due to the symmetric nature of signals during the power swing, symmetrical faults are difficult to be detected. In this paper, a differential power-based fault detection technique is proposed for the detection of symmetrical faults during power swings. The differential power is calculated from the difference in predicted and actual samples of voltage and current. The predicted voltage and current samples are obtained using the autoregression technique. The proposed method is tested for different fault conditions and the results are compared with the available method. The proposed method is found to identify symmetrical faults accurately during slow and fast power swings for different power systems.