A new method for fault detection during power swing in distance protection

During a power swing, currents and voltages behave such as a fault. Therefore, power swing blocking function in distance relays is necessary to discriminate between a power swing and a fault. Otherwise power swings can be considered as a fault and causes relay trip. The main problem happens when during power sings a fault occurs. In this case, distance relays should be unblocked. In this paper, a new method based on the DC component of fault currents will be proposed to detect a fault during power swing blocking. The proposed method can detect single-phase to ground, two-phase to ground and three-phase fault. Applying the new method on a sample network reveals the features of the method.