Park´s transformation based symmetrical fault detection during power swing

Distance relays are blocked during power swings as they are prone to mal-operate in that period. However, if a fault occurs during a power swings, the distance relay must be unblocked to clear the fault with a high degree of reliability. This paper presents a new technique for symmetrical fault detection during power swing using park´s transformation. Park´s transformation theory is applied to convert the three phase voltage and current signals into two signals of direct and quadrature components (d-q). A sample to sample moving window comparison is used for finding power coefficients from voltage and current components of d-q signals. The proposed method is evaluated by comparing with two recently developed approaches. Simulation results are carried out in MATLAB environment by considering different fault situations and results indicate how the limitations of existing methods are overcome by the proposed method.