Fast detector of symmetrical fault during power swing for distance relay

Distance relay should be blocked during power swing to ensure the reliability, but still should trip as soon as possible after an internal fault occurs during power swing. It was very difficult to detect the symmetrical fault reliably and fast during power swing with complex power swing conditions and fault conditions considered. This paper presents a new fast detector of symmetrical fault during power swing. Based on the sudden reduction of absolute value of the change rate of power swing centre voltage (PSCV), the presented detector can detect the symmetrical fault reliably and sensitively in two cycles. This detector is easy to set and immune to the swing period, fault arc, fault location and power angle. EMTP simulations and real-time digital simulator system (RTDS) tests prove the presented detector is fast, sensible and reliable.