Identification of Single-Phase Reclosing Fault on AC Line Based on Virtual Instantaneous Power

Concerning the difficulty in distinguishing between permanent and transient faults on AC line in AC/DC hybrid system due to relatively low amplitudes of fault recovery voltage and fault arc voltage, a method to identify single-phase reclosing fault based on virtual instantaneous power is proposed. First, by analyzing AC-side networks in the case of permanent fault and transient fault, the calculation models of instantaneous power difference between two ends of AC line are built. And then, the instantaneous power difference is decomposed into two parts: virtual instantaneous power which is affected by the currents on two line ends and virtual instantaneous power which is affected by the current on one line end alone. On this basis, according to the feature of virtual instantaneous power affected by the currents on two line ends, i.e., it is 0 in the case of transient fault, but not 0 in the case of permanent fault, a fault nature identification criterion to distinguish between permanent and transient faults is constructed. Finally, simulation tests on RT-LAB platform verify that, the proposed method can correctly identify the fault nature and determine the fault arc extinction time in both permanent and transient fault cases, unaffected by the commutation failure and fault resistance.