An active detection scheme for permanent fault identification before phase-to-phase reclosing in a distribution network

Traditional auto-reclosing may reclose to the permanent fault after a phase-to-phase fault occurs in the distribution line. Thus an active detection scheme for identifying the permanent fault of a distribution network before phase-to-phase reclosing, with additional capacitance, is proposed. The pre-charged additional capacitor is switched to the phase to phase circuit after tripping for several times, and the fault circuit state is identified using the discharge current attenuation characteristics of three phase-to-phase circuits. When the discharge current attenuation characteristics of any circuit are significantly different from those of other circuits, there is a fault in the phase-to-phase circuit. If the discharge current attenuation characteristics of the circuit are highly consistent in the discrimination period, the phase-to-phase fault is considered as a permanent fault. According to the difference of discharge current attenuation characteristics between phase-to-phase circuits, a permanent fault identification criterion and its implementation scheme are established. The simulation results based on PSCAD show that the proposed scheme can accurately identify a permanent phase-to-phase fault in different fault locations and with different transition resistances. This is helpful in avoiding the blindness of reclosing action of a phase-to-phase fault in a distribution network. © 2021 Power System Protection and Control Press.