Discrimination of permanent faults for three-phase autoreclosing based on model identification

A novel permanent fault discrimination method for three-phase auto-reclosing of transmission lines with shunt reactors is proposed. The method takes phase selection results as basis and considers the transient fault model as the reference. It takes currents of shunt reactors as known quantities and calculates the aerial modal component of capacitive currents and voltages of both terminals. The formula is further established for summing the currents of shunt reactors and aerial modal component of capacitive currents of both terminals. In case of a transient fault, the result of the formula is zero because the actual fault model is consistent with the reference. But in case of a permanent fault, the result of the formula is non-zero because the actual fault model is inconsistent with the reference. EMTP simulation results show that the proposed method can reliably and effectively distinguish permanent faults from transient faults and apply to three-phase adaptive reclosure scheme on transmission lines with shunt reactors.