To make up for the deficiency of low reliability that current single phase adaptive reclosures(SPAR) identify faults based on the recovery voltage stage, it is necessary to explore a SPAR optimization algorithm, so that the circuit breakers can identify faults accurately before reclosing, then reclose on a transient fault reliably. The characters of fault phase terminal-voltage and neutral small reactance voltage are analyzed and calculated, and the differences of the fault phase terminal-voltage between the two fault states at the stage of recovery voltage are compared. Considering that there are some misjudged zones caused by beat frequency oscillation on the fault phase voltage, the neutral small reactance voltage is taken as a base value, and the ratio of the difference of calculated and measured on fault phase terminal-voltage to the neutral small reactance voltage is detected through a cycle of beat frequency. Only when all ratios are greater than 1 at the sampling points, a permanent fault is identified. If the ratio of a sampling point is less than 1, the transient fault is identified, the detection is ended and reclosing instruction is sent out. The simulation results of EMTP-ATP show that the optimization scheme can identify the fault status effectively, and be free of fault location and fault resistance.
