基于恢复电压拍频特性的超高压SPAR优化策略

为弥补当前基于恢复电压阶段单相自适应重合闸(SPAR)故障识别可靠性低的缺陷,有必要探究一种SPAR优化算法,使得断路器在重合前准确识别故障状态,可靠重合于瞬时性故障。通过计算分析中性点小电抗电压和故障相端电压特性,对比两种故障状态下故障相端电压在恢复电压阶段的差异,选取中性点小电抗电压作为基准值,利用故障相端电压理论值与实测值之差比上中性点小电抗电压,考虑到故障相端电压存在拍频振荡误判区,将比值经过一个拍频周期的检测,只有当所有采样点处比值都大于1时,才确定为永久性故障；若检测到某采样点处比值小于1,则确定为瞬时性故障,结束检测,发出合闸指令。EMTP-ATP仿真数据表明,该优化策略可有效判别故障状态,并且不受故障位置和过渡电阻影响。

EHV SPAR optimization strategy based on beat frequencycharacteristics of recovery voltage

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.