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针对三相重合闸永久性故障判别方法在单相接地故障时灵敏度不足的问题,提出识别并联电抗器零模电流自由振荡频率的永久性故障判别方法。线路故障且两侧断路器跳开后,由于线路电容和并联电抗器的储能,并联电抗器会出现自由振荡电流。利用最小二乘矩阵束算法获取并联电抗器电流的自由振荡频率。瞬时性故障时,线路零模网络与线模网络在电弧熄灭后停止能量交换,该自由振荡频率等于零模网络固有频率主频;永久性故障时,线路零模网络与线模网络通过故障端口进行能量交换,该自由振荡频率等于零模网络和线模网络固有频率主频的算术平均值。因此,通过计算自由振荡频率的数值即可实现永久性故障判别。EMTP仿真表明,该方法能有效识别永久性故障,且不受故障位置、过渡电阻的影响。
Aiming at the problem of lack of sensitivity in three-phase reclosing permanent fault identification method when the single-phase grounding fault occurs, a permanent fault identification method is proposed to identify the free oscillation frequency of zero-mode current in shunt reactor. After the line is faulty and the circuit breakers on both sides jump off, the free-wheeling current will appear in the shunt reactor due to the storage capacity of the line capacitors and shunt reactors. The Free Oscillation Frequency of Shunt Reactor Current Is Acquired by Least Square Matrix. In the case of an instantaneous fault, the zero mode network and the line mode network stop the energy exchange after the arc is extinguished, and the free oscillation frequency is equal to the natural frequency of the zero mode network. When the permanent fault occurs, the line zero mode network and the line mode network are conducted through the faulty port Energy exchange, the free-running frequency is equal to the arithmetic mean of the natural frequencies of the zero-modulus network and the line mode network. Therefore, a permanent fault can be identified by calculating the value of the free-running frequency. EMTP simulation shows that the method can effectively identify permanent faults and is not affected by fault location and transition resistance.