500kV超高压输电线路发生单相接地故障大部分是瞬时性故障，采用自动重合闸技术使故障线路在短时间内恢复供电，可以大大提高输电的可靠性和连续性。但是重合于永久性故障对系统的稳定性和电气设备带来的危害高于正常短路时。为了避免永久性故障时自动重合闸装置的再次重合对电力系统造成危害，应该在重合闸二次合闸前判断故障的性质，从而实现自适应重合闸。在超高压输电线路中安装并联电抗器可限制过电压，中性点加小电抗可抑制潜供电流的大小，提高合闸成功率，因此对于带并联电抗器输电线路故障性质的判别的研究具有实际意义。 本文研究了500kV带并联电抗器的单回及同杆双回输电线路发生单相接地故障时故障性质的判别方法，主要工作如下： （1）分析了并联电抗器及中性点小电抗在超高压线路中的安装地点、接线方式和选取，以及如何避免串联谐振的发生。建立了线路仿真模型，研究中性点小电抗对潜供电流的抑制作用，从而提高合闸成功率。 （2）研究了带并联电抗器输电线路单相接地故障后恢复电压的特性。瞬时性故障时恢复电压由电容耦合电压和电磁耦合电压组成，永久性故障时恢复电压仅包含电磁耦合电压。分析了带并联电抗器补偿的线路中，故障相端电压、并联电抗器和小电抗电压三者的关系。对断开相电压进行了仿真验证，仿真结果表明，瞬时性故障时并联电抗器和中性点接小电抗两者之间的电压波形差异性大于永久性故障时两者之间的电压波形差异性。 （3）根据信号距离函数的特性，提出了基于时域有限因果离散信号互距离函数的自适应重合闸故障判据，通过检测计算故障相并联电抗器电压和中性点接小电抗电压之间的互距离函数值，根据数值大小判定故障性质。利用仿真软件对不同性质的故障进行仿真，仿真试验结果表明，在不同故障位置、不同过渡电阻的情况下所提出的判别方法可以有效、可靠地判断故障性质。

Most single-phase earth faults of 500kV EHV transmission line are temporary, so that guaranteeing power restoration of faulty lines in a short time, with the use of automatic reclosing lock technology, can greatly improve power transmission’s reliability and continuity. However, harms brought by permanent fault to system’s reliability and electrical equipment are higher than normal short circuit. In order to avoid re-coincide of automatic reclosing lock devices at permanent fault on electric system, it is necessary to judge fault’s nature before secondary closing of reclosing, so as to realize adaptive auto-reclosing. Installing shunt reactors in EHV transmission line can limit overvoltage and low resistance of neutral points can restrain size of secondary arc current and improve closing success rate, so that studies on distinguishing shunt reactors’ transmission line malfunction have significant meanings. In the paper, the author researched single return of 500kV shunt reactors and distinguishing methods for fault nature of double-circuit transmission line’s single-phase earth fault. Main missions are as follows: (1) Analyze installation sites, connection methods, and selection of shunt reactors and small reactors on neutral point on EHV line and how to avoid series resonance. Build line simulation model and research inhibiting effects of small reactors on neutral point on secondary arc current, so as to improve success rate of closing. (2) Research recovery voltage’s characteristics of shunt reactors electric transmission line’s single-phase earth fault. At temporary fault, recovery voltage is made up of capacity coupling voltage and electromagnetic coupling voltage; at permanent fault, recovery voltage only contains electromagnetic coupling voltage. Analyze the relationship of fault phase terminal voltage, shunt reactors, and small reactance voltage in shunt reactors’ compensating lines. Conduct simulation verification on disconnected phase voltage. Simulation results show that voltage waveform differences between shunt reactors and small reactors on neutral point at temporary fault are larger than voltage waveform differences between them at permanent fault. (3) Put forward self-adaptive reclosing failure criteria on mutual-distance function of time-domain limited cause-effect discrete signals, through testing and calculating mutual-distance function value between fault phase shunt reactors’ voltage and small reactors on neutral point, according to features of signal distance functions and numerical size. Simulate faults of different natures with the use of simulation software. Simulation test results show that distinguishing methods mentioned on different fault places and transition resistance can judge fault nature effectively and reliably.