同杆双回线跨线故障保护动作分析

Analysis of Protection Action for Overline Failure of Two Parallel Transmission Lines on the Same Tower

同杆架设双回线发生跨线故障时,两侧保护的动作行为决定了双回线两侧开关的运行状况。通过故障的波形和数据分析了220 kV惠梁双线在近梁溪变侧发生AC相跨线故障后各保护的动作行为,指出光纤差动保护在跨线故障中能够正确选择故障相别并快速跳闸,而高频距离保护由于逻辑本身的缺陷不能正确地选择故障相别,进而不能正确地选相跳闸。还比较了同杆架设双回线发生跨线故障和本线路发生相间故障时故障电流与电压的异同,以及这种异同对保护选相元件的影响,提出了同杆架设双回线为应对跨线故障最好采用两套光纤差动保护,或者一套光纤差动保护、一套分相纵联保护的建议。

When overline failure happens between two parallel transmission lines on the same towor, the breaker operation of the parallel lines is decided on the protection actions of both sides. According to the waves and data of faults, the protection actions are analyzed when there is AC overline failure in Hui-liang Parallel transmission lines at the side of Liangxi substation. The analysis shows that the fiber-optic differential protection can choose the failure phases and act fast when overline failure happens while the high-frequency distance protection can＇t because of logic defects. The differences between the overline failure of parallel lines and inter-phase fault, and the effects of the differences on the faulty phase selector are analysed. It is suggested that two kinds of protections should be chosen for the parallel lines on the same tower, one is fiber-optic differential protection, and the other is pilot protection.