某500 kV线缆混合线路的故障定位方案

针对某500 kV线缆混合输电线路,通过现场实测其内部各段工频参数和波阻抗,分析其分布特性及行波在输电线的传播特性,发现各段工频参数极不均匀,且各段的零序补偿系数之间、波阻抗之间也相差较大；内部固有行波反射点较多,在线缆连接处反射系数较大.根据以上特点,提出分两步的两端阻抗法和分段两端行波法对该输电线路进行故障定位,并基于当前设备条件进行技术经济比较,对线缆混合输电线路推荐采用分段两端电流行波法,可以有效地提高了线缆混合线路故障测距精度.

A Fault Location Scheme for Certain 500 kV Power Transmission Line Consisting of Overhead Line and Submarine Cable

For certain 500 kV power transmission line consisting of overhead line and submarine cable, taking on-site measurement of power frequency parameters and surge impedances inside every section of the transmission line, this paper analyzes the distribution characteristics of these parameters and impedances as well as the propagation property of travelling wave inside the transmission line, pointing out that the power frequency parameters among the sections are significantly asymmetric, and the compensative parameters of zero-sequence impedance are much different and so to the surge impedances. In addition, there is a lot of inherent reflection points of inside travelling wave and the reflection coefficients at the joints between cable and overhead line are large. According to these characteristics two steps are proposed for application of the piecewise two ends impedance method and the piecewise two ends travelling wave method to locate a fault position, and a economic comparison is made between the two methods, and the piecewise two ends travelling wave method with two steps is recommended as it is able to improve effectively the fault-location precision of the power transmission line consistion of overhead line and submarine cable.