The Research Of Fault Location Technique Based On Travelling Wave Principle For High-voltage Overhead-cable Lines

For the high-voltage overhead-cable lines’fault location technique, the wave’s refraction and reflection phenomena of travelling wave surge in overhead transmission line and cable intersection makes the reflection progress more complex, and on the other hand wave’s speed is different before and after the intersection on mixed lines. These factors led to that all the fault location techniques have already brought up used single-ended principles or double-end principles can’t be used on the overhead-cable lines straightly. So the research of fault location technique based on travelling wave principle for high-voltage overhead-cable Lines has the important practical significance. This paper presents a fault location technique based on two kinds of wave principles, give the final distance measurement result with single-ended principles, and can also rapidly and accurately determine fault location. In this paper, the main contents are as follows:(1)The paper analyzed the Traveling wave’s route after the failure in the overhead-cable line. Derived characteristics of traveling waves’amplitude and polarity when it transmitted from the overhead line to cable or from the cable to the overhead line. Gave the conclusion and the simulation proved that it is correct.The analysis of the overhead - cable line’s wave process laid the foundation for researching overhead - cable’s fault location scheme of d wave.(2)For transmission lines, the paper analyzed the wave propagation process and the wave’s refraction and reflection phenomena after the failure. On this basis, the paper proposed a theory based on two waves combined ranging method. First, use single-ended principles to give preliminary fault location. And then give the accurate results by single-ended principles combined initial wave arrival time at both ends. ATP simulations show that the proposed transmission lines’ fault location scheme of combined wave is feasible and fault location accuracy improved obviously.(3)For 35 kV and above high-voltage overhead - cable lines, the paper analyzed the wave propagation process and the wave’s refraction and reflection phenomena after the failure. On this basis, the paper proposed a theory based on two waves combined ranging method. First, Conducive to double-end principle, chose the fault zone based on the initial wave arrival time errors at both ends in the mixed-lines fault. And then use single-ended principles to give preliminary fault location. Finally, give the accurate results by single-ended principles combined initial wave arrival time at both ends in the mixed-lines fault.(4)Establish overhead - cable lines’model by PS CAD to simulate single-phase metal short-circuit, the impedance short-circuit and the high-impedance short circuit, and Simulate the combined traveling wave fault location method of overhead line - cable mixed lines by the obtained fault information and MATLAB software programming。This article proposed high-voltage overhead lines combined with cable fault location method based on the combination of the traveling wave principle, The single end principle gives the final measure result, have higher measurement accuracy. This method can reliably solve that how to accurately find the fault point on mixed line, and has good application prospect.