Study On Cable Fault Location Based On ATP-EMTP Software

Power cable is widely used in the power system, and power cable faults affect the power system reliability. Usually, fault-locating is difficult for undergrounded cables, how to quickly and accurately locate cable faults, recovery and restore power supply become very important. Based on the ATP-EMTP software, this paper researches cable model, high resistance fault breakdown arc model, fault location method in single cable and distribution networks.This paper detailed analyses the wave process. Frequency-dependent cable model is established, which is suitable for simulation of cable fault location because of its attenuation of high-frequency signals.Paper presents three-stage breakdown arc model. Firstly, study on the mechanism of arc, then research the dynamic characteristics of gap arcs and the general arc modeling technique. Through the fault breakdown arc test waveform analysis, high voltage makes the fault point three changing states, the resistance and duration random variation characteristics of the arcing stage and out arc stage can be modeled by random function, while the resistance slow exponential variation characteristics of the arc stage can be modeled by exponential function. The TACS based arc model simulation in ATP-EMTP verifies that the model can meet the requirements of high resistance fault breakdown arc simulation.Research of pulse width in travelling wave fault location and method of determining wave velocity are carried out. Single cable fault-locating simulation combined with frequency dependent cable model and the three-state breakdown arc model proves that TDR method fits low resistivity and open-circuit fault location, and secondary impulse method is suitable for high-resistance fault location.The paper presents a double pulse comparison of the distribution networks cable fault location. The TDR method is difficult to distinguish the tee-offs and faults reflected waveform in the distribution networks with many branches. Double-pulse method compares the reflection of intact phase and faulted phase, the first divergence point is the point of failure, this method avoids waveform confusion caused by tee-offs.The simulation verifies that the method can quickly and accurately locate low resistivity and open-circuit fault in distribution networks.