Research On Fault Location Based On Multi-Point Traveling Wave Detection

The transmission line is an important way of traveling wave transmission in power system.In the actual situation,during the transmission of the fault waveform of DC transmission line on the line,the waveform will be attenuated and distorted by various factors such as air humidity,temperature and long transmission distance,Wave velocity instability will occur,the spread to the remote detection point of the waveform features serious reduction.The thesis first introduces the principle of traveling wave and the transmission method and analyzes the existing classical cases.Then the transform principle of Hilbert-Huang Transform(HHT)and signal processing are discussed.The application of HHT transform in the detection and harmonic analysis of power traveling wave head is also discussed.This paper presents a fault zone identification method based on the wave arrival time of each detection point.The long-distance transmission lines are segmented into zones and multiple current waveform detection points are set up to obtain fault current waveforms.The method of on-line speed measurement is used to measure the velocity of the propagated waveform,which effectively reduces the problem of unstable wave speed and easy attenuation.The arrival time of each wave of the first wave head at each detection point is accurately calibrated by the Hilbert-Huang transform.And then to the theoretical value of the wave to the moment compared with the measured value to determine the fault zone,can effectively improve the accuracy of the fault zone.In this paper,a ±500Kv UHV DC transmission line model is established by using PSCAD /EMTDC software and verified by simulation.After the fault zone is identified,a new fault location method based on multi-point traveling wave current measurement is adopted.The double-end algorithm is used to measure the distance within the zone,which effectively improves the accuracy of ranging.