Research On Traveling Wave Fault Location For Double Circuit Transmission Lines

Double circuit high-voltage transmission lines, with high economical and social benefits, can effectively improve the unit transmission corridor transmission capacity. The complexities of the transmission structure increase the difficulty of fault location. Locating the fault point quickly and reliable after the fault is an issue of great importance to the safe operation of the entire electric power system. According to the characteristics of double circuit transmission lines, researches have been carried out on summarizing the phase-mode transformation and classifying the types of faults, mainly focused on the fault location method based on time and frequency domain.The classification of traveling wave fault location methods, the theory of traveling wave refraction and reflection are introduced. The main factors affecting the fault location are explained. The methods to deduce the phase-mode transformation matrix in different transmission lines are introduced, then summarizing the matrix fitting for double circuit transmission lines.The types of faults in double circuit transmission lines are classified and the models are established using ATP-EMTP software, then the characteristics of transient fault voltage is analyzed. Wavelet transform is applied to location the fault distance without interference and containing the environmental interference. Based on the waveforms and location results, this paper proposed to use the fault location method based on time and frequency domain.The relations between auto-correlation analysis and the cepstrum analysis are explained. The cepstrum analysis can extract natural frequency of fault traveling wave signal and obtain the round-trip time traveling between the fault point and measure point. According to the simulation model, the electrical parameters of double circuit transmission lines and the frequency-dependent velocity are calculated. On this basis, fault location method based on time and frequency domain is achieved. The two methods are applied in different fault types, different ground resistance, different fault distance, different initial angle of fault voltage, different environmental interference, then the result of fault location with two methods are comparatively analyzed. The calculation results show that the time and frequency domain method has high precision when considering the influence of environmental interference and can be used for fault location in double circuit transmission lines.