Single-Ended Traveling Wave Fault Location Method in DC Transmission Line Based on Wave Front Information

摘要

The result of single-ended traveling wave fault location method based on wavelet transform will be affected by false wavelet transform modulus maxima (WTMM) points. In this paper, fault distance/impedance information contained in the wave front of the traveling wave is analyzed first. Then, the fitting method based on generalized logistic function is proposed to extract the fault information. Based on the fitting results, a predictor-corrector fault location method is proposed, which includes the following content. First, the fitting coefficients of the zero-mode fault current wave front are used to estimate fault distance and fault impedance interval. Second, the arrival time of the line-mode fault current reflected wave can be calibrated and the distance calculation formula can be selected according to the fault distance estimation interval. Last, the fault distance will be corrected to be within the fault distance estimation interval, if the first reflected wave is undetected. A model of +/- 400 kV DC transmission project is built in PSCAD/EMTDC. The simulation results show that the fitting coefficients can directly correspond to fault distance/impedance. The proposed method can effectively eliminate the influence of the false WTMM points, and give the accurate fault location results as well as fault impedance interval.