Two terminals protection method for HVDC transmission lines based on maximal overlap discrete wavelet transform and cross-correlation coefficient of traveling wave

This study presents a novel method of HVDC protection based on the maximal overlap discrete wavelet transform (MODWT) and the kurtosis of cross correlation coefficient. Compared with the discrete wavelet transform (DWT), this method does not have data down sampling, and can realize fault identification and fault location at the same time. According to the high frequency content is different under different fault types and different fault area, firstly use of MODWT four layers of fault traveling wave decomposition, the double side of the decomposed high frequency component cross-correlation analysis; subsequently, kurtosis ratio relations to each other to judge fault zone and the fault types, the influence of noise on the protection method is also considered; finally, the maximum coordinate of cross-correlation function is used to calculate the fault location. At the same time, this paper analyzes the reduction of ranging accuracy caused by the decrease of sampling frequency, and further use of the interpolation algorithm for accurate positioning of internal fault. The simulation model of ±800 kV bipolar DC transmission is built in PSCAD/EMTDC, and the simulation analysis is carried out under different fault distance, transition resistance and fault type, the simulation results show that the protection method is not affected by the transition resistance, fault type and noise, and the fault location is more accurate