Lightning Identification Analysis And Fault Location Of Double - Circuit HVDC Transmission Lines On The Same Tower

Double-circuit HVDC on the same tower has good economic and social benefits because of its narrow line corridor, large transmission capacity, long distance transmission. DC line is the important part of double-circuit HVDC transmission system. Because of its long lines, high voltage level, most harsh environments through the region, it can easily lead to failure. In addition, the tower body of double-circuit HVDC on the same tower is higher, it is also easy to be struck by lightning. So the research of fault traveling wave characteristics, lightning identification analysis and accurate fault location method has important practical significance.This paper set up the±500kV double-circuit HVDC system simulation model by PSCAD/EMTDC and analyze the decoupling method of double-circuit HVDC transmission line detailedly. Analyze the physical boundary properties of the double-circuit HVDC transmission line. Discuss traveling wave propagation process and impact factors of traveling wave propagation characteristics under the ground fault. Derive the expression of modulus traveling wave and polar fault traveling wave. Analyze propagation characteristics of different modulus traveling wave at the fault point. Research lightning electromagnetic transient characteristics of double-circuit HVDC transmission by simulation. Distinguish lightning fault, lightning disturbance and common fault of short circuit through the waveform characteristics and high-frequency energy difference among them.This paper describes fault location method of double-circuit HVDC transmission lines in detail which is not dependent on the length of the line, using traveling wave data at both ends of the line to analyze and determine fault traveling wave arrival time, not need to consider the effect of line length on the accuracy of the measurement, simulation results show that the method is better. In addition, introduce the time domain double-end fault location based on two-terminal voltage and current. Simulate at different sampling rates, it is concluded that the ranging effect with high sampling rate is better and the transition resistance has little effect on it. When the positions of lightning and flashover are different, proposed using polar initial traveling wave to locate lighting strike point firstly. Then determine the lightning-side and the distance between lightning and flashover point based on the relationship between the polarity of the follow-up traveling wave and the corresponding distance. Finally locate fault position. Simulation results show that the method is effective.