The Study Of Lightning Protection Performance For UHV Parallel-Two-Circuit-Transmission-Lines

Since the beginning of the new century, the contradictions between energy distribution and load demand in economically developed areas extremely imbalance prompt China’s power industry to vigorously develop the high voltage level, large capacity, long-distance transmission of UHV AC transmission line. However, according to the statistics of the actual operation of the transmission lines at home and abroad, the higher the voltage level of overhead transmission lines, transmission lines caused by being struck by lightning trip accounted for the proportion of the number of line trip will be higher. Therefore, how to design UHV transmission lines lightning protection, problems electric power workers are facing now have not been solved. According to the development trend of China’s UHV AC transmission lines, this paper studies on the1000kV UHV single-pole double-circuit AC transmission lines lightning performance.This paper sets up a1000kV UHV single-pole double-circuit AC transmission line characteristics counterattack simulation model using ATP-EMTP electromagnetic transient simulation software. Take full account of the structural characteristics of typical UHV AC transmission line tower in the process of modeling, select a different position of the tower, as the wave velocity in the multi-wave impedance model; lightning current impulse grounding resistance presents nonlinear characteristics; lightning current hit the top of the transmission line tower, the random nature of the wires in the power frequency voltage waveform; applied probability and statistics to determine Impact Lightning Withstand Level of1000kV UHV single-pole double-circuit AC transmission line.At the same time, this paper also analyzes various factors that impact1000kV UHV single-pole double-circuit AC transmission lines counterattack Lightning Protection Performance. Tower impact resistance on the transmission line counter LIGHTNING PROTECTION PERFORMANCE most sensitive; double circuit transmission line inverse phase sequence arranged to run the counter-attack resistant mine level to be better than the positive phase sequence order; span between the size of the line counterattack resistant to lightning performance of impact is negligible; frequency voltage also have some impact on the counterattack Lightning Protection Performance.Finally, using the improved electrical geometric model which introduces two parameters, strike distance factor and ground inclination, based on the classical electrical geometric model,to analysis and calculate the line failure rate; as well as introduces view that the lightning current magnitude impact the Ray width related to striking distance, amendment the problem of the Statute Law recommended by Ray width formula calculation result greater. The results show that:Equivalent Ray width Overall decreases as the striking distance coefficient increases when it is accompanied by the the ground inclination of the value from small to big, more and more obvious; flashover around Chance analysis rate is affected by the striking distance coefficient value selected with the value decreases.