计及工频电压的输电线路耐雷水平的研究

雷击闪络是引起输电线路跳闸的主要原因,因此必须正确评估设计中的输电线路的防雷性能。耐雷水平是衡量输电线路防雷水平的一个重要的性能指标,它直接影响着电力系统的可靠性和安全性。目前我国耐雷水平的计算多采用规程法,但该方法并没有考虑线路运行中的工频电压对耐雷水平的影响,这与实际情况不符。为此,利用规程法,首先推导了计及工频电压的输电线路耐雷水平的计算公式,随后利用该公式计算了在110~500 kV各电压等级线路中工频电压对线路耐雷水平的影响。分析结果表明:随着电压等级的提高,线路运行中的工频电压对输电线路耐雷水平的影响逐渐增大。因此在超高压和特高压输电线路的设计中必须计及工频电压的影响。

Investigation on the Lightning Withstand Level of Transmission Line Considering Power Frequency Voltage

Lightning flashover is the main reason that causes trip out in the transmission line,hence it is necessary to estimate the lightning performance of the transmission line which is in the designing.Lightning withstand level is an important parameter in estimating lightning protection ability of the transmission line,it effects the reliability and security of the power system directly.At present,regular method is mainly used to calculate the Lightning withstand level,in which the effect of the AC operating voltage on the lightning withstand level of the transmission line is not considered.This conflict with the practical situation.Regular method is used firstly in this paper to deduce a formula for calculating the lightning withstand level which could take the effects of AC operating voltage into account,then the deduced formula t is used to research the influence of AC operating voltage on the lightning withstand level of the transmission line with the voltage level varying from 110 kV to 500 kV.Analysis results show that the effect of the power frequency voltage on the lightning withstand level of the transmission line increases with the increase of the voltage level.Thus power frequency voltage must be considered in the designing of the HV and EHV lines.