多导体配电线路感应雷过电压分析

为分析多导体架空线负载感应雷过电压及架空地线屏蔽特性,利用傅里叶变换计算雷电流的频谱分布,根据求多导体传输线负载响应的BLT方程,在频域内求其外电磁场激励下的电报方程,计算多导体配电线路感应雷过电压的频域响应,再根据傅里叶反变换求得负载端的暂态响应。配电线路感应雷过电压特性及架空地线屏蔽作用的分析结果表明,线路垂直排列时,感应雷在负载端引起的差模干扰较大,大地电导率越小架空地线的屏蔽作用越好。

Analysis of Lightning Induced Voltages on Multiconductor Distribution Lines

The overhead transmission lines are usually naked in the air, overvoltages induced by lightning can cause frequent outages in power systems. The 110 kV and above overhead lines are mainly damaged by direct lightning, but indirect lightning can cause more interruptions than direct strike because of their more frequent occurrence. The calculation of overvoltages induced by indirect lightning is important in the design and lightning protection of transmission line, it is also the study subject of electromagnetic compatibility. A novel method for calculation of the overvoltages induced by nearby lightning is used in this paper. With the Fast Fourier Transformation(FFT), the spectrum of the transient lightning current is calculated. According the BLT equations, which are used to calculate the load respond of multiconductor transmission lines, the Telegraph equations are solved, and the lightning induced voltages are calculated in frequency domain. Then the transient responds are obtained by inverse FFT. The effect of ground conductivity and the presence of shielding line on the magnitude of the induced voltages are studied. The analysis shows that differential model voltages on vertically-configured lines are more higher then that on horizontally-configured ones. The lower the ground conductivity the better the shielding efficiency of overhead grounding line.