基于改进Agrawal模型和FDTD法的感应雷过电压算法

为了计算架空配电线路雷电感应过电压,利用Nucci提出的雷电回击通道模型(MTLE模型),计算雷电回击电流产生的空间电磁场,采用Cooray-Rubinstein公式计算大地电导率影响的水平电场分量,并改进Agrawal场线耦合模型,建立架空配电线路雷电感应过电压方程,基于时域有限差分(FDTD)法,计算10 kV架空线路的雷电感应过电压数值。结果表明,大地电导率对计算结果影响较大,大地电导率使线路上的感应电压幅值降低接近20 kV;不同回击传播速率也影响感应雷过电压的数值。定量计算雷电感应过电压,需要分析各种因素对计算感应雷击过电压的影响,完善计算方法,保障计算准确性,使理论与计算方法适用于实际的配电线路防雷设计,提供有价值的参考依据。

A Calculation Method of Lightning Induced Over Voltage with Improved Agrawal Model and FDTD Method

To calculate the lightning induced over-voltage on overhead distribution lines, by adopting the lightning return stroke mod- el （ MTLE model） proposed by Nucci C A, the paper calculates the electromagnetic field generated by the lightning return stroke. The horizontal electric field with ground conductivity affection is calculated by using the Corray-Rubinstein formula, and an Agrawal model is improved as the coupling of field-to-line model to establish the lightning induced over-voltage equation on overhead distribution lines. Based on finite difference time domain （FDTD） method, values of the lightning induced over-voltage on 10 kV overhead lines are calculated, which shows that calculation results is affected notably with or without considering the ground conductivity, which would reduce the amplitude of voltage on the line to nearly 20 kV. Different return stroke velocities also affect the value of over-voltage. Quantitative calculation of such induced over-voltages needs analysis of various factors influencing lightning induced over-voltage calculation, perfection of calculation methods and ensurance of the calculation accuracy, so as to make the theory and calculation methods suitable for the power distribution lines lightning protection design, and provides valuable reference.