基于多阶FDTD雷电感应过电压计算新方法

New Method of Lightning Induced Over-voltage Based on Multiple Order FDTD

传统的经验公式法估算架空线雷电感应过电压误差大且存在影响因素考虑不全面的局限性。对此提出一种基于多阶时域有限差分的数值计算新方法。该方法采用一阶时域有限差分(FDTD)法计算回击电流所引发的雷电电磁脉冲(LEMP);采用二阶时域有限差分(FDTD 2nd)法求解耦合电路的Agrawal微分方程,计算不同工况时LEMP激励下架空导线的感应过电压。该方法采用多阶FDTD技术实现了高稳定性和高精度的数值计算,与火箭引雷试验对比证明计算准确性。仿真计算表明:回击电流幅值对感应电压幅值影响明显,对波形影响小;回击电流波头陡度对感应电压波形影响较大,对幅值影响较弱;多导线之间有"屏蔽效应",该效应受导线排布方式影响明显。

Traditional empirical formula methods exist great errors and limitations of factors considering in estimating the overhead line lightning induced over-voltage. Therefore, a new numerical method based on multiple order finite difference time domain(FDTD) was proposed in this paper. The lightning electromagnetic pulse(LEMP) near the return channel is obtained by using the FDTD method; The Agrawal differential equations of coupling circuit are solved by the Second-order FDTD method. Based on the two steps, the over-voltage and over-current of overhead line excited by LEMP in different conditions can be obtained. This method achieves high stability and high precision numerical calculation by using multiple order FDTD technology, and compered with observed data from rocket triggered lightning flash, it was verified to be correct. The simulation results showed that: the effect of return stroke current amplitude on the induction voltage amplitude is significantly, and little on waveform; The effect of return stroke current wave gradient on the induction voltage waveform is obviously, and little on amplitude; There is 'shielding effect' between multi-conductor, and the 'effect' affected by conductor arrangement obviously.