变电站瞬态电磁场耦合二次电缆数值方法研究

Study on Numerical Method of Transient Electromagnetic Field Coupling to Secondary Cable in Substations

提出瞬态电磁场耦合细线问题的三维时域有限差分(finite-difference time-domain,FDTD)数值方法的一种改进模型。基于电磁散射理论推导出有限长直细导线终端以及拐角附近的电磁场分量的离散方程。利用改进模型计算电磁脉冲激励下双导体传输线终端负载上的电流电压响应,并进行实验验证。结果表明计算结果与实验结果吻合较好,说明改进的三维FDTD数值模型对研究瞬态场线感应问题是有效的,可用于变电站瞬态电磁场对二次电缆干扰问题的研究。

An improved thin-wire model for the finite-difference time-domain（FDTD） method is proposed in order to evaluate induced effects of transient electromagnetic fields on multi-conductor transmission lines. Discrete equations of the electromagnetic field components near the ends and the corners of finite length straight thin-wire were achieved on the base of electromagnetic scattering theory. For the case of different resistance, transient voltage and current waveforms on the resistors at both ends of double-conductor transmission lines excited by electromagnetic pulse（EMP） were computed. The computed waveforms are exactly validated by the experiment. The results indicate that the improved model of three-dimension FDTD method is effective for analyzing transient induced effects in thin-wire excited by external electromagnetic fields. It can be used for investigating transient electromagnetic fields coupling to secondary cable in substation.