基于XFDTD的箱变开孔金属外壳雷电电磁脉冲防护

Lightning electromagnetic pulse protection ability of box-type substation with slots based on XFDTD

摘要:

为研究户外配电设备对雷电电磁脉冲(LEMP)的防护能力，利用基于时域有限差分法(XFDTD)的全波三维电磁场模拟仿真软件对近场LEMP与户外箱变金属开孔外壳的耦合情况进行仿真模拟，得到3种正面具有不同形状散热孔阵的箱变在距回击点30 m处，其内部距开孔位置5 cm,50 cm和100 cm处的耦合电场强度与电磁功率密度。研究表明，能量主要集中在低频段(2 MHz以下)的LEMP与正面有散热孔阵的变电站腔体发生耦合时，耦合进内部的电磁能量主要集中在开孔附近；对于相同排列方式的孔阵，腔内耦合电磁能量按照长方形、正方形和圆形顺序依次减小，具有圆形孔阵的变电站电磁屏蔽效能最佳；腔体内远离开孔处的电磁危害要小于开孔位置附近，耦合电磁能量可能会严重干扰变电站的正常工作，但不会损坏其内部电子元件。

Abstract:

The ability of outdoor power distribution equipment to protect against the Lightning Electromagnetic Pulse(LEMP) is studied by XFDTD full wave 3D electromagnetic field simulation software based on Finite Difference Time Domain(FDTD) method, including simulating the coupling of the near-field lightning electromagnetic pulse with the cabinet of outdoor box-type substation, which is characterized with slots. The coupling electric field strength and the electromagnetic power density of the three types of substations with different shapes of aperture array are obtained at 30 m from the return point, and at 5 cm, 50 cm and 100 cm from the opening position. It is concluded that when the LEMP whose energy is mainly concentrated on the low frequency band(below 2 MHz) couples on the anterior aperture array, the coupled electric field energy in the substation is mainly focused near the opening. The electromagnetic energy coupling into the substation with rectangular, square and circular aperture arrays decreases in turn, and the substation with circular aperture array has optimum shielding effectiveness. The electromagnetic hazard in the cavity far away from the aperture array is less than that near the opening position. The coupled electromagnetic energy will have impacts on the normal operation of the substation, but will not damage its internal electronic components.