变电所的瞬态电磁环境分析

Analysis on Transient Electromagnetic Environment of Substations

变电所的瞬态电磁环境威胁二次系统的安全运行。采用现场测试和数值计算的方法分析了开关操作时和雷电作用时产生的瞬态电磁场。开关操作时产生的瞬态电场的频率范围为小于15 MHz,持续时间为8μs,主频为DC～1 MHz,上升时间为0.5～1.5μs;瞬态磁场的频率范围为小于20 MHz,持续时间为8～10μs,主频为0.5～3 MHz,上升时间为0.25μs。建议的最大瞬态磁感应强度为400 A/m,电场强度为20 kV/m。雷击变电所的雷电瞬态磁场建议取1 000 A/m。国家推荐性标准GB/T17626.9-1998的要求无法满足变电所实际雷电电磁环境的要求,建议变电所电子设备电磁兼容测试的脉冲磁场抗扰度的要求取1 000 A/m,另外建议对变电所的电子设备的抗扰度试验要增加瞬态电场测试,其强度取20 kV/m。

The transient electromagnetic environment of substation threatens safe operation of secondary systems in a substation. This paper analyzes the transient electromagnetic fields generated by lightning stroke and switching operations based on field tests and numerical simulations. The frequency range of switching transient electrical fields is smaller than 15 MHz, their time duration is 8 μs, the main frequency is in the range from DC to 1 MHz, and the rise time is in the range from 0.5 to 1.5 μs. The frequency range of switching transient magnetic fields is smaller than 15 MHz, their time duration is from 8 to 10 μs, the main frequency is in the range from 0.5 to 3 MHz, and the rise time is about 0.25 μs. The suggested maximum transient magnetic and electrical fields generated by switching operations are 400 A/m and 20 kV/m, respectively. The lightning transient magnetic field in substation is suggested as 1 000 A/m. The criterion for electronic system in substation in national electromagnetic compatibility （EMC）standard GB/T 17626.9-1998 is far smaller than the actual value in substation. The transient magnetic field criterion for the EMC test of electronic system is suggested as 1 000 A/m, and the transient electric field of 20 kV/m is suggested as another new criterion for the EMC test of electronic system.