不同带宽高功率电磁环境对架空线缆耦合效应分析

Coupling effect of high power electromagnetic environments with different bandwidths on overhead cables

为分析典型高功率电磁环境对架空线缆的耦合效应,应用并行时域有限差分算法,计算了在雷电电磁脉冲和两种高空核电磁脉冲环境下架空线缆的外导体感应电流和终端电压波形,分析了不同线缆长度、不同入射波极化方向情况下架空线缆耦合效应的变化规律.研究结果表明:入射波电场方向与线缆方向一致时,耦合效应最为严重;随线缆长度增加,外导体感应电流和终端电压上升沿陡度不变,但峰值变大,波形变宽.当线缆长度增加到可与入射波能量最集中频段波长相比拟时,其峰值达到最大,变化趋于平稳,在频带偏低的LEMP作用下该长度在几千米以上,而HEMP1(贝尔波形)入射时为几百米量级,频带最宽的HEMP2(IEC 1000-2-9)则为几十米量级;在线缆和入射情况相同条件下,LEMP对线缆耦合效应最强,HEMP1次之,HEMP2最弱.

To analyze the coupling effects of typical high power electromagnetic en-vironment on overhead cables, the parallel finite difference time domain（FDTD） al-gorithm is used to calculate the induced current and voltage on the cable under the lightning electromagnetic pulse（LEMP） and two kinds of high-altitude nuclear elec-tromagnetic pulse （HEMP） environments. The variation of the coupling effect of o verhead cable with different cable lengths, different polarizations of the incident wave are analyzed. The results show that the strongest coupling occurrs when the direction of the incident wave is along with the cable and as the cable length increa-ses, the rising edges of the induced current and terminal voltage are almost un-changed, but the waveforms are amplified and broaden. There is no future increase in the peak of induced voltage, when the line length increases to be equivalent to the corresponding wave is most concentrated.such a cable length can reach several miles for LEMP, hundreds of meters for HEMP1 （Baer wave）, and tens of meters for the wide band HEMP2 （IEC 1000-2-9）. It also shows that under the same conditions, the LEMP coupling effect is strongest, followed by HEMP1, HEMP2.