高压单芯电缆工频运行下金属护套雷电冲击电压的仿真研究

Simulation of Study Lightning Impulse Voltage of Metal Sheath of High Voltage Single Core Cable Considering Power Frequency Operation

为了研究高压单芯电缆金属护套冲击电压的影响因素,本研究用PSCAD/EMTDC建立220 kV架空线-高压单芯电缆线路模型并仿真雷电绕击架空线后沿线入侵电缆的波过程,在工频运行条件下,通过改变电缆接地方式、电缆参数以及雷电流参数,研究对金属护套雷电冲击电压幅值的降低作用。结果表明:其他条件相同时,采用首端接地方式的不接地点金属护套雷电冲击电压幅值比末端接地方式和交叉互联接地方式降低约90%;由于金属护套在交叉互联点发生换位,导致金属护套雷电冲击电压幅值最大相在第二个互联点处由侵入相变为非侵入相;通过改变电缆长度、分段均匀度以及排列方式等方法对金属护套雷电冲击电压的降低作用有限,仍需增设电压保护器加以限制;雷电流入侵电缆工频电压波谷时,能比入侵波峰时降低约80%的金属护套雷电冲击电压。

In order to study the influencing factors of the lightning impulse voltage of the metal sheath of the high-voltage single-core cable.PSCAD/EMTDC is used to establish the 220 kV overhead line high voltage single core cable line model,and simulates the wave process of invading cable along the line after lightning around the overhead line.Under the condition of power frequency operation,the method of reducing the lightning impulse voltage amplitude of metal sheath is studied by changing the cable grounding method,cable parameters and lightning current parameters.The results are as follows:when other conditions are the same,the amplitude of lightning impulse voltage of ungrounded metal sheath with head grounding can be reduced by about 90% compared with end grounding and cross interconnection groun-ding;Due to the transposition of metal sheath at the cross interconnection point,the phase with the maximum amplitude of lightning impulse voltage of metal sheath changes from invasive phase to non-invasive phase at the second interconnection point;The reduction of lightning impulse voltage of metal sheath is limited by changing the cable length,section uniformity and arrangement,so it is still necessary to add voltage protector;When the lightning current invades the power frequency voltage trough of the cable,the lightning impulse voltage of the metal sheath can be reduced by about 80% compared with the peak of the invasion wave.