基于ATP-EMTP高压电缆接地线金属护层悬浮电压仿真分析

Simulation Analysis the Floating Voltage of Metal Sheath Layer Based on ATP-EMTP for High Voltage Cable Grounding Wire

摘要: 若输电电缆接地系统遭到破坏，电缆金属护套对地电压将会升高，可能达到极高的危险数值。过高的感应电压不仅危害人身安全，还将造成绝缘层击穿，进而降低电缆的载流量，甚至击穿外护套绝缘，引发电缆线路运行事故。针对这一问题，本文利用电磁暂态分析软件ATP-EMTP对实际运行的输电电缆进行建模仿真，通过控制参数变量计算了不同接地线故障情况下电缆金属护套可能出现的悬浮电位值。计算得知当某段电缆仅一侧的直接接地线或交叉互联线被盗，若断开点距离另一侧直接接地点长度较短，则其金属护套的感应电压仍在安全值以下；但当单侧接地线被盗的110 kV电缆长度达到20 km左右(220 kV电缆长度达到10 km左右时)，其金属护套的感应电压幅值将超过国标规定值300 V；当某段金属护套“悬浮”，即该段电缆两侧的直接接地线或交叉互联线均被盗时，其感应电压将上升到非常危险的数值，达到数十千伏。

Abstract: If the grounding system of the transmission cable is damaged, the floating voltage of the sheath layer of power cable will increase, even reaching the extremely high value of danger. High inductive voltage not only endangers workers safety, but also causes insulation layer breakdown, thus re-ducing the carrying capacity of cable, even breaking down the outer sheath insulation, causing cable line operation accident. In order to solve this problem, the electromagnetic transient analysis software ATP-EMTP is used to model and simulate the running transmission cable. By controlling the simulation parameters, the floating voltage of the sheath layer of power cable under different ground wire faults is calculated. The calculation shows that when the direct grounding wire or cross-connected grounding wire of one side of the cable is stolen, the inductive voltage on the metal sheath layer is still below the safe value when the disconnecting point is not too far from the other side of the direct grounding point. When the length of 110 kV cable is about 20 km and the length of 220 kV cable is about 10 km, the inductive voltage amplitude of metal sheath layer will exceed the specified value of national standard. When a piece of metal sheath layer is “suspended”, that is, the direct grounding wire or cross-connected grounding wire on either side of the cable is stolen, the inductive voltage will rise to a very dangerous value, reaching tens of thousands of volts.