高压单芯电缆金属护套回路缺陷感应电压的仿真研究

Simulation Study on Induced Voltage of Metal Sheath Circuit Defect of High Voltage Single Core Cable

高压电缆附件发生故障时会造成金属护套感应电压的突变,当感应电压过高时,不仅易诱发电缆绝缘击穿,影响电缆的安全稳定运行,还会威胁人员安全。为此采用PSCAD建立了高压单芯电缆的仿真模型,针对单端接地和交叉互联接地两种接地方式及相应附件故障引起的金属护套回路缺陷,对电缆金属护套的对地感应电压进行了仿真计算。结果表明:电缆附件缺陷导致金属护套回路拓扑发生改变是引起金属护套感应电压改变的直接原因,金属护套失去有效接地后的感应电压会远高于正常时的感应电压。对于单端接地方式的电缆,金属护套回路新增对地支路引起的感应电压超出了国标规定的安全运行电压范围。对于交叉互联接地方式的电缆,金属护套开路缺陷引起的感应电压较小,不会威胁电缆的安全运行。该研究结果可为优化电缆接地方式及保障电缆运维安全起到参考作用,为电缆附件故障识别提供帮助。

Failure of a high-voltage cable accessory can cause a sudden change in the induced voltage of the metal sheath.When the induced voltage is too high,it is not only easy to induce cable insulation breakdown,affecting the safe and stable operation of the cable,but also threatening the safety of personnel.Therefore,the simulation model of high-voltage single-core cable was established by PSCAD.Aiming at the metal sheath circuit defects caused by the faults of the metal sheath of the single-ended grounding and cross-interconnection grounding methods and the corresponding accessories,the ground induction voltage of the metal sheath of the cable is simulated and calculated.The results show that the change of the circuit topology of the metal sheath caused by the defects of cable accessories is the direct cause of the change of the induced voltage of the metal sheath.The induced voltage of the metal sheath after the loss of effective grounding will be much higher than the normal induced voltage.For cables with single end grounding,the induced voltage caused by the newly added branch circuit to the ground in the metal sheath circuit exceeds the safe operation voltage range specified in the national standard.For the cable with cross interconnection grounding mode,the induced voltage caused by the open circuit defect of the metal sheath is small,which will not threaten the safe operation of the cable.The research results can play a reference role in optimizing the cable grounding mode and ensuring the safety of cable operation and maintenance,and help the fault identification of cable accessories.