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高速铁路中雷电流是造成电缆绝缘破坏的一个重要因素,当输电线路遭受雷击时,雷电流将通过线路与电力电缆的连接点侵入电缆,并造成电缆主绝缘和护层绝缘的破坏。因此利用PSCAD/EMTDC软件建立单芯电缆的暂态分析模型,仿真分析了雷击点位置、避雷器、电缆护层保护器、电缆并联根数的影响。分析结果表明:雷电流幅值越大,离雷击点距离越近,雷电过电压越大;当雷击点与电缆接头处的距离小于100 m时,会在电缆线芯与护层上产生数十万V的电压,足以破坏电缆绝缘。此时需要加装避雷器与电缆护层保护器将电缆线芯和电缆护层的雷电过电压限制在其残压内,同时可以增加电缆并联根数来降低线芯电流与护层电压,以提高电缆的绝缘水平和供电可靠性。
The lightning current in high-speed railway is an important factor that causes the cable insulation damage. When the transmission line is struck by lightning, the lightning current intrudes into the cable through the connection point between the line and the power cable, and causes the damage of the cable main insulation and the insulation of the sheath. Therefore, using PSCAD / EMTDC software to establish a single-core cable transient analysis model, simulation analysis of the location of lightning strike point, arrester, cable sheath protector, the number of cables in parallel effect. The results show that the larger the lightning current amplitude is, the closer the distance to the lightning strike point is and the larger the lightning overvoltage. When the distance between the lightning strike point and the cable joint is less than 100 m, tens of tens V voltage of 10,000 V enough to damage the cable insulation. In this case, surge arresters and cable sheath protectors are required to limit the lightning overvoltages of the cable cores and the cable sheathing within its residual voltage. At the same time, the number of cables in parallel can be increased to reduce the core current and the sheath voltage so as to improve Cable insulation level and power supply reliability.