接地系统互连风场雷电浪涌分析

Lightning Surge Analysis of Wind Farm with Interconnected Grounding System

雷电对风电场的正常运行构成了严重威胁,需要详细研究雷电浪涌对其危害。利用PSCAD软件搭建简单风电场模型,分析风机塔筒高度对塔底雷击暂态电位的影响,讨论接地系统互连情况下连接电缆敷设方式、雷击点位置、土壤电阻率对浪涌传播的影响。仿真结果表明:风机塔筒越高,塔底雷击暂态电位越大,波形振荡越明显;接地系统互连能够降低塔底暂态电位,但效果并不显著,连接电缆敷设方式对于降低暂态电位幅值几乎没有效果;采用互连接地系统时,浪涌会传播至其他相连风机,距离雷击点越远的风机,塔底入地电流和暂态电位幅值越低;土壤电阻率增大,塔底雷击暂态电位越大,过电压会对变压器等设备绝缘产生危害,需要尽可能采取措施降低塔筒接地电阻。

Lightning has posed serious threat to the normal operation of wind farms, it is necessary to study the lightning surge characteristic. A simple model of the wind farm was established in PSCAD. The influence of height of the wind turbine on transient potential at the bottom of the wind turbine was analyzed. The influence of laying modes of the interconnecting cable, lightning stroke position and soil resistivity on lightning surge propagation were discussed. Simulation results show that： the transient potential at the bottom of the wind turbine increases with height of the wind turbine ; interconnected grounding system can reduce transient voltage to a certain extent and laying modes of the interconnecting cable have little effect on transient voltage. Surge will propagate from a wind turbine that has been struck to others which have not, but transient voltage and current decrease with distance from lightning stroke position. Soil resistivity has greater effect on transient potential at the bottom of the wind turbine which may lead to damage to equipment insulation. It is important to reduce grounding resistance of the tower as low as possible.