海洋环境对海上风场接地系统雷击暂态特性影响研究

Influence of Ocean Environment on Lightning Strike Transient Characteristics of Offshore Wind Farms Grounding System

海上风力发电产业的蓬勃发展面临日益严重的雷电灾害威胁,为有效指导海上风电机组的雷电防护研究,需要研究海洋环境对海上风场接地系统雷击特性的影响。利用PSCAD软件搭建简化海上风场模型,讨论海洋土壤分层环境下上层海水深度和下层土壤电阻率对风机接地系统雷击暂态响应的影响,分析增加接地体长度对于降低暂态过电压的效果。仿真结果表明:风机遭受雷击后,浪涌会传播至其他相连风机,距离雷击点越远的风机,塔底暂态电位幅值越低。下层海床土壤电阻率越大,风机塔底暂态电位幅值越高。上层海水深度越大,风机塔底暂态电位幅值越小。上层海水电阻率固定时,风机塔底暂态电位随着土壤反射系数的增大而增加。随着接地体长度的增加,风机塔底暂态电位逐渐降低,但降低趋势趋缓,且受下层海床土壤电阻率的影响增大。

The rapid development of offshore wind power generation is facing increasingly serious lightning disasters. In order to protect offshore wind turbines properly, it is necessary to study the influence of ocean environment on lightning strike characteristics of offshore wind farms grounding system. A simplified model of the offshore wind farms is established in PSCAD. Effects of soil layered structure and soil resistivity on transient voltage on the grounding system are discussed. Protection effect of increasing length of the grounding system is also analyzed. Simulation results show that： lightning surge will propagate from the struck wind turbine to others, but transient voltage decreases with distance from lightning strike position; transient voltage increases with the increasing of the bottom soil resistivity and decreasing of the seawater depth. Transient voltage rises as the increment of soil reflection coefficient. Protection effect increases as the length of the grounding system increases, tending to saturation in certain rising extent which is affected by the bottom soil resistivity.