风机接地装置的冲击特性研究

Research on Impact Characteristics of Fan Grounding Device

随着风电场的大规模建设以及风机位置的特殊性,雷电对风机危害的事故愈发频繁,为保证风电机组的安全运行,可靠的接地装置是风机防雷工程中的关键组成部分。以CDEGS软件作为仿真计算工具,通过建立风机接地网仿真模型,比较了雷电流作用下不同形状接地网的冲击特性,讨论了雷电流注入点、土壤电阻率、接地网埋深和雷电流波形对风机接地装置冲击特性不同程度的影响。仿真结果表明:多圆环接地网比单圆环接地网具有更好的散流性,采取接地网中心引流的方式可得到最小冲击接地电阻;土壤电阻率的增大会导致冲击接地电阻增大,不过增大的幅度逐步降低;仅增加接地网埋深对其降阻效果不明显,工程中应根据地理环境选择适当的埋深;对于同一雷电流注入点,当雷电流波前时间缩短时,冲击接地电阻将会增大。采用加装水平接地极和圆环不等间距布置的措施,对风机接地网的降阻效果比较明显,仿真结果对实际工程中设计风机的接地装置有一定指导意义。

With the large-scale construction of wind farms and the special location of wind turbines,lightning-related accidents against wind turbines are becoming more frequent,in order to ensure the safe operation of wind turbines,reliable grounding devices are a key component in wind turbine lightning protection engineering.The simulation model of the fan grounding grid is established,used CDEGS software as a simulation calculation tool,the impact characteristics of different shapes of grounding grids under lightning current are compared,the effects of lightning current injection point,soil resistivity,grounding grid depth and lightning current waveform on the impact characteristics of the fan grounding device are discussed.Simulation results show that the multi-ring grounding grid has better diffusivity than single-ring grounding grid,the minimum impact grounding resistance can be obtained by taking the grounding of the grounding grid;an increase in soil resistivity leads to an increase in the impact grounding resistance,but the magnitude of the increase is gradually reduced;only increasing the buried depth of the grounding grid has no obvious effect on reducing the resistance,in the project,the appropriate depth should be selected according to the geographical environment;for the same lightning current injection point,when the lightning current wavefront time is shortened,the impact grounding resistance will increase.This article adopts measures to install horizontal grounding poles and rings with unequal spacing,the effect of reducing the resistance of the fan grounding grid is obvious,the simulation results have certain guiding significance for designing the grounding device of the fan in actual engineering.