风电机组典型接地装置的降阻措施冲击试验研究

Impulse Test Study on Decreasing Resistance Measures of Typical Grounding Devices of Wind Turbine Generators

良好的接地装置是风电机组防雷的重要保证,而冲击特性是衡量风电机组接地装置电气性能优劣的重要指标。文中采用冲击大电流试验装置模拟雷电流,对风电机组典型接地装置—环形接地体及其在不同土壤环境下的改型结构进行冲击特性模拟试验。引入了冲击特性变化率的概念来定量描述冲击电流峰值对接地装置冲击接地电阻的影响,其值大小反映影响强弱,符号反映影响趋势,结合冲击特性变化率对试验数据进行对比分析,结果表明:针对上层电阻率高、下层电阻率低的土壤结构,加装深入到下层土壤的垂直接地体可显著降低接地装置的冲击接地电阻,但其冲击特性变化率由-0.36Ω/k A变化到-0.07Ω/kA;在总接地体长度不变的情况下,将环形接地体改型为环形和水平射线的组合接地体可在电流峰值一定范围内降低接地装置的冲击接地电阻,但更为显著的是接地体的冲击特性变化率变化到-0.8Ω/kA。试验结果对风电机组接地装置降阻改型及其研究工作有一定指导意义。

Great grounding devices are important measures of thundering prevention of wind turbine generator systems and the impulse characteristics is major index to judge if the grounding devices good or not. In this paper, using the high impulse current generate to simulate the lightning impulse current, conducting impulse characteristics test to the typical grounding conductors of wind turbine generator systems-annulus grounding conductors and its improvements. The concept of the rate of change impulse characteristics is proposed, to quantitatively describe the common affects of spark effect and other impulse properties on the impulse grounding resistance, its value reacts the size of the strength, its symbol reacts the trend. Considering the rate of change impulse characteristics, the results discover that when the soil have two levels that the upper resistance is higher than the lower, adding vertical grounding conductors reaching to the lower soil lever can decrease the impulse grounding resistance apparently, and change the rate of impulse characteristics from-0.36 Ω/kA to-0.07Ω/kA; When the length of the grounding conductors is stationary, replacing the annulus grounding conductors by the annulus conductors with level branch can decrease the impulse grounding resistance, but more significant is the rate of impulse characteristics change to-0.8Ω/kA. The results have some guidance for the wind turbine grounding device selection.