风电机组雷电过电压的仿真分析

Simulation Analysis on Overvoltage in Wind Turbines by Lightning Stroke

雷击会对风电机组造成严重损坏,是影响风场安全运行的主要因素。在雷击过程中,雷电流流经塔体,并通过电磁场的耦合作用,在塔体内部三相电缆和机组变压器上产生雷电过电压,影响内部设备的正常运行。通过电磁暂态软件PSCAD搭建了比较全面的风电机组模型,对风电机组的暂态过电压进行计算分析,并研究了不同大小的接地电阻以及不同接地方式对风电机组过电压分布的影响。计算结果表明良好的接地系统有利于降低电缆上的过电压,但不能改变塔体上过电压的最大值,而接地方式的不同对过电压影响巨大,两种接地方式各有优劣。最后为风电机组加入避雷器,验证了防雷设计的有效性,仿真结果为风电机组的安全、经济的防雷设计提供了参考依据。

As one of the important factors affecting the secure operation of wind farm, lightning strikes can cause serious damage to wind turbines. In the process of lightning, when the lightning current flows through the wind tower, overvoltage may appear on the three-phase cable and transformer by the coupling effect of electromagnetic field. As a result, the normal operation of wind turbines will be affected. The study built a comprehensive wind turbine model and calculated the level of transient overvoltage in PSCAD. Various ground resistances and two earthing modes were simulated, to observe transient phenomena in wind tower and cable. The calculating results show that the lower ground resistance helps to reduce the overvoltage on the cable but fails to reduce the maximum of the overvoltage on the wind tower. Moreover, earthing mode has great influence on wind turbine system, and each has advantages and disadvantages. At last the case verifies the effectiveness of the lightning protection design when the arrestors were installed. Consequently, a reasonable lightning protection design is applicable according to the calculating results.