风电机组箱式变压器低压侧雷电过电压仿真

针对某高山风电场风机塔顶遭受雷击，造成风电机组塔外箱式变压器（简称箱变）损坏事故，分析了箱变低压侧雷电过电压产生的机理，根据风机-箱变系统防雷配置情况，建立了ATP-EMTP仿真模型。利用该模型计算了电涌保护器（surge protective device，SPD）接入时和脱开后箱变低压侧的电压，并分析了雷电流波形、幅值及接地网冲击接地电阻对箱变低压侧电压的影响，同时计算了低压侧短路后的工频续流。计算结果表明，SPD脱开后低压侧电压超过了箱变的冲击耐压值（12 kV），低压侧工频续流为4.50～8.75 kA。由于开关型SPD无法切断工频续流，提出将其更换为无续流的氧化锌避雷器，推荐避雷器型号为YH10W-0.8/3.0，并通过仿真计算进行了防雷效果验证。

Box-Type Transformer Lightning Overvoltage Simulation at Low-Voltage Side in Wind Turbines

Aimed at damage accidents of box-type transformer outside wind turbine when the top of wind tower being struck by lightning, an ATP/EMTP simulation model is established according to wind turbine-box type transformer system lightning protection, which is based on the mechanism analysis of the lightning overvoltage of box-type transformer at low-voltage side. We use this model to calculate the lightning overvoltage of box-type transformer at low-voltage side when surge protective device (SPD) is connected and disconnected, and analyze the influences of the waveform and peak of lightning current, impulse grounding resistance on the voltage on the low voltage side of box-type transformer. Meanwhile, we calculate the power frequency current after the low-voltage side short circuit of transformer. The calculation result shows that the potential differences of low-voltage side of transformer when SPD is disconnected exceed the impulse withstand voltage 12kV, and the power frequency current at low-voltage side is 4.50-8.75 kA. Because switch-type SPD cannot cut off power frequency current, it is suggested that switch-type SPD should be replaced by zinc oxide arrester (YH10W-0.8/3.0) without follow current, whose lightning protection effect is verified by simulating calculation.