Box-Type Transformer Lightning Overvoltage Simulation at Low-Voltage Side in Wind Turbines
Man Yuwe · Electric Power Construction · 2016
Aimed at damage accidents of box-type transformer outside wind turbine when the top of wind tower being struck by lightning,an ATP / EM TP 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 lowvoltage side of box-type transformer. M eanwhile,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 voltage12 k V,and the power frequency current at low-voltage side is 4. 50-8. 75 k A. 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 followcurrent,whose lightning protection effect is verified by simulating calculation.