| With the vigorous promotion of wind power generation system,more and more attention has been paid to the safe and stable operation of wind turbines.The impact of frequent lightning accidents on wind turbines is particularly prominent.On the one hand,lightning stroke accident will make the transient potential of each part of the unit change strongly,on the other hand,it will cause the change of internal magnetic field.These phenomena will affect the motor and power electronic equipment of the wind turbine,and may interfere with the normal operation of the wind turbine.It will also cause some components and equipment of the wind turbine,or even complete damage of it,leading to the direct shutdown of the wind turbine.In order to study the distribution of the transient overvoltage and the magnetic field in the tower barrel caused by lightning current in wind turbines,a wind turbine model was built in ATP/EMTP simulation software to simulate lightning accidents under different lightning current parameters,and its transient characteristics were studied.The lightning strikes on different parts of the blades of wind turbines were simulated separately.The distribution law of lightning overvoltage is analyzed,the improvement measures are put forward and the rationality is verified.Then the influence of the change of lightning current wave head time on the transient potential distribution of blades and tower barrels is studied.The transient potential drop ratios of different parts are compared,and the transient process differences of different parts are analyzed.Finally,the grid of tower barrels is divided to study the three-dimensional transient potential distribution rules of wind turbine tower barrels.Law.For electromagnetic field analysis,the wind turbine model including blade,engine room and tower barrel is simulated in ANSYS finite element software,and the variation of magnetic induction intensity of different parts under different lightning parameters is studied after applying external circuit excitation.According to Lorentz condition,starting from Maxwell equations,the induced electromagnetic field produced by lightning current elements is calculated,and a certain part of the tower barrel is obtained by vector synthesis.The magnetic induction intensity at discrete points in a space area is compared with the results of ANSYS simulation of the magnetic induction intensity at different parts of the tower barrel to verify the feasibility of the method.The research results can provide quantitative basis for subsequent lightning protection research and reduce the tedious steps of finite element simulation. |
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