Research On Fiedd-to-line Coupling Of Lightning Electromagnetic Interference Of Electronic Equipment In Wind Turbine

With the increase of the capacity of wind turbines and the continuous expansion of the scale of wind farms,the height of the wind turbine body and the length of the blades also continue to increase.Its probability of being struck by lightning is greatly increased.Among the components of the wind turbine,the lightning damage rate of the control system is the highest.With the large application of high-integration microelectronic equipment in the control system of the unit,the probability of its interference by lightning electromagnetic pulses has greatly increased.In order to better guide the lightning electromagnetic protection design of the wind turbine,so that the normal operation of its internal weak current control system can be ensured and the economic losses caused by lightning strike disasters can be reduced.In this paper,lightning transient model of tower and coupling model of transmission line inside tower are built.It is of great significance to study the field-to-line coupling of the internal cable for the electromagnetic interference of electronic equipment.The research contents of this paper mainly include the following aspects:When the wind turbine is struck by lightning,the cables laid along the tower will induce induced overvoltage under the lightning electromagnetic pulses.According to the transmission line distribution parameter theory and the derivation method of the Taylor transmission line model,the transmission line model of the tower barrel and cable is analyzed.Considering the changes in the spatial structure of the wind turbine tower barrel,this paper improves the parameters of the telegraph equation of the"tower barrel--cable shielding layer" transmission line model in the time domain.The coupling mechanism of the cable shielding layer in the tower barrel is analyzed,which under the lightning electromagnetic pulse field.The wind turbine tower barrel is modeled by electromagnetic simulation software.The distribution of spatial electromagnetic field inside the tower barrel is simulated during lightning strike.It provides data for further calculation and analysis of the transient response of the cable under lightning electromagnetic pulse in the tower.Based on the transfer impedance and transfer admittance of the cable shield layer,the coupling relationship between the shield layer and the core wire is established.The response of shielding layer and core wire is calculated and analyzed quantitatively Discuss the influence of factors such as the grounding method of the cable shielding layer,the distance between the cable and the tower barrel,the number of cables,and the arrangement of the cables on their response.In the three-dimensional full-wave electromagnetic simulation software,the slotted shielding cavity model inside the wind turbine tower barrel is built.Through the simulation of the electric field intensity inside the slotted shielding cavity which under the excitation of plane wave,the influence of the shape,area and arrangement of the slot is analyzed.The response of the cables under different grounding modes of the shielding layer is simulated and analyzed by the method of combining field and circuit.For the crosstalk problem between the cables passing through the shielding cavity,the coupling response of the through cable inside the tower during lightning strike is analyzed.The response of crosstalk coupling between shielded twisted pair and coaxial cable under different conditions is discussed by simulation.The research work of this paper mainly focuses on the lightning transient response of the tower barrel and the coupled response of the cable.It provides a theoretical support for the protection of weak electricity system inside the tower barrel of wind turbine during lightning strike.The analysis method for the lightning protection design of the weak electricity system is provided,which has certain theoretical significance and reference value.