Impact Optimization Of Grounding Grid For Three-dimensional Voltage Equalization Structure Of Wind Farm Research And Application

Wind turbines are affected by lightning,such as location,climate,soil conditions and their own height,so the good grounding system is an indispensable part of the wind farm.However,early design pays more attention to whether the safety characteristics of the grounding device under the power frequency current are up to standard,and there are few studies on impact characteristics and ground pressure equalization.When the wind farm is struck by lightning,there will be problems such as uneven distribution of impact potential and local potential increase around the fan,causing box breakdown and communication damage,and personal and power grid safety is seriously threatened.Under the background of the global wind power installed capacity and the scale of wind farm construction expanding year by year,it is extremely necessary and urgent to study and optimize the impact characteristics of wind turbines.The paper analyzes the influencing factors and damage forms of lightning accidents from the aspects of wind turbine altitude,thunderstorm activity intensity and soil resistivity,and analyzes the impact characteristics of traditional horizontal grounding devices from soil parameters,grounding grid parameters and lightning current parameters.Study and analyze the law of the grounding device and the maximum step voltage distribution when the lightning current enters the ground.In order to better improve the impact characteristics of the wind farm grounding device subjected to lightning strikes,based on the research of the traditional horizontal ring grounding device of the wind farm and some existing auxiliary resistance reduction measures,a new type of three-dimensional equalizing structure is proposed.In order to improve the lightning strike of the wind farm,the distribution of the impact potential around the fan is uneven,and the local potential is raised.Through the theoretical calculation,the effect of reducing the resistance of the single-layer and multi-layer horizontal ring grounding device and the three-dimensional equalizing structure is compared.The CDEGS simulation software was used to compare the ground potential rise and maximum step voltage distribution around the two grounding devices,and the optimization of the three-dimensional equalization structure spacing and the replacement of the intermediate layer were carried out.In the Zhangzhou Qingjing Wind Farm,the new three-dimensional equalizing structure was applied in actual engineering.According to the field survey of the wind farm,13 wind turbines of the wind farm were grouped according to the soil resistivity interval,and were classified into Class A and Class B,Class C.Then,the design and impact grounding resistance of each type of fan are calculated,and the appropriate amount of bentonite anti-corrosion preservative can be used to effectively reduce the grounding resistance of the grounding grid and stabilize the grounding parameters.Finally,through simulation software,the descending gradient of ground potential and the maximum step voltage distribution around the fan are observed,and the ability of the new three-dimensional equalizing structure to improve the distribution of impact potential and enhance the vertical discharge of lightning current is verified.