The Influence Of Wind Farm On Local Atmospheric Boundary Layer Is Studied Based On Mesoscale Model

With China,s strong support for the distributed development of the wind power industry,promoting local consumption,reducing the loss caused by long-distance transport of electricity,and promoting the full utilization of wind energy in low-wind speed plain areas such as the central and southeastern regions are conducive to the realization of the overall development goals of China,s wind power industry.Wind farms in plain areas are mainly located in human living areas and farmland.Many studies have shown that the operation of wind farms has an impact on local climate,which may indirectly affect crops in human living areas.Therefore,it is very important to study the real impact process of climate factors on local ecological environment.Based on the mesoscale numerical model(WRF),coupled with the wind farm parameterization model(WFP),this paper explores the influence of array wind farm operation on the spatial distribution of wind speed,atmospheric turbulence intensity,temperature and humidity in the local atmospheric boundary layer and the change of atmospheric boundary layer height,and then studies the change of local atmospheric boundary layer under different wind speed,wind direction and temperature.The mesoscale model is used to simulate the real wind farm.Based on the measured data,the accuracy of the coupling model is verified,and a set of physical parameterization schemes suitable for local terrain and environment with high accuracy is selected.Taking 11 × 11 array wind farms as the research object,the influence of wind farm operation on wind speed,atmospheric turbulent kinetic energy,temperature and relative humidity and atmospheric boundary layer height in local atmospheric boundary layer is explored.The results show that the operation of wind farm has the greatest influence on wind speed and atmospheric turbulent kinetic energy,and the influence height can reach 500 m.At the surface height,the wind speed decreases in the upwind direction and increases in the downwind direction.The most serious loss of wind speed is at the hub height of 125 m.The atmospheric turbulent kinetic energy in the three-dimensional space remains enhanced,and the maximum atmospheric turbulent kinetic energy is near the height of 192 m on the top of the wind wheel.In the height from the surface to 70 m,the temperature in the upwind direction decreases and the temperature in the downwind direction increases,and the temperature rise is the largest at the height of 61 m at the bottom of the wind wheel.The variation of soil temperature is consistent with the atmospheric temperature,and the influence depth is 0.11 m.The change of relative humidity in the near-surface layer height is opposite to the change of temperature.The relative humidity decreases in the upwind direction and downwind direction,and the humidity decreases the most at the61 m height at the bottom of the wind wheel.The surface soil moisture also shows the law of increasing upwind and decreasing downwind.Wind farm operation has little effect on surface pressure.The larger the scale of the wind farm,the more obvious the increase of the atmospheric boundary layer height in the internal area of the wind farm,and the stronger the decrease of the atmospheric boundary layer height downstream of the wind farm.Taking the wind farm in the North China Plain as the research object,this paper explores the influence of real wind farm operation on the wind speed at the hub height,the atmospheric turbulence intensity at the vertex height of the wind wheel,the temperature at the vertex height of the wind wheel,the relative humidity at the vertex height of the wind wheel and the height of the atmospheric boundary layer.The results show that below the rated wind speed,the greater the wind speed,the more serious the wind speed loss.When the incoming wind speed is greater than the rated wind speed,the wake recovery speed is faster and the wake influence range is smaller.The variation range and degree of atmospheric turbulence intensity increase with the increase of wind speed,and the increase of wind speed can not promote the phenomenon of temperature and humidity increase in the downstream of wind farm,but will inhibit it.The greater the incoming wind speed,the more obvious the decrease of the downstream atmospheric boundary layer height.When the incoming wind speed is greater than the rated wind speed,the downstream atmospheric boundary layer height will increase due to the high turbulence intensity caused by the high wind speed incoming flow.In the sub-main wind direction(36 °),the overall layout of the wind farm is parallel to the incoming wind direction,the wind speed loss is the most serious,the atmospheric turbulence intensity increases the most,and the atmospheric boundary layer height decreases the most.In the main direction(180 °),the influence of wind farm on downstream temperature and humidity is higher than that of other wind directions.Compared with the inversion stratification,the wake of the wind farm in the decreasing stratification recovers faster and the atmospheric turbulence intensity changes stronger.The height of the downstream atmospheric boundary layer increases with decreasing stratification,and the changes of downstream temperature and relative humidity are opposite to those of inversion stratification,but the degree of change is much smaller than that of inversion stratification.The higher the wind speed,the lower the total power loss rate of the wind farm.The total power loss rate in the secondary main direction is the largest,up to 33 %.The total power loss rate in the decreasing stratification is 7.5 % lower than that in the inversion stratification.The research results of this paper can provide a reference for the impact of the site selection of wind farms in low-altitude plains on the local atmospheric environment,which is conducive to the efficient and healthy development of wind farms.