Study On The Flow Field Of Wind Farm With The Coupling Of Terrain Effect And Wake Effect

In recent years,the wind power industry has developed rapidly.In some countries and regions,the installed capacity of wind power has exceeded that of traditional fossil energy.At present,available flat terrain wind resources have been exhausted,and new onshore wind farms are transferred to the areas with low wind speed and high terrain complexity.Therefore,the study of wind farm flow field with complex terrain is an important part of wind power research field.Wake effect refers to the phenomenon that wind speed decreases and turbulence intensity increases downstream of the wind turbine after the incoming wind passes through the rotating wind turbine,which leads to the power reduction and fatigue load increase.At the same time,the complex terrain makes the atmospheric environment of the wind field(wind shear,atmospheric stability,turbulence intensity and air separation,etc.)complicated and changeable.The coupling of the two makes the flow field more complex,which has a great influence on the performance of the wind turbine.In this paper,the internal wind field flow field under the combined action of terrain and turbine wake is taken as the research object,and the following three aspects of experimental research and mechanism analysis are mainly carried out:Firstly,the change of turbulence intensity in complex terrain and the influence of turbulence intensity on wind turbine wake are studied.Turbulence intensity is an important factor affecting the wake characteristics of wind turbines,which directly affects the turbine wake recovery speed.In this paper,the wake flow field and atmospheric environment were measured by laser doppler radar.The variation of turbulence intensity with different time period and height is studied.The development and variation of the width,depth and velocity attenuation of wind turbine wake are investigated.The relationship between wake characteristics and turbulence intensity is analyzed.The results show that the turbulence intensity changes slightly when the temperature is low,and the turbulence intensity decreases with the lower altitude.When the temperature is high,the influence of height on turbulence intensity is small.Secondly,the turbine wake characteristics and the interaction of turbine wakes with different turbine diameter are studied.Using laser doppler radar to scan the wake interaction area,turbine wake characteristics under different wind speed,turbine wake characteristics with different turbine diameter and the interaction of different turbine wake is studied,and SCADA data is combined to analyze the performance of power generating.Finally,the wake characteristics of wind turbines and the performance of wind turbines under different working conditions on a complex terrain are studied.According to the wind direction and wind turbine arrangement,three typical working conditions are selected: full wake working condition,half wake working condition and independent wake working condition.Studies show that altitude is not the only factor affecting the wind speed,and terrain slope and terrain length also play a significant role.Meanwhile,compared with the full wake condition,the power of the wind turbine in half-wake condition is increased by 15%.In this paper,laser doppler radar is used to conduct experimental analysis on the wind field under the coupling action of terrain and wake,and then the variation characteristics of wind turbine power under the coupling action of the two are studied.The results in this paper provide experimental data for the internal flow field mechanism analysis of wind farms on complex terrain,and provide a reference for wind turbine layout optimization and collaborative control.