The Analysis And Application Of Wind Turbine Wake Effect

With the decrease of traditional energy,wind energy as a kind of renewable clean energy,attracts increasing attentions in recent years.For the usage of wind power,it is the most common way to transform wind energy to electrical energy.In the wind farm,when the smooth air through the turbine blades drives the wind turbine rotation,there exists a wake effect under the wind direction due to the rotation of the wind turbine and the blade blocking effect.In the wake effect region,the phenomena will generate turbulence,eddy current,and so on,and all of them will have an effect on the power of downstream wind turbines and reduce the service life of the wind turbines.If the wake effect is not controlled properly,it will reduce not only the utilization of wind resources,but also the overall efficiency of wind farms.In view of the phenomenon of the wake effect on the power output of wind turbines,this thesis,from the perspective of wind turbine thrust coefficient,puts forward to a method to increase the total output power of the wind farm.The major contributions of this thesis are as follows:(1)Based on the Jensen wake model,this thesis devotes to control the thrust coefficient of the upper turbines and to improve the comprehensive wind turbines output accompanied by the optimization of power generation.(2)Analyzing the superposition of wake speed,which get the model of wake superposition and the speed of every wind turbine after superposition.Through fitting the wind energy utilization coefficient and the thrust coefficient,the wind turbine model of output power is further refined to get the final mathematical expressions.(3)Carrying out three-dimensional numerical simulation for a single wind turbine,the wake effect of the wind turbine is examined from the viewpoint of fluid mechanics.As found in the data analysis results from Matlab,the upstream wake of wind turbine has a great influence on the downstream wind turbine power output.Thus,it is necessary to consider the wake effect when calculating the wind farm power output.(4)Increasing the serial number of wind turbine,this thesis develops the calculation method of maximizing the output power after the serial distribution of N wind turbines.The arrangement of wind turbines in the wind farm is analyzed.In order to reduce the influence of wind turbine wake,the staggered arrangement should be considered during the construction of wind farms.Finally,this thesis develops the optimal output control platform.The platform provides the original data and control operation which can adjust the wind turbines' thrust coefficient.The theoretical results from this thesis provides a guideline for the wake effect control in reality.