| Yawed wind turbine wakes will experience lateral deflection.The aim to reduce the power loss of downstream turbines caused by wake shielding effect and to increase the output power of the whole wind farm can be achieved by reasonable yaw control strategy,which is the frontier hot topic of current wind power research.However,the strategy which has better universality and effectiveness needs further research.In order to solve this problem,the single row turbine and the whole wind farm are taken as the research objects.Under neutral atmospheric conditions,the power optimization operation based on the yaw of wind turbine is studied systematically.A control strategy on turbine thrust coefficient,wake decay coefficient and turbine spacing is proposed,which has been validated and further developed in aligned turbines and wind farms.The main research contents of the thesis are as follows:(1)The large eddy simulation method is used to analyze the wake of a single yawed turbine with different yaw angles,and the wake deflection and the counter-rotating vortex pair of the wake under yawed condition of the wind turbine are reproduced.(2)A control strategy about the turbine thrust coefficient,wake expansion coefficient,and turbine spacing for aligned wind turbines is proposed.Taking aligned turbines as the research object,the cooperative yaw optimization is carried out under different surface roughness,different turbine spacings and turbine thrust coefficients.According to the optimization results,the optimal yaw control strategy is simplified to a solution space containing only two yaw angles.One of them is the yaw angle of the first turbine,and the other is the yaw angle of the second to(N-1)-th turbine.In the cooperative yaw optimization control,the yaw angle of each wind turbine can be solved by the proposed formulas,and furthermore,an optimized control strategy is proposed.The effectiveness of the proposed optimization control strategy is validated by large eddy simulation.The results show that for aligned turbines,the cooperative yaw optimization can significantly increase the power generation of the whole wind farm;when the thrust coefficient is 8/9,the turbine spacing is 7 times the rotor,the yaw coordinated control is adopted for 5 aligned turbines,and the total power can be increased by 17.5%.(3)A cooperative optimization control method combining yaw control and thrust distribution is proposed,which significantly improves the operating efficiency of ideal wind farms and actual wind farms.Through the yawed wake model and genetic algorithm,the cooperative yaw optimization,thrust coefficient optimization,and the combined optimization of yaw and thrust coefficient in the ideal wind farm and the actual wind farm were studied,and it was found that all the three methods can effectively increase the whole wind farm power.When the wake loss is moderate,the cooperative yaw optimization alone and the cooperative optimization of thrust distribution can increase the total power of the wind farm by 1%～2%,and the improvement effect of the combination of the two optimization methods can raise to 3%～4%.The cooperative yaw optimization strategy proposed in this paper can provide an important reference for the cooperative yaw control of wind farms under different flow conditions,different turbine spacings and different surface roughness,and has important engineering application value.The whole field optimization method proposed in this paper can provide a reference for the operation control of smart wind farms in the future. |
