Research On Optimal Pitch Control Strategies For Straight-bladed Vertical Axis Wind Turbine

Faced with the increasing severity of the energy crisis and globalenvironmental issues such as pollution, development of renewable energy sources isimminently. As a fan, which can convert wind energy into electrical energy, windturbine is an important tool for the exploitation of wind energy at present.According to the direction of the fan shaft, wind turbine can be divided intohorizontal axis and vertical axis wind turbine fan. Because of the horizontal axiswind turbine has a higher utilization of wind energy, the theory and technology ofwhich are already quite mature, the research of vertical axis wind turbine is notattractting the world's attention, because of its lower utilization of wind energy. Inrecent years, small vertical axis is gradually favored, because of the potential abilityto adapt to the complex of small vertical axis wind turbine, as well as thedevelopment of large-scale vertical axis wind turbine. Papers will take the lift typestraight blade vertical axis wind turbines as the study, basing on the pitch angle thatcan significantly alter the characteristics of the aerodynamic performance of theblades, aims to improve its self-starting performance and efficiency of wind energyutilization.Traditional multi-sided flow tube (Double-Multiple-StreamTube, DMST) fanperformance evaluation methods has a feature of simple principle andcomputationally efficient. Paper has been based on aerodynamic decomposition ofpitch and calculation principles elaborated, to improve DMST program for threeaspects: first, joining the correction of dynamic stall; second, adding the effects ofvariable pitch angle; third, improve the convergence program. After improvement ofthe program, the accuracy and convergence of vertical axis wind turbineperformance is evaluated, and it can be used to calculate the distance pitch fan.Paper has established a straight vertical axis wind turbine blade pitch angleoptimization model combined with genetic algorithm and based on the platform ofDMST. It has obtained the optimal pitch angle curves under different tip speed ratio,which is Initiative control the pitch angle of the optimal strategy. Through theanalysis of the tangential and normal force coefficients and wind utilization curve,it has show that the optimized utilization of wind energy has been significantly improved. The active pitch control strategy can be applied to research independentcontrol device easy to install large vertical axis wind turbine, and passive pitchcontrol device is suitable for low-cost small vertical axis wind turbine of water inthe town or the complex flow field.CFD numerical has simulated the variable pitch fan operation flow field, whichhas also demonstrated the effectiveness of the pitch control on the energy efficiencyof mining. In addition, paper has designed a passive pitch control mechanism basedon the optimal pitch angle curve. The pitch angle of the mechanism is close tooptimized pitch angle during wind wheel rotation process by adjusting the size ofthe agency members. Through compara and analysis, it shows that passive pitchcontrol mechanism can improve the utilization of wind energy and startingperformance.