PARAMETER COMBINATION AERODYNAMIC ANALYSIS OF NEW PITCH ANGLE CONTROL STRATEGY FOR VERTICAL AXIS WIND TURBINE

Vertical axis wind turbines with large angle of attack at low tip speed ratios suffer from severe flow separation. The blade angle of attack can be adjusted by pitch to reduce the blade flow separation and improve its aerodynamic efficiency. The H-type Darrieus vertical axis wind turbine is used as the research object. Based on the variation law of angle of attack with phase angle, a pitch angle control strategy is proposed. This control method is characterized by a proportional decrease in the angle of attack at different phase angles. The angle of attack decreases significantly at large angles of attack, while the change is small at small angles of attack. The effect is then verified by numerical calculation. The results show that the proposed pitch angle control strategy can significantly improve the power coefficient. The control strategy approach with different parameter combinations is also better than the single parameter control strategy, although the wind energy capture efficiency in 0°-180° (windward region) and 180°-360° (leeward region) will affect each other. In addition, the discontinuous pitch angle velocity will lead to torque fluctuation, which can be eliminated by fitting the pitch curve with a weight function. © 2023 Science Press. All rights reserved.