Pitch Control Applied to Troposkein-shaped Darrieus Vertical Axis Wind Turbines: Power and Loads Impacts

Abstract. The present study investigates the novel application of pitch control to a troposkein-shaped Darrieus vertical axis wind turbine (VAWT). Despite the widespread usage of pitch control in horizontal axis wind turbines and straight-bladed H-type VAWTs, pitch control has never been implemented in a troposkein-shaped Darrieus VAWT due to its prohibitively complex curved blade geometry. In this work, a stall-regulated Darrieus VAWT is converted to a pitch-controlled design using partial-span blade and strut pitching. The performance of the pitch-controlled rotor is analyzed using a free-wake vortex code (CACTUS) and compared to that of the stall-regulated design. Results indicate that pitching only a partial blade span and/or struts enables the regulation of rated power in a Darrieus VAWT. Further, this new application of pitch control in troposkein-shaped Darrieus VAWTs provides a significant increase in annual energy production (AEP) and significant reduction of fatigue loads (i.e., damage equivalent loads) for thrust, lateral, and torque loads. However, these improvements come at the cost of increased peak thrust loads. The findings of this study lay the foundation for promising new operating strategies using partial span blade pitch and/or strut pitch control for troposkein-shaped Darrieus VAWTs.