Multi-objective calibration of vertical-axis wind turbine controllers: balancing aero-servo-elastic performance and noise
Abstract. Vertical-axis wind turbines (VAWTs) are considered promising solutions for urban wind energy generation due to their design, low maintenance costs, and reduced noise and visual impact compared to horizontal-axis wind turbines (HAWTs). However, deploying these turbines close to densely populated urban areas often triggers considerable local opposition to wind energy projects. Among the primary concerns raised by communities is the issue of noise emissions. Noise annoyance should be considered in the design and decision-making process to foster the social acceptance of VAWTs in urban environments. For the first time, psychoacoustic annoyance is employed as an indicator to satisfy the noise objective in a controller calibration, as this novel metric provides a more reliable estimate of the human perception of wind turbine noise than conventional sound metrics. At the same time, maximising the operational efficiency of VAWTs in terms of power generation and actuation effort is equally important. This paper addresses the pivotal trade-off between operational performance and noise emissions from a controller calibration perspective. A multi-objective optimisation approach is used to obtain the optimal set of controller calibration solutions balancing the discussed objectives. To maximise the flexibility of controller calibration, the combined wind speed estimator and tip-speed ratio (WSE-TSR) tracking controller is employed as an advanced partial-load control scheme often considered in industrial turbines, and the Kω2 controller serves as a baseline strategy for comparison. By applying a multi-criteria decision-making method (MCDM), optimal solutions are found that strike a balance between power extraction, actuation effort, and psychoacoustic annoyance. An assessment of these trade-offs, using a frequency-domain framework and mid-fidelity time-domain aero-servo-elastic simulations, yields insights into the meaningful performance metrics of the optimally calibrated WSE-TSR tracking controller. The MCDM results indicate the potential application of this controller in small-scale urban VAWTs to attain power gains of up to 39 % on one side and to trade-off a reduction in actuation effort of up to 25 % at the cost of only a 2 % power decrease and a 6 % increase in psychoacoustic annoyance on the other side compared to the baseline. These findings confirm the flexible structure of the optimally calibrated WSE-TSR tracking controller, effectively balancing aero-servo-elastic performance with noise emissions.
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