Control based power smoothing for aggregated vertical axis wind turbines

Soraghan, Conaill Eoin and Leithead, William and Yue, Hong (2012) Control based power smoothing for aggregated vertical axis wind turbines. In: EWEA 2012 The European Wind Energy Association, 2012-04-16 - 2012-04-19.

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Abstract

Recently there has been renewed interest in the potential of vertical axis wind turbines (VAWTs), particularly, at very large scale of 10 MW or above owing to their structural simplicity. A significant disadvantage for many types of VAWTs is that the generated power is inherently periodic in nature. This power quality issue is exacerbated as the turbines increase in size and are aggregated requiring the transmission system to withstand large transients. These periodic perturbations in power can be smoothed out by permitting the rotor speed to vary; however, operation in this manner results in a poor capacity factor. A new approach to smoothing the power fluctuations from aggregated VAWTs is proposed, whereby a controller for a small group of turbines is used to adjust the relative phase of the periodic power output from individual machines while maintaining the overall performance of the turbines in a group. Simulation of this control scheme demonstrates that the fluctuations in the aggregated power can be significantly reduced without affecting the mean aggregated power output. The control strategy has been tested by simulation for a range of farm configurations at various wind speeds. The results indicate that the proposed control scheme becomes more effective for increased number of turbines.