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The Scientific World Journal
Volume 2014 (2014), Article ID 406382, 9 pages
Research Article

Linear and Nonlinear Schemes Applied to Pitch Control of Wind Turbines

Department of Automation, Tsinghua University, Beijing 100084, China

Received 24 June 2014; Accepted 11 August 2014; Published 3 September 2014

Academic Editor: Linni Jian

Copyright © 2014 Hua Geng and Geng Yang. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Linear controllers have been employed in industrial applications for many years, but sometimes they are noneffective on the system with nonlinear characteristics. This paper discusses the structure, performance, implementation cost, advantages, and disadvantages of different linear and nonlinear schemes applied to the pitch control of the wind energy conversion systems (WECSs). The linear controller has the simplest structure and is easily understood by the engineers and thus is widely accepted by the industry. In contrast, nonlinear schemes are more complicated, but they can provide better performance. Although nonlinear algorithms can be implemented in a powerful digital processor nowadays, they need time to be accepted by the industry and their reliability needs to be verified in the commercial products. More information about the system nonlinear feature is helpful to simplify the controller design. However, nonlinear schemes independent of the system model are more robust to the uncertainties or deviations of the system parameters.