Balancing fatigue damage and turbine performance through innovative pitch control algorithm

ABSTRACT Improvements to current pitch control strategies are explored by analysing the addition of a dynamic peak‐shaving algorithm, called the load limiting algorithm (LLA). The goal of this dynamic peak‐shaving algorithm is to reduce blade fatigue damage caused by wind gusts without sacrificing energy capture. This paper introduces a multivariate procedure based on the Taguchi method to systematically test different controller configurations and evaluate the algorithm's effectiveness. The LLA was tested through numerical analysis and field experiments. Numerical studies were performed on the Controls Advanced Research Turbine (CART) and the National Renewable Energy Laboratory (NREL) 5 MW model. Field testing was conducted on the CART. The primary metrics of LLA effectiveness were blade fatigue damage, measured in 20 year damage equivalent loads (DEL) for root flap bending and annual energy production (AEP). Numerical results indicate a reduction in weighted flap bending DEL (Flap DEL) for both turbine platforms. The CART demonstrates a reduction of 3.2% with a half‐percent loss in AEP. The LLA is markedly more effective on the NREL 5 MW, demonstrating a reduction of 5–9% in Flap DEL with a drop of 1–3% in AEP. Secondary benefits such as DEL reductions for other components, operating extreme blade loads, and pitch duty cycle were also explored.Copyright © 2011 John Wiley & Sons, Ltd.