Modeling and Modern Control of Wind Power

Chapter 4Optimal Control Strategies of Wind Turbines for Load Reduction

Shuju Hu and Bin Song

Institute of Electrical Engineering, Chinese Academy of Sciences

4.1 Introduction

A modern large-scale wind turbine is a complex multi-body system including blades, wind wheel, drivetrain, generator, nacelle, tower and other components. With wind turbines becoming large scale and lightweight [1], the flexibility of components is increasing and the natural frequency of the system is gradually reducing. Meanwhile, due to non-stable factors, such as wind shear, the tower-shadow effect and turbulence, the dynamic loads on wind turbines are very complex. As wind turbines bear long-term dynamic loads, many components will suffer dynamic stress, thereby causing fatigue damage [2]. Fatigue damage is one of the main forms of failure of wind turbine mechanical parts and structural components, so it must be of concern during design and operation processes [3]. To improve the reliability and lifetime of wind turbines, loads must be reduced. Therefore, the research on control strategies for wind turbines for load reduction has attracted both domestic and international attention.

Wind turbine load reduction control comprises passive control and active control. Passive control is realized by selection of suitable elastic support components for damping the wind turbine, so that vibrational restriction and load reduction can be achieved. Although the structure of passive control devices is simple, ...