Dynamic Loads of Variable-Speed Wind Energy Conversion System

Two basic control goals for wind energy conversion system (WECS) can be summarized as increasing its annual energy yield and extending its service life. The former can be achieved by using an optimum power control strategy, which is quite a mutual technology right now. Meanwhile, the way to achieve the latter cannot be evidenced so far. It has been found out that the service life of WECS is closely related to the amount of dynamic loads it bears. In the research of this paper, three major dynamic loads, namely, aerodynamic load, transient load, and transit load, are studied. First, definitions and the generating mechanisms of different dynamic loads are given. Then, corresponding attenuating strategies are proposed, and their operational principles are elaborated. Finally, the proposed control strategies are combined into one low-dynamic load power control strategy, which is an improved version of the commonly used power control strategy for WECS in the industry. The load-attenuating effects are validated by applying comparative experimental tests performed by a 10-kW variable-speed fixed-pitch WECS test rig setup in the laboratory.