Fatigue Loads Mitigation on Horizontal Axis Wind Turbines Using Aerodynamic Devices. A Survey

Abstract

The paper presents overview of source loads and aerodynamic techniques that are feasible for fatigue load reduction on large horizontal axis wind turbines. The article highlights the effects of increasing wind turbine rotor diameter on fatigue load, and feasible aerodynamic techniques that can be employed to reduce fatigue load. Increased in fatigue load is critical as current and future horizontal wind turbines are designed of large rotor blades. Increase in size of wind turbines has been elicited by highly demand for clean energy nowadays as well as need to decrease the cost of energy per kilo watt. As the rotor diameter increases in size, so do effects of air loads acting on the blades. The pitch control systems installed with a purpose of controlling such effects are approaching their capability limits. They are unable to dump sudden, high varying air loads associated with fluctuating wind speed on time. As these effects occur repeatedly during operation of wind turbines, they can cause premature failure or permanent damage of major components due to fatigue load accumulation. In overall, the service life of wind turbine can drastically reduce or high operational and maintenance costs are likely to rise up due to frequent downfalls of unplanned maintenance schedules. Therefore, alternative methods rather than pitch control are reviewed that can improve wind turbines efficiency. The paper concludes by analyzing possible opportunities in future.