Fault-Tolerant Individual Pitch Control of a Wind Turbine with Actuator Faults

Abstract

The sizes of wind turbines have been steadily increasing over the past decade, especially on the offshore sites. The greater structural flexibility of such machines necessitates considerations of reliable load mitigation techniques in order to alleviate the effects of asymmetric wind loads and fatigue. This paper proposes a reliable load mitigation scheme, referred to as ‘fault-tolerant individual pitch control’, which involves adjustments in pitch angles of the wind turbine blades individually in the presence of blade pitch actuator faults. The proposed scheme consists of a collective pitch control augmented with an individual pitch control, and a fault detection and diagnosis system. Simulation results obtained for a large-scale offshore wind turbine with a stochastic wind field illustrate effectiveness as well as fault-tolerance of the proposed scheme compared to the scheme based on control of pitch angles collectively. Moreover, the proposed scheme not only ensures more uniform output power with reduced loads on the turbine, but also tolerates the effects of possible faults in pith actuators of the blades.