Impact of pitch actuator fault on 10-MW semi-submersible floating wind turbine

Abstract

The pitch actuator of the offshore wind turbine has a high failure rate, and this fault will lead to aerodynamic imbalance on the floating system, especially when the 10 MW wind turbine is applied. In this paper, the impact of actuator faults on the floating platform motion and turbine structure is investigated. The 10-MW OO-Star semi-submersible platform is used as the reference structure. The fault discussed in this study involved one blade seizing, followed by an emergency shutdown. Coupled non-linear aero-hydro-servo-elastic simulations were carried out in the time domain using OpenFAST. The platform motions and structural loads caused by the fault were compared with the normal operating conditions. The effects of the pitch rate at the initial fault on the loads of the critical components are presented. The results revealed that imbalanced loads due to blade seizing can lead to particularly large excitations of the dynamic responses of the wind turbine. The maximum lateral nacelle acceleration is increased by 27.9%. In addition, the parametric study on the effects of the pitch rate for feathering blade was carried out. It was found that the pitch rate of 8 deg/s is favorable to alleviate the structural loads.