Adaptive Robust Fault-Tolerant Control Design for Wind Turbines Subject to Pitch Actuator Faults

Afef Fekih,Saleh Mobayen,Chih-Chiang Chen

doi:10.3390/en14061791

Abstract

This paper proposes an adaptive fault tolerant control (FTC) design for a variable speed wind turbine (WT) operating in the high wind speeds region. It aims at mitigating pitch actuator faults and regulating the generator power to its rated value, thereby reducing the mechanical stress in the high wind speeds region. The proposed FTC design implements a sliding mode control (SMC) approach with an adaptation law that estimates the upper bounds of the uncertainties. System stability and uniform boundedness of the outputs was proven using the Lyapunov stability theory. The proposed approach was validated on a 5 MW three-blade wind turbine modeled using the National Renewable Energy Laboratory’s (NREL) Fatigue, Aerodynamics, Structures and Turbulence (FAST) wind turbine simulator. The controller’s performance was assessed in the presence of several pitch actuator faults and turbulent wind conditions. Its performance was also compared to that of a standard SMC approach. Mitigation of blade pitch actuator faults, generation of uniform power, smoother pitching actions and reduced chattering compared to standard SMC approach are among the main features of the proposed design.

Highlights

Wind energy is among the most promising and fastest growing sustainable energy source
The above results confirm the high effectiveness and robustness of the designed control system. They highlight the ability of the proposed adaptive sliding mode control (SMC) to successfully accommodate for the fault effects on the dynamics of the wind turbine (WT)
Comparison analysis with a standard SMC approach showed that the reliance on an adaptive gain in the SMC design resulted in smoother pitching actions, smaller gains and reduced chattering compared to the standard SMC approach

Summary

Introduction

Wind energy is among the most promising and fastest growing sustainable energy source. In the high wind speed region, wind turbines (WTs) are operated to maintain the generated power at its nominal value by controlling the pitch angle and the generator torque Designs such as proportional integral derivative (PID) control [3], neural network based-PI control [4], optimal control [5], linear parameter varying (LPV) control [6], gain scheduling [7], robust control [8], adaptive control [9] and fuzzy logic control [10] have traditionally been considered to control wind turbines. An Integral Terminal Sliding Mode (ITSMC) approach, with gains auto-tuned using a fuzzy system, was proposed in [31] for DFIG-WT Though it improved the wind turbine’s performance in the presence of faults and disturbances, its implementation was computationally challenging.

Pitch Actuator Model

Controller Design

Simulation Results

Conclusions