Fault-tolerant Control Strategy Research For Wind Energy Conversion System

Improving the performance of wind energy conversion system (WECS) is of interest tothe wind energy industry as it provides an opportunity to reduce the cost of generatingelectricity from the wind. The cost of generating wind energy is largely determined by theefficiency of the wind energy capture and reliability of the system. Fault-tolerant controlstrategy for WECS has received significant attentions in recent years. On the basis of homeand abroad advanced fault-tolerant control strategy and fully understanding the workingprinciple of maximum wind energy capture for WECS, the following research work has beencarried out:For sensor failure of the T-S modeling WECS, by using fault-tolerant control ideas thatthe remaining state feedback circuits averagely share control action of the failure circuit, afeedback control-law is reconstructed, thus active fault-tolerant controller based on statefeedback is designed. The simulation results indicate that when a sensor is failure, the statefeedback fault-tolerant control system has the function of no disturbed transposition fromnormal control to fault-tolerant control, the stable operation of WECS on the condition offault can be guaranteed, and the effectiveness of fault-tolerant controller can be verified.Actuator faults for WECS are considered, the continual gain actuator faults are convertedinto system’s parameter uncertainties by analyzing the state equation of WECS, and then theT-S fuzzy model of WECS is established. Using state feedback of parallel distributedcompensation structure, robust fault-tolerant controller is designed as WECS suffers fromactuator faults, and the system stability can be proved. The simulation results indicate systemcan still achieve maximum wind energy capture below the rated wind speed on the conditionof actuator faults, the degree of fault deterioration is retarded, and the utilization rate of theunit is also improved.A novel active fault tolerant control strategy based on sliding mode control theory isproposed for the actuator fault in WECS. By collecting the real-time status of the actuatorfaulty and normal conditions, a sliding mode fault observer is designed, and then the actuatorfaults are reconstructed realizing the fault detection. Depending on the reconstructed fault, acompensation to the sliding mode controller is provided, so the reliable control to WECS canbe guaranteed, therefore active fault-tolerant function is realized for actuator faults．Somesimulation experiments are carried out. The results show that actuator faults for WECS can beaccurately reconstructed by the sliding mode fault observer, under the condition of noaffecting the dynamic performance of WECS, the maximum wind energy capture can still beachieved by active compensation fault-tolerant controller.