Fault-tolerant Design Of Doubly-fed Wind Power Generation Control System

As the most mature and most promising renewable energy technology,wind power generation technology has attracted global attention,but wind turbines are in a remote and harsh environment and are not easy to maintain and overhaul.With the rapid increase of the capacity of the grid-connected wind turbine assembly machine,the reliable operation of the wind turbine is becoming more and more important.Through the control of the dual PWM converter,the double-fed wind generator achieves variable speed constant frequency,but the converter is a device with higher failure rate in the wind power generation system.In order to enable uninterrupted operation of the double-fed wind generator after the converter switching device fails,fault-tolerant control of the open-circuit fault of the PWM-side converter is studied in this paper.Through the qualitative analysis of the mathematical model of the doubly-fed wind generator and the grid-side converter under normal operation,the main control target of the grid-side converter is obtained.Based on this research,a fault-tolerant converter topology with simple structure and no redundancy is adopted at the grid side of the doubly-fed wind power generator,and the mathematical model of the converter in the d-q coordinate system is established.Based on this mathematical model,a dual closed-loop control system for fault-tolerant grid-side PWM converters is designed.A compensating scheme is designed for the unbalanced voltage on the DC side after the fault of the converter and the fault-tolerant converter is adopted.A SVPWM modulation technique suitable for three-phase four-switch is proposed.A fault-tolerant network-side PWM converter is proposed to control the dynamic switching strategy of the control system.Finally,in MATLAB/Simulink,a simulation model of a doubly-fed wind generator set based on a fault-tolerant grid-side PWM converter was built.After the failure of the grid-side PWM converter,the current,voltage,and active power of the rotor side of the doubly-fed wind turbine generator were measured.Power,grid current,voltage and DC bus voltage were simulated.The simulation results show that the fault-tolerant line-side PWM converter can maintain a constant DC-link voltage and ensure a power factor of 1 after a fault occurs.