Research On Fault-tolerant Operation Wind Power Generation System And Its Multi-mode Power Control

Wind power generation offers efficient solutions to the current global energy and environmental challenges.Furthermore,it is the most viable renewable energy in terms of technology and economic feasibility.China is actively optimizing her energy patterns by advocating for distributed wind power generation,local power generation,local consumption,and strives to improve the utilization level of wind energy resources.Therefore,there is a need to develop wind power generation systems with high efficiency and operational reliability.Considering the high failure rate level of the electromechanical components in the wind power generation system,as well as the characteristics of strong nonlinearity,uncertainty,and large disturbance operation.Much research is being performed on the design of a wind power generation system with fault-tolerant running motor and nonlinear control theory to improve the working performance further.This study research was focused on the fault-tolerant wind power generation system using a permanent magnet fault-tolerant motor.The study was performed based on mathematical modeling,characteristic analysis,fault-tolerant motor design,power generation control of the system in normal and fault states,and hardware-in-the-loop simulation.The detailed contents include:1.The overall-wind-speed range power control strategy of wind power generation system is studied.According to the cut in,rated and cut out three kinds of wind speeds,the system running state is divided into four modes.The working requirements and switching conditions of the MPPT operating mode,as well as the constant power operating mode are given.The second-order extended state observer(ESO)is designed to estimate wind turbine real-time aerodynamic torque,so that the angular speed of the switching command between the four modes can be obtained.Simulation results verify the correct effectiveness of the proposed power control strategy.2.The four-phase six-pole structure fault-tolerant permanent magnet(FTPM)motor based on Halbach array is developed.The simplification decoupling mathematical model of permanent magnet motor in dq-axis coordinate system is established.The model is unified with permanent magnet motors.The structure of the FTPM field oriented vector control system with fault phase compensation fault tolerance strategy is given.The electromagnetic parameter calculated is completed.Through the Maxwell 2D / Simplorer field-circuit co-simulation and principle prototype experiment,the good back EMF sinusoidal output,as well as good fault tolerance and fault isolation capability are verified.3.Aiming at the problem of incomplete decoupling and strong cross-coupling of dq-axis current inner loop of permanent magnet motor,the MPPT Back-stepping control of permanent magnet direct-drive wind power generation system based on torque observer is proposed.Using nonlinear disturbance observer(NDO)wind turbine aerodynamic torque is estimated.In the framework of FOC decoupling control strategy,the dq-axis current decoupling command signals are obtained by constructing the virtual control laws and Lyapunov functions,and the actual dq-axis input voltage control laws ud and uq are derived.The correctness and effectiveness of the Back-stepping controller are verified by comparison with the PID controller.4.In order to enhance the ability of the overall-wind-speed power generation outer loop to suppress the model uncertainty,parameter perturbation and wind speed disturbance,the dynamic sliding mode control(DSMC)strategy for the permanent magnet direct-drive wind power generation system based on power exponential approach rate is proposed.The outer loop controller is built on the dq-axis current inner loop Back-stepping control framework.According to the requirements of power generation operation in overall-wind-speed working area,the outer loop control law is designed by sliding mode control(SMC)based on power exponential approach law,in which the negative feedback term of the sliding mode switching function amplitude is adopted.The dynamics sliding mode control law involves a first-order integral process of the control input signal.Comparative experiments verify that the proposed control strategy can improves the smoothness,accuracy and robustness of power generation control,and has the ability to effectively suppress chattering.5.Aiming at the unpredictable problem of partial loss of actuator effectiveness caused by failure,the novel angular speed tracking dynamic model of wind power generation system based on generalized disturbance is established,and then the new MPPT adaptive active fault-tolerant control(AFTC)method is proposed.The active fault-tolerant control law does not depend on system model parameters and fault information.Using the bias-based nonlinear state feedback and the adaptive online real-time estimation method of the disturbance term boundary value,the fast and effective compensation for faults and disturbances is realized.The first-order integral of the active fault-tolerant control law is taken as the actual power control output.This can further smooth the power generation regulation process and ensure that there is no static difference in the power tracking control.Through multi-strategy comparison experiments,the robustness and self-adaptation of the proposed method to fault mitigation are verified.6.The rapid control prototype(RCP)hardware-in-the-loop simulation system based on LabVIEW FPGA platform is proposed for MPPT simulation test.The overall architecture and development process is given.On the LabVIEW RT real-time operating platform,the real-time simulation models of wind speed,wind turbine,permanent magnet generator,as well as MPPT rapid control prototype are built.The wind power generation system power converter by the structure of uncontrolled rectifier series boost converter is developed,and the NI-PXI hardware-in-the-loop simulation system is constructed.The test results verify the efficiency,flexibility and effectiveness of the system.