Robust Control For Grid Connection And Maximum Power Tracking Of Permanent-magnet Direct-driven Wind Power Systems

Maximum power point tracking control of wind power generation is the researchpriorities in wind power technology，and grid wind power is the most economical way forlarge-scale use of wind energy. Moreover, control strategy is the key technique to utilizeand development wind energy but also improve power quality. Therefore, the main workof this paper contains: capturing maximum wind power and the grid connection of thedirect-driven permanent magnet wind power generation system are investigated, thespecific work are as follows:Through to analysis the working principle of the wind turbine, drive train, permanentmagnet synchronous generator, double PWM converter, the nonlinear mathematical modelto describe the complete dynamic characteristics of direct-drive permanent magnet windpower generation system is established.Research on the maximum power point tracking control problem of the direct-drivenpermanent magnet synchronous generator. Use the rotor flux-orientation control strategyand the robust back stepping nonlinear control techniques to design a robust trajectorytracking controller. Adjust the wind power system by control the torque of stator current,to achieve the capturing maximum wind energy and the stability of the system. Thetheoretical analysis and simulation results show that the designed controller can ensure thewind power system works in the safe and reliable status, and fulfill the goal of capturingmaximum wind power under the condition of exist in the uncertain parameters and theexternal interference.Research on the control method of the direct-drive permanent magnet wind powergeneration system for grid connection. On the basis of the maximum power point trackingproblem of direct drive permanent magnet wind generator, adding the rectifier inverter tolink, the control strategy is investigated for direct-driven permanent magnet wind powergeneration systems under normal grid conditions.The wind power system ismathematically modeled by using the field-oriented vector-transformation of the rotor andvoltage-oriented vector of grid control. The rotor-side and grid-side converter controllersare designed in integration by utilizing nonlinearity robust control technology. The theoretical analysis shows that the proposed controller can guarantee the system to achievethe maximal absorption of wind power, constant dc-bus voltage in the desired nominalvalue and also to produce the desired reactive power through the grid side convertercontrol, and constant voltage constant frequency output with respect to variablewind-speed, parameter uncertainties and disturbance. The effectiveness and validity of theproposed strategy is validated by the simulation.