Control Of Variable-speed Variable-pitch Wind Generation System

With the increasingly serious problem of global energy, new energy has been takenattention by worldwide. Wind energy, because of the characteristic of clean andrenewable, has become the focus in the energy research. In resent years, the exploitand utilization of wind energy has been developed rapidly. The variable speed andvariable pitch wind turbine is one of the mainstream model of the wind energyconversion system. And the pitch control technology has become one of the mostimportant control methods in wind energy conversion system.In the paper, we studied the level control problem of wind power system above therated wind speed. We described the operating principle of wind power generationsystem, then a mathematical model of wind turbine is established. It is not conductiveto the design of the controller because the variable speed variable pitch wind turbinehas a strong nonlinear. In the selected system work point, we used Taylor formula inthe wind power generation system mathematical model to obtain a linear model. Thenwe designed the controller to make sure the system maintained constant power outputabove the rated wind. In the process of controller designing, we chose wind as adisturbance input and pitch angle as a control input. The PID control method is used inthe pitch controller design for the first order model, simulation results have verifiedthe control effect. For the third order model, we applied pole placement, linearquadratic regulator design method and DAC design method in pitch controller design.Simulation results in matlab show that considering the changes in drive shaft torsionforce, the full state feedback law designed by pole placement and linear quadraticregulator design method ensured the wind turbine has a constant output in the selectedwork point. The DAC ensured the system has a constant output even the wind is not inthe selected work point. At last, a robust H2/H∞multi-objective controller is designedin order to reduce the mechanical load during the wind power generation systemoperating. The simulation results show that in the application of the robust controller,not only ensured the wind power generator system has a constant power output, butalso reduced the mechanical load during the wind power generation system operating.