Research On Primary Frequency Regulation Control Strategy Of 1.5MW Permanent Magnet Direct-drive Wind Turbine

In order to handle the more and more severer problems of energy and environmental,wind power has been widely developed in the world.The variable speed wind turbine is the mainstream in the current wind farm,and it is also the future direction of development,however,its output is decoupled from the frequency of the power grid,and there is no reserved capacity under the maximum wind energy tracking mode,which leads to the lack of primary frequency regulation capability of the unit.The large-scale variable speed wind turbine connect to the grid,it will reduce the frequency stability of the system.Wind power participating in the frequency regulation of the power grid is considered to be the necessary capability of wind power field in the future.Therefore,it is of great significance to research the control strategy of wind power frequency regulation.Reserved capacity and primary frequency regulation control strategy of wind turbine under different working conditions was researched in this paper,in which the 1.5MW permanent magnet direct-drive wind turbine(PMWT)is taken as the research object.Following is the main research work:(1)The paper analyzes the structure and constitution of PMWT and establishes the mathematical model of the wind turbine including rotor,the variable propeller actuator,the permanent magnet synchronous generator and the converter.The traditional active power control strategy is analyzed,which lay a theoretical foundation for the research of primary frequency regulation.(2)There is no reserved capacity for wind turbines,and it has no primary frequency regulation capability,the coordinated control strategy for active load reduction of overspeed and variable pitch is proposed.The strategy can give full play to the advantage of overspeed control and avoid the insufficiency of pitch control,making the unit can maintain a constant proportion of reserved capacity under all wind speed.The traditional active power control strategy is improved based on that the output characteristics of each wind speed zone are analyzed in detail,the active load reduction control of the unit under all the wind is realized by changing the speed tracking curve and improving the traditional variable pitch control algorithm.(3)On the basis of active load reduction,the primary frequency regulation control strategy on variable coefficient of adjustment is proposed.The spare capacity of wind turbine is different in different wind speeds,the strategy adopts variable coefficient of adjustment,the adjustment coefficient is determined by the real-time reserve capacity,the more the spare capacity,the more unbalanced power will be assumed,and the reserved capacity will be rationally utilized.The unit calculate the frequency regulation reduction ratio according to real time power and active power increment and realize primary frequency regulation by controlling the load reduction ratio.(4)In order to verify the effectiveness of the active load reduction and primary frequency regulation control strategy proposed in this paper,the model is established in MATLAB/Simulink.The simulation results show that the active load reduction control strategy based on coordinated overspeed and variable pitch can adopt preferentially over-speed control to make the unit effectively achieve load reduction requirement under all wind speedwhich reserve the spare capacity for primary frequency regulation.The primary frequency regulation control strategy of wind turbine based on variable coefficient of adjustment can effectively improve the frequency stability of the system and reduce the pressure of conventional frequency regulation unit,and use reasonably reserved capacity of the wind turbine.