Control Strategy Research On Virtual Synchronous Generator Of Permanent-magnet Direct-driven Wind Power System

As the largest,green and clean renewable energy in the world,wind energy has developed rapidly in recent years.However,due to the randomness and intermittence of wind energy,the wind power generation system has a great impact on the grid when it is connected to the grid,which is not conducive to the stability of the power grid.In order to solve this problem,the virtual synchronous generator control used in direct drive wind power system,not only solves the problems of the impact of wind power on the power grid caused,but also can deal with large-scale wind power or high penetration of wind power system.The idea of direct drive wind power system AC side and fed power and virtual synchronous generator control strategy proposed in this paper can also be applied to other new energy generation systems.The contents of this paper are as follows:First,the research status of virtual synchronous generator is summarized,and the structure of virtual synchronous generator applied to direct drive wind power generation system is proposed,that is,the direct drive wind power generation system’s AC side and energy storage,and the virtual synchronous generator control strategy is adopted.A direct drive permanent magnet wind power generation system is built,and the control of the side controlled power network side voltage is achieved by system control.It has laid a good foundation for the study of the direct drive wind power system controlled by the virtual synchronous generator.Then,the energy storage device is used in wind power system because of the application of the virtual synchronous generator control in the wind power system.Therefore,it is necessary to study the influence of the introduction of energy storage on the stability of the power grid.The electromagnetic torque analysis method based on the electromechanical time building with energy storage device of single machine infinite power system scale mathematical model of the single machine infinite system mechanism of damping power oscillation device is studied,explains the principle of different control strategies affect the grid equivalent inertia coefficient,synchronous coefficient and damping coefficient.The research shows that the P,I and D controllers respectively change the equivalent damping coefficient,the synchronization coefficient and the inertia coefficient of the system,and the three equivalent coefficients increase with the increase of the coefficient.Finally,according to the similarity between synchronous generator and grid connected inverter,there is a good correspondence between the two mathematical models on the time scale of DC voltage,so the virtual synchronous generator control is designed.The control strategy mainly includes the virtual synchronous generator algorithm,the virtual governor and the virtual excitation regulator.The virtual synchronous generator control strategy is applied to the simulation and analysis of energy storage off-grid operation,energy storage grid-connected operation,direct drive wind power generation system off-grid and grid-connected.Simulation results show that the virtual synchronous generator control can increase the system inertia.Virtual synchronous generator has the same characteristics of regulation and load power distributionand with traditional synchronous generator.