Research On Control Strategy Of Virtual Synchronous Generator Based On Energy Function

With the rapid development of distributed generation technology,micro-grid technology has received more and more attention.The micro-grid not only improves the flexibility of distributed power supply,but also has advantages in eliminating the output of new energy and stabilizing the system.As a key link between renewable energy and grid connection,grid-connected inverter has the advantages of flexible control and fast response.However,its lack of inertia and damping has adversely affected the stable operation of the system.Therefore,Virtual Synchronous Generator(VSG)technology emerges as the times require.By using the characteristics of synchronous generators,the virtual synchronous generator makes the output of the inverter inertia and damping,which improves the stability of the microgrid operation.Distributed power supply compatibility.In this paper,the grid-connected inverter is taken as the research object.According to the mathematical model of the synchronous generator,the control structure of the virtual synchronous generator is established,and the virtual synchronous generator controls the external characteristics of the synchronous generator.Secondly,according to the nonlinear characteristics of the power system,the fourth-order mathematical model of the synchronous generator is adopted,and the virtual synchronous generator control is designed by using the Hamilton system method from the energy point of view.Considering the close relationship between damping coefficient and system stability,the damping compensation term is added to the rotor motion equation,and the control law of valve and excitation coordination control is derived.Based on this control law,a virtual synchronous generator control based on compensation damping coefficient is designed.Finally,the effectiveness of the proposed control strategy is verified by the simulation software platform.The smaller the inertia coefficient is,the smaller the amplitude of the system frequency fluctuation is,and the shorter the time required to reach the stable value is.The larger the damping coefficient is,the smaller the amplitude of the system frequency fluctuation is,and the longer it takes to reach the stable value.The virtual synchronous generator control based on the compensation damping coefficient is compared with the virtual synchronous generator control based on the Hamilton system method.The simulation results show that the proposed control strategy not only better simulates the external characteristics of the synchronous generator,but also improves The stability of the system;reduce the impact of disturbance on the system and enhance the robustness of the system.