Research On Control Method Of Virtual Synchronous Generator For Photovoltaic Grid Connected Inverter

With the development of industry,the demand for energy is increasing day by day.At present,traditional energy sources are increasingly scarce,and the use of traditional energy sources has brought serious environmental pollution.This has made renewable energy power generation technology widely concerned by researchers,and the proportion of photovoltaic power in the power system has also continued to increase.In recent years,photovoltaic power has become a hot research field of power system.The photovoltaic power supply is connected to the grid through a grid-connected inverter composed of power electronic devices,which is called the most effective access method.However,the photovoltaic grid-connected inverter composed of power electronic devices lacks inertia and damping characteristics.Based on this situation,it is more difficult to realize the safety and stability control of the power system at this stage.The virtual synchronous generator technology changes the control strategy structure,so that the photo voltaic grid-connected inverter has the inertia and damping characteristics of the synchronous generator when controlling the inverter operation.Therefore,its research is of great significance for the improvement of system stability.At this stage,both at home and abroad are very focused on the research and application of this technology.Based on this background,the research on the photovoltaic grid-connected inverter based on virtual synchronous generator control is carried out.(1)Based on the virtual synchronous generator theory,the control strategy of the photovoltaic grid-connected inverter is studied,and the corresponding mathematical model is established.Photovoltaic grid-connected inverter control has natural advantages,so a virtual synchronous generator control model is designed on this basis,and the feasibility of virtual synchronous generator technology is verified by simulation.Based on the three points of voltage,frequency and harmonic,an improved control strategy is proposed,and related mathematical modeling is carried out.(2)Calculate the mathematical control principle of the virtual synchronous generator,design and establish the control structure of the control system on active and reactive power according to the mathematical principle,and use MATLAB to establish the mathematical model of the virtual synchronous generator,and then obtain the simulation results through the simulation experiment.The results corroborate the accuracy of the model.(3)The photovoltaic grid-connected control strategy of the virtual synchronous generator is studied and analyzed,and the grid-connected power frequency and excitation characteristics of the virtual synchronous generator are obtained.The microgrid control strategy in the case of symmetrical fault drop is analyzed,and a reliable and safe microgrid operation control strategy with low voltage ride-through capability based on virtual synchronous generator is proposed.(4)The simulation results show that the output voltage of the photovoltaic grid-connected inverter based on the virtual synchronous generator control can quickly achieve selfsynchronization with the grid voltage on the premise of ensuring the power supply of the load,and in the event of voltage sags and other faults or failures in the system.In the event of load access and other faults,the system is less affected when it runs stably and has good dynamic performance.