Research On Control Of Photovoltaic Grid Connected Inverter Based On Virtual Synchronous Generator

In recent years,various clean energy sources have flourished.Among them,photovoltaic grid-connected power generation technology has attracted more and more attention because of its simple process,low noise,and no pollution.It has become the most promising new energy power generation in the world.One of the technologies.The photovoltaic inverter based on the idea of virtual synchronous generator realizes the grid-connected control by simulating the characteristics of the synchronous generator.Compared with the traditional control method,it effectively improves the performance of photovoltaic grid-connected power generation.Combined with scientific research projects,research is carried out on photovoltaic grid-connected inverters controlled by virtual synchronous generators.The main research contents include:Overall structure design of photovoltaic grid-connected power generation system.Analyze the internal structure of the two-stage photovoltaic grid-connected power generation system,including Boost converter and DC/AC inverter,introduce the control strategies used in each link,including the maximum power point tracking control strategy,the photovoltaic grid-connected inverter's The modulation strategy of SVPWM and the double closed-loop control strategy of photovoltaic inverter system.Research on control strategy of virtual synchronous generator.The rotor motion equation,flux linkage equation and electromagnetic transient relationship of the synchronous generator are used to mathematically model the virtual synchronous generator;the working principles of the active-frequency controller and reactive-voltage controller of the virtual synchronous generator are carried out Analysis.Design of pre-synchronized grid-connected control scheme of virtual synchronous generator.A pre-synchronization control strategy with phase-locked loop is researched and designed,which can automatically adjust the frequency,amplitude and phase of the VSG output voltage before grid connection,to achieve safe and fast grid connection of the virtual synchronous generator.Design of an improved virtual synchronous generator active power control strategy.Aiming at the limitation of parameter optimization of VSG in grid-connected mode,an improved virtual synchronous generator control strategy with differential negative feedback is proposed to improve its dynamic characteristics during grid-connected.simulation Research.Build a VSG grid-connected simulation model in Matlab/Simulink simulation software,research and analyze its output indicators through the simulation results,and finally conclude that the designed improved VSG grid-connected control strategy can meet the grid-connected runtime The technical requirements of the microgrid for photovoltaic inverter power supply.