Research On Control Technology Of Inverter Based On Virtual Synchronous Generator Technology

With the increasing depletion of traditional fossil energy and the increasingly serious environmental pollution,more and more attention has been paid to new energy generation.As a link between new energy and traditional large power grids,Grid-connected inverters have naturally received unprecedented attention.In this paper,the control technology of inverter is studied by using the grid-connected inverter as the research object and combining with the virtual synchronous Generator(VSG)technology.Firstly,the traditional inverter control technology,including PQ control,V-f control and Droop control,is introduced,because the traditional control technology can not solve the shortcoming of low inertia and no damping of inverter circuit,VSG control technology has become a research hotspot at home and abroad,and the focus of this paper is put forward: Research on inverter control technology based on VSG.Secondly,this paper expounds the regulation mechanism of the traditional synchronous generator participating in the frequency and voltage of power system,establishes the mathematical model of the traditional generator,realizes the VSG control of the inverter by introducing the rotor equation into the control loop of the inverter,and emphatically explains the design method of the VSG and the excitation controller.The influence of moment of inertia on the dynamic performance of the system is discussed and verified by Matlab/Simulink simulation.Based on the above research basis,this paper illustrates the effect of moment of inertia and damping coefficient on the dynamic performance of the system,and with the help of exponential function,an adaptive VSG design method is proposed,which verifies the effectiveness in suppressing overshoot and improving system stability through Matlab/Simulink simulation.Then,the effects of moment of inertia,damping coefficient and line impedance on the active power and reactive power of the inverter areanalyzed in detail when multi-VSG is operated in parallel.A multi-parallel VSG with improved Q-U Droop control based on virtual impedance method is proposed.The power sharing strategy is verified by Matlab/Simulink simulation software to improve the effectiveness of the proposed control strategy in VSG transient power sharing.Finally,aiming at the problem of the bus voltage drop of the island microgrid caused by the traditional virtual impedance method,a parallel VSG reactive power allocation strategy based on the virtual capacitor method is proposed by simulating the characteristics of the parallel capacitor at the output of the traditional synchronous generator.Under the premise of accurate distribution of VSG reactive output power,the voltage of the busbar is increased.Finally,the effectiveness of the proposed control strategy is verified by Matlab/Simulink simulation.