Research On Control Strategy Of The Voltage Source Type Inverter With Virtual Synchronous Generator Characteristics

The distributed generation process has many advantages,such as simple,no noise and no pollution.Therefore,distributed power systems get more and more attention,its penetration is promoting in power systems.However,conventional distributed grid power control adopts the model of power electronic grid inverter,which has the fast response speed,the small inertia.So the distributed generation can not guarantee the stability of voltage and frequency,and distribution network micro grid is lack of necessary damping,which undoubtedly restrict the large-scale development of the distributed power grid power.In view of the above problem,based on Virtual Synchronous Generator(Virtual Synchronous Generator,VSG),a grid-connected power generation system structure is proposed.Firstly,the corresponding relation of inverter and synchronous generator model is researched,then from the speed regulation frequency modulation,moment of inertia and excitation voltage regulation to design the control strategies of the voltage source type inverter with VSG characteristics,which makes the distributed generation supply similar characteristics of synchronous generator in power systems and automatically participate in the regulation.Then,a current decoupling control strategy based on ADRC control technology was presented to the dq axis current coupling problem of the grid inverter with VSG characteristics under synchronous reference frame.This strategy regarded current coupling between dq axes and inductance parameter variation as a disturbance of the system,which estimated by extended state observer,and the error was eliminated through the feed forward compensation of ADRC,then current decoupling between dq axes was realized in the true sense.Finally,According to VSG in the operation of the island,because of its low capacity and small inertia,the stability is much worse than the large power grid,the change of the load will have a greater impact on VSG.On the basis of traditional droop control strategy,a control strategy of VSG with frequency no-error adjustment based on ADRC was designed.The validity and effectiveness of the proposed control strategy is verified by comparing with the traditional PI control effect on the PSCAD/EMTDC simulation platform.