Research On Three-phase Inverter Control Based On Virtual Synchronous Generator Technology

With the increase of penetration of new energy grid,inertia and damping of power grid decrease relatively,which brings influence and challenge to the stable operation of power grid.As a control strategy of grid-connected converter,virtual synchronous generator technology makes up for the deficiency of traditional grid-connected inverters by simulating the external characteristics of synchronous generators in traditional grid-connected power generation systems.It contributes to the regulation and stability of system voltage and frequency,and is expected to promote the further development of new energy generation technology.The main contents of this paper are as follows:(1)The principle of grid-connected three-phase inverters based on virtual synchronous generator technology is elaborated,including model establishment,parameter design,small signal model establishment and steady-state and dynamic simulation research using simulation software.(2)The influence of parameter variation of virtual synchronous generator on system output is studied.According to the difference between virtual synchronous generator and traditional synchronous generator,that is,the parameters of transient process are flexible and adjustable,an improved multi-parameter Coordinated Adaptive control algorithm is presented based on the existing research.The simulation results show that the proposed control algorithm has better transient regulation performance.(3)The control strategy of virtual synchronous generator under unbalanced voltage is studied.The double current loop control strategy of positive and negative sequence current sequencing control is expounded.The control strategy of multi-objective under unbalanced voltage is realized by giving different negative sequence current instructions based on double current loop control.A control strategy of virtual synchronous generator controlled by single current loop under unbalanced voltage is presented.The simulation results show that the control strategy has better control effect of balanced current.An improved multi-objective control strategy for virtual synchronous generator under unbalanced voltage is presented.The control strategy is implemented by giving different power reference instructions.The theoretical analysis and the correctness of the control strategy are verified by simulation experiments.