| As a form of intelligent access of distributed power generation system, micro-grid has broad prospects for development, which can increase distributed generation penetration rate and lessen impacts on power system stability. In micro-grid, micro-grid inverters which configure storage units on the DC side can effectively stabilize power fluctuations and play a key role in maintaining the stability of voltage and frequency of micro-grid. In this paper, micro-grid inverter based on virtual synchronous generator (VSG) control strategy is studied. Drawing on the characteristics of traditional synchronous generators, control strategies, and the methods of stability analysis, the concrete implementation of VSG has been designed. The stability of VSG are studied and the optimal allocation of energy storage units is analyzed. The main contents of this paper are as followed:1) Based on the relative references home and abroad, a survey has been done about micro-grid background, definition, characteristics, development. The control strategies of micro-grid inverter are summarized and the research status of VSG has been focused on.2) The basic principle of VSG is elaborated in detail, the main circuit topology and control structure of micro-grid inverter based on VSG is described and the selection of inner-loop feedback variables based on multi-loop feedback control strategies is analyzed.3) Aimed at the specific implementation of VSG control strategy, the implementation and design of stator electric equation, rotor swing equation, governor, excitation controller is studied and the difference and relation with traditional synchronous generator is analyzed.4) Aimed at the operation characteristics of micro-grid inverter based on VSG control, the research of VSG stability analysis status is summarized, the effects of the VSG key parameters on system stability based on small-signal model is studied. An improved VSG control strategy based on virtual damping compensation is proposed and the VSG and droop control is compared. The dynamic model of power angle based on dq coordinate is discussed.5) The energy storage units configuration of VSG is quantitatively analyzed and calculated, the optimal control of VSG based on variable inertia and damping is proposed, adopting linear quadratic optimal control and the inertia and damping of VSG are configured dynamically.6) The simulation and experiment platform of micro-grid inverter system based on VSG control are built and the verifications of the VSG control algorithm and the theory analysis are done both in simulation and experiment. The final simulation and experiment results show the validity of analysis and feasibility of the scheme. |
PDF Full Text Request