Modeling And Stability Analysis Of Microgrid With Dynamic Phasors

With the continuous promotion and application of renewable energy generationtechnologies, high-frequency PWM inverter based micro-grid and its control technologyare becoming increasingly important. Micro-grid modeling and stability analysis are thekey issues for system optimization design, and research on this direction is of greatsignificance.Based on the in-depth analysis of the traditional high-frequency switching convertermodeling techniques, the dynamic phasor modeling method was proposed, It solved thelimited problem in the traditional state-space average method when meets the "smallripple" conditions , and concurred the shortcomings of long simulation time in the detailedtime domain model. In this paper, the high-frequency Boost circuit is taken as example.Considering DC component and switching fundamental frequency component whichaccount for the main components, a dynamic phasor model of the Boost circuit isestablished, which realize the application of dynamic phasors in high-frequency switchingconverters. On this basis, the models of single-phase and three-phase inverter areestablished. Comparing the simulation results with those under the detailed time-domainmodel, it’s proved that the dynamic phasor method can not only correctly describe thesystem characteristics under steady process, but also well track the dynamic changes in thesystem .This novel method can save simulation time by using a larger step size to improvesimulation speed and it’s suitable for large-scale systems.The dynamic phasor model of three-phase inverter control system based on P/f andQ/U droop control was established and further the system stability analysis was given inthis paper. It also derived the range of droop coefficient values to meet the requirements ofsystem stability. MATLAB simulation verified the validity of the dynamic phasor modeland the system stability analysis. Simulation and analysis results also showed that themethod of increasing virtual impedance can be used to improve system stability.