Micro-grid Modeling And Stability Analysis With Different Micro-source Interfaces

To overcome weak of large scale power grid and distributed generation application, micro-grid has become a research hotspot of many electricity researchers due to its numerous advantages. Micro-grid is quite different with the traditional grid, mainly reflected in the more kinds of micro-source in the micro-grid. The modeling and stability analysis is the theoretical foundation of the optimal control of micro-grid and the development of micro-grid technology is inseparable from advanced control strategies, so the research in micro-grid modeling and stability analysis is important.This paper divided micro-sources into synchronous generator interfaces and inverter interface micro-sources according to the different micro-source. In order to analyze the reciprocal influence among these three typical micro-sources and the impact of the coexistence of multiple micro-sources on the stability and dynamic characteristics of the micro-grid. This paper detailed deduced the small signal stability models of the synchronous generator, asynchronous generator and voltage source inverter interface and combining them with the network and load equations and then using coordinate transformation method to establish a unified small signal model of micro-grid. Among them, PQ and PV control strategies were proposed and the detailed small signal models of them were deduced to analyze the influence on microgrid when the system parameters under different control strategies. After that an expansion small perturbation model for multi-micro-source micro-grid was put forward according to the modeling established above.The eigenvalues were calculated by programming in Matlab when the micro-grid in grid-connected operation or island operation. Furthermore, through calculating the sensitivity of the dominant characteristic roots to different parameters to analyze and compare the influence to the stability of the system while the system parameters change under different control strategies and the corresponding conclusions may provide decision-making basis for the control of micro-grid.