Control and simulation of grid-connected micro-grid

Grid-connected control method and simulations of the micro-grid are presented in the paper. The typical configuration of the micro-grid is presented. In order to ameliorate the effect of power quality during the grid- connected process, the power flow in the micro-grid is analyzed based on the characteristic of frequency and active power, and the time when the difference value of the voltage between the main grid and the micro-grid become zero is chosen as the best chance to connect. In the grid-connected mode, P/Q control is adopted. By the simulation tool Matlab/Simulink, different grid-connected processes are simulated and compared. The frequency and active power fluctuations are analyzed. The results indicate that the control method is effective in dominating the micro-grid during the grid-connected mode, and the choice of the best chance to connect has a great effect on the power quality in the micro-grid.