Improved high performance control strategy for micro grid islanded operation

With the grid-connected mode turning into the isolation mode, the control strategy of micro-grid is changed into voltage control from current control. The control strategy with load voltage in outer loop and inductance current in inner loop is able to make micro grid into isolation operation rapidly and steadily. In this paper, an accurate simulation model of micro grid connection operation with an LCL grid-connected filter is built based on the platform of MATLAB/SIMULINK. Then the simulation model works from grid-connected state to isolation state. In the isolation operation, an improved control strategy of load voltage in outer loop and inductance current in inner loop is applied so as to get more rapid dynamic response and comparatively better steady performance. Simulations and theoretical analysis fully verify that the proposed control strategy can safely guarantee the micro-grid operates with the isolation state from the grid connection state very smoothly.