Modeling, control and testing of a voltage-source-inverter-based microgrid

Microgrids are low-voltage distribution networks comprising various distributed generators (DGs), storage devices, and controllable loads that can operate either interconnected or isolated from the main distribution grid as a controlled entity. This paper concentrates on the modeling and control of a voltage-source-inverter-based microgrid. Considering the dispersion of DGs and loads, the controllers are designed using different control strategies respectively corresponding to the types of the DGs and ways of combining of storage devices. The Power and Voltage Controller coupled with the microsources provides fast response to disturbances and load changes without relying on communications. PQ control can realize the designated control of real and reactive power of DGs according to actual operation situation. V/f control can realize power sharing between different DGs when the load power changes, and provide frequency support when in the islanded mode. With the implementation of the unified controller, the inverter-based microgrid system is able to switch between islanding and grid-connected modes without disrupting connected critical loads. The two control strategies have been verified in simulation using MATLAB/SIMULINK by switching between interconnected and islanded modes.