Dynamic modeling of microgrid for grid connected and intentional islanding operation

Microgrid is defined as the cluster of multiple distributed generators (DGs) such as renewable energy sources that supply electrical energy. The connection of microgrid is in parallel with the main grid. When microgrid is isolated from remainder of the utility system, it is said to be in intentional islanding mode. In this mode, DG inverter system operates in voltage control mode to provide constant voltage to the local load. During grid connected mode, the Microgrid operates in constant current control mode to supply preset power to the main grid. The main contribution of this paper is summarized as 1) Design of a network based control scheme for inverter based sources, which provides proper current control during grid connected mode and voltage control during islanding mode. 2) Development of an algorithm for intentional islanding detection and synchronization controller required during grid reconnection. 3) Dynamic modeling and simulation are conducted to show system behavior under proposed method using SIMULINK. From the simulation results using Simulink dynamic models, it can be shown that these controllers provide the microgrid with a deterministic and reliable connection to the grid.