Microgrid control and management of state transition period

In Microgrid energy is normally transmitted from source to grid through converters and this makes the output components of microsources (MSs) easier to control. Control technologies for Microgrid are focused on the output of the inverter part. There are two fundamental approaches: PQ control and droop control. For different co-operation between MSs and energy storage devices, there are several control approaches including pure droop control, reverse droop control, inverter based control, primary energy source control, autonomous control and multi-agent based control. [1] In most of the control strategies, except the multi-agent based control, the parameters used for control come from local measurements without communication with other MSs. In this paper, a Microgrid model with two MSs is used to test PQ control and droop control algorithms respectively. A rate of change of frequency algorithm is used for islanding detection. The results demonstrate that with load shedding strategy, the Microgrid can operate stably either in connection mode or in islanding mode. It is also able to transfer from one state to another smoothly.