In a microgrid with multi-microsources

precise output power control and seamless transition of micro-source converters between grid-connected and islanding operation modes are of great significance for the stability of voltage and frequency and the power flow control in a microgrid. The control method of adaptive dual virtual impedances and power compensation conductance based on local voltage and current measurement is proposed

by which active and reactive power control for voltage source inverters (VSIs) can be decoupled and the VSIs can share loads proportionally to their capacity in the islanding mode. Meanwhile

a voltage compensation mechanism is embedded in the droop control

which can refine the power quality in the islanding mode

power control quality in the grid-connected mode

and realize unified control of the microgrid. Furthermore

the parameters of the proposed controller are optimized with small signal models in both grid-connected and islanding modes. Simulation and experiment results have verified the proposed control method. This work is supported by National Basic Research Program of China (973 Program) (No. 2009CB219708)

National Natural Science Foundation of China (No. 51077033) and Specialized Research Fund for the Doctoral Program of Higher Education (SRFDP) of China (No. 201301111110005).