Power control strategy design in an islanded microgrid based on virtual frequency

Droop control strategy is widely used in autonomous control of microgrid. As resistance is the main characteristic of low-voltage microgrid, the P-V droop control method was used in VSI active power distributing to provide voltage support for grid. Also, that of current source inverter is discussed and a constant power band is introduced. On the other hand, a new control strategy “Q-δ droop control strategy based on virtual frequency” is proposed for VSI reactive power control. When applying the new reactive power control strategy, the change of virtual frequency is leading to the change of the phase angle, therefore fluctuations of real frequency caused by loads variation can be avoided, so the power allocation is more reasonable and the microgrid is more stable. Feasibility and effectiveness of the strategy is confirmed by MATLAB simulation.