The integrated control strategy of microgrid based on the voltage source inverter

Based on the voltage source inverter, the master-slave control strategy of constant power-constant voltage and frequency (PQ-VF) or peer-to-peer control strategy of Droop is usually adopted to improve the efficiency of distributed generation and ensure the safe and reliable operation of microgrid. It is found that the subordinate sources rely heavily on the principal source in the master-slave control, and the stability of frequency and voltage in the microgrid is poor in the peer-to-peer control. To solve the above problems, the advantages of these two control strategies are synthesized. Then, the new control strategy combining the master-slave control and peer-to-peer control is proposed in the paper. In the proposed strategy, the VF control strategy is applied in the principal source grid-connected inverter. The Droop control strategy is applied in the subordinate sources grid - connected inverter. The simulation models of three microgrid systems based on PQ-VF, Droop, and the proposed control strategy are established under Digsilent software. Moreover, the running states of established three microgrid systems are compared through typical simulation events. The results demonstrate the proposed control strategy can not only achieve the smooth switching between the running states of grid connected operation and grid isolated operation, but also can suffer the influence of DG´s switching between grid connected operation and grid isolated operation. Furthermore, the safety and reliability of microgrid are improved efficiency.