Decentralized Cooperative Control Strategy of Microsources for Stabilizing Autonomous VSC-Based Microgrids

In designing procedure of a power sharing controller for a voltage source converter (VSC)-based microgrid with no communication link, three issues should be considered. Firstly, in VSC-based microgrids, which use droop controller method, the desired frequency of VSCs is altering regarding the output active power. Consequently, the conventional load frequency control techniques are inappropriate since their operation is based on a fixed pre-specified desired frequency. Secondly, to prevent circulating current and thermally overstressing, all DGs should participate in active power supply. In addition, since there is no communication link, the steady state value of each micro-source active power is unknown. Therefore, the conventional fixed active power control method for DGs is not appropriate. Thirdly, when the microgrid loads are increased, the output power of VSCs is increased rapidly; however, the output power of each VSC´s primary source could not change in the same rate to respond. It causes the DC voltage of VSCs to decrease, which could affect the appropriate performance of VSCs. In this paper, a novel control strategy for VSCs and an energy storage system in a VSC-based microgrid without communication link accompanied with a novel hybrid model of VSC-based DGs, which considers primary source effect, is proposed.