Research on Virtual Impedance Anti Sag Control Technology Based On Multi Micro Source Low Voltage Microgrid

摘要

For low-voltage micro-grid systems with multiple micro-sources with different rated capacities, the performance of load power distribution in proportion to the capacity of micro-sources is very important to the stability and efficient operation of the system. The inverse droop control strategy has the problem of active power distribution error due to the unbalanced line impedance of micro-grid. The virtual impedance can suppress this error, but the traditional virtual impedance method will lead to large voltage sag. Therefore, a novel inverse droop control method with virtual impedance is proposed, which can realize the power distribution in proportion to capacity and ensure the stability of voltage and frequency. Finally, a low-voltage micro-grid system with six specific micro-sources is built on the PSCAD / EMTDC platform to simulate the multi-mode operation under Island / grid-connected mode, and the effectiveness of the control strategy is verified comprehensively.