Study On Coordinated Control Strategy Of Microgrid Based On Power Electronic Transformer

Microgrid can effectively improve the ability of power grid to absorb distributed energy. The new structure with power electronic transformer (PET) as the core of energy management is the new development direction of microgrid. A micro grid control strategy for coordinated operation of PET and energy storage is proposed. The interface converter of energy storage adopts constant voltage and constant frequency control to maintain the stability of voltage and frequency of micro grid. The low-voltage AC interface of PET connected to micro grid integrates the control of virtual synchronous generator to adjust the mechanical reference power according to the state of energy storage. Energy storage responds to the power fluctuation in microgrid rapidly, while PET maintains the stability of energy storage capacity through two-way power regulation and ensures the "flexible" exchange of power between microgrid and grid. Because energy storage and PET are controlled as voltage source interface at the same time, when one of them fails, the microgrid can still operate smoothly. Under this control strategy, microgrid operation can ensure the maximum efficiency of intermittent distributed energy utilization, and improve the stability, reliability and user friendliness of microgrid operation. Simulation and hardware in the loop hardware in the loop experiment results verify the correctness and effectiveness of the proposed control strategy.