Coordinated Control Strategy with Inertia of Grid-Forming Two-Stage Energy Storage Converters

In order to make grid-forming two-stage energy storage converters provide inertia support to grid by DC-link capacitor, a novel coordinated control strategy is proposed in this paper. Inertia control and Q-V droop control is realized in DC/AC converter and P-f droop control is realized in DC/DC converter. DC/AC converter adjusts the output frequency according to the deviation of DC-link voltage, which makes it able to support grid by the capacitor inertia in grid-forming mode. Considering that DC/DC converter cannot detect frequency directly, it is designed to detect the deviation of DC-link voltage to realize P-f droop control by a proportional controller of voltage. And a deviation controller is designed in DC/DC converter to ensure the DC-link voltage is adjusted within the limits of safety allowed. Experiments are conducted and the results verify the proposed strategy is feasible and effective.