A Coordinated Control Scheme to Realize Uninterruptible Power Supply for AC-side System in AC/DC Hybrid Distribution Grid

A coordinated control scheme of storage-connected DC/DC converter and interface AC/DC converter is proposed to supply power to AC-side system under both grid-connected mode and isolated mode in AC/DC hybrid distribution network. To avoid changes in control strategy and maintain the stability of DC voltage, the DC/DC converter performs constant voltage control on the DC bus. The interface converter adjusts the output active power according to the current and the state of charge of the energy storage battery to ensure the stability of the DC voltage, under grid-connected mode. While the amplitude and frequency of the AC-side voltage is controlled when the AC main grid fails and is disconnected, thereby realizing uninterruptible power supply for the AC-side system. Simulations and experiments verify the effectiveness of the proposed control strategy and prove the stability of the system during normal operation and mode switching.