Multiport Current-Limiting Interline Dynamic Voltage Restorer for Power Quality Enhancement in Renewable DC Microgrid

DC microgrid is regarded as a promising architecture for integrating renewable energy generators, energy storage devices, and sensitive loads with multiple voltage/current levels in oil/gas field systems. However, with the increasing penetration of renewables and power electronics, voltage sag/swell power quality issues and rapid, high-magnitude over-currents challenges under various transient and fault conditions need urgent attention. This paper presents a novel solution of multiport current-limiting interline dynamic voltage restorer (MCL-IDVR), which employs a shared one-battery energy storage unit and an N+1-port improved active full-bridge converter topology to achieve coordinated compensation among multiple circuits. The multiple output ports of this device can be simultaneously connected in series to DC lines with different voltage and current levels, enabling two coordinated functions of voltage sag/swell compensation and customizable energy-feedback fault current limiting. The working principles, control strategies, and operational modes of the MCL-IDVR are elaborated in detail. Its technical performance is validated through MW-class oilfield DC microgrid simulations and kW-class scaled-down experimental tests. Results demonstrate the device’s efficacy in mitigating voltage fluctuations and suppressing fault currents, proving the feasibility and practicality of the MCL-IDVR solution.