Stability Enhancement of Modular Multilevel Converter - High Voltage Direct Current Systems Interacted with Weak Power Grid Based on Current-mode Virtual Inertia Control

Abstract The extensive growth of large-scale flexible high voltage direct current (HVDC) transmission systems compromises the strength alternating (AC) power grid. Sub-synchronous oscillations will likely arise within such HVDC systems, which would significantly threaten grand electric system’s stable operation. A current-type enhanced virtual inertia control is proposed to suppress sub-synchronous induced by a weak AC grid in modular multilevel converter (MMC)-based systems. Firstly, small signal model MMC established study stability system under Focally, current-mode inertial grid’s oscillation directly taking as variable. Finally, approach verified using both offline and real-time simulation based on Chongqing-Hubei MMC-HVDC system. results demonstrate that strategy can efficiently interacting with grid, enhances reliability