Multi-Functional Intelligent MMC-Based HVDC Converter

With the pervasive adoption of power electronics in power systems, the system dynamics and the stability are dictated by the control instead of physical components and inertia. To ensure the stable and robust operation of the fast-evolving and increasingly complex grid, we need the grid to become more "intelligent", i.e., to be able to detect and adapt to the evolving grid conditions. Thus, this paper introduces a multi-functional intelligent HVDC converter. By replacing the redundant silicon (Si)-based submodules in modular multilevel converter (MMC) with fast-switching, silicon carbide (SiC)-based full bridge submodules, the converter can inject perturbations in a wide frequency spectrum, without substantial modification of the conventional MMC topology or control strategy. Conse-quently, this converter obtains three significant functionalities including: 1) in-situ impedance measurement to perform stability analysis, 2) active damping and active filtering to preemptively mitigate resonance and enhance the power quality, and 3) assistance to fault current suppression in case of DC side faults. The simulation results show the promising potential of the proposed converter, paving the way for its integration into real-world HVDC infrastructures.