An Improved Power Oscillation Suppression Control for Inertia Support of Grid-Forming VSC-HVDC

The conventional inertia support control of grid forming (GFM) VSC-HVDC transmission system is prone to causing power oscillations with larger rate of change of frequency (RoCoF). Aiming for this technical issue, an improved power oscillation suppression control strategy is proposed. Firstly, the basics of the inertia support is introduced, and the limitations of the existing method is also briefly described. And then, the idea by using of the internal energy of MMC to suppress the potential power oscillation is proposed. The key of this method lies in how to regulate the submodule capacitor energy through capacitor voltage control. The calculation method of capacitor voltage reference is demonstrated to suppress the AC or DC side power oscillation in the process of inertia support. Finally, the effectiveness of the proposed power oscillation control is verified through PSCAD/EMTDC simulation. A stable and relatively fast inertia support operation is derived.