Impedance-Based Modeling and Analysis of Stabilization Control for MMC-HVDC

Oscillationphenomenon has been reported in modular multilevel converter-based high-voltage DC (MMC-HVDC) transmission system. Many methods have been proposed to suppress the oscillation and improve the system stability, however, few papers have analyzed the influence of stabilization control on MMC impedance analytically. Impedance model of MMC considering additional stabilization control is derived in this paper. Based on this impedance model, the influence of stabilization control on MMC impedance are studied, and an optimal design method for controller parameters of the stabilization strategy is proposed to maximize the phase margin of the MMC-HVDC system. Furthermore, this paper points out that stabilization method based on oscillating voltage feedback is more effective than stabilization method based on oscillating current feedback, and the reason is analyzed. Finally, the above results are verified by simulation.