Analysis of the Effect Reactive Power Component on the Internal Power Dynamics of Modular Multilevel Converter with Active Power Oscillation Damping Strategy

Abstract

In this paper, the effect of reactive power component on internal power dynamics of Modular Multilevel Converter (MMC) is analyzed with Active Power oscillation damping (APOD) strategy under asymmetry grid condition. The APOD strategy is one of the representative imbalance control strategies, which can eliminate oscillations on active power and DC link voltage. Many papers focusing on APOD strategy assumed that the output power of each phase is consistently identical. The assumption is based on which only active power is supplied to the grid, however, a phase power imbalance could be caused by the reactive power component. This paper shows that the tendency of phase power imbalance by reactive power components, and high-fidelity PSCAD/EMTDC time-domain simulations are performed based on a 200 MW ±120 kV symmetric monopole MMC–HVDC system.