Modeling and stability analysis of modular multilevel HVDC converters

A nonlinear averaged model of MMCs is proposed that considers the SM capacitor insertion dynamics and takes into account the current control loops that follow widely used vector control approach. A stability analysis framework is presented by exploiting the linear time-periodic (LTP) nature of this system. The averaged model, developed in MATLAB/Simulink, is benchmarked against a detailed model in EMTDC/PSCAD. The 1000-MW, ±320-kV INELFE VSC-HVDC link is considered in the case study.