A Dynamic Phasor Model of an MMC With Extended Frequency Range for EMT Simulations

This paper presents a new dynamic phasor (DP) model of a modular multilevel converter (MMC) with extended frequency range for direct interfacing to an electromagnetic transient (EMT) simulator. The internal dynamics of the MMC are modeled considering dominant harmonic components of each variable. To model the external dynamics of the converter, a novel construct referred to as a base-frequency DP is employed, which allows to capture and model any number of frequency components of external variables without a significant increase in computational burden. The proposed model is validated against detailed EMT models by comparing its results for an inverter system, a back-to-back high-voltage direct current system, and a 12-bus power system built in PSCAD/EMTDC simulator. Simulation results prove that the new model is significantly more computationally efficient than existing models and is capable of maintaining a high level of accuracy. Experimental verification on a scaled-down laboratory setup is also included.