Modeling Techniques for MMC Employed on VSC-HVDC Schemes

Abstract

Modular multilevel converters (MMC) are presently the converter topology of choice for voltage-source converter high-voltage direct-current (VSC-HVDC) transmission schemes due to their very high efficiency. These converters are complex, yet fast and detailed electromagnetic transients simulation modelsare necessary for the research and development of these transmission  schemes. Excellent work has been done in this area, though little objective omparison of the models proposed has yet been undertaken. This paper compares for the first time, the three leading techniques for producing detailed MMC VSC-HVDC models in terms of their accuracy and simulation speed for several typical simulation cases. In addition, an  improved model is proposed which further improves the computational efficiency of one method. This paper concludes by presenting evidence-based recommendations for which detailed models are most suitable for which particular studies.

Index Terms—Accelerated model, electromagnetic-transient (EMT) simulation, HVDC transmission, modular multilevel converter (MMC), voltage-source converter (VSC).