Linearized DQ averaged model of modular multilevel converter

Abstract

This paper proposes a linearized model of Modular Multilevel Converter (MMC) in DQ frame. The proposed MMC model has a modular structure and can be linked with other power elements such as AC and DC subsystems. The main challenge of developing DQ model of MMC is to deal with the multiplication terms in dynamic equations of MMC. In this paper, the multiplication terms are done in ABC frame and results are transferred to DQ frame after ignoring the higher harmonics. The detailed model is implemented in PSCAD/EMTDC and the proposed linearized model is implemented in Matlab in a modular form. The results of the two models show very good matching which in turn confirm the accuracy of the proposed model. Therefore, this model permits modern control design techniques to be employed on MMC, including eigenvalues studies and frequency domain analysis.