Dynamic Phasor Modeling of Simplified Modular Multilevel Converter
Xia Huangrong1, Han Minxiao1, Yao Shujun1, Wan Lei2
1. School of Electric and Electronic Engineering North China Electric Power University Beijing 102206 China; 2. China Electric Power Research Institute Beijing 100192 China
Abstract：Modular multi-level converter (MMC) contains large number of sub-modules (SMs) consisted by switches. The simulation duration and scale are limited by the electromagnetic model of MMC-HVDC; electromechanical model cannot show internal characteristics like circulating current; time domain analytical mathematical model is complicated and lacking in flexibility at circulating current analysis. In order to achieve fast calculation of MMC AC and DC voltage and current, this paper derived dynamic phasor model of MMC basing on the switching function model and state equation model. The state equation of each order dynamic phasor was calculated in Matlab to obtain external and internal voltage and current, including 2nd circulating current. The results were compared with electromagnetic transient model in Matlab/Simulink at transient and steady situation, as well as the simulation time. The conclusions suggest that output voltage and current in the AC system and circulating current in the DC system, which are computed by the dynamic phasor model, are identical with the results of electromagnetic transient model. The dynamic phasor model is accurate and efficient.
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2015, Vol. 30 
