The concept of a flexible power electronics substa-tion(FPES)was first applied in the Zhangbei DC distribution network demonstration project.As a multi-port power electronics transformer(PET)with different AC and DC voltage levels,the FPES has adopted a novel topology integrating modular multilevel converter(MMC)and four-winding medium frequency transformer(FWMFT)based multiport DC-DC converter,which can significantly reduce capacitance in each sub-module(SM)of a MMC and also save space and cost.In this paper,in order to accelerate speed of electromagnetic transient(EMT)simulations of FPES based hybrid AC/DC distribution systems,an averaged-value model(AVM)is proposed for efficient and accurate representation of FPES.Assume that all SM capacitor voltages are perfectly balanced in the MMC,then the MMC behavior can be modeled using controlled voltage sources based on modulation voltages from control systems.In terms of the averaged current transfer characteristics among the windings of the FWMFT,we consider that all multiport DC-DC converters are controlled with the same dynamics,a lumped averaged model using controlled current and voltage sources has been developed for these four-port DC-DC converters connected to the upper or lower arms of the MMC.The presented FPES AVM model has been tested and validated by comparison with a detailed IGBT-based EMT model.Results show that the AVM is significantly more efficient while maintaining its accuracy in an EMT simulation.

Hong Liu;Zhanfeng Deng;Xialin Li;Li Guo;Di Huang;Shouqiang Fu;Xiangyu Chen;Chengshan Wang

Key Laboratory of Smart Grid of Ministry of Education,Tianjin University,Tianjin 300072,China;State Key Laboratory of Advanced Power Transmis-sion Technology,Global Energy Interconnection Research Institute,Beijing 100220,China;Guangzhou Power Supply Bureau of Guangdong Grid Co.,Ltd.,Guangzhou 510620,China;State Grid Jibei Electric Power Economic Research Institute,Beijing 100038,China;State Key Laboratory of Reliability and Intelligence of Electrical Equipment,Hebei University of Technology,Tianjin,China

中国电机工程学会电力与能源系统学报（英文版）

[1]Hong Liu;Zhanfeng Deng;Xialin Li;Li Guo;Di Huang;Shouqiang Fu;Xiangyu Chen;Chengshan Wang-.The Averaged-value Model of a Flexible Power Electronics Based Substation in Hybrid AC/DC Distribution Systems)[J].中国电机工程学会电力与能源系统学报（英文版）,2022(02):452-464

substa,Zhangbei,FWMFT

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