The concept of a flexible power electronics substation(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 vo...The concept of a flexible power electronics substation(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.展开更多
为确保含四绕组变压器的变电站保护整定可靠性,需研究精细化的四绕组变压器暂态模型及其短路计算等值电路。分析常规变压器等值电路的不足,推导了修正的耦合漏感等值电路,根据三相三柱式四绕组变压器的拓扑结构,运用对偶性原理建立了基...为确保含四绕组变压器的变电站保护整定可靠性,需研究精细化的四绕组变压器暂态模型及其短路计算等值电路。分析常规变压器等值电路的不足,推导了修正的耦合漏感等值电路,根据三相三柱式四绕组变压器的拓扑结构,运用对偶性原理建立了基于耦合漏感的四绕组变压器电路-磁路暂态模型;利用漏磁路的互阻抗远小于漏阻抗的特点,推导了用于短路计算的四绕组变压器简化等值电路以及零序阻抗。根据某地220 k V变电站实例进行仿真计算,结果表明所提出的四绕组变压器暂态模型及短路计算方法能够更准确地计算含四绕组变压器变电站的短路电流。展开更多
基金This work was supported in part by the National Nature Science Foundation of China(51977142)。
文摘The concept of a flexible power electronics substation(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.
文摘为确保含四绕组变压器的变电站保护整定可靠性,需研究精细化的四绕组变压器暂态模型及其短路计算等值电路。分析常规变压器等值电路的不足,推导了修正的耦合漏感等值电路,根据三相三柱式四绕组变压器的拓扑结构,运用对偶性原理建立了基于耦合漏感的四绕组变压器电路-磁路暂态模型;利用漏磁路的互阻抗远小于漏阻抗的特点,推导了用于短路计算的四绕组变压器简化等值电路以及零序阻抗。根据某地220 k V变电站实例进行仿真计算,结果表明所提出的四绕组变压器暂态模型及短路计算方法能够更准确地计算含四绕组变压器变电站的短路电流。
