基于模块化多电平结构的高压大功率DC-DC变换器拓扑研究

发布时间：2018-02-08 22:31

本文关键词： DC-DC变换器新型拓扑结构 MMC-HVDC 海上风电场 LCC-HVDC　出处：《华北电力大学(北京)》2014年硕士论文　论文类型：学位论文

【摘要】：随着直流电网概念的提出,大容量新型直流输电装备成为了研究热点。DC-DC变换器是直流电网的重要组成部分,一般直流电网中使用的变换器电压等级较高,而现有的高压直流变换器技术不够成熟,因此急切需要一种可应用于高压大功率场合的DC-DC变换器。基于模块化多电平(Modular Multilevel Converter,MMC)拓扑结构,提出了一种可应用于未来直流电网的模块化多电平DC-DC变换器。论文首先介绍了研究学者在过去几十年时间里所提出的高压大功率DC-DC变换器拓扑,总结现有高压大功率变换的解决思路和方法,包括功率器件的串并联技术、多电平技术、变换器子模块的串并联技术等。介绍基于这三种技术的高压大功率DC-DC变换器拓扑结构,工作原理以及不同拓扑的优缺点。其次,提出了一种单向降压型DC-DC变换器,阐述了 DC-DC变换器拓扑结构、工作原理,对比子模块串并联技术介绍了该DC-DC变换器的优势。PSCAD/EMTDC环境下的仿真实验表明新型DC-DC变换器可以很好地实现直流变压功能,开关频率低且损耗小,直流电压电流波形理想。在此基础上,提出一种双向DC-DC变换器,该变换器可实现功率的双向流动。介绍了双向变换器的拓扑结构和工作原理,针对变换器的功率传输能力,提出了两相DC-DC变换器和多相DC-DC变换器,以适应大功率场合,并通过仿真验证了两相DC-DC变换器可以很好地实现直流变压功能,且电压电流波形理想。最后提出单向DC-DC变换器的和双向DC-DC变换器的控制策略,仿真验证控制策略的可行性与可靠性。在所提拓扑结构的基础上,分析DC-DC变换器的应用前景,如海上风电场的直流互联,VSC(Voltage Source Converter)与LCC(Line Commutated Converter)的互联,多终端高压直流输电系统给远程负荷供电等。这些应用前景表明了 DC-DC变换器在未来直流电网建设中一定会担当起举足轻重的角色。
[Abstract]:With the introduction of DC network concept, large capacity new DC transmission equipment has become a research hotspot. DC-DC converter is an important part of DC network. However, the existing high voltage DC / DC converter technology is not mature enough, so it is urgent to have a kind of DC-DC converter which can be used in high voltage and high power situation. Based on the modularized multilevel Modular Multilevel converter (MMC) topology, A modularized multilevel DC-DC converter for future DC networks is proposed. Firstly, the topology of high voltage and high power DC-DC converters proposed by researchers in the past decades is introduced. This paper summarizes the existing ideas and methods of high-voltage high-power conversion, including series-parallel technology of power device, multi-level technology, series-parallel technology of converter submodule, etc. The topology structure of high-voltage and high-power DC-DC converter based on these three technologies is introduced. The working principle and the advantages and disadvantages of different topologies. Secondly, a unidirectional step-down DC-DC converter is proposed, and the topology and working principle of the DC-DC converter are described. In this paper, the advantages of the DC-DC converter are introduced by comparing submodule series-parallel technology. The simulation results show that the new DC-DC converter can achieve the DC voltage function well, and the switching frequency is low and the loss is low. Based on the ideal waveform of DC voltage and current, a bidirectional DC-DC converter is proposed, which can realize the bidirectional flow of power. The topology and working principle of the converter are introduced, and the power transmission ability of the converter is discussed. A two-phase DC-DC converter and a multi-phase DC-DC converter are proposed to adapt to the high power situation. The simulation results show that the two-phase DC-DC converter can achieve the DC voltage function well. Finally, the control strategies of unidirectional DC-DC converters and bi-directional DC-DC converters are proposed, and the feasibility and reliability of the control strategies are verified by simulation. Based on the proposed topology, the application prospects of DC-DC converters are analyzed. For example, the direct current interconnection of offshore wind farms, the interconnection of VSC Commutated converters and LCC(Line Commutated converters, The applications of multi-terminal HVDC power supply system to remote load show that DC-DC converters will play an important role in the construction of DC power network in the future.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM46

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