面向直流配电网尾端功率变换的组合式直流变压器研究

发布时间：2018-05-14 18:34

本文选题：直流配电网 + 高频隔离　；参考：《东北电力大学》2017年硕士论文

【摘要】：现有交流配电网已经无法满足未来用户多样化的用电需求和大量新能源的接入,而直流配电网却有着交流网无法比拟的优势,诸如提高电容量和电能质量、快速独立地控制有功功率、接入可再生能源灵活便捷等,无疑将会成为未来配电网研究的主要方向。本文着力于未来直流配电网功率变换应用研究,提出了一种新型高频隔离型组合式直流变压器(ADCT)概念,利用标准化模块来构建所期望的系统结构,并通过临近控制来协调模块功率,进而实现整体平衡。本文采用LLC谐振变换器作为组合式直流变压器的标准化模块,通过串并联结构组建直流变换系统。LLC谐振变换器可实现前后端完全软开,转换效率高,而且其电压钳位特性可自然实现前串后并(ISOP)型系统的输入电压均衡(IVS)。本文详细推导了LLC谐振变换模块的电压增益,并通过实验绘制了增益曲线,证明了电压钳位特性实现ISOP型系统电压平衡的可行性。利用电压钳位特性,结合电磁耦合电流平衡(MC-CB)单元,本文提出了临近控制概念并对MC-CB单元进行了详尽的理论推导和仿真分析,证明了MC-CB单元实现前并后并(IPOP)型系统电流均流控制的可行性。之后,提出了新型IS-IPOP型结构,结合临近控制可开环实现电压电流的独立控制。本文所提出的组合式直流变压器动态性能优越,系统稳定可靠,可实现系统模块的有载投切和冗余备份,方便现场操作,具有很大的应用前景。最后,搭建的组合式直流变压器硬件实验系统也验证了本文方案的有效性和合理性。
[Abstract]:The current AC distribution network has been unable to meet the diversified needs of future users and access to a large number of new sources of energy, but the DC distribution network has the incomparable advantages of AC network, such as improving the capacity and power quality. Rapid and independent control of active power and flexible and convenient access to renewable energy will undoubtedly become the main research direction of distribution network in the future. This paper focuses on the application of power conversion in the future DC distribution network, and proposes a new concept of high-frequency isolated combined DC transformer ADCT, which uses standardized modules to construct the desired system structure. The module power is coordinated by proximity control, and the overall balance is realized. In this paper, the LLC resonant converter is used as the standardized module of the combined DC transformer, and the DC conversion system .LLC resonant converter is constructed by series-parallel structure, which can realize the complete soft opening of the front and rear end and the high conversion efficiency. Moreover, the voltage clamping characteristic can naturally realize the input voltage equalization of the forward and back ISOP- type system. In this paper, the voltage gain of the LLC resonant conversion module is deduced in detail, and the gain curve is drawn through experiments. It is proved that the voltage clamping characteristic is feasible to realize the voltage balance of the ISOP type system. Based on the characteristics of voltage clamp and electromagnetic coupling current balance (MC-CBC) unit, the concept of proximity control is proposed, and the theoretical derivation and simulation analysis of the MC-CB element are given in detail. It is proved that the current sharing control of MC-CB unit is feasible. After that, a new type of IS-IPOP structure is proposed, which can realize the independent control of voltage and current. The combined DC transformer presented in this paper has the advantages of superior dynamic performance, stable and reliable system, can realize on-load switching and redundant backup of the system module, and is convenient for field operation, and has a great application prospect. Finally, the combined DC transformer hardware experimental system is built to verify the validity and rationality of the proposed scheme.
【学位授予单位】：东北电力大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM41

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