基于组合拓扑的并网逆变技术研究

The grid-connected inverter (GCI) is one of the key techniques in renewable energy generation, smart macro-grid and distributed power system. Since the problems of heat dissipation, EMI and so on caused by the centralized processing of large power, a technique of distributed and intelligent GCI based on combinatorial topology (CT) is proposed in this project. The theory of CT is studied first which included the stability analysis, the combination rules and extension methods for CT. Besides, the series of criteria is developed to evaluate the new CT inverters. The asymmetrical topology combination is then researched, which means the inverter combines the topologies with different voltage, current , switching frequency, even with different function in order to minimize the voltage or current resolution, increase the equivalent switching frequency, and so on. The GCI based on series connected CT is researched, which uses the combination of low voltage converter taking the replace of high voltage converter, in order to improve the performance. The distributed GCI based on symmetrical topology combination is also researched, which includes designing the combination structures with good extensibility, the corresponding controller, synchronous technique and communication method, and optimizing the sub-topology and the combinatorial system as well. This project also researches on the intelligent combinatorial GCI to improve the flexibility and reliability of CT based GCI by redundancy configuration, fault diagnosis and topology rebuilding. This project tries to develop a new potential direction for the research of GCI topology, and develop the foundation of theory and practice for the next generation of GCI technology.

并网逆变技术是智能微网、分布式发电等领域的关键技术之一，为了改善功率流集中处理带来的散热、电磁干扰等问题，本项目提出了基于组合拓扑的并网逆变技术。项目首先研究组合拓扑理论，分析拓扑组合的稳定性，探索拓扑组合规律、扩展方法，制定组合拓扑的评价准则；其次研究不对称拓扑组合并网逆变，利用不同电压、电流、开关频率，甚至不同功能的拓扑组合，产生更加精细的电压、电流分辨率，更高的等效开关频率；研究串联组合并网逆变，利用低压变流技术实现高压变流器，来获得更高的性能；研究基于规模化并联组合的分布式功率流处理技术，研究其拓扑管理系统，设计系统结构，以及相应的控制、同步和通信方案，进而研究智能化的组合式并网逆变技术，根据组合式变流器丰富的运行模式和优化方法，利用冗余配置、故障诊断、拓扑重组的方式提高系统的适应性和可靠性。通过本项目研究，为并网逆变的拓扑研究提供新的方向，为下一代并网逆变技术奠定基础。

并网逆变技术是分布式发电等领域的关键技术之一，为改善功率流集中处理带来的散热、电磁干扰等问题，本项目研究基于组合拓扑的并网逆变技术。项目依据计划对组合式并网逆变技术进行了系统和深入的研究，探索了级联、串联、并联形式下对称和不对称拓扑组合的基本形成规律和评价准则，研究并取得的重要进展有：①研究了级联型并网逆变器，指出不对称拓扑级联可主要用于提高并网逆变器的电平数，以减少无源滤波器的需求，以此提出了有功和无功功率分别处理的级联拓扑和控制方案，能够实现电平数大幅增加，而不需要额外增加储能电容，作为一种有效的硅进铜退方案，为并网逆变器的系统集成提供了新的解决方案；②研究了串联拓扑技术，针对传统串联方式引起的工频功率脉动问题，提出了磁路耦合的解决方案，可以通过磁路并联，在隔离变压器对各路功率流进行合并，从而让三相脉动功率相互补充，无需额外增加工频储能，为提高电力电子变压器这类隔离型并网逆变器提供了高功率密度解决方案；③提出了一种特殊的单端口组合变换器，刻画其特点和原理，并对其应用做了探索，尤其指出了利用单端口拓扑的组合能够用低压器件实现高压功率变换的功能，并且能够用于实现电感滤波这类的无功换流功能，有广泛的应用潜力；④研究了并联组合拓扑，针对并网逆变器面临的普遍性问题，从电网阻抗估算、自适应控制、有源阻尼以及数字延迟补偿等多个角度进行了研究，并提出一些独特的解决方案，为分布式发电中大量并网逆变器并联涉及的稳定性问题提供了新的思路；⑤项目还通过对组合拓扑的综合分析和评估，筛选和指出有潜力的组合拓扑方式，为后续研究提供指导。项目研究在各项研究内容上都取得了成果，共发表SCI/EI论文13篇，其中SCI收录5篇，申请国家发明专利2项，已授权1项，项目培养博士生3名，硕士生6名，并有一篇获评浙江省优秀硕士论文。本项目的研究达成了项目计划书设定的研究目标，并取得了预期成果。