局部阴影条件下基于MMC的光伏并网系统研究

发布时间：2018-05-15 23:26

本文选题：光伏发电 + 局部阴影　；参考：《湖南工业大学》2017年硕士论文

【摘要】：随着社会的高速发展,人类对能源的需求在不断增加,常规的不可再生资源也越来越紧缺。为了解决能源短缺与环境污染问题,人们开始把目光投向取之不尽且无污染的太阳能。光伏发电是目前利用太阳能使用最多的发电技术,在局部阴影条件下光伏电站并网优化一直是该技术领域的一个研究热点与难点,而对光伏并网系统的拓扑结构进行优化是解决这一问题的有效途径之一。本文结合模块化多电平拓扑结构在分布式能源发电中的独特优势,对一种基于模块化多电平的光伏并网拓扑结构以及其控制策略进行优化改进。首先,分析了光伏电池的物理模型及其输出特性模型,在此基础上推导出光伏阵列的数学模型,分析在局部阴影条件下光伏阵列功率失配的原因。然后介绍双极式发电系统的拓扑结构,分析了BOOST电路的工作原理。介绍了模块化多电平变流器(modular mutilevel converter,MMC)的基本结构和运行机理,并结合了两者的工作特性,对基于MMC的光伏发电系统结构进行了优化设计,同时分析了该系统的基本运行原理。其次,对本文所改进的光伏并网系统的启停过程进行分析,设计了系统的启停控制流程和相应的控制器;对光伏阵列最大功率点跟踪的原理进行分析,结合对所提拓扑运行特性的分析,为其设计了相应的最大功率点跟踪控制策略,可实现各个光伏组件的最大功率点电压捕获;分析了系统的并网过程,设计了并网控制器,实现光伏发电系统并网的稳定运行。最后,根据改进的拓扑结构及针对该系统所设计的控制策略,用MATLAB/Simulink软件进行仿真实验。根据仿真结果得出结论,所改进的光伏并网系统拓扑结构在局部阴影条件下能够稳定运行。而且相对于常规集中式并网结构,本系统还具有太阳能的利用率高、谐波含量低等优点。
[Abstract]:With the rapid development of society, the demand for energy is increasing, and the conventional non-renewable resources are becoming more and more scarce. In order to solve the problem of energy shortage and environmental pollution, people began to focus on the inexhaustible and non-polluting solar energy. Photovoltaic (PV) generation is the most widely used power generation technology at present. Under the condition of local shadow, grid-connected optimization of photovoltaic power station has been a hot and difficult research topic in the field of photovoltaic power generation. One of the effective ways to solve this problem is to optimize the topology of grid-connected photovoltaic system. Based on the unique advantages of modularized multilevel topology in distributed energy generation, this paper optimizes and improves a modularized multilevel photovoltaic grid-connected topology and its control strategy. Firstly, the physical model of photovoltaic cell and its output characteristic model are analyzed, and the mathematical model of photovoltaic array is derived, and the reason of power mismatch in local shadow condition is analyzed. Then the topology of bipolar generation system is introduced and the working principle of BOOST circuit is analyzed. This paper introduces the basic structure and operation mechanism of modular multilevel converter (Modular mutilevel convertor MMC), combines their working characteristics, optimizes the structure of photovoltaic power generation system based on MMC, and analyzes the basic operation principle of the system. Secondly, the starting and stopping process of the improved photovoltaic grid-connected system is analyzed, and the control flow of the system and the corresponding controller are designed, and the principle of the maximum power point tracking of the photovoltaic array is analyzed. Combined with the analysis of the operation characteristics of the proposed topology, the corresponding maximum power point tracking control strategy is designed for it, which can realize the maximum power point voltage capture of each photovoltaic module, and the grid-connected process of the system is analyzed, and the grid-connected controller is designed. To realize the stable operation of photovoltaic power system. Finally, according to the improved topology and the control strategy designed for the system, the simulation experiment is carried out with MATLAB/Simulink software. According to the simulation results, it is concluded that the improved photovoltaic grid-connected system topology can operate stably under the condition of local shadow. Compared with the conventional centralized grid-connected structure, the system also has the advantages of high utilization of solar energy and low harmonic content.
【学位授予单位】：湖南工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM615

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