基于Z源逆变器的光伏并网系统的研究

发布时间：2018-03-17 13:55

本文选题：Z源逆变器　切入点：光伏并网　出处：《湖南大学》2015年硕士论文　论文类型：学位论文

【摘要】：伴随着社会经济的快速发展,各国对于能源的需求越来越迫切。化石能源消耗殆尽,将难以维持人类社会发展的可持续性,因此寻找新能源取代化石能源显得尤为重要。太阳能由于无污染、易获取、取之不尽等特点而获得人们的广泛关注。目前利用太阳能发电主要包括光伏发电和光热发电。光伏发电由于具有较高的能量利用率而成为学者研究的重要课题。本文采用Z源逆变器来取代传统光伏并网系统结构当中的DC/DC变换电路和逆变器,对于Z源逆变器及其在光伏并网系统中的应用进行了相关的研究。本文首先介绍了Z源逆变器的工作原理以及常见的调制策略,在此基础上分析直通零矢量对于Z源逆变器电感电流纹波的影响,进而提出一种改进的Z源调制策略。该调制策略相较于传统的调制策略可以更有效地减小Z源逆变器的Z源电感电流纹波和Z源电容电压纹波,进而提高Z源逆变器输出交流波形的质量。其次,本文介绍了常见的Z源逆变器拓扑结构及其特点。在传统拓扑结构研究的基础上,引入一种开关耦合电感单元,来取代传统拓扑结构中的电感,进而使得Z源逆变器电压增益能力得到明显加强。这为Z源逆变器如何提高电压增益能力提供了一种新方法,并且该方法对于光伏发电、风力发电等输入电压小、电压增益要求高的场合具有广泛的应用价值。再者,本文采用状态空间平均法对Z源逆变器建模,并介绍了两种常见的基于Z源逆变器的光伏并网系统控制策略,即Z源电容电压恒压控制策略和基于电压空间矢量的单级控制策略。本文以Z源电容电压恒压控制策略为基础,利用MATLAB搭建了光伏并网系统的仿真。最后,本文设计了功率为2kW的基于Z源逆变器的光伏并网系统实验平台。在这个过程中,介绍了主电路中的电感、电容、开关管等参数选取依据;设计了相关的硬件电路,主要包括电压电流检测电路、过零检测电路、IGBT驱动电路;以控制芯片TMS320F28335为基础进行了软件的设计,主要包括主程序、AD中断程序、频率捕获和网压同步中断程序、EPWM中断程序和故障中断程序的设计。最后,通过实验调试得到了相应的实验波形,实验结果表明基于Z源逆变器光伏并网系统实现了升压和并网的功能。
[Abstract]:With the rapid development of social economy, the demand for energy is becoming more and more urgent. Fossil energy consumption will be difficult to maintain the sustainability of human social development. So it's particularly important to find new sources of energy instead of fossil fuels. Solar energy is easy to access because it's pollution-free. At present, solar power generation mainly includes photovoltaic power generation and photothermal power generation. Photovoltaic power generation has become an important topic for scholars because of its high energy efficiency. In this paper, Z-source inverter is used to replace the DC/DC converter and inverter in the traditional photovoltaic grid-connected system. The Z-source inverter and its application in photovoltaic grid-connected system are studied. Firstly, the principle of Z-source inverter and its modulation strategy are introduced. On the basis of this, the effect of zero-pass vector on current ripple of Z-source inverter is analyzed. Furthermore, an improved Z-source modulation strategy is proposed, which can reduce the current ripple of the Z-source inductor and the voltage ripple of the Z-source capacitor more effectively than the traditional modulation strategy. Then the quality of the output AC waveform of Z-source inverter is improved. Secondly, the common topology and characteristics of Z-source inverter are introduced. Based on the research of traditional topology, a switching coupled inductance unit is introduced. It provides a new method for how to improve the voltage gain ability of Z-source inverter, and it is also useful for photovoltaic power generation. Wind power generation, such as small input voltage and high voltage gain, has wide application value. Furthermore, the state space averaging method is used to model the Z-source inverter. Two common control strategies of photovoltaic grid-connected system based on Z-source inverter, Z source capacitor voltage constant voltage control strategy and single stage control strategy based on voltage space vector, are introduced in this paper, which is based on Z-source capacitor voltage constant voltage control strategy. The simulation of photovoltaic grid-connected system is built by using MATLAB. Finally, a 2kW experimental platform of photovoltaic grid-connected system based on Z-source inverter is designed. In this process, the inductance and capacitance of the main circuit are introduced. The related hardware circuits are designed, including voltage and current detection circuit, zero-crossing detection circuit and IGBT-driven circuit. The software is designed based on the control chip TMS320F28335. It mainly includes the design of main program AD interrupt program, frequency capture and network voltage synchronous interrupt program EPWM interrupt program and fault interrupt program. Finally, the corresponding experimental waveform is obtained through experimental debugging. The experimental results show that the photovoltaic grid-connected system based on Z-source inverter achieves the functions of boosting and grid-connected.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM464;TM615

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