光伏发电系统直流变换器的设计.doc.doc

光伏发电系统直流变换器的设计 摘 要 太阳能是一种新型的绿色可再生能源，具有储量大、利用经挤、清洁环保等优点。因此，太阳能的利用越来越受到人们的重视，而太阳能光伏发电技术的应用更是人们普遍关注的焦点。近年来，随着国内多个多晶硅生产项目的陆续完成，我国即将实现光伏电池原材料的自给，大规模推广光伏并网发电系统的时代即将到来。目前国内实际应用的光伏发电系统仍以独立系统为主，并网系统则刚刚起步，而且国内自主研制的光伏并网系统存在着系统运行不稳定，可靠性低的弱点而且保护措施不全，容易引起事故，与建筑一体化的问题也没有得到很好考虑。在上述背景下，本文在光伏发电技术方面做了若干设计工作。 太阳能电池的输出特性受外界环境因素如光照、温度的影响，为了跟踪太阳能电池的最大功率点，提高太阳能电池的利用率，常在光伏发电系统中加入由最大功率点跟踪算法控制的直流变换环节。本文重点研究了应用于中小功率的多支路、两级式的光伏并网系统的直流变换器。 本文在介绍了太阳能电池的发电原理的基础上，探讨了进行最大功率点跟踪的必要性及利用直流变换器实现太阳能电池最大功率点跟踪的原理。在介绍和分析现有的最大功率点跟踪算法之后，本文使用MATLAB对两种常用的最大功率点跟踪算法：扰动观察法和电导增量法进行了仿真研究，进而提出了一种变步长的电导增量法，改善了最大功率点跟踪的动态性能。 关键词：光伏并网，最大功率点跟踪，MATLAB建模，直流变换器 THE DESIGN OF PHOTOVOLTAIC SYSTEM DC/DC CONVERTER ABSTRACT The solar energy is one kind of green and renewable energy source which has the advantages of big reserve, low cost, and do not pollute the environment. Therefore, the use of solar energy is attracting more and more people’s attentions, and the solar photovoltaic technology is generally the focus of attention. In recent years, along with the completion of many domestic polycrystalline silicon production projects one after another, our country will soon realize self-sufficiency in the material of photovoltaic cells, the era of promoting large-scale grid-connected PV system is just around the corner. At present, the application of the photovoltaic system is still based on independent ones and grid-connected system is still in its infancy. In addition，there are weaknesses of Instability in the running, low reliability and lacks of protective measures in domestic photovoltaic system and the problem of building with construction is not considered. With the above background，we have carried out a number of studies on the subject of photovoltaic power generation technology. The output characteristics of the solar cell are affected by environmental factors such as light，temperature. In order to track the maximum power point of the solar cells to increase the utilization of them, the DC/DC converters which are controlled