光伏发电系统建模及功率控制方法研究

发布时间：2018-06-05 00:11

本文选题：光伏电池 + 光伏发电系统　；参考：《兰州理工大学》2014年硕士论文

【摘要】：随着人类社会的发展与进步,化石能源逐渐匮乏,环境问题日益突出,寻求清洁、可再生能源已成为当下解决能源问题的根本途径。光伏发电以其资源储量大、清洁环保等优点,成为目前最具大规模开发、利用前景的新能源利用方式之一。由于光伏电池输出功率受辐照强度、环境温度以及负载特性等外部因素影响剧烈,因此尽管光伏发电技术已曰趋成熟但仍存在发电效率低、成本偏高等问题。为了提高光伏电池对太阳能的利用效率,光伏电池应能及时适应外部环境变化而始终工作在最大功率点处。因此,深入研究光伏发电系统的动态行为特性与最大功率跟踪方法(MPPT)是一项非常有意义的工作。本文以光伏发电系统为研究对象,在研究了光伏电池工作原理的基础上,建立起光伏电池的数学模型,并详细分析了光伏电池的输出特性；基于对光伏系统具有最大光电转换效率的考虑,对比几种常见DC/DC变换电路,提出由Buck电压转换电路来实现最大功率跟踪；通过对光伏发电系统的动力学行为特性、光伏发电系统中重要参数的详细分析,研究对比了几种最大功率跟踪控制策略的控制效果。首先,本文从光伏发电的物理基础(光生伏特效应)出发,通过分析光伏电池的等效电路,利用MATLAB/SIMULINK仿真平台建立光伏电池的仿真模型；在此基础上研究光伏电池的输出特性；通过对光伏电池等效串联内阻的分析,简化仿真模型,方便最大功率控制策略的分析与研究。其次,通过对独立光伏发电系统特点的分析,比较几种常见的DC/DC变换电路拓扑结构的优缺点,选定由Buck变换器实现MPPT算法；在理论分析的基础上建立起由Buck变换器为基础的光伏电池最大功率跟踪仿真系统,并分析光伏发电系统的动力学行为特性,同时对其中几个重要参数的作用进行研究。最后,寻找光伏电池的最优工作点,最大化光电转换效率,是光伏发电的核心内容。其中,应用最为广泛的最大功率点是艮踪控制方法是扰动观察法和电导增量法。本文从原理上详细描述了扰动观测法、基于功率预测的扰动观测法以及模糊控制等常见MPPT技术,并在MATLAB仿真平台的基础上,对几种常用的MPPT技术进行了仿真研究,提出改进的MPPT算法——模糊PID算法。仿真结果表明,模糊PID控制算法具有明显优势,可以在外界环境突然变化的情况下快速、准确的跟踪光伏阵列的最大功率点,并显著减小光伏阵列在最大功率点附近的振荡,最大程度的降低由此带来的能量损失,提高了光伏系统的发电效率,相对于普通MPPT算法具有优越性。
[Abstract]:With the development and progress of human society, fossil energy is gradually scarce, environmental problems become increasingly prominent, the search for clean, renewable energy has become the basic way to solve the energy problem. Photovoltaic power generation has become one of the most large-scale development and utilization of new energy with the advantages of large reserves, clean and environmental protection. Because the output power of photovoltaic cells is strongly affected by external factors such as radiation intensity, ambient temperature and load characteristics, although photovoltaic power generation technology has become more mature, there are still some problems such as low efficiency and high cost. In order to improve the efficiency of solar energy utilization, photovoltaic cells should be able to adapt to the changes of external environment and always work at the maximum power point. Therefore, it is very meaningful to study the dynamic behavior and the maximum power tracking method of photovoltaic system. On the basis of studying the working principle of photovoltaic cell, the mathematical model of photovoltaic cell is established, and the output characteristic of photovoltaic cell is analyzed in detail. Based on the consideration of the maximum photovoltaic conversion efficiency of photovoltaic system, compared with several common DC/DC conversion circuits, a Buck voltage conversion circuit is proposed to achieve maximum power tracking. Based on the detailed analysis of important parameters in photovoltaic power generation system, the control effects of several maximum power tracking control strategies are studied and compared. First of all, based on the physical basis of photovoltaic generation (photovolt effect), by analyzing the equivalent circuit of photovoltaic cells, the simulation model of photovoltaic cells is established by using MATLAB/SIMULINK simulation platform, and the output characteristics of photovoltaic cells are studied. By analyzing the equivalent series internal resistance of photovoltaic cells, the simulation model is simplified to facilitate the analysis and research of the maximum power control strategy. Secondly, by analyzing the characteristics of the independent photovoltaic power generation system, comparing the advantages and disadvantages of several common DC/DC conversion circuit topologies, Buck converter is selected to implement the MPPT algorithm. Based on the theoretical analysis, a photovoltaic cell maximum power tracking simulation system based on Buck converter is established, and the dynamic behavior of photovoltaic power generation system is analyzed. At the same time, some important parameters are studied. Finally, it is the core content of photovoltaic power generation to find the optimal working point and maximize the photovoltaic conversion efficiency. The most widely used maximum power point is the perturbation observation method and conductance increment method. In this paper, some common MPPT techniques, such as disturbance observation method, disturbance observation method based on power prediction and fuzzy control, are described in detail in principle. Based on the MATLAB simulation platform, several common MPPT techniques are simulated and studied. An improved MPPT algorithm, fuzzy PID algorithm, is proposed. The simulation results show that the fuzzy PID control algorithm has obvious advantages, it can track the maximum power points of photovoltaic arrays quickly and accurately in the case of sudden changes in the external environment, and significantly reduce the oscillation of photovoltaic arrays near the maximum power points. It can reduce the energy loss and improve the efficiency of photovoltaic system, which is superior to the conventional MPPT algorithm.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM615

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