离网型光伏发电装置控制策略研究及系统设计

发布时间：2018-09-04 16:33

【摘要】：太阳能是资源量最大、分布最普遍的可再生能源，对其进行有效地开发和利用一直是各国追求的目标。光伏发电是太阳能资源的一种有效利用形式，对缓解电力紧张和减少环境污染具有重大意义。目前光伏发电方式有并网型和离网型两种，其中并网型的装机容量较大，而离网型光伏发电方式因具有安装方便、不受电网政策限制、成本相对较低等特点同样具有广阔的应用前景。基于以上背景，本文对离网型光伏发电装置进行了控制策略研究并以ARM控制器为核心设计了一套离网型光伏发电系统。在分析了离网型光伏发电系统的研究现状和系统设计中的技术难点之后，本文综合考虑了发电设备和储能设备之间的相互配合问题，设计了系统的整体结构，包括光伏板、蓄电池、Boost变换器、双向Buck/Boost变换器和全桥逆变器。为了实现对光伏板发电能力的最大化利用，本文重点研究了光伏最大功率跟踪（MPPT）算法。通过Matlab仿真实验发现了目前工程中普遍使用的扰动观察法的缺点，之后进行了两次算法改进，设计了方便可行的改进型变步长扰动观察法，很好地缓解了最大功率跟踪时稳态精度和响应速度无法兼顾的矛盾。为了延长蓄电池的使用寿命，本文分析了蓄电池的充放电特性，对比了工程中常用蓄电池充电方法的优缺点，选择了两段式充电方法并通过仿真实验证明了其可行性。此外，本文还对整体结构中涉及的每个功率变换器设计了匹配的控制策略，针对光伏板、负载和蓄电池三者运行时的不同状态设计了系统的6种工作模式，给出了适合本文的能量管理控制策略。系统设计也是本文的重要内容。针对中小功率家用电器的需求，，本文制定了系统各个子模块的功率参数和电压等级，对主电路中用到的三种功率变换器进行了详细的硬件电路设计和元器件参数计算，并参考计算结果进行了器件选型。之后，基于STM32F103ZET6设计了系统的控制电路，包括供电电路、传感器电路、采样电路、MOSFET驱动及其保护电路、全桥逆变控制电路和人机界面。为了进一步验证系统设计的合理性，本文搭建了一个小功率离网型光伏发电系统实验平台，完成了控制电路调试实验和MPPT实验，给出了相关实验波形。另外，还成功实现了正弦波全桥逆变功能，证明了全桥逆变主电路及其控制电路设计的可靠性。
[Abstract]:Solar energy is the most abundant and widely distributed renewable energy. Photovoltaic power generation is an effective use of solar energy resources, which is of great significance to alleviate the power shortage and reduce environmental pollution. At present, there are two types of photovoltaic power generation, grid-connected and off-grid, in which the installed capacity of grid-connected type is large, while the off-grid photovoltaic power generation mode is not restricted by the power network policy because of its convenient installation. The characteristics of relatively low cost also have broad application prospects. Based on the above background, the control strategy of off-grid photovoltaic power plant is studied in this paper, and a set of off-grid photovoltaic power generation system is designed with ARM controller as the core. After analyzing the current research situation of off-grid photovoltaic power generation system and the technical difficulties in the system design, this paper comprehensively considers the coordination between generation equipment and energy storage equipment, and designs the overall structure of the system, including photovoltaic panels. Battery boost converter, two-way Buck/Boost converter and full-bridge inverter. In order to maximize the power generation capacity of photovoltaic panels, this paper focuses on the research of photovoltaic maximum power tracking (MPPT) algorithm. Through the Matlab simulation experiment, the shortcomings of the disturbance observation method which is widely used in engineering are found, and then the algorithm is improved twice, and a convenient and feasible variable step size disturbance observation method is designed. The contradiction between steady-state precision and response speed in maximum power tracking is well alleviated. In order to prolong the service life of the battery, the charge-discharge characteristics of the battery are analyzed, the advantages and disadvantages of the common battery charging methods in engineering are compared, the two-stage charging method is selected and its feasibility is proved by simulation experiments. In addition, a matching control strategy is designed for each of the power converters involved in the whole structure, and six operating modes of the system are designed for the different states of the photovoltaic panel, the load and the battery. An energy management control strategy suitable for this paper is presented. System design is also an important part of this paper. According to the demand of medium and small power household appliances, the power parameters and voltage levels of each sub-module of the system are worked out, and the detailed hardware circuit design and component parameter calculation of three kinds of power converters used in the main circuit are carried out. The device selection is carried out with reference to the calculation results. Then, the control circuit of the system is designed based on STM32F103ZET6, including power supply circuit, sensor circuit, sampling circuit, MOSFET driver and protection circuit, full-bridge inverter control circuit and man-machine interface. In order to further verify the rationality of the system design, a small power off-grid photovoltaic system experimental platform is built, the control circuit debugging experiment and MPPT experiment are completed, and the related experimental waveforms are given. In addition, the sinusoidal full-bridge inverter is successfully realized, which proves the reliability of the design of the full-bridge inverter main circuit and its control circuit.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM615

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