基于功率前馈的单级式三相光伏并网逆变器的研究

发布时间：2018-07-06 20:45

本文选题：单级式光伏逆变器 + 最大功率点跟踪　；参考：《燕山大学》2014年硕士论文

【摘要】：单级式光伏并网系统仅需要一级能量变换就可以完成最大功率点跟踪(MPPT)和并网两个功能，因此在效率和成本上都有较大的优势，但是与此同时也会带来一些缺点，如控制复杂，直流母线电压过高等，所以深入研究单级式光伏并网逆变系统，对于未来新能源问题的解决有重要的研究价值和研究意义。本文以单级式三相光伏并网逆变器为研究对象。首先分析了光伏电池的原理与输出特性并建立其数学模型，，根据光伏电池的输出特性对比分析定电压跟踪法、扰动观察法和电导增量法这三种常用MPPT算法的优缺点。在此基础上提出了一种“钟摆式”MPPT算法，同时对该算法进行了理论分析，并将其与传统扰动观察法进行仿真对比，突出了“钟摆式”MPPT算法的优势。其次，对单级式三相光伏并网逆变器的数学模型与控制策略进行了详细的研究与分析。针对传统双环控制中直流母线电压响应慢，不利于MPPT的快速搜索，本文将功率前馈算法应用于本系统的的外环控制中，并将其与传统的双环PI控制进行仿真对比。此外，针对实际并网控制中调节器设计不合理，参数试凑等问题，对PI调节器参数设计进行了深入研究，通过详细的理论推导得出一种新型设计PI调节器的方法。在完成MPPT算法与逆变器控制策略的分析后，将“钟摆式”MPPT算法与基于功率前馈的双环控制相结合，对单级式三相光伏并网逆变系统进行了整体的仿真研究。最后，本文对整个系统的硬件和软件进行了详细的设计。在设计的基础上搭建了一套3kVA的单级式三相光伏并网逆变器样机，通过数字控制，完成了整个系统的实验验证。实验结果验证了“钟摆式”MPPT算法以及基于功率前馈控制方案的可行性和有效性。
[Abstract]:The single-stage photovoltaic grid-connected system needs only one stage energy conversion to complete the two functions of maximum power point tracking (MPPT) and grid-connected, so it has great advantages in efficiency and cost, but at the same time, it will bring some disadvantages, such as complex control. The DC bus voltage is too high, so the research of single-stage photovoltaic grid-connected inverter system has important research value and significance for solving the problem of new energy in the future. In this paper, the single-stage three-phase photovoltaic grid-connected inverter is taken as the research object. Firstly, the principle and output characteristics of photovoltaic cells are analyzed and their mathematical models are established. According to the output characteristics of photovoltaic cells, the advantages and disadvantages of three common MPPT algorithms, namely, constant voltage tracking method, disturbance observation method and conductance increment method, are compared and analyzed. On this basis, a kind of "pendulum" MPPT algorithm is proposed, and the theoretical analysis of the algorithm is made, and compared with the traditional perturbation observation method, the advantages of the "pendulum" MPPT algorithm are highlighted. Secondly, the mathematical model and control strategy of single-stage three-phase photovoltaic grid-connected inverter are studied and analyzed in detail. In view of the slow voltage response of DC bus in the traditional double loop control, which is not conducive to the fast search of MPPT, this paper applies the power feedforward algorithm to the outer loop control of the system, and compares it with the traditional double loop Pi control. In addition, the parameter design of Pi regulator is studied deeply, and a new design method of Pi regulator is derived through the detailed theoretical derivation, aiming at the unreasonable design of regulator and parameter trial and error in practical grid-connected control. After the analysis of MPPT algorithm and inverter control strategy, the "pendulum" MPPT algorithm is combined with the dual-loop control based on power feedforward to simulate the single-stage three-phase photovoltaic grid-connected inverter system. Finally, the hardware and software of the whole system are designed in detail. On the basis of the design, a 3kVA single-stage three-phase photovoltaic grid-connected inverter prototype is built, and the whole system is verified by digital control. The experimental results demonstrate the feasibility and effectiveness of the "pendulum" MPPT algorithm and the power feedforward control scheme.
【学位授予单位】：燕山大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM464;TM615

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