非隔离型单相光伏并网逆变器及其共模电流抑制的研究

发布时间：2019-03-07 17:31

【摘要】：随着全球能源危机和环境污染日益严重,开发利用清洁的可再生能源势在必行,其中太阳能作为可再生能源,不仅绿色环保,而且分布广泛,受到了广泛重视。光伏并网发电是利用太阳能的重要途径,而光伏并网逆变器作为光伏并网发电系统的核心,其效率影响整个光伏并网发电系统的效率。在各种光伏并网逆变器中,非隔离型光伏并网逆变器由于具有体积小、效率高、成本低等优点而受到人们的青睐,但非隔离型系统的共模电流对人身以及设备安全易造成潜在威胁。基于此,针对非隔离型单相光伏并网逆变器及其共模电流的抑制,本文进行了深入的研究,具体内容如下:第一,分析了隔离型和非隔离型光伏并网逆变器的工作原理,比较了各自的优缺点。第二,分析了非隔离型单相光伏并网逆变器共模电流产生机理,以及寄生电容对共模电流的影响。从逆变器拓扑结构和PWM调制策略出发,研究了从改变调制方式和拓扑结构的角度来抑制共模电流的方法。通过MATLAB仿真平台的搭建,仿真验证了共模电流抑制方法的有效性。第三,研究分析了两级式光伏并网逆变器的控制策略。前级升压电路采用变步长扰动观测法以实现光伏阵列的最大功率点跟踪(MPPT),解决了定步长扰动观测法存在的振荡和误判问题;后级逆变电路采用双闭环控制策略,稳定了中间直流侧电压,实现了对电流的快速控制。通过MATLAB仿真平台的搭建,验证了控制策略的可行性。最后,在理论分析和仿真的基础上,对系统进行了软硬件设计,采用了DSP2812作为控制核心,搭建了光伏并网发电系统实验平台。实验结果和仿真结果基本一致,验证了系统设计的可行性及共模电流抑制方法的有效性。
[Abstract]:With the global energy crisis and environmental pollution increasingly serious, the development and utilization of clean renewable energy is imperative, in which solar energy as renewable energy, not only green, but also widely distributed, has received extensive attention. Photovoltaic grid-connected power generation is an important way to use solar energy, and photovoltaic grid-connected inverter as the core of photovoltaic grid-connected generation system, its efficiency affects the efficiency of the whole photovoltaic grid-connected generation system. Among all kinds of photovoltaic grid-connected inverters, non-isolated photovoltaic grid-connected inverters are popular because of their advantages such as small size, high efficiency and low cost. However, the common-mode current of the non-isolated system is a potential threat to the safety of human beings and equipment. Based on this, aiming at the non-isolated single-phase photovoltaic grid-connected inverter and its common-mode current suppression, this paper carries on in-depth research as follows: firstly, the principle of isolated photovoltaic grid-connected inverter and non-isolated photovoltaic grid-connected inverter is analyzed. The advantages and disadvantages of each are compared. Secondly, the generation mechanism of common-mode current and the effect of parasitic capacitance on common-mode current of non-isolated single-phase photovoltaic grid-connected inverter are analyzed. Based on the inverter topology and PWM modulation strategy, the common-mode current suppression method is studied from the angle of changing the modulation mode and topology. The validity of the common-mode current suppression method is verified by the MATLAB simulation platform. Thirdly, the control strategy of two-stage photovoltaic grid-connected inverter is studied and analyzed. The variable step-size perturbation observation method is used to realize the maximum power point tracking (MPPT), of photovoltaic array, which solves the oscillation and misjudgment problems of the constant step-size disturbance observation method. The double closed loop control strategy is adopted in the back stage inverter circuit, which stabilizes the voltage of the intermediate DC side and realizes the fast control of the current. Through the establishment of MATLAB simulation platform, the feasibility of the control strategy is verified. Finally, on the basis of theoretical analysis and simulation, the hardware and software design of the system is carried out. DSP2812 is used as the control core, and the experimental platform of photovoltaic grid-connected power generation system is built. The experimental results are consistent with the simulation results, which verify the feasibility of the system design and the effectiveness of the common-mode current suppression method.
【学位授予单位】：安徽工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM464;TM615

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