光伏并网发电系统及其漏电流控制策略的研究

发布时间：2018-02-27 18:32

本文关键词： 光伏发电系统太阳能电池逆变器漏电流无差拍电流控制　出处：《河南师范大学》2014年硕士论文　论文类型：学位论文

【摘要】：随着经济的不断发展，生活质量的提高，人们对能源的需求量不断增加，然而化石能源的日益枯竭。绿色、环保、可持续、和谐的再生能源得到人们的亲睐。因为太阳能资源广泛、永久、绿色能源、且不受地域影响等优点成为新能源的新秀。太阳能发电即光伏发电成为各国能源研究的重要方向，，并逐渐显示出其良好的应用前景。由于太阳能能量密度低，且光伏发电系统的占地面积较大、成本高、受气候的影响较大等限制使得光伏发电的效率较低。因此，加深对太阳能光伏发电系统的研发，尤其是提高光伏发电整体的效率，这对缓解人类日前的能源危机有着非常重大的意义。其中，太阳能电池是光伏发电的主要部件，因此怎样提高电池的发电效率是当今研究的热点。光伏电池的输入输出特性受到其自身制作工艺、太阳光照强度，还有电池工作时温度的影响。所以各种光伏电池通用仿真模型相继提出。且因为光伏电池通用仿真模型复杂、难懂等问题使得光伏电池的仿真难度增大，对实际的实验造成更大的限制。本文介绍一种简单、明了的新型仿真模型。该模型对光伏电池中几个重要参数进行模块化处理，使得模型可以清晰的得到不同温度和光照强度对光伏电池参数的影响。并结合新型的MPPT跟踪方法，验证该模型的正确性。然而，如何更有效率、更高品质的转换成为人们可以直接利用的电量，也是迫在眉睫的。无变压器并网逆变器拥有效率高、体积小、质量轻和成本低等优势，迅速成为各国科研人员的研究热点。但变压器的消除，使得光伏(PV)系统和电网之间形成较大的共模漏电流，增加并网电流的高次谐波，还有可能危害到设备和人员安全。因此漏电流的消除对无变压器光伏并网逆变器普及和发展至关重要。本文分析了单相并网逆变器漏电流产生机理，建立了考虑寄生参数的共模谐振电路等效模型，并分析对称参数和不对称参数下，不同开关调制方法、电网电压、滤波电感以及寄生电容对漏电流的影响。最后通过无差拍电流控制的单相光伏并网逆变电路，并基于无差拍电流控制原理提出了对占空比进行补偿的补偿方法。并通过系统仿真和实验数据，验证方法的正确性。故本文提出了一种新型的电池仿真模型，提高对光伏电池仿真模型的理解，从而加强对实际实验的可操作性。并且通过无差拍电流控制的单相光伏并网逆变电路，说明了漏电流对逆变电流以及MPPT的影响。并提出了对占空比进行补偿的补偿方法，消除漏电流对逆变电流以及MPPT稳定的影响，实现系统的高质量并网电流的输出和最大功率的准确跟踪。
[Abstract]:With the development of economy and the improvement of quality of life, the demand for energy is increasing. However, fossil energy is drying up day by day. The harmonious renewable energy is favored by people. Because solar energy resources are extensive, permanent, green energy, and are not affected by geographical impact and other advantages of new energy rookie. Solar power, that is, photovoltaic power generation has become an important direction of energy research around the world. Because of the low energy density of solar energy, the large area of photovoltaic power generation system, high cost, climate influence and so on, the efficiency of photovoltaic power generation is low, because of the low energy density of solar energy, the high cost of photovoltaic power generation system, and the great influence of climate on the efficiency of photovoltaic power generation. It is of great significance to deepen the research and development of solar photovoltaic power system, especially to improve the overall efficiency of photovoltaic power generation. Among them, solar cells are the main components of photovoltaic power generation, so how to improve the efficiency of photovoltaic cells is a hot topic. There is also the effect of temperature when the cell is working. So a variety of general simulation models for photovoltaic cells have been put forward one after another. And because the general simulation model of photovoltaic cells is complex and difficult to understand, it is more difficult to simulate photovoltaic cells. This paper introduces a simple and clear new simulation model, which modularizes several important parameters in photovoltaic cells. The model can clearly get the influence of different temperature and light intensity on the parameters of photovoltaic cell, and combined with a new MPPT tracking method to verify the correctness of the model. However, how to convert more efficiently and qualitatively into the electric energy that people can use directly is also urgent. The grid-connected inverter without transformer has the advantages of high efficiency, small size, light mass and low cost, etc. But with the elimination of transformers, a large common mode leakage current is formed between PV system and power grid, which increases the high harmonics of grid-connected current. Therefore, the elimination of leakage current is very important for the popularization and development of transformer-free photovoltaic grid-connected inverters. In this paper, the mechanism of leakage current generation of single-phase grid-connected inverters is analyzed. The equivalent model of common-mode resonant circuit with parasitic parameters is established, and the different switching modulation methods and grid voltage are analyzed under symmetric and asymmetric parameters. The influence of filter inductance and parasitic capacitance on leakage current. Finally, the single-phase photovoltaic grid-connected inverter controlled by non-beat current is adopted. Based on the principle of non-beat current control, a compensation method for duty cycle compensation is proposed, and the correctness of the method is verified by system simulation and experimental data. Therefore, a new battery simulation model is proposed in this paper to improve the understanding of photovoltaic cell simulation model, so as to enhance the maneuverability of practical experiments, and through single-phase photovoltaic grid-connected inverter circuit without beat current control. The effect of leakage current on inverter current and MPPT is explained. A compensation method for duty cycle compensation is proposed to eliminate the effect of leakage current on inverter current and MPPT stability. The output of high quality grid-connected current and the accurate tracking of maximum power are realized.
【学位授予单位】：河南师范大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM615

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