交错反激式光伏并网微型逆变器研究

发布时间：2018-01-11 16:40

本文关键词：交错反激式光伏并网微型逆变器研究　出处：《中南大学》2014年硕士论文　论文类型：学位论文

【摘要】：世界范围内的能源短缺和环境污染问题使得可再生能源的利用受到越来越多的重视,太阳能光伏发电以其清洁无污染、不受地域限制等优势而发展迅速。常规集中式光伏并网发电系统逐渐显现其在商业和民用市场的劣势,光伏并网微逆变器具有发电效率高、系统容量扩展灵活、安装维护简单和冗余设计等优点,研发高性能微逆变器将为分布式光伏发电提供技术和设备支撑。本文以交错反激式光伏并网微逆变器为研究对象,对其工作在CCM方式下的系统特征进行分析并设计相应控制策略,全文的主要工作如下： (1)建立了CCM工作方式下开关周期内原副边绕组电流的时域关系式,得出了系统临界连续输出功率,分析出半电网周期内微逆变器工作在DCM和CCM相结合的方式,并用系统连续率CR表征CCM工作区间所占的比重。 (2)对微逆变器主电路关键元器件进行了参数设计和选型,包括直流侧功率解耦电容,反激变压器,反激开关管、输出整流二极管和工频换向桥功率器件和并网滤波器,为系统控制策略的设计提供参数依据。 (3)建立了基于任意准稳态工作点控制输入到并网电流输出的传递函数,得出了额定功率下π／2电角度处RHP零点对系统跟踪性能影响最大的结论,并基于这一准稳态工作点设计了电流内环Q-PR控制器。 (4)提出了分阶段、相结合控制的改进MPPT算法,即微逆变器启动阶段应用开路电压法,光伏组件功率波动较小时应用变步长扰动观察法,功率波动较大时应用短路电流法,以获得良好的稳态跟踪精度和动态跟踪性能；针对轻载下基于CCM设计的并网电流控制器适用度降低和谐波含量增大的问题,提出了双模式控制策略及模式选择控制器的实现原则,实现轻载时系统控制方式切换到DCM并网电流控制方式,提高了轻载并网电流品质。 (5)搭建了Matlab/Simulink仿真系统和250W微逆变器系统平台,仿真和实验结果均验证了上述系统分析的正确性和所设计的控制策略的有效性和可行性。
[Abstract]:Worldwide energy shortage and environmental pollution make the use of renewable energy more and more attention. Solar photovoltaic power generation is clean and pollution-free. Conventional centralized photovoltaic grid-connected generation system gradually shows its disadvantages in commercial and civil markets. Photovoltaic grid-connected microinverters have high generation efficiency and flexible system capacity expansion. With the advantages of simple installation and maintenance and redundant design, the development of high-performance microinverters will provide technical and equipment support for distributed photovoltaic power generation. This paper takes the interleaved flyback photovoltaic grid-connected micro-inverter as the research object, analyzes the system characteristics of the system working in the CCM mode and designs the corresponding control strategy. The main work of this thesis is as follows: 1) the time-domain relationship of the primary secondary winding current in the switching cycle under the CCM operation mode is established, and the critical continuous output power is obtained. The combination of DCM and CCM is analyzed in the semi-grid cycle, and the proportion of CCM in the range of CCM is characterized by the CR of system continuity. The key components of the main circuit of the micro-inverter are designed and selected, including DC side power decoupling capacitance, flyback transformer and flyback switch. The output rectifier diode and power frequency commutation bridge power device and grid-connected filter provide parameter basis for the design of system control strategy. A transfer function based on arbitrary quasi-steady-state operating point control to the output of grid-connected current is established, and the conclusion that RHP 00:00 at 蟺 / 2 electric angle at rated power has the greatest influence on the tracking performance of the system is obtained. The Q-PR controller of current inner loop is designed based on the quasi-steady operation point. In this paper, an improved MPPT algorithm, which combines the control with the control, is proposed, that is, the open circuit voltage method is used in the start-up phase of the micro-inverter, and the variable step perturbation observation method is used to observe the small power fluctuation of the photovoltaic module. The short-circuit current method is used to obtain good steady-state tracking accuracy and dynamic tracking performance when the power fluctuation is large. In order to reduce the applicability and increase the harmonic content of grid-connected current controller based on CCM under light load, a dual-mode control strategy and the realization principle of mode selection controller are proposed. The system control mode is switched to DCM grid-connected current control mode under light load, and the quality of light-load grid-connected current is improved. Matlab/Simulink simulation system and 250W micro-inverter system platform are built. The simulation and experimental results verify the correctness of the system analysis and the effectiveness and feasibility of the proposed control strategy.
【学位授予单位】：中南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM464

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