小功率光伏并网逆变器研究
发布时间：2018-09-10 11:51
【摘要】：分布式光伏并网技术近年得到了大力的发展,已成为一个研究热点。小功率光伏并网逆变器是分布式光伏并网系统的重要组成部分,采用MPPT技术可大幅提高光伏并网发电系统的效率。本文就小功率光伏并网逆变器的拓扑结构、MPPT技术、以及准比例谐振逆变控制开展了研究。 本文研究了光伏电池在单一光照和局部阴影时的输出特性,并针对局部阴影下光伏电池输出的多极值现象改进了两步法MPPT,改进后的算法结合了粒子群算法(PSO)与电导增量法(INC)的优点,在光照发生变化时采用PSO寻找到最大功率点的大致范围,然后采用INC跟踪最大功率点。 本文分析了逆变器的工作原理与控制方式,在电流内环引入准PR控制。准PR控制技术具有近似于零的静态误差以及优秀的靠扰能力；并加入功率前馈控制,提升了系统的动态性能。 最后,设计了小功率单级式光伏并网逆变器的硬件电路,包括逆变电路、控制电路、信号采样与调理电路,并设计了系统的软件,实现了MPPT和并网电流控制。并通过实验验证了MPPT算法的可行性,与逆变器输出电流的THD的满足并网要求。
[Abstract]:Distributed photovoltaic grid-connected technology has been greatly developed in recent years and has become a research hotspot. Low-power photovoltaic grid-connected inverter is an important part of distributed photovoltaic grid-connected system. The efficiency of grid-connected photovoltaic system can be greatly improved by using MPPT technology. In this paper, the topology structure of low power photovoltaic grid-connected inverter (MPPT) and quasi-proportional resonant inverter control are studied. In this paper, the output characteristics of photovoltaic cells under single illumination and local shadows are studied. The improved two-step MPPT, algorithm combines the advantages of particle swarm optimization (PSO) and conductance increment method (INC) to solve the multi-extremum phenomenon of photovoltaic cell output under local shadow. PSO is used to find the approximate range of the maximum power point when the illumination changes, and then INC is used to track the maximum power point. The working principle and control mode of inverter are analyzed in this paper. Quasi PR control is introduced into the current inner loop. The quasi-PR control technology has a static error of approximately zero and excellent ability to rely on disturbance, and the power feedforward control is added to improve the dynamic performance of the system. Finally, the hardware circuit of single-stage photovoltaic grid-connected inverter is designed, including inverter circuit, control circuit, signal sampling and conditioning circuit. The software of the system is designed to realize MPPT and grid-connected current control. The feasibility of MPPT algorithm is verified by experiments, and the THD of inverter output current meets the grid connection requirements.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM464;TM615
本文编号：2234362
[Abstract]:Distributed photovoltaic grid-connected technology has been greatly developed in recent years and has become a research hotspot. Low-power photovoltaic grid-connected inverter is an important part of distributed photovoltaic grid-connected system. The efficiency of grid-connected photovoltaic system can be greatly improved by using MPPT technology. In this paper, the topology structure of low power photovoltaic grid-connected inverter (MPPT) and quasi-proportional resonant inverter control are studied. In this paper, the output characteristics of photovoltaic cells under single illumination and local shadows are studied. The improved two-step MPPT, algorithm combines the advantages of particle swarm optimization (PSO) and conductance increment method (INC) to solve the multi-extremum phenomenon of photovoltaic cell output under local shadow. PSO is used to find the approximate range of the maximum power point when the illumination changes, and then INC is used to track the maximum power point. The working principle and control mode of inverter are analyzed in this paper. Quasi PR control is introduced into the current inner loop. The quasi-PR control technology has a static error of approximately zero and excellent ability to rely on disturbance, and the power feedforward control is added to improve the dynamic performance of the system. Finally, the hardware circuit of single-stage photovoltaic grid-connected inverter is designed, including inverter circuit, control circuit, signal sampling and conditioning circuit. The software of the system is designed to realize MPPT and grid-connected current control. The feasibility of MPPT algorithm is verified by experiments, and the THD of inverter output current meets the grid connection requirements.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM464;TM615
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