光伏并网逆变器的建模与控制器设计

发布时间：2018-02-28 18:20

本文关键词： 光伏并网逆变器建模电压环前馈 PI控制重复控制　出处：《浙江大学》2014年硕士论文　论文类型：学位论文

【摘要】：光伏并网发电系统是目前的热点研究问题。并网逆变器是光伏并网发电系统中关键的一环,对其进行研究有着重要的理论与实际意义。文章分析了光伏并网逆变器的研究现状,研究目标包括：单相并网逆变器电压电流双环建模；基于两相静止坐标系下的三相并网逆变器电流环建模；并网电流控制技术；最大功率点跟踪以及孤岛效应功能。通过搭建实验平台来进行理论验证。对单相并网逆变器,采用前级为BOOST的两级式拓扑,其中前级实现最大功率点跟踪(MPPT)功能,后级采用单电感滤波实现并网电流控制。对常用的MPPT功能进行了比较,采用变步长扰动观察法作为MPPT方法。对后级电压电流双环进行了建模,确定了采用比例积分(PI)双环控制的基本方案；详细分析了直流电压环的建模过程,对常用控制方案进行了对比；针对直流母线电容电压上存在的扰动,对电压环加进前馈以改善输出波形的稳态以及动态性能,以较简单的控制方法实现对电压扰动的有效抑制。对孤岛现象的产生进行分析,在实验中使用被动检测法与主动检测法相结合的方法实现孤岛保护。对三相并网逆变器,采用了三相三线制的单级拓扑。对三相锁相环进行了介绍。分析了LCL滤波器的特性,由于LCL滤波器谐振尖峰的存在,需要引入阻尼保证系统的稳定。对比了常见的有源阻尼与无源阻尼方案,为使系统简化,最终采用在滤波电容上串接电阻的无源阻尼方案。对LCL滤波器的参数进行了详细设计。对基于LCL滤波器的三相单级并网逆变器进行了建模,在两相静止坐标轴上对控制系统进行设计。对比了电流控制方案,提出了重复控制结合PI补偿的复合控制方案,能够同时保留重复控制以及PI控制的优点,提高系统的性能。在对原理进行分析之后,对所采用的方案进行了基于MATLAB/simulink的仿真研究,并分别搭建了单相逆变器以及三相逆变器的实验样机及平台,对实验结果进行分析。
[Abstract]:Grid-connected photovoltaic power generation system is a hot research issue at present. Grid-connected inverter is a key link in grid-connected photovoltaic power generation system. It has important theoretical and practical significance to study the grid-connected photovoltaic inverter. This paper analyzes the research status of grid-connected photovoltaic inverter. The research objectives include: voltage and current double loop modeling of single-phase grid-connected inverter; current loop modeling of three-phase grid-connected inverter based on two-phase static coordinate system; grid-connected current control technology; The function of maximum power point tracking and islanding effect is verified by building the experimental platform. For single-phase grid-connected inverter, a two-stage topology is adopted, in which the former stage realizes the maximum power point tracking (MPPT) function, the latter stage uses a single inductor filter to control the grid-connected current. The common MPPT functions are compared. The variable step size perturbation observation method is used as MPPT method to model the double loop of the back stage voltage and current, and the basic scheme of the double loop control with proportional integration is determined, and the modeling process of the DC voltage loop is analyzed in detail. For the disturbance of DC bus capacitor voltage, the voltage loop is fed forward to improve the steady and dynamic performance of the output waveform. The effective suppression of voltage disturbance is realized by a simple control method, and the occurrence of islanding phenomenon is analyzed. In the experiment, the passive detection method combined with the active detection method is used to realize the islanding protection. The three-phase three-wire topology of three-phase grid-connected inverter is adopted. The three-phase phase-locked loop is introduced. The characteristics of LCL filter are analyzed. Because of the existence of resonance peak of LCL filter, It is necessary to introduce damping to ensure the stability of the system. In order to simplify the system, the common active damping and passive damping schemes are compared. Finally, the passive damping scheme of series resistance on filter capacitor is adopted. The parameters of LCL filter are designed in detail. The three-phase single-stage grid-connected inverter based on LCL filter is modeled. The control system is designed on the two-phase static coordinate axis. Compared with the current control scheme, the compound control scheme of repetitive control combined with Pi compensation is proposed, which can preserve the advantages of repetitive control and Pi control simultaneously, and improve the performance of the system. After analyzing the principle, the scheme is simulated based on MATLAB/simulink, and the experimental prototype and platform of single-phase inverter and three-phase inverter are built, and the experimental results are analyzed.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM464;TM615

【参考文献】