LCL型三电平并网逆变器研究

发布时间：2018-07-06 17:02

本文选题：光伏发电 + 三电平并网逆变器　；参考：《重庆理工大学》2017年硕士论文

【摘要】：近年来,光伏发电技术因其效率高、能源获取可再生以及对环境零污染等优点得到了国内外广泛的关注并加以研究与应用。其中,并网逆变器作为光伏发电技术中的核心环节,其性能的好坏直接影响着光伏发电系统的可靠性和并网电流的质量,从而影响着光伏发电技术的发展和推广,故对并网逆变器的深入研究有着重要意义。本论文主要工作为:本文以LCL型二极管箝位型(NPC)三电平并网逆变器作为研究对象,对NPC三电平逆变器的工作原理进行分析,给出了其SVPWM的调制算法。同时,针对NPC三电平固有的中点平衡问题进行了分析并给出了中点平衡控制策略。针对LCL型NPC三电平并网逆变器,在ABC三相静止坐标系、αβ两相静止坐标系和dq两相旋转坐标系下的数学模型。针对dq坐标系中出现的LCL参数耦合的问题,通过框图等效的方式,推导出了一种将LCL参数完全解耦的前馈解耦方案。本文根据NPC三电平逆变器的工作方式以及我国光伏并网标准的规定,探索出了一种适用于三电平并网逆变器的LCL滤波器参数选取规则。通过对NPC三电平输出纹波的分析和LCL滤波器中个参数对并网逆变器输出电流谐波的影响,采用三维图形分析的方式确定出LCL滤波器参数。本文对LCL滤波器固有特性(谐振问题)对并网逆变器系统产生不稳定问题,分析了无源阻尼和有源阻尼的控制方式。在此基础上,采用电容电流与并网电流双闭环的控制策略控制LCL型NPC三电平并网逆变器。同时,对控制策略中外环PI调节器和内环P调节器的参数给出了设计方法。在Matlab/Simulink中搭建系统仿真模型,对第3章选取的LCL滤波器参数和第4章中采用的并网控制策略进行仿真验证。同时,采用TMS320F2812设计了一台1.5kW的LCL型NPC三电平并网逆变器实验样机,本文主要对硬件系统中主电路、IPM驱动电路、电压电流检测调理电路和下位机系统等方面进行了设计,并对软件系统中三电平SVPWM生成、AD采样、控制算法环路和与下位机串口通信等部分进行了介绍。最后,根据仿真和实验结果,说明了本文三电平逆变器SVPWM、LCL参数选择方法、LCL解耦方法和电容电流与并网电流双闭环并网控制策略的有效性和可行性。
[Abstract]:In recent years, photovoltaic power generation technology has been widely studied and applied at home and abroad because of its high efficiency, renewable energy and zero pollution to the environment. Among them, grid-connected inverter as the core link of photovoltaic generation technology, its performance directly affects the reliability of photovoltaic power system and the quality of grid-connected current, thus affects the development and promotion of photovoltaic power generation technology. Therefore, it is of great significance to study the grid-connected inverter in depth. The main work of this thesis is as follows: in this paper, the LCL diode clamped (NPC) three-level grid-connected inverter is taken as the research object. The principle of NPC three-level inverter is analyzed, and its SVPWM modulation algorithm is given. At the same time, the neutral-point balancing problem inherent in NPC three-level is analyzed and the neutral-point balance control strategy is given. Aiming at the LCL NPC three-level grid-connected inverter, the mathematical models in ABC three-phase stationary coordinate system, 伪尾 two-phase stationary coordinate system and dq two-phase rotating coordinate system are presented. In order to solve the coupling problem of LCL parameters in dq coordinate system, a feedforward decoupling scheme is derived by using the block diagram equivalent method to decouple the LCL parameters completely. According to the operation mode of NPC three-level inverter and the regulation of our country's photovoltaic grid-connected standard, a rule of selecting LCL filter parameters suitable for three-level grid-connected inverter is explored in this paper. Based on the analysis of NPC three-level output ripple and the influence of one parameter in the LCL filter on the output current harmonics of grid-connected inverter, the parameters of the LCL filter are determined by three-dimensional graphic analysis. In this paper, the inherent characteristics (resonance problem) of LCL filter are analyzed for the instability of grid-connected inverter system, and the control methods of passive damping and active damping are analyzed. On this basis, the LCL NPC three-level grid-connected inverter is controlled by a double-closed loop control strategy of capacitive current and grid-connected current. At the same time, the design method of Pi regulator and P regulator is given. The system simulation model is built in Matlab / Simulink. The LCL filter parameters selected in Chapter 3 and the grid-connected control strategy adopted in Chapter 4 are simulated and verified. At the same time, a 1.5kW LCL NPC three-level grid-connected inverter experiment prototype is designed with TMS320F2812. This paper mainly designs the main circuit of the hardware system, such as IPM drive circuit, voltage and current detection conditioning circuit and lower computer system, etc. The three level SVPWM generation AD sampling, the control algorithm loop and the serial port communication with the lower computer in the software system are also introduced. Finally, according to the simulation and experimental results, the effectiveness and feasibility of the LCL decoupling method and the dual closed-loop grid-connected control strategy of capacitive current and grid-connected current for three-level inverter SVPWMN LCL are demonstrated.
【学位授予单位】：重庆理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM464

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