基于LCL滤波器三相三电平并网逆变器研究

发布时间：2018-01-20 21:25

本文关键词： 三电平SVPWM LCL滤波器数字控制有源阻尼 DSP FPGA　出处：《燕山大学》2014年硕士论文　论文类型：学位论文

【摘要】：随着光伏发电的飞速发展，光伏逆变并网日渐成为光伏发电的重要环节，本课题基于这一背景，针对基于LCL滤波器三相三电平逆变器并网系统进行了研究。考虑到设备体积，成本等问题，本课题采用二极管箝位型三电平逆变器(Three-phase Three-level NPC Inverter)拓扑结构，并详细分析了其三种开关工作状态，建立了各自工作状态所对应的数学模型；本课题为了方便实现系统数字化控制，采用三电平SVPWM脉宽调制的方式，并给出了其数字化实现形式。由于LCL滤波器各参数存在耦合关系，所以现阶段LCL滤波器参数选取都比较盲目。本科题基于这一原因，详细分析了LCL滤波器参数变化对并网电流谐波抑制，纹波衰减和谐振频率的影响。并依照所得结论结合现阶段电网对并网系统各项要求，，提出通过程序最优选取LCL滤波器参数的方式。最后用该方法对LCL滤波器参数作出选择。本课题通过对基于LCL滤波器三相三电平逆变器并网系统建模的分析，发现其在dq坐标轴下，d轴分量与q轴分量存在较强的耦合关系，所以该系统的控制策略决定采用基于PR控制器的电容电流内环，并网电流外环的双电流环控制方式，并采用高阶系统零极点配置方法对控制器参数进行设计，最后运用MATLAB软件作了仿真验证，仿真结果验证了理论分析。最后依照课题研究要求，搭建基于LCL滤波器并网逆变器系统实验平台，选用DSP(TMS320F28335)与FPGA(EP3C25Q240C8N)作为系统数字控制器的主控芯片，对三电平SVPWM实现，逆变器并网相关实验作了验证。
[Abstract]:With the rapid development of photovoltaic power generation, grid-connected photovoltaic inverter is becoming an important link in photovoltaic power generation. This topic is based on this background. A three-phase three-level inverter grid-connected system based on LCL filter is studied. Considering the equipment volume, cost and so on. In this paper, the three-phase Three-level NPC Inverter topology of diode clamped three-level inverter is used. The three switching states are analyzed in detail, and the corresponding mathematical models are established. In order to realize the digital control of the system, the three-level SVPWM pulse width modulation is adopted, and the digital realization is given. Because of the coupling relationship between the parameters of the LCL filter, the selection of the parameters of the LCL filter is blind at this stage. The effects of LCL filter parameters on harmonic suppression, ripple attenuation and resonant frequency of grid-connected current are analyzed in detail. The method of selecting the parameters of LCL filter by program is put forward. Finally, the parameters of LCL filter are selected by this method. By analyzing the modeling of grid-connected three-phase three-level inverter based on LCL filter, it is found that there is a strong coupling relationship between d-axis component and q-axis component under dq coordinate axis. Therefore, the control strategy of the system decided to use the internal capacitive current loop based on PR controller and the double current loop control mode of the grid current outer loop, and designed the controller parameters by using the zero-pole assignment method of the high-order system. Finally, MATLAB software is used to verify the simulation results, and the theoretical analysis is verified by the simulation results. Finally, according to the research requirements of the subject, the experimental platform of grid-connected inverter system based on LCL filter is built. DSP TMS320F28335) and FPGA EP3C25Q240C8N) are selected as the main control chip of the digital controller. The three-level SVPWM is realized. The related experiments of grid-connected inverter are verified.
【学位授予单位】：燕山大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM464

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