交互并联逆阻型三电平变流器电压平衡与环流抑制策略研究

发布时间：2018-04-20 22:02

本文选题：逆阻型三电平变流器 + 交互式并联　；参考：《东南大学》2017年硕士论文

【摘要】：近年来,新能源发电技术的快速发展为电力电子技术的发展带来了机遇,变流器作为电能转换的核心部件,是决定系统并网运行稳定性和安全性的关键部分,因此成为研究的重点领域。一方面,逆阻型三电平变流器具有输出电压与电流波形畸变小、功率因数高、器件开关损耗低,耐压等级高,模块集成简单等优点。另一方面,模块化交互并联系统以其灵活性和扩展性强的特点,成为目前研究和开发的热点。基于此背景,本文展开了基于多机交互式即公共直流交流母线并联的逆阻型三电平变流器系统研究。首先,针对逆阻型三电平变流器的拓扑结构,对其电路原理进行了分析,详细分析了一个工频周期内逆阻型三电平变流电路的八种工作状态,以及每种工作状态对应的输出电平情况。然后分别针对abc坐标系下、a-β坐标系下以及dq0坐标系下对逆阻型三电平变流电路进行了建模。针对dq坐标系下的逆阻型三电平变流器电路数学模型,进行变流器并网控制策略的研究,分析了三相锁相环与电流环的控制方式。其次,本文阐述了逆阻型三电平变流器的SVPWM调制策略的原理及步骤,分析了直流侧中点电位不平衡的原因,提出了针对单机逆阻型三电平变流器,一种基于调整冗余小矢量作用时间的SVPWM调制算法的中点电压平衡控制策略,并拓展到多机逆阻型三电平变流器交互并联系统,分别针对非共享中线和共享中线结构进行了分析,比较得出共享直流侧中线的逆阻型三电平变流器交互并联结构更能满足系统的控制要求。再次,本文针对多机逆阻型三电平变流器交互并联系统,通过9种并联环路的分析,详细阐述了环流的产生机理、建模以及分类。通过分析得知,对于采用LCL滤波器和电流环并网控制的逆阻型三电平变流器,高频零序环流分量被有效的抑制,因此低频零序环流分量成为环流的主要成分。本文提出了一种基于PR控制器的低频零序环流分量抑制策略,并结合逆阻型三电平变流器直流侧中点电压平衡控制策略,提出了与环流抑制的整体控制。每一台逆阻型三电平变流器都单独控制,以达到每台变流器的精确控制。最后,通过MATLAB/SIMULINK软件搭建仿真模型,对逆阻型三电平变流器并网控制策略、SVPWM调制算法、中点电压平衡以及环流抑制策略进行仿真分析,验证了所提出的控制策略的可行性和有效性。
[Abstract]:In recent years, the rapid development of new energy generation technology has brought opportunities for the development of power electronics technology. As the core component of power conversion, converter is the key part that determines the stability and security of the system. Therefore, it has become the key area of research. On the one hand, the inverse resistive three-level converter has the advantages of low output voltage and current waveform distortion, high power factor, low switching loss, high voltage resistance, simple module integration, and so on. On the other hand, modular interactive parallel system has become a hotspot in research and development because of its flexibility and expansibility. Based on this background, this paper develops the research of inverse resistive three-level converter system based on multi-machine interaction, that is, common DC busbar parallel connection. Firstly, aiming at the topology structure of inverse resistive three-level converter, the circuit principle is analyzed, and eight working states of inverse resistive three-level converter in a power frequency cycle are analyzed in detail. And the output level situation corresponding to each working state. Then the inverse resistive three-level variable current circuit is modeled in abc coordinate system and dq0 coordinate system respectively. Aiming at the mathematical model of inverse resistive three-level converter circuit in dq coordinate system, the grid-connected control strategy of converter is studied, and the control mode of three-phase phase-locked loop and current loop is analyzed. Secondly, this paper describes the principle and steps of SVPWM modulation strategy of inverse resistive three-level converter, analyzes the causes of unbalanced neutral point potential on DC side, and puts forward a three-level inverter for single-machine inverse resistive type. A neutral-point voltage balance control strategy based on SVPWM modulation algorithm based on adjusting redundant small vector action time is extended to a multi-machine inverse resistive three-level converter interactive parallel system. The structure of non-shared midline and shared midline are analyzed respectively. It is concluded that the interactive parallel structure of the inverse-resistive three-level converter with the shared DC neutral line can meet the control requirements of the system better. Thirdly, based on the analysis of 9 parallel loops, the mechanism, modeling and classification of the circulation are described in detail for the multi-machine inverse resistive three-level converter interactive parallel system. The analysis shows that the high frequency zero sequence circulation component is effectively suppressed for the inverse resistive three-level converter controlled by LCL filter and current loop, so the low frequency zero sequence circulation component becomes the main component of the circulation. In this paper, a low-frequency zero-sequence circulation component suppression strategy based on PR controller is proposed. Combined with the neutral-point voltage balance control strategy on the DC side of the inverse resistive three-level converter, the overall control of the current suppression is proposed. Each inverse resistive three-level converter is controlled separately to achieve the precise control of each converter. Finally, the simulation model is built by MATLAB/SIMULINK software to simulate the control strategy of inverse-resistive three-level converter, such as SVPWM modulation algorithm, neutral-point voltage balance and circulation suppression strategy. The feasibility and effectiveness of the proposed control strategy are verified.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM46

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