MMC逆变器的控制策略研究

发布时间：2018-05-11 10:00

本文选题：模块化多电平逆变器(MMC) + 调制技术　；参考：《中国舰船研究院》2017年硕士论文

【摘要】：近些年来,随着电力电子技术的飞速发展,高压大功率电力电子设备的研究与开发受到了来自国内外学术界以及工业界的广泛关注。其中,模块化多电平逆变器(Modular Multilevel Converter,MMC)凭借着其独特的拓扑结构以及突出的应用优势迅速成为了高压大功率场合的研究热点。为了使MMC能够得到更好的应用,本文主要围绕其控制策略:调制技术、子模块直流电容均压策略以及环流抑制策略展开相关研究工作。本文分析了MMC拓扑结构与工作原理,建立了MMC数学模型。研究了两种PWM调制:载波层叠调制和载波移相调制在MMC中的实现方法,并分析了这两种调制各自的特点以及对MMC特性的影响。针对载波层叠调制的特点,本文研究了两种基于电容电压排序的子模块均压策略:基于分配开关脉冲的排序法和基于计算子模块投入数量的排序法。通过仿真证明了这两种均压策略的有效性,并得出基于计算子模块投入数量的排序法是在工程实际应用中更为合适的均压策略。但是基于计算子模块投入数量的排序法依然存在着导致MMC系统开关器件动作频繁、损耗大的问题,本文针对此问题对这种策略进行了优化,引入了子模块电容电压值的上、下限作为判定依据,有效地降低了系统的开关损耗。针对载波移相调制的特点,本文研究了两种基于电容电压闭环控制的子模块均压策略:基于双闭环控制的均压策略和基于单闭环控制的均压策略。通过仿真证明了这两种均压策略的有效性,并得出基于单闭环控制的均压策略是在工程实际应用中更为合适的均压策略。最后本文对MMC环流的表达式与性质进行了推导,针对环流的性质研究了一种基于二倍频负序变换的环流抑制策略,并通过仿真证明了这种策略的有效性。
[Abstract]:In recent years, with the rapid development of power electronics technology, the research and development of high-voltage and high-power power electronic devices have attracted wide attention from both the academic and industrial circles both at home and abroad. Among them, the modular multilevel inverter (Modular Multilevel Converter, MMC) relies on its unique topology and outstanding application advantages. In order to make a better application of high voltage and high-power situation, in order to make MMC better application, this paper mainly focuses on its control strategy: modulation technology, sub module DC capacitor voltage sharing strategy and circulation suppression strategy. This paper analyzes the MMC topology and working principle, and establishes a MMC mathematical model. Two kinds of PWM modulation: carrier cascade modulation and carrier phase shift modulation in MMC, and analyze the respective characteristics of the two modulation and the influence on the MMC characteristics. In view of the characteristics of the carrier cascade modulation, this paper studies two sub module voltage sharing strategies based on the capacitor voltage ordering: the sorting method based on the distribution switch pulse and the based on the distribution switch pulse. The ranking method for calculating the number of sub modules is given. Through simulation, the validity of the two methods is proved, and the ranking method based on the number of calculated sub modules is more suitable for the practical application of the engineering. But the sorting method based on the number of calculated sub modules still leads to the MMC system switching device. In this paper, the strategy is optimized, the upper of the capacitor voltage value of the sub module is introduced, the lower limit is used as the decision basis, and the switching loss of the system is reduced effectively. In this paper, two sub module voltage sharing strategies based on the capacitance voltage close loop control are studied in this paper. Based on the double closed loop control strategy and the single closed loop control strategy, the validity of these two kinds of voltage sharing strategies is proved by simulation, and the mean pressure strategy based on single closed loop control is more appropriate in the practical application of the engineering. Finally, the expression and properties of the MMC loop flow are derived and the results are given. A loop suppression strategy based on two frequency multiplier negative sequence conversion is studied and the effectiveness of the strategy is proved by simulation.

【学位授予单位】：中国舰船研究院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM464

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