模块化多电平换流器的多层次仿真建模与控制研究

发布时间：2018-05-22 10:11

本文选题：模块化多电平换流器 + 系统建模　；参考：《大连海事大学》2017年硕士论文

【摘要】：柔性直流输电技术现如今在高压直流输电领域的地位是传统技术无法替代的。但是若将基于两、三电平的柔性直流输电系统应用在实际直流输电系统中,则存在诸多缺陷,尤其在电压等级以及耗损和占地面积等问题上困难重重。经过缜密的调研,本文研究了基于模块化多电平换流器(Modular Multilevel Converter,MMC)的直流输电系统,具有很高的输出电平,且其电平可以灵活调节,因为采用模块化设计,可以有效的降低开关频率,应用在直流输电系统尤其是功率较大的情况下,能带来巨大的经济效益。本文研究了 MMC的拓扑结构与工作原理,主要工作内容如下:1.研究基于子模块和子模块组的拓扑结构以及闭锁、半闭锁和解闭锁状态,提出了子模块和子模块组的等效电路以及数学模型,通过其等效电路及数学模型,可以模拟子模块和子模块组的闭锁、半闭锁和解闭锁工作状态,并对其等效电路和数学模型进行了简化。在此基础上,根据四种不同程度的简化模型,搭建MMC的仿真模型,可以根据不同的需求,在具体研究MMC的各项指标时,选用不同的模型进行简化仿真。2.基于MMC的不同简化程度的仿真模型,研究载波移相电压调制,分组调制算法以及最近电平逼近调制,基于以上算法,提出取整修正量移位算法。这种算法首先对大规模的子模块进行分组以便简化仿真建模,对每个组进行不同的阶梯波调制,每个组的阶梯波采用不同的修正量进行取整,最后进行整合,可达到类似载波移项的效果。取整修正期间,用独立的可控电压源代替每个子模块组。同时,因为此过程需要添加直流分量,子模块组之间的电压还可以得到均衡。3.对MMC中桥臂之间环流的产生进行了详细分析,并进行一系列的数学计算和坐标变换,通过变换的坐标,推倒出等效电路,进而设计倍频负序环流抑制控制器。最后对所设计的控制器搭建模型进行验证,结果表明了其有效性。
[Abstract]:Nowadays, the position of flexible DC transmission technology in HVDC field is irreplaceable by traditional technology. However, if the two or three level flexible DC transmission system is applied to the actual HVDC system, there will be many defects, especially in the voltage level, loss and occupation area and so on. After careful investigation, this paper studies the DC transmission system based on modular multilevel converter Modular Multilevel converter MMC. It has high output level and can be adjusted flexibly because of the modular design. It can reduce the switching frequency effectively, and can bring huge economic benefits when applied to HVDC transmission system, especially in the case of high power. In this paper, the topological structure and working principle of MMC are studied. The main work is as follows: 1. Based on the topology structure of sub-module and sub-module group, and the state of latchup and semi-latchup, the equivalent circuit and mathematical model of sub-module and sub-module group are proposed, and the equivalent circuit and mathematical model of sub-module and sub-module group are put forward. It can simulate the working state of submodule and sub-module group, and simplify the equivalent circuit and mathematical model. On this basis, according to four different degree of simplification model, MMC simulation model can be built according to different needs, in the specific study of the various indicators of MMC, different models can be selected to simplify the simulation. 2. Based on different simplified simulation models of MMC, the carrier phase shift voltage modulation, packet modulation algorithm and nearest level approximation modulation are studied. Based on the above algorithms, an integer correction shift algorithm is proposed. In this algorithm, the large-scale sub-modules are grouped in order to simplify the simulation modeling, each group is modulated with different step waves, and the step waves of each group are integrated with different correction quantities. Similar carrier shift effect can be achieved. During rounding correction, each submodule group is replaced by an independent controllable voltage source. At the same time, because DC components are added to the process, the voltage between submodules can also be equalized. 3. The generation of the circulation between the bridge arms in MMC is analyzed in detail, and a series of mathematical calculation and coordinate transformation are carried out. Through the transformation of the coordinates, the equivalent circuit is pushed down, and a frequency doubling negative sequence loop suppression controller is designed. Finally, the designed controller model is verified and the results show its effectiveness.
【学位授予单位】：大连海事大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM46;TM721.1

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