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  本文選題：模塊化多電平換流器 + 系統(tǒng)建模��； 參考：《大連海事大學》2017年碩士論文

【摘要】：柔性直流輸電技術現如今在高壓直流輸電領域的地位是傳統(tǒng)技術無法替代的。但是若將基于兩、三電平的柔性直流輸電系統(tǒng)應用在實際直流輸電系統(tǒng)中,則存在諸多缺陷,尤其在電壓等級以及耗損和占地面積等問題上困難重重。經過縝密的調研,本文研究了基于模塊化多電平換流器(Modular Multilevel Converter,MMC)的直流輸電系統(tǒng),具有很高的輸出電平,且其電平可以靈活調節(jié),因為采用模塊化設計,可以有效的降低開關頻率,應用在直流輸電系統(tǒng)尤其是功率較大的情況下,能帶來巨大的經濟效益。本文研究了 MMC的拓撲結構與工作原理,主要工作內容如下:1.研究基于子模塊和子模塊組的拓撲結構以及閉鎖、半閉鎖和解閉鎖狀態(tài),提出了子模塊和子模塊組的等效電路以及數學模型,通過其等效電路及數學模型,可以模擬子模塊和子模塊組的閉鎖、半閉鎖和解閉鎖工作狀態(tài),并對其等效電路和數學模型進行了簡化。在此基礎上,根據四種不同程度的簡化模型,搭建MMC的仿真模型,可以根據不同的需求,在具體研究MMC的各項指標時,選用不同的模型進行簡化仿真。2.基于MMC的不同簡化程度的仿真模型,研究載波移相電壓調制,分組調制算法以及最近電平逼近調制,基于以上算法,提出取整修正量移位算法。這種算法首先對大規(guī)模的子模塊進行分組以便簡化仿真建模,對每個組進行不同的階梯波調制,每個組的階梯波采用不同的修正量進行取整,最后進行整合,可達到類似載波移項的效果。取整修正期間,用獨立的可控電壓源代替每個子模塊組。同時,因為此過程需要添加直流分量,子模塊組之間的電壓還可以得到均衡。3.對MMC中橋臂之間環(huán)流的產生進行了詳細分析,并進行一系列的數學計算和坐標變換,通過變換的坐標,推倒出等效電路,進而設計倍頻負序環(huán)流抑制控制器。最后對所設計的控制器搭建模型進行驗證,結果表明了其有效性。
[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.
【學位授予單位】：大連海事大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TM46;TM721.1

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本文編號：1921637