本文選題：模塊化多電平變流器 + 充電控制�。� 參考：《哈爾濱工業(yè)大學》2014年碩士論文

【摘要】：隨著電力電子技術(shù)向著高壓、大功率變換方向的不斷發(fā)展，尤其是電壓源型變流器在柔性直流輸電系統(tǒng)中的廣泛應(yīng)用，針對大功率變流器的研究越發(fā)重要。然而，傳統(tǒng)兩電平及多電平變流器在高壓領(lǐng)域應(yīng)用時控制復(fù)雜，擴展性差，成為了其發(fā)展的制約瓶頸。模塊化多電平變流器(Modular Multilevel Converter,MMC)因其具有模塊化結(jié)構(gòu)，在傳統(tǒng)變流器優(yōu)勢的基礎(chǔ)上，增加了向不同電壓等級的擴展性，更加適用于輸電領(lǐng)域。本文首先對MMC拓撲結(jié)構(gòu)，運行原理，數(shù)學模型，及PWM調(diào)制策略進行了分析，基于以上分析對內(nèi)部環(huán)流成分及模塊電容容量的計算進行了研究。 其次，針對MMC啟動時模塊電容電壓的建立進行了研究，提出了從交流側(cè)為電容恒流充電的方法，將上、下橋臂各視為兩并聯(lián)于同一電網(wǎng)的變流器，進行解耦控制，為模塊電容恒流充電。本文提出的充電方法，不僅避免了過流沖擊現(xiàn)象，而且同一橋臂電容同時充電，充電快速，一致性好。 再次，針對模塊電容電壓平衡及環(huán)流控制問題，分析了現(xiàn)有控制方法，從能量角度推導出了上、下橋臂之間平衡控制的最快途徑。本文提出相間電容電壓平衡結(jié)合環(huán)流抑制，相內(nèi)橋臂間與橋臂內(nèi)平衡的三級控制策略，通過相間電壓平衡結(jié)合環(huán)流控制，實現(xiàn)相間電壓均衡，并將環(huán)流控制為直流量，消除環(huán)流諧波的目的，相內(nèi)通過橋臂之間與橋臂內(nèi)的平衡控制，平衡了相內(nèi)電容電壓。 然后，針對基于MMC換流站的輸電系統(tǒng)的控制，分析了功率控制原理，利用前饋解耦控制達到對有功和無功功率分量的獨立控制目標。在此基礎(chǔ)上，對MMC互聯(lián)交流電網(wǎng)異常工況下給出應(yīng)對措施，分別對具有高阻抗電網(wǎng)和電網(wǎng)電壓不平衡情況時，得出換流站控制方式，使MMC換流站能夠帶故障安全運行。 最后，，本文設(shè)計搭建了MMC實驗樣機平臺，通過Matlab仿真對提出方法研究，并在實驗裝置上進行驗證。結(jié)果均表明提出方法的正確性和有效性。
[Abstract]:With the development of power electronics technology towards high voltage and high power conversion, especially the wide application of voltage source converter in flexible DC transmission system, the research of high power converter becomes more and more important. However, the traditional two-level and multilevel converters have complex control and poor expansibility when they are applied in the high voltage field, which has become the bottleneck of their development. Modular multilevel converters MMC (Modular multilevel Converters MMC) is more suitable for transmission because of its modularized structure and the advantages of traditional converters which increase the expansibility to different voltage levels. In this paper, the topology, operation principle, mathematical model and PWM modulation strategy of MMC are analyzed. Based on the above analysis, the calculation of the internal circulation composition and the capacitance capacity of the module is studied. Secondly, the establishment of module capacitor voltage during MMC start-up is studied, and the method of charging capacitor constant current from AC side is put forward. The upper and lower arms are regarded as two converters parallel to the same power grid, and decoupling control is carried out. Constant current charge for module capacitance. The charging method proposed in this paper not only avoids the phenomenon of overcurrent shock, but also charges simultaneously with the same bridge arm capacitance, which makes the charging fast and consistent. Thirdly, aiming at the problems of capacitor voltage balance and circulation control of modules, the existing control methods are analyzed, and the fastest way to balance control between upper and lower arms is deduced from the angle of energy. In this paper, a three-stage control strategy of capacitor voltage balance and interphase voltage balance is proposed to realize the voltage balance between two phases, and the circulation is controlled as a direct flow rate by combining the voltage balance between the phases with the current suppression, and the balance between the two arms of the phase and the inside of the bridge arm. The purpose of eliminating the circulation harmonics is to balance the capacitance voltage between the two arms. Then, the principle of power control is analyzed for the control of transmission system based on MMC converter station. The feedforward decoupling control is used to achieve the independent control goal for active and reactive power components. On this basis, the countermeasures are given for MMC interconnected AC power grid under abnormal working conditions. When there are high impedance power grid and voltage imbalance, the control mode of converter station is obtained, so that MMC converter station can operate safely with fault. Finally, the MMC experimental prototype platform is designed and built, and the proposed method is studied by Matlab simulation, and verified on the experimental device. The results show that the proposed method is correct and effective.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TM46

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本文編號：2109833