新型模塊化多電平柔性直流輸電技術(shù)及仿真研究
發(fā)布時(shí)間：2018-01-08 20:03
本文關(guān)鍵詞：新型模塊化多電平柔性直流輸電技術(shù)及仿真研究 出處：《長沙理工大學(xué)》2014年碩士論文 論文類型：學(xué)位論文
更多相關(guān)文章： 模塊化多電平換流器 MMC拓?fù)?/b> 模型預(yù)測控制 子模塊電容均壓 PSCAD/EMTDC
【摘要】：柔性直流輸電(High voltage direct current based on voltage source converter, VSC-HVDC)在清潔能源傳輸和海上供電等方面的巨大技術(shù)優(yōu)勢讓它成為了近幾年的研究熱點(diǎn)。本文對VSC-HVDC的最新研究成果——模塊化多電平換流器(Modular multilevel converter, MMC)的拓?fù)浣Y(jié)構(gòu)和控制方法展開研究。首先,文章對MMC三種最基本的子模塊(Sub-module, SM)半橋子模塊、全橋子模塊及箝位雙子模塊進(jìn)行分析,比較了它們的運(yùn)行方式、工作原理以及各自的缺點(diǎn)。由半橋子模塊組成的MMC使用電子元器件數(shù)量最少,開關(guān)頻率最低,相對損耗小,是當(dāng)前最主流的MMC拓?fù)?但由于不具備直流故障穿越能力一定程度限制了其發(fā)展；全橋子模塊組成的MMC具備直流故障穿越能力,但需要的電子元器件數(shù)量多,損耗大,成本高；箝位雙子模塊組成的MMC優(yōu)點(diǎn)在于,有直流故障穿越能力,相對于全橋MMC也減少了電子元器件使用量,但相比于半橋子模塊組成的MMC,電子元器件使用量仍然較多,開關(guān)損耗較大。對此論文采用一種新的混合型MMC拓?fù)浣Y(jié)構(gòu),MMC橋臂由半橋子模塊和筘位雙子模塊共同組成,在保留了箝位雙子模塊直流故障穿越能力的同時(shí),能進(jìn)一步降低換流器電子元器件的使用數(shù)量和系統(tǒng)損耗。其次,論文對柔性直流輸電的控制系統(tǒng)進(jìn)行了研究。MMC控制系統(tǒng)中現(xiàn)有的調(diào)制策略主要有脈寬調(diào)制(Pulse width modulation, PWM)策略和階梯波調(diào)制策略,對此論文介紹了現(xiàn)有工程中最主流的調(diào)制方法——載波移相脈寬調(diào)制(CPS-PWM)。MMC控制系統(tǒng)通常分為系統(tǒng)級控制、換流站級控制和換流閥級控制,但換流站級控制現(xiàn)有的直接電流控制策略在抑制MMC環(huán)流方面效果不佳且算法復(fù)雜。為了解決這個(gè)問題,論文提出一種新型MMC模型預(yù)測控制策略(Model predictive control, MPC),應(yīng)用于MMC的環(huán)流抑制和子模塊均壓：根據(jù)MMC-HVDC系統(tǒng)的離散時(shí)間數(shù)學(xué)模型建立對應(yīng)的預(yù)測模型,然后通過求解定義的成本函數(shù)最優(yōu)化問題,得到每個(gè)MMC子模塊的最佳開關(guān)狀態(tài),實(shí)現(xiàn)MMC子模塊的電容電壓平衡,達(dá)到抑制循環(huán)電流的目的。最后,論文在PSCAD/EMTDC中搭建MMC-HVDC系統(tǒng)仿真模型,對新型混合子模塊MMC進(jìn)行直流故障穿越仿真,仿真結(jié)果表明,新型混合子模塊MMC在減少了電子元器件使用量的情況下,依然保留了直流故障穿越能力。文章對提出的新型MPC控制策略穩(wěn)態(tài)仿真分析也證明了新型MPC控制策略具有良好的子模塊電容均壓效果和環(huán)流抑制作用,具有一定的工程使用價(jià)值。
[Abstract]:High voltage direct current based on voltage source converter. VSC-HVDC). Because of its great technical advantages in clean energy transmission and offshore power supply, it has become a research hotspot in recent years. In this paper, the latest research achievement of VSC-HVDC is modularized multilevel converter (. Modular multilevel converter. The topology and control methods of MMC) are studied. First of all, three basic sub-modules of MMC, Sub-Module (SM1) half-bridge sub-module, are studied in this paper. The whole bridge module and the clamped double module are analyzed, and their operation mode, working principle and their shortcomings are compared. The MMC composed of half bridge module uses the least number of electronic components. The switching frequency is the lowest and the relative loss is small. It is the most popular MMC topology at present, but its development is limited to a certain extent due to the lack of DC fault traversing capability. The MMC composed of the whole bridge module has the ability of DC fault crossing, but it needs a large number of electronic components, large loss and high cost. The advantage of the clamped two-submodule MMC is that it has the ability of DC fault traversing, compared with the full-bridge MMC, it also reduces the use of electronic components, but compared with the half-bridge sub-module of the MMC. The use of electronic components is still high, and the switching loss is high. In this paper, a new hybrid MMC topology is proposed, which consists of half bridge module and Reed twin module. At the same time, it can further reduce the number of electronic components of converter and the loss of the system. In this paper, the control system of flexible direct current transmission is studied. The main modulation strategies in the MMC control system are pulse width modulation. PWM) strategy and step wave modulation strategy. In this paper, the most popular modulation method-carrier phase-shifted pulse-width modulation (CPS-PWMU. MMC) control system is introduced, which is usually divided into system-level control. Converter station level control and converter valve level control, but the existing direct current control strategy of converter station level control in the suppression of MMC circulation is not good and the algorithm is complex, in order to solve this problem. In this paper, a new predictive control strategy for MMC model, Model predictive control (MPC), is proposed. It is applied to MMC circulation suppression and sub-module voltage equalization: according to the discrete time mathematical model of MMC-HVDC system, the corresponding prediction model is established, and then the optimization problem of cost function is solved by solving the defined cost function optimization problem. Get the best switching state of each MMC submodule, realize the capacitor voltage balance of MMC submodule, and achieve the purpose of restraining the cycle current. Finally. In this paper, the simulation model of MMC-HVDC system is built in PSCAD/EMTDC, and the DC fault traversing simulation of a new hybrid sub-module MMC is carried out. The simulation results show that. The new hybrid sub-module MMC can reduce the usage of electronic components. The steady-state simulation analysis of the proposed new MPC control strategy also proves that the new MPC control strategy has a good effect of capacitor voltage equalization and circulation suppression. Has certain engineering use value.
【學(xué)位授予單位】：長沙理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TM721.1
【參考文獻(xiàn)】
相關(guān)期刊論文 前1條
1 韋延方;衛(wèi)志農(nóng);孫國強(qiáng);孫永輝;滕德紅;;適用于電壓源換流器型高壓直流輸電的模塊化多電平換流器最新研究進(jìn)展[J];高電壓技術(shù);2012年05期
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