本文選題：風(fēng)力發(fā)電 + 雙饋電機(jī)　； 參考：《華中科技大學(xué)》2014年碩士論文

【摘要】：隨著傳統(tǒng)化石能源的日益稀少以及全球氣候的不斷惡化，以太陽(yáng)能、風(fēng)能為代表的新能源越來(lái)越受到各個(gè)國(guó)家的親睞。中國(guó)由于幅員遼闊、風(fēng)能資源豐富，使得近年來(lái)中國(guó)的風(fēng)電產(chǎn)業(yè)快速發(fā)展，中國(guó)已成為全球風(fēng)電裝機(jī)容量第一大國(guó)。但中國(guó)及世界上大多數(shù)風(fēng)電場(chǎng)都集中在偏遠(yuǎn)地區(qū)，例如中國(guó)的“三北”（華北、東北、西北）以及東南沿海。這些地區(qū)的電網(wǎng)較為薄弱，電網(wǎng)的波動(dòng)嚴(yán)重影響了風(fēng)電機(jī)組的穩(wěn)定運(yùn)行，并且在電網(wǎng)故障引起的電壓驟降情況下，風(fēng)機(jī)大面積脫網(wǎng)引起的區(qū)域電網(wǎng)頻率降低，大量損失出力又將威脅電網(wǎng)的安全運(yùn)行。因此，現(xiàn)行的風(fēng)電并網(wǎng)規(guī)范中，電網(wǎng)故障時(shí)，風(fēng)電機(jī)組自動(dòng)脫網(wǎng)以自我保護(hù)的運(yùn)行方式不再被允許，并且在故障期間，風(fēng)機(jī)需要向電網(wǎng)提供一定的有功和無(wú)功以幫助電網(wǎng)電壓恢復(fù)。雙饋感應(yīng)電機(jī)（DFIG）以其調(diào)速范圍寬、勵(lì)磁變頻器容量小等優(yōu)點(diǎn)，成為風(fēng)電機(jī)組中的主流機(jī)型。同時(shí)，因其與電網(wǎng)半耦合的結(jié)構(gòu)和易受電網(wǎng)波動(dòng)影響的特點(diǎn)，使雙饋電機(jī)的低電壓穿越技術(shù)（LVRT）成為目前工業(yè)界和學(xué)術(shù)界的研究熱點(diǎn)。如何提高雙饋電機(jī)承受深度故障的低電壓穿越能力以及在故障期間對(duì)電網(wǎng)提供最大程度的支撐具有重要的現(xiàn)實(shí)意義。 本文首先調(diào)研了國(guó)內(nèi)外關(guān)于雙饋電機(jī)故障下暫態(tài)特性分析的研究現(xiàn)狀，總結(jié)了現(xiàn)有的撬棒（Crowbar）投切策略及其優(yōu)缺點(diǎn)。在雙饋電機(jī)的數(shù)學(xué)模型基礎(chǔ)上，推導(dǎo)了端口電壓發(fā)生對(duì)稱(chēng)跌落、投入撬棒后，定子磁鏈、定轉(zhuǎn)子電流的解析表達(dá)式，并在表達(dá)式的基礎(chǔ)上分析了各暫態(tài)量的幅值、變化規(guī)律等特性。通過(guò)對(duì)比表達(dá)式的計(jì)算結(jié)果與MATLAB/Simulink中的仿真結(jié)果，驗(yàn)證了解析表達(dá)式的準(zhǔn)確性。從解析表達(dá)式中抽離出撬棒阻值與暫態(tài)特性的關(guān)系，分析了不同撬棒阻值對(duì)故障期間系統(tǒng)功率、電磁轉(zhuǎn)矩波動(dòng)的影響，并結(jié)合轉(zhuǎn)子電流峰值計(jì)算及直流母線電壓鉗位效應(yīng)，給出了一種撬棒阻值的選取方案。該方案將有助于實(shí)際工程中選取合適的撬棒參數(shù)。 通過(guò)感應(yīng)電動(dòng)勢(shì)的估算，分析了現(xiàn)有主動(dòng)控制方法應(yīng)對(duì)電網(wǎng)故障的控制極限，并指出在現(xiàn)有的實(shí)際電機(jī)參數(shù)約束下，撬棒電路在實(shí)現(xiàn)深度低電壓穿越中的必要性。接著，提出了基于感應(yīng)電動(dòng)勢(shì)估算的撬棒投切策略：當(dāng)電壓突變、轉(zhuǎn)子側(cè)電流超過(guò)安全值時(shí)，撬棒投入并封鎖轉(zhuǎn)子變流器輸出，防止變流器過(guò)流損壞，同時(shí)，實(shí)時(shí)估算感應(yīng)電動(dòng)勢(shì)的大小，一旦感應(yīng)電動(dòng)勢(shì)低于直流母線電壓，即可退出撬棒，切回變流器控制。與現(xiàn)有的撬棒投切策略相比，本文所提出的策略在可靠保護(hù)變流器的基礎(chǔ)上，更具靈活性，可根據(jù)不同的故障深度選擇撬棒作用時(shí)間，，并且適用于電壓階躍恢復(fù)帶來(lái)的暫態(tài)過(guò)程。
[Abstract]:With the increasing scarcity of traditional fossil energy and the worsening of global climate, the new energy, represented by solar energy and wind energy, is increasingly popular in various countries. Because of its vast territory and abundant wind energy resources, China has become the largest wind power generation country in the world, because of the rapid development of wind power industry in recent years. But China and most of the world's wind farms are concentrated in remote areas, such as China's "three north" (North, Northeast, Northwest) and southeast coastal areas. In these areas, the power grid is relatively weak, the fluctuation of the grid seriously affects the stable operation of wind turbines, and in the case of voltage sudden drop caused by the fault of the power grid, the frequency of the regional power network caused by a large area of fan de-grid is reduced. A great deal of loss will threaten the safe operation of power grid. Therefore, in the current wind power grid connection specification, when the power grid fails, the self-protection operation mode of the wind turbine automatic disconnection is no longer allowed, and during the failure period, Fans need to provide a certain amount of active and reactive power to the grid to help the grid voltage recovery. Doubly-fed induction motor (DFIGM) has become the mainstream type of wind turbine because of its wide speed range and small capacity of excitation inverter. At the same time, because of its structure of half-coupling with the power grid and the characteristics of easy to be affected by the fluctuation of the power network, the low-voltage traversing technology of the doubly-fed machine (LVRTT) has become a hot research topic in industry and academia at present. How to improve the low voltage traversing ability of the doubly-fed machine to withstand the deep fault and provide maximum support to the power network during the fault period has important practical significance. In this paper, firstly, the research status of transient characteristics analysis of double-fed machine under fault is investigated, and the current switching strategy of crowbar and its advantages and disadvantages are summarized. On the basis of the mathematical model of the double-fed machine, the analytical expressions of stator flux and stator rotor current after the symmetrical drop of port voltage and crowbar are derived, and the amplitude of each transient quantity is analyzed based on the expression. The law of change, etc. The accuracy of the analytical expression is verified by comparing the calculation results with the simulation results in MATLAB/Simulink. The relationship between the Rod resistance and the transient characteristics is analyzed from the analytical expression. The effects of different Rod resistance values on the power and electromagnetic torque ripple of the system during the fault period are analyzed. The peak value of rotor current and the voltage clamping effect of DC busbar are combined with the calculation of the peak value of rotor current and the effect of voltage clamping of DC busbar. A scheme for selecting the resistance of crowbar is presented. This scheme will be helpful to select appropriate parameters of crowbar in practical engineering. Based on the estimation of induction electromotive force, this paper analyzes the control limit of existing active control methods to deal with power grid faults, and points out the necessity of prying rod circuit in realizing depth and low voltage crossing under the constraints of actual motor parameters. Then, a pry-bar switching strategy based on induction electromotive force estimation is proposed: when the voltage changes and the rotor side current exceeds the safe value, the crowbar inputs and blocks the output of the rotor converter to prevent the converter from overcurrent damage, at the same time, The size of induction electromotive force is estimated in real time. Once the inductive EMF is lower than DC bus voltage, it can exit the crowbar and cut back the converter control. Compared with the existing crowbar switching strategy, the proposed strategy is more flexible on the basis of reliable protection converter, and can select the action time of crowbar according to different fault depth. And it is suitable for transient process caused by voltage step recovery.
【學(xué)位授予單位】：華中科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類(lèi)號(hào)】：TM614

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