【摘要】：特高壓輸電是解決我國能源和電力發(fā)展的治本之策。近年來,直流輸電因其"輸送容量大,輸電距離遠(yuǎn)"的優(yōu)點(diǎn)而被我國輸電工程所廣泛采用。換流變壓器閥側(cè)套管是直流輸電系統(tǒng)中的關(guān)鍵器件,其性能的穩(wěn)定性直接關(guān)系到直流輸電系統(tǒng)的安全穩(wěn)定運(yùn)行。工作電壓形式復(fù)雜和直流工程中電流巨大的雙重影響導(dǎo)致?lián)Q流變閥側(cè)套管故障頻發(fā)。因此,本文通過仿真計(jì)算、實(shí)驗(yàn)研究等手段分析了換流變閥側(cè)套管運(yùn)行中電熱場的分布規(guī)律;通過模擬套管典型故障,研究了套管故障狀態(tài)下的放電特征以及電場特征,可為發(fā)現(xiàn)套管絕緣的薄弱區(qū)域,研究套管故障的產(chǎn)生與發(fā)展機(jī)理提供參考�；诟墒絊F6換流變壓器閥側(cè)套管實(shí)際結(jié)構(gòu)尺寸,運(yùn)用有限元仿真軟件INFOLYTICA建立換流變壓器套管仿真模型,計(jì)算在直流、交流、極性反轉(zhuǎn)等典型激勵(lì)作用下?lián)Q流變壓器套管的電場,以此對比分析了不同類型激勵(lì)下?lián)Q流變閥側(cè)套管的電位、電場分布規(guī)律,并討論了套管電容芯子中的鋁箔對于套管電場的優(yōu)化作用。針對直流輸電工程中電流等級(jí)進(jìn)一步提高,換流變閥側(cè)套管過熱情況嚴(yán)重的問題。通過運(yùn)用仿真軟件SIMULINK計(jì)算了換流變閥側(cè)套管所承受電流的頻譜特征,并通過現(xiàn)場測量調(diào)研了負(fù)荷高峰期換流變壓器油的溫度情況,以此掌握了換流變閥側(cè)套管運(yùn)行時(shí)的工作電流、溫度等環(huán)境條件。進(jìn)一步通過設(shè)計(jì)模擬換流變閥側(cè)套管運(yùn)行環(huán)境的大電流溫升試驗(yàn)平臺(tái),對換流變壓器套管樣品開展了溫升試驗(yàn)。通過合理地制定溫升試驗(yàn)程序,在套管電容芯子軸向、徑向關(guān)鍵位置布置溫度探頭,獲得了實(shí)驗(yàn)中套管不同位置的溫度結(jié)果。以此研究了套管樣品在溫升實(shí)驗(yàn)中的熱態(tài)變化規(guī)律以及換流變閥側(cè)套管在運(yùn)行時(shí)的穩(wěn)態(tài)溫度場分布規(guī)律。針對換流變閥側(cè)套管在實(shí)際運(yùn)行中的故障發(fā)生情況。設(shè)計(jì)、加工了模擬芯體電容屏擊穿、芯體中混入金屬顆粒、芯體中混入氣泡、芯體中產(chǎn)生裂紋等四種典型故障的套管模型。并在實(shí)驗(yàn)室條件下模擬直流套管運(yùn)行環(huán)境對四類故障套管模型開展了局部放電試驗(yàn)研究,統(tǒng)計(jì)了四類故障下套管模型放電次數(shù)與單次放電量之間的關(guān)系,分析了直流套管在四類典型故障下的放電特征,并結(jié)合電場仿真分析了四類典型故障套管的電場分布特征,為研究直流套管故障產(chǎn)生與發(fā)展的機(jī)理提供了參考。
[Abstract]:UHV transmission is a fundamental solution to the development of energy and power in China. In recent years, DC transmission has been widely used in transmission projects in China because of its advantages of large transmission capacity and long transmission distance. Valve side casing of converter transformer is the key device in HVDC system, and its performance stability is directly related to the safe and stable operation of HVDC system. The complex form of working voltage and the great influence of current in DC engineering lead to frequent failure of casing on the side of flow changing valve. Therefore, by means of simulation calculation and experimental research, the distribution law of electrothermal field in casing operation on the side of valve changing valve is analyzed in this paper, and the discharge characteristics and electric field characteristics under casing fault state are studied by simulating typical casing fault, which can provide reference for finding the weak area of casing insulation and studying the generation and development mechanism of casing fault. Based on the actual structure size of valve side casing of dry SF6 converter transformer, the simulation model of converter transformer casing is established by using finite element simulation software INFOLYTICA. The electric field of converter transformer casing under typical excitation, such as DC, AC, polarity reversal and so on, is calculated, and the distribution law of potential and electric field of converter valve side casing under different types of excitation is compared and analyzed. The optimization effect of aluminum foil in casing capacitance core on casing electric field is also discussed. In order to further improve the current level and overheat the casing on the side of the flow valve in DC transmission project, the overheating of the casing on the side of the flow valve is serious. The spectrum characteristics of the current borne by the flow valve side casing are calculated by using the simulation software SIMULINK, and the temperature of the converter transformer oil at the peak load period is investigated by field measurement, so as to master the working current, temperature and other environmental conditions of the flow valve side casing. Furthermore, the temperature rise test of converter transformer casing sample was carried out by designing a high current temperature rise test platform to simulate the operating environment of the casing on the side of the converter valve. By reasonably formulating the temperature rise test program and arranging the temperature probe in the axial and radial key positions of the casing capacitance core, the temperature results of the casing at different positions in the experiment are obtained. Based on this, the thermal state variation of casing samples in temperature rise experiment and the steady state temperature field distribution of casing on the side of flow changing valve are studied. In view of the failure of the casing on the side of the flow changing valve in actual operation. Four typical fault casing models are designed and fabricated, which simulate the breakdown of capacitance screen in the core, the metal particles in the core, the bubbles in the core and the cracks in the core. The partial discharge test of four kinds of fault casing models is carried out under laboratory conditions to simulate the operating environment of DC casing. The relationship between discharge times and single discharge capacity of four kinds of fault casing models is counted, the discharge characteristics of DC casing under four typical faults are analyzed, and the electric field distribution characteristics of four kinds of typical fault casing are analyzed by electric field simulation. It provides a reference for the study of the mechanism of DC casing fault generation and development.
【學(xué)位授予單位】：西南交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TM721.1;TM41

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本文編號(hào)：2504978