本文選題：變壓器 + 雷電侵入波　； 參考：《重慶大學》2014年碩士論文

【摘要】：變壓器是電力系統(tǒng)的核心設(shè)備，它的安全運行關(guān)乎整個電力系統(tǒng)的可靠性。在決定變壓器雷電沖擊絕緣水平時，較為精確地掌握變壓器上的實際雷電過電壓水平是合理選擇設(shè)備絕緣配合的前提。而目前，有關(guān)站內(nèi)變壓器雷電侵入波統(tǒng)計規(guī)律分析及其對變壓器內(nèi)絕緣影響的研究較少，變壓器絕緣設(shè)計和耐壓測試仍然采用傳統(tǒng)的標準雷電波，而實際作用在變壓器上的雷電侵入波卻是非標準的波形。鑒于此，研究變壓器實測雷電侵入波的統(tǒng)計規(guī)律以及實測雷電侵入波對變壓器油紙絕緣性能的影響不僅能夠完善有關(guān)雷電波的理論研究，更能為變壓器合理的絕緣設(shè)計以及站內(nèi)雷電防護提供技術(shù)依據(jù)和支撐，具有重要的理論價值和工程實用價值。 首先，本文基于某110kV變壓器上長達六年的雷電侵入波監(jiān)測數(shù)據(jù)，利用數(shù)字濾波技術(shù)，提取了侵入波的有用信號，提出采用能量法和DE法求取侵入波的時間參數(shù)，并對時間參數(shù)進行統(tǒng)計分析。統(tǒng)計結(jié)果表明：變壓器雷電侵入波為衰減振蕩的電壓波形，，其振蕩主頻主要集中在10kHz以內(nèi)；侵入波的波頭時間和波尾時間均比標準雷電波長，且時間參數(shù)服從對數(shù)正態(tài)分布規(guī)律；波頭時間和波尾時間具有較強的相關(guān)性，二者的相關(guān)性可用一個帶狀區(qū)域表示。 然后，搭建了沖擊過電壓試驗平臺，基于雷電侵入波的統(tǒng)計結(jié)果，選取具有50%概率的實測雷電侵入波(20/198μs)和標準雷電波展開對比試驗，并研究不同過電壓時間參數(shù)對油紙絕緣50%擊穿電壓的影響。試驗結(jié)果表明：在1.2~26μs的試驗波頭時間范圍內(nèi)，絕緣紙的50%擊穿電壓與過電壓波的波頭時間關(guān)系較大，而波尾時間對50%擊穿電壓的影響不大。且絕緣紙的厚度、層數(shù)以及老化程度不同時，過電壓時間參數(shù)對絕緣紙50%擊穿電壓的影響程度不同。 最后，基于COMSOL Multiphysics有限元仿真軟件，建立了油紙絕緣仿真模型，計算了油紙絕緣介質(zhì)在過電壓作用下的電位分布和電場分布，以及在不同時間參數(shù)過電壓作用下油紙絕緣系統(tǒng)接地極流過的電流。仿真結(jié)果表明：當正極性過電壓作用時，流過絕緣系統(tǒng)的電流分為正負極性兩個部分，存在正極性最大值和負極性最大值，且以位移電流為主。正極性電流的大小主要與沖擊電壓的波頭部分的電壓變化率有關(guān)；負極性電流的大小主要與沖擊電壓的波尾部分的電壓變化率有關(guān)。正極性電流的最大值始終明顯大于負極性電流的最大值，因此，當正極性過電壓作用時，正極性電流是影響絕緣介質(zhì)電氣性能的主要因素。
[Abstract]:Transformer is the core equipment of power system, its safe operation is related to the reliability of the whole power system. When determining the lightning impact insulation level of transformers, it is the premise of reasonable selection of equipment insulation to accurately grasp the actual lightning overvoltage level on the transformer. At present, there are few studies on the statistical law of lightning intrusion wave and its influence on transformer insulation, and the traditional standard lightning wave is still used in transformer insulation design and voltage withstand test. But the actual action on the transformer lightning intrusion wave is a non-standard waveform. In view of this, the study on the statistical law of the measured lightning intrusion wave and the effect of the measured lightning intrusion wave on the insulation performance of transformer oil paper can not only improve the theoretical research on the lightning wave. It can provide technical basis and support for reasonable insulation design of transformer and lightning protection in station. It has important theoretical value and practical value in engineering. Firstly, based on the monitoring data of lightning intrusion wave on a 110kV transformer for six years, the useful signal of intrusion wave is extracted by digital filtering technique, and the time parameter of intrusion wave is obtained by energy method and DE method. The time parameters are analyzed statistically. The statistical results show that the transformer lightning intrusion wave is the voltage waveform of attenuation oscillation, and its main oscillation frequency is mainly less than 10 kHz, and the wave head time and wave tail time of the intrusive wave are both higher than those of the standard lightning wave length. The correlation between the wave head time and the wave tail time can be expressed in a zonal region. Then, an impulse overvoltage test platform is set up. Based on the statistical results of lightning intrusion wave, a 50% probability lightning intrusion wave (20 / 198 渭 s) and a standard lightning wave are selected to carry out a comparative test. The effect of different overvoltage time parameters on 50% breakdown voltage of oil-paper insulation was studied. The experimental results show that in the range of 1.2 ~ 26 渭 s, the 50% breakdown voltage of the insulator paper is closely related to the time of the overvoltage wave, but the wave tail time has little effect on the 50% breakdown voltage. The thickness, the number of layers and the aging degree of the insulator paper are different, and the influence of the overvoltage time parameters on the 50% breakdown voltage of the insulator paper is different. Finally, based on COMSOL Multiphysics finite element simulation software, the simulation model of oil-paper insulation is established, and the potential distribution and electric field distribution of oil-paper insulating medium under the action of overvoltage are calculated. And under the action of different time parameter overvoltage, the current of the earth pole of oil-paper insulation system. The simulation results show that when the positive polarity overvoltage is applied, the current flowing through the insulation system can be divided into two parts: positive and negative polarity, and the displacement current is the main one. The magnitude of positive current is mainly related to the rate of voltage change in the head part of impulse voltage, and the magnitude of negative current is mainly related to the rate of change of voltage in the end part of impulse voltage. The maximum value of positive current is always larger than that of negative current. Therefore, the positive current is the main factor affecting the electrical performance of insulating dielectric when the positive overvoltage is applied.
【學位授予單位】：重慶大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TM862

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