【摘要】：換流變壓器閥側套管是重要的電力設備,其絕緣性能的好壞關系著套管乃至換流變壓器的安全性、可靠性。干式SF_6氣體絕緣直流套管因其優良的電氣性能,越來越多的被應用于換流變壓器,然而當前針對其絕緣檢測技術方面的研究較少,鑒于此,本文針對干式SF_6氣體絕緣直流套管的絕緣特征量進行了研究工作,設置了電容屏豁口缺陷、金屬微粒缺陷、受潮缺陷3種缺陷套管模型,并制備了正常電容芯子進行比對。本文的研究內容與成果如下:測量了不同套管模型在工頻高壓和不同頻率低電壓下介質損耗因數和電容量。在工頻高壓下,受潮缺陷的介質損耗因數最大,而金屬微粒缺陷芯子電容量最大。從頻域介電譜測試結果來看,不同缺陷套管電容芯子電容量和介質損耗因數都隨頻率的減小而增大,但不同缺陷套管電容芯子兩項參數增加的幅度不同。四支電容芯子電容量的差別隨施加電源頻率的減小而減小,介質損耗因數差別則隨施加電源頻率的減小而增大。進行了直流局部放電試驗,測試了套管電容芯子直流局放特征量。不同缺陷電容芯子放電量和放電次數存在較大差異,金屬微粒缺陷電容芯子隨著放電量的增大,放電次數先增多后減少,并在35 pC附近達到最大值;電容屏豁口缺陷電容芯子放電集中在30 pC以下,且分布較為均勻。受潮缺陷電容芯子放電集中在25 pC以下,且放電次數較多。通過計算偏斜度、陡峭度和局部峰值個數,確定了不同缺陷套管此3個特征參數的范圍。測試了套管電容芯子在直流局部放電情況下SF_6氣體的分解產物。在SF_6氣體分解產物檢測試驗中,三種缺陷情況下SOF_2、SO_2F_2、SO_2的含量在檢測初期增長較快,金屬微粒缺陷和受潮缺陷情況下SO_2產氣率比CF_4高,而電容屏豁口缺陷正好相反。選擇SOF_2/SO_2F_2、CF_4/SO_2、(SOF_2+SO_2F_2)/(CF_4+SO_2)三種組分含量的比值作為表征不同缺陷的特征值,經過計算得到三種缺陷特征組分比值。不同缺陷的特征組分比值范圍不同,可用該比值表征不同的缺陷類型。本文通過對干式SF_6氣體絕緣直流套管絕緣特征量進行探索性研究,得到的結果及結論對套管絕緣檢測提供了重要支持,具有實際應用價值。
[Abstract]:Valve side bushing of converter transformer is an important power equipment, its insulation performance is related to the safety and reliability of casing and converter transformer. Dry SF_6 gas insulated DC bushing is more and more widely used in converter transformers because of its excellent electrical performance. However, there are few researches on the insulation detection technology at present, in view of this, In this paper, the insulation characteristics of dry-type SF_6 gas insulated DC sleeving are studied. Three kinds of defect casing models are set up, such as capacitor gap defect, metal particle defect and dampened defect, and the normal capacitance core is prepared for comparison. The main contents and results of this paper are as follows: dielectric loss factor and capacitance of different casing models are measured at different frequency and low voltage. At power frequency and high voltage, the dielectric loss factor of damped defect is the largest, while the capacitance of metal particle defect core is the largest. From the dielectric spectrum measurement results in frequency domain, the capacitance and dielectric loss factor of different defective casing capacitive cores increase with the decrease of frequency, but the amplitude of the two parameters of different defect casing capacitive cores is different. The difference of the capacitance of the four capacitor cores decreases with the decrease of the frequency of the applied power supply, and the difference of the dielectric loss factor increases with the decrease of the frequency of the applied power supply. DC partial discharge test was carried out, and the DC discharge characteristic of bushing capacitor core was tested. The discharge quantity and discharge times of different defect capacitive mandrel have great difference. With the increase of discharge quantity, the discharge times of metal particle defect capacitor core increase first and then decrease, and reach the maximum value near 35 pC. The discharge of capacitor core is below 30 pC, and the distribution is more uniform. The discharge of capacitive core with dampened defect is below 25 pC, and the discharge frequency is more. By calculating the deflection degree, steepness degree and the number of local peak values, the range of these three characteristic parameters of different defective casing is determined. The decomposition products of SF_6 gas under DC partial discharge were measured. In the test of SF_6 gas decomposition products, the content of SOF_2,SO_2F_2,SO_2 increases rapidly in the early stage of detection under three kinds of defects, and the gas production rate of SO_2 is higher than that of CF_4 under the condition of metal particle defect and damped defect, but the defect of capacitor screen gap is just the opposite. The ratio of SOF_2/SO_2F_2,CF_4/SO_2, (SOF_2 SO_2F_2) / (CF_4 SO_2) components was chosen as the eigenvalue of different defects, and the ratios of three defect characteristic components were calculated. The range of characteristic component ratios of different defects is different, which can be used to characterize different defect types. In this paper, the insulation characteristics of dry SF_6 gas insulated DC sleeving are studied. The results and conclusions provide important support for the insulation detection of the sleeving, and have practical application value.
【學位授予單位】：華北電力大學(北京)
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TM41

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本文編號：2235890