基于差异性的变压器直流电阻变化量阈值分析
首发时间:2019-06-28
摘要:变压器绕组连同套管直流电阻变化量是预试试验中的一个关键指标,目前试验规程规定的阈值过于笼统,尚缺乏相关差异性的分析研究。针对此问题,文中利用数理统计方法分析了变压器直流电阻变化量阈值的差异性。首先,文章统计了云南省84台变压器6年的直流电阻试验数据并计算其相邻年份变化量;其次,结合主观图示法与客观假设检验法判断直流电阻变化量的正态分布;最后,利用置信区间并考虑一定裕度确定直流电阻变化量的差异性阈值。分析结果表明,按电压等级(500kV及220kV)和高低压绕组分类时,直流电阻变化量阈值存在显著差异,能够为变压器状态评估提供借鉴。
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The analysis of transformer DC resistance variation threshold differences
Abstract:The change of the direct current (DC) resistance of transformer winding and bushing is a key indicator in the preventive test. The threshold currently used in the test procedure is too rough and there is still a lack of analysis and research on the relevant differences. This paper uses a mathematical statistics method to analyze the different threshold of the DC resistance variation of transformer winding and bushing. At the beginning, a six-year DC resistance test data of 84 transformers in Yunnan Province has been collected and the variations in each following year have been calculated and compared. Then, by successfully combining subjective graphic method and objective hypothesis test method, the normal distribution of DC resistance variation is determined. At the end, the different threshold of DC resistance variations are determined by using the confidence interval in considering a certain margin. The analysis reveals that there are differences in the threshold of DC resistance variations between voltage levels (500kV and 220kV) and between high and low voltage windings so it provides a good reference for transformer condition assessment.
Keywords: transformer, DC resistance variation, threshold, differences, normal distribution
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