极性反转电压下油纸复合绝缘击穿机理初步探讨

发布时间：2019-02-23 12:50

【摘要】：为解决换流变压器阀侧主绝缘所面临的击穿问题,探讨了极性反转电压下油纸复合绝缘的击穿机理。利用平板电极模型,在极性反转、台阶升压直流和缓慢升压直流3种电压类型下,对油隙、浸油纸板和油纸复合绝缘3种样品进行了击穿电压试验研究。测量了极性反转电压下流过3种样品的电流,在此基础上确定了油纸复合绝缘的等值电路,建立了电压方程并进行了电压分布数值解析。研究结果表明,油隙击穿电压随电压施加时间增加明显下降,浸油纸板击穿电压基本不随电压施加时间变化。油隙样品不在极性反转过程击穿。浸油纸板和油纸复合绝缘样品全部在极性反转过程击穿,极性反转造成击穿电压下降。由绝缘电流核算的变压器油的绝缘电阻非线性,它随施加电场强度升高而下降,暂态时还随电场施加时间增加而下降。由剩余电流核算的浸油纸板的绝缘电阻符合欧姆定律。在极性反转过程,受变压器油绝缘电阻非线性影响,油纸复合绝缘中油隙分布电压会快速反转后持续较高的水平,这一计算值与变压器油击穿电压试验结果相吻合。
[Abstract]:In order to solve the breakdown problem of main insulation on valve side of converter transformer, the breakdown mechanism of oil-paper composite insulation under polarity reversal voltage is discussed. Using the plate electrode model, the breakdown voltage of three kinds of samples, oil gap, oil-impregnated paperboard and oil-paper composite insulation, were tested under three kinds of voltage types: reversal of polarity, step boost DC and slow boost DC. Based on the measurement of the current flowing through three samples under the polarity reversal voltage, the equivalent circuit of oil-paper composite insulation is determined, the voltage equation is established and the numerical analysis of the voltage distribution is carried out. The results show that the gap breakdown voltage decreases obviously with the increase of the time of applied voltage, while the breakdown voltage of impregnated oil paperboard does not change with the applied time of voltage. The oil gap sample does not break down during polarity reversal. The composite insulation samples of oil-impregnated paperboard and oil-paper all breakdown in the process of polarity reversal, and the breakdown voltage decreases due to the reversal of polarity. The insulation resistance of transformer oil calculated by insulation current is nonlinear, which decreases with the increase of electric field intensity, and decreases with the increase of electric field applied time in transient state. The insulation resistance of oil-impregnated paperboard calculated by residual current conforms to Ohm's law. In the process of polarity reversal, due to the nonlinear influence of transformer oil insulation resistance, the distribution voltage of oil gap in oil-paper composite insulation will continue to be higher after fast inversion. This calculated value is in agreement with the test results of transformer oil breakdown voltage.
【作者单位】：哈尔滨理工大学电气与电子工程学院;国网黑龙江省电力科学研究院;
【基金】：国家重点基础研究发展计划资助(973项目)(2011CB 211707)~~
【分类号】：TM855

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