【摘要】 高压直流输电系统出现潮流反转时,换流变压器会经受极性反转电压,内部积聚的空间电荷导致电场畸变,威胁绝缘安全.为了探究油、纸二者在老化过程中对油纸试样空间电荷的作用,将130℃, 140℃, 150℃, 160℃加速热老化实验后的油纸试样解耦,即取出部分老化油纸试样中的绝缘油保存,用石油醚浸泡除去油浸纸试样中残留的变压器油,进而制备出老化变压器油浸渍的未老化绝缘纸及未老化变压器油浸渍的老化绝缘纸试样.油、纸二者耐热等级不同,其在高温热老化时,随着老化温度的升高,会发生不同的物理化学反应,利用电声脉冲法测量了不同油纸组合在极性反转电压下的空间电荷特性,讨论了高温老化及变压器油老化、绝缘纸老化对极性反转电压下油纸绝缘系统的影响.实验结果表明,极性反转前,变压器油老化与油纸共同老化对油纸复合绝缘空间电荷特性具有相同的影响,均在地电极附近出现同极性电荷的积聚,随着老化状态的加深,同极性电荷积聚现象逐渐明显,去极化时电荷消散速率变慢;绝缘纸老化对油纸复合绝缘空间电荷特性的影响与油老化截然相反,在试样地电极附近出现了异极性电荷的积聚,试样内部电荷积聚现象未随着绝缘纸老化状态的加深而发生明显的变化.综上可知,油老化状态对油纸复合绝缘电气性能的影响占据主导地位,本研究可为工程中换油研究提供实验依据.更多还原

【Abstract】 When the power flow in the HVDC transmission system reverses, the converter transformer experiences polarity reversal voltage, and the accumulated space charge causes electric field distortion and threatens the insulation safety. To explore the effect of the aging states of oil and paper on the space charge of the oil-paper samples, the oil-paper samples were decoupled after accelerated thermal aging tests at 130℃, 140℃, 150℃, and 160℃; the insulating oil in some aging oil-paper samples was removed and preserved, and the residual transformer oil in oil-paper samples was removed by petroleum ether immersion. Furthermore, the unaged insulating paper sample impregnated with aging transformer oil was prepared. The electro-acoustic pulse method was used to measure the space charge characteristics of various oil-paper combinations under polarity reversal voltage, and the effects of high-temperature aging,transformer oil aging, and insulation paper aging on oil-paper insulation system under polarity reversal voltage were discussed. The experiment results show that before the polarity reversal, transformer oil aging together with the oiled paper composite insulation space charge properties of the paper have the same effect near the ground electrode with polarity occurring in charge accumulation.As the aging of the state deepens, the polarity charge accumulation phenomenon gradually becomes obvious, and the polarization charge dissipation rate slows down. The influence of the aging of insulating paper on the space charge characteristics of oil-paper composite insulation is quite opposite to that of oil aging; the accumulation of heteropolar charge near the ground electrode of the sample does not change noticeably with the deepening of the aging state of insulating paper. In summary, the influence of the oil aging state on the electrical properties of oil-paper composite insulation plays a dominant role, and this study can provide an experimental basis for oil change research in engineering.更多还原