Space Charge Behaviors of Ester Liquid and Kraft Paper Double-Layer Insulation Systems at Polarity Reversal
Space Charge Behaviors of Ester Liquid and Kraft Paper Double-Layer Insulation Systems at Polarity Reversal
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极性反转时酯液和牛皮纸双层绝缘体系的空间电荷行为
DOI：
10.1109/icdl49583.2022.9830956
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Zhongdong Wang
中科院分区：
文献类型：
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作者：
Abdelrahman M. Alshehawy;Z. Mu;S. Matharage;Qiang Liu;Zhongdong Wang
在基于线路换向变换器的高压直流输电系统中，换流变压器液固绝缘系统承受交直流复合应力。此外，当高压直流系统的潮流方向发生反转时，绝缘系统会发生电压极性反转。在直流电压下，绝缘材料中注入并产生空间电荷，并在液固界面处积累。因此，在极性反转期间，绝缘液体受到可能导致电击穿的高电场。研究了作为矿物油潜在替代品的酯类液体在高压直流换流变压器中的空间电荷行为。研究了极性反转条件下酯液和牛皮纸双层样品的空间电荷行为。采用一种合成酯和一种天然酯，并以矿物油为基准。采用脉冲电声技术对空间电荷分布进行了测量。在极性反转之前，我们观察到酯-牛皮纸样品在界面区域出现了更多的负电荷，导致纸层中的电场更高。极性反转后，酯-牛皮纸样品新的空间电荷分布建立更快。因此，与矿物油样品相比，这些样品中的液体层经历的电场畸变持续时间更短。
The liquid-solid insulation system of converter transformers used in line commutated converter based HVDC systems is subjected to combined AC and DC stresses. In addition, the insulation system is subjected to voltage polarity reversal when the direction of the power flow of the HVDC system is reversed. Under DC voltage, space charges are injected and generated in the insulating materials and then accumulate at the liquid-solid interfaces. Thus, during polarity reversal, the insulating liquid is subjected to a high electric field that may result in electrical breakdown. This paper studies the space charge behaviors of ester liquids as a potential alternative to mineral oil in HVDC converter transformers. Space charge behaviors in ester liquid and Kraft paper double-layer samples were studied under polarity reversal. A synthetic ester and a natural ester were used and benchmarked by a mineral oil. Pulsed Electro-Acoustic technique was used to measure the space charge distribution. Before polarity reversal, it was observed that ester-Kraft paper samples have more negative charges appeared at the interfacial region, leading to a higher field in the paper layer. After polarity reversal, ester-Kraft paper samples show a faster establishment of new space charge distribution. Therefore, the liquid layer in these samples experiences a shorter duration of electric field distortion compared to the samples with mineral oil.