基于Kerr效应法的油纸复合绝缘交直流复合电场测量

The Measurement of AC-DC Composite Field for Oil-Paper Insulation System Based on The Kerr Electro-optic Effect

油纸复合绝缘作为换流变压器阀侧绕组的主绝缘形式,在正常工况下同时承担着交、直流复合电压,阀侧绕组的电场分布比普通电力变压器更为复杂,而目前的仿真研究均缺乏有效的试验验证。本文基于变压器油的Kerr效应,搭建了油纸绝缘结构下光学空间电场的二维测量平台,实现了变压器油中电场的在线分布式测量。针对双层纸板的交叠绝缘结构,实际测量不同交直流比例电压下,交、直流电场的分布特性。试验结果表明:①交流电场分布具有明显的结构对称特性,且油中各处交流电场与外施交流电压保持线性关系。②直流电场分布不具有对称性。在正极性直流电压下,纸板覆盖上电极的单层纸板区域电场远小于纸板覆盖下电极的单层纸板区域,且直流电场强度不随外施直流电压线性增长。不同位置处空间电荷积聚的差异是直流电场分布非对称性的主要原因。

The valve winding in the converter transformer withstands combined AC-DC voltage in normal condition. The distribution of electric filed in the valve winding is much more complicated than ordinary power transformer. In order to study the electric field distribution under combined AC-DC voltage for oil paper insulation, a combined AC-DC source was constructed. The electric field distribution of oil-paper insulation model was measured by Kerr electro-optic effect, under combined AC-DC voltage with different composite ratios of DC-AC. The results indicate that： ①AC electric field distribution is symmetric. The AC field rises up with the increase of the applied AC voltage linearly. ② DC electric field distribution is non-uniform and asymmetric caused by the difference of the space charge accumulated on the oil paper interface; the electric field intensity of the oil in the right side is much stronger than that in the left side for the insulation model with two overlapping pressboard barriers inserted into a plane oil gap.