变压器油间气泡局部放电对绝缘性能的影响

Effect of Partial Discharges of Air Bubbles between Transformer Oils on Insulation Performance

准确描述电力变压器匝间短路故障时油中产生的气泡对绕组间绝缘性能的影响,对其稳定运行具有重要意义。针对变压器绕组匝间短路故障,首先建立瞬态模式下变压器“电路-磁场”的多物理场耦合模型,探究故障情况下变压器绕组的电流和电磁特征;进而建立变压器匝间短路建模,磁电耦合及场强分布,进一步分析变压器油中气泡的放电特性,最后利用COMSOL软件建立仿真模型。将收集到的一台油浸式变压器连续运行数据及筛选出的低压短路故障时的数据进行仿真。仿真结果表明:电场在穿过气泡时会产生畸变,场强瞬间增大,并且电场的畸变次数随着气泡数量的增加而增多,匝间变压器油绝缘强度下降,对变压器的绝缘性能造成较大影响。

Accurately describing the impact of air bubbles generated in the oil on the insulation performance between windings during inter-turn short-circuit faults in power transformers is of great significance for their stable operation.For the transformer winding turn-to-turn short circuit fault,firstly,a multi-physical field coupling model of transformer “circuit-magnetic field” in transient mode was developed,while the current and electromagnetic characteristics of transformer windings under fault conditions were investigated.Then the modeling of the transformer turn-to-turn short circuit,the magneto-electric coupling,and the field strength distribution were established,and the characteristics of the discharge of air bubbles in the transformer oil were further analyzed.Finally,COMSOL software was utilized to establish the simulation model.The collected data of continuous operation of an oil-immersed transformer and the selected data of low voltage short circuit fault were simulated.The simulation results show that the electric field will produce distortion when passing through the bubbles,the field strength value increases instantly,and the distortion of the electric field increases with the increase of the number of bubbles,the insulation strength of the transformer oil between the turns decreases,and the insulation performance of the transformer is greatly affected.