极不均匀电场下绝缘油中气泡动力学特性与迁移机制

Bubble Dynamics and Migration Mechanism in Insulation Oil Under Extremely Inhomogeneous Electric Field

变压器油中气泡的存在容易引发局部放电,导致绝缘油劣化。为厘清油浸式电力设备内部复杂电场作用下气泡的迁移与畸变规律,该文通过实验方法观测绝缘油中气泡在极不均匀交流电场作用下的动力学特性,并利用数值模拟分析气泡在不同场强下的迁移路径、速率、畸变程度等特征。结果表明,电场力对气泡具有拉伸和推离作用,且会加速气泡的上升运动,对微米级气泡尤甚,气泡被拉伸的方向始终平行于电场方向。场强足够大时,小气泡会出现“成对”上升现象,对电场的增强效应变大,“气泡对”交界面处场强增强系数可达2.28,使得气泡内部更易发生局部放电,应在设备设计和运行时引起重视。实验与仿真结果基本一致,验证了仿真模型的合理性。

The existence of bubbles in transformer oil is easy to cause partial discharge,resulting in the deterioration of insulating oil.In order to clarify the migration and distortion law of bubbles under the action of complex electric field in oil immersed power equipment,the dynamic characteristics of bubbles in insulating oil under extremely inhomogeneous AC electric field were observed by using experimental methods,and the migration path,rate and distortion degree of bubbles under different field intensities were analyzed by means of numerical simulation.The results show that the electric field force can stretch and push away the bubbles,and accelerate the upward movement of the bubbles,especially for micron bubbles;the stretching direction of the bubbles is always parallel to the direction of the electric field.When the field strength is large enough,the small bubbles will rise in pairs,which will increase the enhancement effect on the electric field.The field strength enhancement coefficient at the interface of“bubble pair”can reach 2.28,making it easier for partial discharge to occur inside the bubbles,which should be paid attention to in equipment design and operation.The experimental and simulation results are basically consistent,which verifies the rationality of the simulation model.