交直流复合电压下流动变压器油中金属微粒运动规律和局部放电特性研究

Motion Behaviors and Partial Discharge Characteristics of Metallic Particles in Moving Transformer Oil under AC/DC Composite Voltage

流动变压器油中自由金属微粒引起的局部放电(PD)特性与其运动规律密切相关。该文利用搭建的变压器油循环流动装置,获得了交直流复合电压作用下流动油中自由金属微粒的运动特性,同时研究了流动油中自由金属微粒引发的PD特性。试验结果显示,在交流电压下PD最剧烈;当复合电压中直流分量增多时,起始放电电压降低,放电重复率、放电量和单位时间累积放电量增大。为分析试验结果,构建了复合电压下的层流固-液两相流模型,仿真得到自由金属微粒的运动轨迹,仿真结果显示在交流电压下微粒只在下电极附近上下往复运动,并频繁与电极发生碰撞;外施电压含有直流分量时,微粒在上、下电极间往复运动,且落点间距随着直流分量的增加而变窄,仿真与实验结果具有较好的一致性。最后,该文根据验证后的仿真模型,分析了金属微粒运动对PD特性的影响机制。

The characteristics of PD of free metal particles in flowing transformer oil are closely related to its motion behaviors.In this paper,a circulation flow device of transformer oil and an observation system of particle motion under AC-DC composite voltage were established,and the movement characteristics of free metal particles were obtained.In addition,the PD experiment under AC-DC composite voltage was carried out,and the PD characteristics were obtained.It was found that the PD intensity under AC voltages was the strongest.The PD inception voltages became lower,and discharge repetition rates,mean discharge magnitude,and accumulation discharge magnitude per were stronger as the DC component increased.In order to analyze the experimental results,a laminar solid-liquid two-phase flow model coupled with electric fields was constructed to simulate particle trajectories.It was found that the particles under AC voltages only moved back and forth near the lower electrode,colliding with electrode frequently.When applied voltages contained DC components,the particles moved back and forth between the parallel electrodes.And the landing-point spacing became shorter as the DC component increased.And the simulation result was highly consistent with the experimental results.Based on the validated simulation model,the influence of the applied voltages on PD characteristics was clarified.