电极覆纸时流动变压器油中金属微粒局部放电特性研究

Partial Discharge Characteristics of Metal Particles in Flow Transformer Oil with Paper-covered Electrodes

本研究建立了变压器油循环流动装置,开展了含金属微粒流动变压器油的局部放电(PD)实验,并提取PD特征参数,结合流动变压器油中金属微粒的运动行为,讨论电极覆纸情况对流动变压器油中金属微粒PD的影响机制。结果表明:相比于电极裸露的情况,电极覆盖绝缘纸时,测得的局部放电起始电压升高,放电幅值和频率降低。在双电极裸露与仅下电极覆纸的情况下,放电集中在0°~90°和300°~360°两个相位区间,而在双电极覆纸的情况下,放电相位主要集中在45°和160°附近。绝缘纸的存在会使金属微粒在纸上滞留,并导致两个相邻碰撞点之间的水平距离增加。此外在电极覆纸后油中电场会减小,使得微粒运动时的垂直速度减小,降低了微粒与极板的碰撞频率,导致局部放电强度有所削弱,放电相位分布发生改变。

A transformer oil circulating flow device was established, the flow transformer oil containing metal particles was conducted partial discharge(PD) experiment, and the PD characteristic parameters were extracted.By combining with the movement behavior of metal particles in flow transformer oil, the influence mechanism of electrode covering paper on the PD of metal particle in flow transformer oil was discussed. The results show that when the electrode is covered with paper, the partial discharge initial voltage(PDIV) increases, and the discharge amplitude and frequency decrease. When the double electrodes are bare or only the lower electrode is covered with paper, the discharge concentrates in two phase sections of 0°-90°and 300°-360°. When the two electrodes are covered with paper, the discharge phases concentrate near 45°and 160°mainly. The metal particles will be settled on the paper because of the existence of insulating paper and lead to the increase of horizontal distance between two adjacent collision points. In addition, after the electrode is covered with paper, the electric field in the oil will decrease, which makes the vertical velocity of the particles decrease and the collision frequency between particles and electrodes decrease, resulting in the decrease of PD strength and change of the discharge phase distribution.