无机纳米颗粒抑制中压电缆终端气隙缺陷局部放电的有效性

针对中压电缆终端气隙缺陷中的局部放电(PD)导致终端绝缘迅速劣化的问题,提出了一种在气隙缺陷处填充TiO_2复合涂料抑制终端PD的方法,从终端PD特征及缺陷表面的微观形貌特征两方面研究了TiO_2复合涂料填充对缺陷处绝缘的影响。通过在10k V电缆终端中设计典型的气隙缺陷,并在缺陷处填充复合涂料进行电热老化对比试验,测试分析了不同老化时刻下终端的PD特征,并对老化后期缺陷的表面形貌特征进行分析。通过建立气隙缺陷的有限元模型,结合电场仿真进一步阐述复合涂料填充对终端PD及缺陷表面形貌特征的影响机制。研究结果表明:填充TiO_2复合涂料后终端PD放电能量得到大幅减小,随着老化时间的增加,终端放电重复率及放电相位分布差异较小;气隙缺陷表面较平整,填充后团聚物中碳含量降低了31%,验证了气隙缺陷处填充TiO_2复合涂料可以抑制终端PD发展,并减缓终端绝缘的劣化。

Validity of Inorganic Nano-Particles on the Suppression of Partial Discharge in Air Gap Defects for Medium Voltage Cable Terminations

To avoid insulation deterioration caused by partial discharge (PD) in air gap defects of medium voltage cable terminations, a new method of suppressing PD was presented by filling nano-TiO2 composite coatings into the defects. The influence on insulation was investigated by analyzing PD characteristics and surface morphology of the defect. The defects were designed and the electrical-thermal aging experiments were performed in a 10kV termination. PD characteristics and surface morphology were analyzed. Moreover, the finite element model of the defect was established to discuss the impact mechanism of the composite coatings to PD and surface morphology. The results show that PD energy reduces significantly after filling the composite coatings, and the discharge repetition rate and phase distribution difference are not obvious with the increasing of aging time. In addition, the surface of the defect is smooth and carbon content of the agglomerated particles decreases by 31%. It is also indicated that nano-TiO2 composite coatings can suppress PD development and retard insulation deterioration.