加速老化下油纸绝缘气隙缺陷模型放电的特征演化与参量表征研究

Evolutional Behavior and Parameters Characterization of Partial Discharge from a Cavity Defect in Oil/Paper Insulation Under Aging Conditions

气隙放电是变压器内最为常见的放电形式,通过检测其放电发展程度来表征油纸老化程度有助于对变压器放电危险性进行定量评估。为研究不同老化状态下的油纸绝缘内部气隙放电的发展特性,提出表征老化程度和放电危险度的特征量,通过加速热老化制备4种不同老化程度的油纸绝缘试品,搭建油纸绝缘局部放电试验平台,在阶升电压下获得局部放电发展过程中的放电谱图。研究发现,随着老化程度的加深,局部放电起始电压和击穿电压总体呈下降趋势,且放电量的威布尔尺度参数α值和平均放电功率P变化较为显著;连续放电时间差Δt对放电发展阶段和绝缘老化程度反应灵敏,可用于放电危险度评估指标。

Cavity induced discharge has been acknowledged one of the most common form of partial discharge（PD） in transformers. Figuring out the PD evolutional behavior of oil-paper insulation cavity defect under various aging conditions would contribute to the quantitative evaluation of risk in transformers. To investigate the developing characteristics of the cavity induced discharge and offer the parameters charactering aging degree and discharge risk of the insulation, four oil-paper insulation samples with different aging degrees were prepared by accelerating thermally aging procedures, and a PD detection platform of oil-paper insulation was established to obtain the PRPD pattern. Conclusions can be drawn that： PD inception voltage and breakdown voltage show a decreasing trend with aging condition; the Weibull scale parameter α and average discharge power P change remarkably; and the time interval（At） between two consecutive discharges shows a tight correlation with the discharging stage and aging condition of the insulation, indicating that it is applicable to quantitative risk assessment of the insulation in the presence of PD.