基于介损和电容量的电流互感器运行分布规律及现场应用研究

Research on Operation Distribution Law and Field Application of Current Transformer Based on Dielectric Loss and Capacitance

为提高设备状态评价精确性,提前发现设备潜伏性隐患,通过统计分析广州电网2006—2021年油纸电容型电流互感器(current transformer,CT)停电试验数据电容量变化和介损统计分布规律,绘制数据整体分布图,得到介损和电容整体分布呈现中间高两端低的分布特征。通过建立经验累计分布特性,绘图分析其90%和95%分位点或累积分布概率值,提出了不同电压等级下电容量变化率和介损值注意值,35 kV、110 kV、220 kV、500 kV油纸电容型CT电容量变化注意值可分别取±5%、±4%、±3%、±3%,介损注意值可分别取为0.6%、0.5%、0.4%、0.4%。分析不同运行年限、生产厂家等因素对统计分布规律特性的影响。结合注意值对在运CT进行排查,发现运行中有2台CT可能存在缺陷,进行停电诊断性试验,发现其中1台110 kV CT存在重大隐患,验证了注意值预警的可行性。

In order to improve the accuracy of equipment condition evaluation and find the potential hidden dangers of the equipment in advance,this paper statistically analyzes the capacitance change and dielectric loss statistical distribution law of oil paper capacitive current transformer(CT)test data of Guangzhou power grid from 2006 to 2021,draws the overall distribution diagram of the data,and obtains that the overall distribution of dielectric loss and capacitance presents the distribution characteristics of high in the middle and low at both ends.By establishing the empirical cumulative distribution characteristics,the paper analyzes the 90%and 95%quantiles or cumulative distribution probability values by means of drawing and proposes the electric capacity change rates and dielectric loss attention values at different voltage levels.The capacitance change attention values of 35 kV,110 KV,220 kV and 500 kV oil paper capacitive CT can be taken as±5%,±4%,±3%and±3%respectively,and the dielectric loss attention values as 0.6%,0.5%,0.4%and 0.4%respectively.T he paper also analyzes the influence of different operating years,manufacturers and other factors on the statistical distribution characteristics.Finally,combined with the attention values,it is found that there may be defects in two CT in operation.The diagnostic test of power failure is carried out and it is found that one 110 kV CT has major defects and hidden dangers,which verifies the feasibility of the attention value.