TEV与HFCT法测量开关柜局部放电的特性对比

Comparative Study on the Switchgear Partial Discharge Characteristics Based on Transient Earth Voltage and Pulse Current Detection Methods

探究了暂态对地电压(transient earth voltage,TEV)法对于开关柜局部放电现象的检测性能,并与脉冲电流检测的效果进行了对比。研究了二者对于不同类型局部放电的检出能力;分析了2种方法测量下4种局部放电PRPD(phase resolved partial discharge)图谱的相似性与差异;通过统计特征参数计算研究了2种检测方法的测量结果随外施电压变化而变化的趋势。结果表明,与传统的高频脉冲电流检测法(highfrequency current transformer,HFCT)相比,暂态对地电压法对于开关柜局部放电的测量信噪比较低,检测效果稍逊,但更适用于微弱尖端放电。从PRPD图谱上来看,2种方法在不同类型局部放电的脉冲幅值特征与相位区间上具有很强的一致性,但在脉冲集中度等方面存在一定区别。随外施电压变化,TEV与HFCT得到的偏斜度、陡峭度变化趋势一致,2种方法均能有效反映局部放电的放电特征。

The transient earth voltage(TEV)method is studied in detection performance for switchgear partial discharge,and compared with the pulse current detection method.In addition,the detection capabilities of the two methods are studied for different types of partial discharge,and the similarities and differences of the PRPD(phase resolved partial discharge)spectra of four partial discharge types measured by two methods are analyzed.The variations of the detection results with the applied voltage are analyzed through calculating the statistical characteristics.The results show that,compared with the conventional high-frequency current transformer(HFCT)method,the TEV method has a lower signal-noise ratio in detecting switchgear partial discharge with a slightly inferior detection performance,but it is more suitable for detecting weak tip discharge;in terms of PRPD spectra,the two methods have strong consistency in pulse amplitude characteristics and phase intervals for different types of partial discharge,but there are some differences in pulse concentration and other aspects.With the change of applied voltage,TEV and HFCT methods have the same variation trend of skewness and steepness,and both methods can effectively reflect the discharge characteristics of partial discharge.