Oil immersed power transformer is the main electrical equipment in power system.Its operation reliability has an important impact on the safe operation of power system.In the process of production,installation and ope...Oil immersed power transformer is the main electrical equipment in power system.Its operation reliability has an important impact on the safe operation of power system.In the process of production,installation and operation,its insulation structure may be damaged,resulting in partial discharge and even breakdown inside the transformer.In this paper,S9-M-100/10 oil immersed distribution transformer is taken as the research object,and the distribution laws of electromagnetic field and temperature field in transformer under normal operation,inter turn short circuit and inter layer short circuit are simulated and analyzed.The simulation results show that under normal conditions,the temperatures at the oil gap between the transformer core and the high and low voltage windings and the middle position of the high-voltage winding are high.When there are inter turn and inter layer short circuit faults,the electromagnetic loss of the fault part of the transformer increases,and the temperature rises suddenly.The influence of the two faults on the internal temperature field of the transformer is different,and the influence of the inter turn short circuit fault on the temperature nearby is obvious.The analysis results can provide reference for the thermal fault interpretation and fault classification of transformer.展开更多
针对传统电缆故障定位法受波速和噪声影响导致的波头识别不准确及故障定位精度差问题,提出一种基于小波降噪、经验小波变换(empirical wavelet transform,EWT)和Teager能量算子(Teager energy operator,TEO)的电缆故障定位方法。首先,...针对传统电缆故障定位法受波速和噪声影响导致的波头识别不准确及故障定位精度差问题,提出一种基于小波降噪、经验小波变换(empirical wavelet transform,EWT)和Teager能量算子(Teager energy operator,TEO)的电缆故障定位方法。首先,利用改进的双端行波法消除波速对测距偏差的影响。然后,采用小波降噪法对采集的故障信号进行去噪。进一步应用EWT方法对降噪信号进行分解,提取降噪信号的高频分量。在此基础上,通过TEO能量曲线变化确定首端波头及近端反射波的到达时间,从而计算出电缆故障点到检测位置的距离。仿真结果表明,基于小波降噪和EWT-TEO的电缆故障定位方法对不同信噪比和故障电阻都具有良好的适应性和可靠性,能实现精确的电缆故障定位。展开更多
无励磁分接开关出现放电性故障会严重危害变压器安全运行。介绍了一起500 k V变压器交接试验过程中脉冲局部放电试验异常的案例,应用脉冲电流法、特高频法、超声波法等多维局部放电检测技术进行时差定位,成功诊断了变压器无励磁分接开...无励磁分接开关出现放电性故障会严重危害变压器安全运行。介绍了一起500 k V变压器交接试验过程中脉冲局部放电试验异常的案例,应用脉冲电流法、特高频法、超声波法等多维局部放电检测技术进行时差定位,成功诊断了变压器无励磁分接开关内部异物放电故障;通过材质成分分析判断异物为动触头旋转轴压环的机加工碎屑,异物位于无励磁分接开关动触头旋转轴位置,随挡位切换而移动,导致各个挡位均可检测到局部放电,且脉冲局部放电量随挡位变化而变化。展开更多
基金Science and Technology Project of State Grid Gansu Electric Power Company(No.52272219000Q)。
文摘Oil immersed power transformer is the main electrical equipment in power system.Its operation reliability has an important impact on the safe operation of power system.In the process of production,installation and operation,its insulation structure may be damaged,resulting in partial discharge and even breakdown inside the transformer.In this paper,S9-M-100/10 oil immersed distribution transformer is taken as the research object,and the distribution laws of electromagnetic field and temperature field in transformer under normal operation,inter turn short circuit and inter layer short circuit are simulated and analyzed.The simulation results show that under normal conditions,the temperatures at the oil gap between the transformer core and the high and low voltage windings and the middle position of the high-voltage winding are high.When there are inter turn and inter layer short circuit faults,the electromagnetic loss of the fault part of the transformer increases,and the temperature rises suddenly.The influence of the two faults on the internal temperature field of the transformer is different,and the influence of the inter turn short circuit fault on the temperature nearby is obvious.The analysis results can provide reference for the thermal fault interpretation and fault classification of transformer.
文摘针对传统电缆故障定位法受波速和噪声影响导致的波头识别不准确及故障定位精度差问题,提出一种基于小波降噪、经验小波变换(empirical wavelet transform,EWT)和Teager能量算子(Teager energy operator,TEO)的电缆故障定位方法。首先,利用改进的双端行波法消除波速对测距偏差的影响。然后,采用小波降噪法对采集的故障信号进行去噪。进一步应用EWT方法对降噪信号进行分解,提取降噪信号的高频分量。在此基础上,通过TEO能量曲线变化确定首端波头及近端反射波的到达时间,从而计算出电缆故障点到检测位置的距离。仿真结果表明,基于小波降噪和EWT-TEO的电缆故障定位方法对不同信噪比和故障电阻都具有良好的适应性和可靠性,能实现精确的电缆故障定位。
文摘无励磁分接开关出现放电性故障会严重危害变压器安全运行。介绍了一起500 k V变压器交接试验过程中脉冲局部放电试验异常的案例,应用脉冲电流法、特高频法、超声波法等多维局部放电检测技术进行时差定位,成功诊断了变压器无励磁分接开关内部异物放电故障;通过材质成分分析判断异物为动触头旋转轴压环的机加工碎屑,异物位于无励磁分接开关动触头旋转轴位置,随挡位切换而移动,导致各个挡位均可检测到局部放电,且脉冲局部放电量随挡位变化而变化。
