The acoustic emission(AE)method has been widely recognized for the detection of incipient insulation fault phenomenon(partial discharge,PD)in power transfomiers,nevertheless,the installation and placement of AE sensor...The acoustic emission(AE)method has been widely recognized for the detection of incipient insulation fault phenomenon(partial discharge,PD)in power transfomiers,nevertheless,the installation and placement of AE sensors should be taken into full consideration.In this manuscript,a three-dimensional multiphysics model was established and simulated to research the characteristics of the propagation in the transformer wall.Furthermore,a piezoelectric transducer was used to detect PD ultrasonic signals and verify the simulation results in the laboratory.To ensure the accuracy of the detection,an optical fiber sensor based on the Sagnac interference principle was designed and adopted.The variation of the amplitude of the ultrasonic signal with distance reveals the characteristics of the ultrasonic signal propagating in the transformer wall.The distribution of sound pressure on the upper and lower surfaces of the simulation model proved that ultrasonic waves propagate in the form of symmetrical Lamb waves in the transformer wall.Moreover,the amplitude of the AE attenuates due to absorption and refraction loss,and local fluctuations on account of acoustic interference.Thus,a stable signal detected by an AE sensor does not represent the absence of PD in a transfomier.To improve the reliability of AE detection,it is proposed in this manuscript that repeated movement of the AE sensor is necessary to obtain a suitable measurement position.Similarly,it is necessary to adjust the position of the AE sensor in order to locate the PD source well.In addition,this study is expected to provide a theoretical analysis and a fiber sensor to address the problem of sensor placement in AE detection.展开更多
超声波检测方法在电力设备绝缘状态检测定位中应用广泛。针对局部放电超声测向MUSIC算法存在的采样率要求高、计算复杂度大等不足,提出基于定向超声阵列信号强度信息的定向多重信号分类(directional multiple signal classification,Dir...超声波检测方法在电力设备绝缘状态检测定位中应用广泛。针对局部放电超声测向MUSIC算法存在的采样率要求高、计算复杂度大等不足,提出基于定向超声阵列信号强度信息的定向多重信号分类(directional multiple signal classification,Dir-MUSIC)算法。在阐述该算法理论模型和应用条件基础上,针对均匀圆盘超声阵列,仿真研究了不同增益方向图主瓣宽度、不同信噪比条件下Dir-MUSIC算法的测向精度。仿真结果表明8阵元阵列在-5 dB信噪比、方向图主瓣宽度为90°~120°时测向精度最高,均方根误差小于2°。最后基于研制的微型机电系统麦克风(microelectro-mechanical system,MEMS)定向超声阵列进行了测向试验,结果表明8阵元圆盘超声阵列测向均方根误差最小为2.76°,测向标准差最小为2.72°,验证了Dir-MUSIC算法的有效性与准确性。展开更多
特高频(ultra high frequency,UHF)局放检测是变压器油纸绝缘缺陷定位的常用方法,实际应用过程中局放定位准确性易受噪声和传感器布置方式影响。为保证变压器油纸绝缘缺陷局放定位检测有效性,文中首先建立油纸绝缘缺陷UHF局放定位检测平...特高频(ultra high frequency,UHF)局放检测是变压器油纸绝缘缺陷定位的常用方法,实际应用过程中局放定位准确性易受噪声和传感器布置方式影响。为保证变压器油纸绝缘缺陷局放定位检测有效性,文中首先建立油纸绝缘缺陷UHF局放定位检测平台,在常规K-means方法的基础上,提出基于修正聚类分界的变压器油纸绝缘缺陷局放抗干扰定位方法,有效降低了定位误差。然后针对样本聚类分界混叠问题,选择最优修正系数L为1.1时,UHF局放定位误差可减小至0.1 m内,验证了文中方法的有效性。最后分析不同传感器布置方式的定位误差变化规律,提出变压器油纸绝缘缺陷检测用UHF传感器优化布置方案,可为变压器局放在线监测传感器布置及定位提供参考。展开更多
文摘The acoustic emission(AE)method has been widely recognized for the detection of incipient insulation fault phenomenon(partial discharge,PD)in power transfomiers,nevertheless,the installation and placement of AE sensors should be taken into full consideration.In this manuscript,a three-dimensional multiphysics model was established and simulated to research the characteristics of the propagation in the transformer wall.Furthermore,a piezoelectric transducer was used to detect PD ultrasonic signals and verify the simulation results in the laboratory.To ensure the accuracy of the detection,an optical fiber sensor based on the Sagnac interference principle was designed and adopted.The variation of the amplitude of the ultrasonic signal with distance reveals the characteristics of the ultrasonic signal propagating in the transformer wall.The distribution of sound pressure on the upper and lower surfaces of the simulation model proved that ultrasonic waves propagate in the form of symmetrical Lamb waves in the transformer wall.Moreover,the amplitude of the AE attenuates due to absorption and refraction loss,and local fluctuations on account of acoustic interference.Thus,a stable signal detected by an AE sensor does not represent the absence of PD in a transfomier.To improve the reliability of AE detection,it is proposed in this manuscript that repeated movement of the AE sensor is necessary to obtain a suitable measurement position.Similarly,it is necessary to adjust the position of the AE sensor in order to locate the PD source well.In addition,this study is expected to provide a theoretical analysis and a fiber sensor to address the problem of sensor placement in AE detection.
文摘特高频(ultra high frequency,UHF)局放检测是变压器油纸绝缘缺陷定位的常用方法,实际应用过程中局放定位准确性易受噪声和传感器布置方式影响。为保证变压器油纸绝缘缺陷局放定位检测有效性,文中首先建立油纸绝缘缺陷UHF局放定位检测平台,在常规K-means方法的基础上,提出基于修正聚类分界的变压器油纸绝缘缺陷局放抗干扰定位方法,有效降低了定位误差。然后针对样本聚类分界混叠问题,选择最优修正系数L为1.1时,UHF局放定位误差可减小至0.1 m内,验证了文中方法的有效性。最后分析不同传感器布置方式的定位误差变化规律,提出变压器油纸绝缘缺陷检测用UHF传感器优化布置方案,可为变压器局放在线监测传感器布置及定位提供参考。
