A balancing method was used to build a DC partial discharge （PD） testing circuit for electrical equipment,and a narrow-band detection system was designed using detection resistance and a filter. After signal accesse...A balancing method was used to build a DC partial discharge （PD） testing circuit for electrical equipment,and a narrow-band detection system was designed using detection resistance and a filter. After signal accessed a high-speed digital acquisition （DAQ） card,the system was triggered to extract a single partial discharge （PD） signal. To eliminate the interference pulses caused by power supply ripple,etc.,the time domain and frequency domain features of pulses were extracted. Based on the features,cluster analysis was used to exclude interference pulses. Two-dimensional and three-dimensional histograms were obtained by use of the Δt method. Then,22 discharge statistical operators were calculated for the two-dimensional charts. Lastly,the defective capacitors were tested to verify the system＇s ability. The results show that the system is capable of PD detection in electrical equipment.展开更多
The chaotic characteristics of time series of five partial discharge （PD） patterns in oil-paper insulation are studied. The results verify obvious chaotic characteristic of the time series of discharge signals and t...The chaotic characteristics of time series of five partial discharge （PD） patterns in oil-paper insulation are studied. The results verify obvious chaotic characteristic of the time series of discharge signals and the fact that PD is a chaotic process. These time series have distinctive features, and the chaotic attractors obtained from time series differed greatly from each other by shapes in the phase space, so they could be used to qualitatively identify the PD patterns. The phase space parameters are selected, then the chaotic characteristic quantities can be extracted. These quantities could quantificationally characterize the PD patterns. The effects on pattern recognition of PRPD and CAPD are compared by using the neural network of radial basis function. The results show that both of the two recognition methods work well and have their respective advantages. Then, both the statistical operators under PRPD mode and the chaotic characteristic quantities under CAPD mode are selected comprehensively as the input vectors of neural network, and the PD pattern recognition accuracy is thereby greatly improved.展开更多
High-voltage storage capacitors(hereinafter call capacitors for short)have been widely used in pulsed power technology.In accordance with the actual work conditions of capacitors,direct current partial discharge(DCPD)...High-voltage storage capacitors(hereinafter call capacitors for short)have been widely used in pulsed power technology.In accordance with the actual work conditions of capacitors,direct current partial discharge(DCPD)detection was put forward.The whole test system was based on the impedance balance circuit characterized by good configuration and anti-interference ability.Through DCPD detection on capacitors which contained four typical defects respectively,test results revealed that DCPD signals could well reflect the state of capacitor insulation.DCPD distribution spectra of capacitors containing four typical defects were obviously different.Defects in capacitors could be exactly judged by computer–aided pattern recognition based on support vector machine(SVM).展开更多
Exploitation of equipment with cross linked polyethylene (XLPE ) insulation requires its condition monitoring and diagnostic. Traditionally diagnostics of insulation is carried out by means of partial discharge detect...Exploitation of equipment with cross linked polyethylene (XLPE ) insulation requires its condition monitoring and diagnostic. Traditionally diagnostics of insulation is carried out by means of partial discharge detection. However, such identification of a defect, for example, void, inclusion or treeing, does not say about its danger from a point of view of full insulation gap breakdown and insulation construction failure. For this purpose a 29 kV CN-CV cable sample is studied. The experiment is based on research for determination of the dependencies between PD characteristics in XLPE upon time and three dimension PD patterns of corresponding treeing. The investigations were carried out by means of electrical measurement of PD current and simultaneous optical recording of treeing image. The needleplane electrode is applied as the electrode. As a result, -q-n PD patterns which are used as the bases to bush tree initialization and growth can be obtained. Test results show that PD pattern recognition can be applied as a powerful tool for recognizing electrical tree initialization and growth. This can make a good basis for on-line condition monitoring of high voltage power cable.展开更多
文摘A balancing method was used to build a DC partial discharge （PD） testing circuit for electrical equipment,and a narrow-band detection system was designed using detection resistance and a filter. After signal accessed a high-speed digital acquisition （DAQ） card,the system was triggered to extract a single partial discharge （PD） signal. To eliminate the interference pulses caused by power supply ripple,etc.,the time domain and frequency domain features of pulses were extracted. Based on the features,cluster analysis was used to exclude interference pulses. Two-dimensional and three-dimensional histograms were obtained by use of the Δt method. Then,22 discharge statistical operators were calculated for the two-dimensional charts. Lastly,the defective capacitors were tested to verify the system＇s ability. The results show that the system is capable of PD detection in electrical equipment.
基金supported by National Natural Science Foundation of China(No.50877064)
文摘The chaotic characteristics of time series of five partial discharge （PD） patterns in oil-paper insulation are studied. The results verify obvious chaotic characteristic of the time series of discharge signals and the fact that PD is a chaotic process. These time series have distinctive features, and the chaotic attractors obtained from time series differed greatly from each other by shapes in the phase space, so they could be used to qualitatively identify the PD patterns. The phase space parameters are selected, then the chaotic characteristic quantities can be extracted. These quantities could quantificationally characterize the PD patterns. The effects on pattern recognition of PRPD and CAPD are compared by using the neural network of radial basis function. The results show that both of the two recognition methods work well and have their respective advantages. Then, both the statistical operators under PRPD mode and the chaotic characteristic quantities under CAPD mode are selected comprehensively as the input vectors of neural network, and the PD pattern recognition accuracy is thereby greatly improved.
基金Supported by the National Natural Science Foundation of China(Grant No.10476022)Doctoral Innovation Fund of Southwest Jiaotong University
文摘High-voltage storage capacitors(hereinafter call capacitors for short)have been widely used in pulsed power technology.In accordance with the actual work conditions of capacitors,direct current partial discharge(DCPD)detection was put forward.The whole test system was based on the impedance balance circuit characterized by good configuration and anti-interference ability.Through DCPD detection on capacitors which contained four typical defects respectively,test results revealed that DCPD signals could well reflect the state of capacitor insulation.DCPD distribution spectra of capacitors containing four typical defects were obviously different.Defects in capacitors could be exactly judged by computer–aided pattern recognition based on support vector machine(SVM).
基金The project supported by the Science and Engineering Reserch Fund of Southwest JiaotongUniversity(1999 XM02) and the Startup F
文摘Exploitation of equipment with cross linked polyethylene (XLPE ) insulation requires its condition monitoring and diagnostic. Traditionally diagnostics of insulation is carried out by means of partial discharge detection. However, such identification of a defect, for example, void, inclusion or treeing, does not say about its danger from a point of view of full insulation gap breakdown and insulation construction failure. For this purpose a 29 kV CN-CV cable sample is studied. The experiment is based on research for determination of the dependencies between PD characteristics in XLPE upon time and three dimension PD patterns of corresponding treeing. The investigations were carried out by means of electrical measurement of PD current and simultaneous optical recording of treeing image. The needleplane electrode is applied as the electrode. As a result, -q-n PD patterns which are used as the bases to bush tree initialization and growth can be obtained. Test results show that PD pattern recognition can be applied as a powerful tool for recognizing electrical tree initialization and growth. This can make a good basis for on-line condition monitoring of high voltage power cable.
