Papers by Keyword: Partial Discharge (PD)

Abstract: Travelling wave method is commonly used for partial discharge (PD) location since the past. However, for a long cable, the attenuation of PD pulse propagation could be significant. This is due to more energy loss during the propagation of pulse, which can affect the sensitivity of the PD source location within cable insulation. In this work, PD pulse propagation along cable insulation from the defect site was modelled using finite element analysis (FEA). The model was used to simulate the electric field distribution in the cable insulation due to the PD pulse propagation and to calculate the attenuation constant. The effect of cable length and PD source location in the cable insulation on the attenuation constant was also studied. Through this work, a better understanding of PD pulse propagation and attenuation constant using the FEA model geometry that has been developed can be attained.

Abstract: The degradation of polymer insulation is affected by many factors. One of the main factors is surface discharge. In this work, the characteristics of surface discharge on different types of polymer insulation material under different types of electrode shapes were studied. The insulation materials used were high density polyethylene (HDPE), low density polyethylene (LDPE) and polypropylene (PP). Different types of electrode shape used were sharp, flat and sphere electrodes. From the experiments that have been performed, surface discharge characteristics were found to be influenced by the type of insulation material and the electrode shape. Hence, a better understanding on the characteristics of surface discharges may be attained.

Abstract: This paper presents a comparative study of partial discharge (PD) detection technique of power transformer model. The acoustic emission (AE) method was applied to detect the signal from PD-origin in a model of the power transformer tank according to IEEE standard C57.127. The Time Difference of Arrival (TDOA) technique was additionally applied. In the experiment, a simulated PD-origin was set up inside the transformer tank. Four acoustic sensors were installed on the tank surface, which were used to detect and provide the signal to a signal amplifier and data recorder. Multifunction Compact NI-DAQ 9223 was used together with 1 slot Chassis model 9191 in order to transfer the data to computer by using LAN or wireless system. The AE signal of PD-origin was then collected and analyzed with the Lab View program to identify the location of PD-origin. All physical dimensions of power transformer such as width, length and height and position of each acoustic sensor (in centimeters) were loaded into the main program. Then, the pattern of PD-origin was simulated at different positions in oil-filled transformer tank model. Finally, the localization result was displayed in a graphic user-interface screen. The acquired signal from this method was subsequently compared with the conventional PD detection method using IEC60270 standard in order to observe the PD. The experimental results were satisfactory and could be applied practically.

Abstract: Problematic issues insulation of power cable systems (PCS) based on the design and development of non-destructive methods are considered in the paper. The basic components of the PCS, destroying the insulation, are determined. The analytical method for assessing the oxidation processes of cellulose with the definition of the most probable is proposed. The approach for identifying the main processes of destruction of the insulation allows more detail to present background to the development of partial discharges (PD) in insulation and to identify measures for minimizing processes that lead to the destruction of the insulation PCS.

Abstract: In general, the presence of moisture and other impurities inside the insulator or oil can cause the breakdown of the power transformer. Polarization and Depolarization Current (PDC) is one of the technique to assess the condition of insulation oil in power transformer and can be applied in many electrical apparatus such as power cables and on load tap changer as well as to estimate conductive and moisture content of the insulation. Basically, it is a technique that is based on time domain measurement and has been used since 1990. For this research, the PDC data will be analyzed using graphical method and statistical technique to classify the transformer faults into a proper range. Lastly, it will be validated with the results from previous research. The output of the research work revealed that in term of the sequence, the results obtain in both graphical technique and the statistical technique is identical with the results presented in previous research. Hence, the range of the faults started with partial discharge, followed by arcing and lastly is the overheating.

Abstract: In order to study different types of partial discharge inspired by defects in GIS and increase the rate of correct identification on defects, four kinds of typical insulation defects physical model are designed based on the insulation defects of 110 kV GIS and its partial discharge characteristics. Ten feature parameters including the signal peak and kurtosis are acquired from 222 groups of partial discharge signal data, and recognized by BP neural network which is optimized by input genetic algorithm. Recognition results show that this method works well, owning a higher recognition rate than adaptive momentum BP neural network

Abstract: This paper describes the design and implementation of the on-line monitoring software system of partial discharge in GIS based on the combination of acoustic and electric in detail. The field operation experience show the system is stable and reliable which can meet the need of GIS on-line monitoring.

Abstract: This paper summarizes the application situation of the ultra-high frequency (UHF) method in gas insulated switchgear (GIS) partial discharge detection, as well as the differences between internal and external UHF sensors. The performance indicators of internal sensors are introduced, and five main types of internal sensors are discussed and evaluated. In addition, several problems to be solved are posed for researchers.

Abstract: Most optical hydrogen sensors are based on light intensity measurement and light intensity detection is vulnerable to the light source output and the optical fiber arrangement. To overcome the shortcomings, an optical fiber based sensor based on fiber Bragg grating (FBG) technique which is capable to measure the concentration of hydrogen dissolved is described in this paper. To examine the availability of monitoring initial hydrogen generation, a needle-to-plate partial discharge (PD) model was setup in the lab. The results between wavelength shifts of optical hydrogen sensor well agreed with conventional dissolved gas analysis (DGA), proving a potential utilization in the detection of dissolved hydrogen in power transformer.

Abstract: In order to study the application of Weibull distribution in cable partial discharge pattern recognition. We apply a 10kV 30m XLPE cable for this study. Then design four kinds of typical artificial defect model and analyze each of defect model’s discharge pulse signals. Finally, estimate the Weibull distribution of signals by use of the maximum likelihood method. The results show that Weibull probability distribution is similar to partial discharge amplitude distribution, the shape parameter β can be used to identify different types of discharge.