XLPE 절연약화로 인한 케이블 부분방전시 초음파를 이용한 위상 변화 분석

김규호,김진형,김경신 대한전기학회 2022 전기학회논문지 Vol.71 No.10

This study compared the phase difference between corona discharge in the presence of XLPE insulator and corona discharge under normal conditions when partial discharge occurred in power cable using PRPD technique. In order to analyze the physical values detected by the sensor as measurable data, it was converted into a CVS (comma-separated values) file through the PRPD method and analyzed through the Excel program. XLPE insulator is the main insulation material for CNCV cables, which is currently the most used. At 22.9kV, electrical, physical, and chemical defects as well as producer defects can occur. This defect causes partial discharge. If the fault point is identified and taken action at an early stage, it will be helpful in preventing a major power accident. Many accidents are being prevented in the field due to the preventive maintenance technology using the partial discharge diagnosis technology

Detection of the Ultrasonic Signals due to Partial Discharges in a 154kV Transformer

Kweon, Dong-Jin,Chin, Sang-Bum,Kwak, Hee-Ro The Korean Institute of Electrical Engineers 2002 KIEE International Transactions on Electrophysics Vol.c2 No.6

We have developed an on-line ultrasonic detector to monitor partial discharge in an operating transformer. The ultrasonic sensor has 150[KHz] resonance frequency and contains a pre-amplifier with 60[㏈] gain. The on-line ultrasonic detector has 50~300[KHz] frequency band-pass filter to remove electrical and mechanical noises from the transformer. This detector has an ultrasonic signal discrimination algorithm which discriminates ultrasonic signals due to partial discharge in a transformer. A moving average method of ultrasonic signal number was employed to effectively monitor the increasing trend of the partial discharge. This paper describes an experience of partial discharge detection in a 154[㎸] operating transformer using an ultrasonic detector. With regards to gas analysis in oil, C2H2 gas was produced with a warning level in this transformer We detected ultrasonic signals on the transformer steel wall, and estimated the position of partial discharge. With further inspection, we found carbonized marks due to partial discharge on the supporting bolt which fastens the windings.

A Study on Partial Discharge Diagnostic System for Power Cable using RLCR

Park, Keeyoung,Choi, Hyungkee,Lee, Chulhee,Hong, Soomi Korea Electric Power Corporation 2016 KEPCO Journal on electric power and energy Vol.2 No.1

This system is a diagnosis system that checks whether it causes a partial discharge of a power cable or not. It is to classify normal from abnormal-normal, PD (Partial Discharge) sound through analysis of RLCR (Relative Level Crossing Rate) and spectrogram energy algorithm. Partial discharge diagnostic system has a function that stores PD sound and analyzes the data. The wave shape of PD sound is similar to noise and is systematically generated by partial discharge. Therefore, in this paper, we could discreminate between normal and abnormal case using relative level crossing rate (RLCR) and spectrogram of frequency energy rate.

25.8㎸ GIS 부분방전 측정전용 UHF센서 개발

최문규(Mun-Gyu Choi),차한주(Hanju Cha) 대한전기학회 2016 전기학회논문지 Vol.65 No.6

25.8㎸ GIS part generated by sensors to measure contact an inflow of noise depending on the extent of the measured discharge occurs often not easy. Partial discharge signal measurement sensor suitable for developing a more useful measurements at the scene to this, partial discharge waveform analysis developed a sensor, and to utilize forSensor on the development of the most important is VSWR decided to (voltage standing wave ratio) voltage standing-wave ratio less than 1.5 and decided less than at the full spectrum bands that are measured, this time Return loss, as measured value by absolute criteria 14.0 ㏈ produced the sensor, designed to or more. UHF 1.5∼0.5 ㎓ bandwidth spectrum to be measured in GIS. UHF bands were designed to be able to measure the best signal. Recently, 25.8㎸ GIS production company has been increasing variety of GIS were made open spacer in partial discharge in accordance with the not very easy to detect the signal. The sensor is designed height of four cm external spacer is attachment GIS in an influx of outside noise measurement, and be so manufactured as to facilitate the least we’ve done. Also, since partial discharge which occur can measure the frequency of the 170㎸ GIS external partial-discharge signals that occur at the scene of insulation applied to the spacer. Features, and also derived good results using global positioning. Also measured discharge point about sensors that are stable and the reliability of the development and local substation equipment failure occurring signal analysis through the discharge for the prevention of widely. There should be to believe that used.

부분방전 패턴인식을 위해 EMC센서를 이용한 최적화된 RBFNNs 분류기 설계

정병진(Byeong-Jin Jeong),이승철(Seung-Cheol Lee),오성권(Sung-Kwun Oh) 대한전기학회 2017 전기학회논문지 Vol.66 No.9

In this study, the design methodology of pattern classification is introduced for avoiding faults through partial discharge occurring in the power facilities and local sites. In order to classify some partial discharge types according to the characteristics of each feature, the model is constructed by using the Radial Basis Function Neural Networks(RBFNNs) and Particle Swarm Optimization(PSO). In the input layer of the RBFNNs, the feature vector is searched and the dimension is reduced through Principal Component Analysis(PCA) and PSO. In the hidden layer, the fuzzy coefficients of the fuzzy clustering method(FCM) are tuned using PSO. Raw datasets for partial discharge are obtained through the Motor Insulation Monitoring System(MIMS) instrument using an Epoxy Mica Coupling(EMC) sensor. The preprocessed datasets for partial discharge are acquired through the Phase Resolved Partial Discharge Analysis(PRPDA) preprocessing algorithm to obtain partial discharge types such as void, corona, surface, and slot discharges. Also, when the amplitude size is considered as two types of both the maximum value and the average value in the process for extracting the preprocessed datasets, two different kinds of feature datasets are produced. In this study, the classification ratio between the proposed RBFNNs model and other classifiers is shown by using the two different kinds of feature datasets, and also we demonstrate the proposed model shows superiority from the viewpoint of classification performance.

배전용 가스절연개폐기 부분방전 진단의 적정 주파수 분석

고현상(Hyeonsang Ko),윤성호(Seongho Yoon),김정태(Jeongtae Kim) 대한전기학회 2019 전기학회논문지 Vol.68 No.11

In order to improve the accuracy of partial discharge diagnosis by distinguishing internal partial discharge and external noises in distribution grade SF6 gas-insulated switchgear, partial discharges were measured for the on-site operated switchgears. Floating discharges due to water immersion defect in bushing, SF6 gas leakage defect, poor conductor-contact defect etc. were considered as internal discharges, and discharge by peeling semi-conductor paint in bushing was considered as external discharge. As a result, the main frequency bands of internal and external discharges were identified, and it was proposed that frequency bands of the partial discharge sensor would be designed in the range from 250MHz to 350MHz for detecting internal partial discharges.

방사전자파를 이용한 고분자애자의 오손량 분류기법

박재준,Park Jae-Jun 한국전기전자재료학회 2006 전기전자재료학회논문지 Vol.19 No.2

Recently, diagnosis techniques have been investigated to detect a Partial Discharge associated with a dielectric material defect in a high voltage electrical apparatus, However, the properties of detection technique of Partial Discharge aren't completely understood because the physical process of Partial Discharge. Therefore, this paper analyzes the process on surface discharge of polymer insulator using wavelet transform. Wavelet transform provides a direct quantitative measure of spectral content in the time~frequency domain. As it is important to develop a non-contact method for detecting the kaolin contamination degree, this research analyzes the electromagnetic waves emitted from Partial Discharge using wavelet transform. This result experimentally shows the process of Partial Discharge as a two-dimensional distribution in the time-frequency domain. Feature extraction parameter namely, maximum and average of wavelet coefficients values, wavelet coefficients value at the point of $95\%$ in a histogram and number of maximum wavelet coefficient have used electromagnetic wave signals as input signals in the preprocessing process of neural networks in order to identify kaolin contamination rates. As result, root sum square error was produced by the test with a learning of neural networks obtained 0.00828.

Partial Discharge Localization Based on Detailed Models of Transformer and Wavelet Transform Techniques

Hassan Hosseini, Seyed Mohammad,Rezaei Baravati, Peyman The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.3

Partial Discharge (PD) is a physical phenomenon, which causes defects and damages to the insulation. This phenomenon is regarded as the most important source of fault and defect in power transformers. Therefore, methods of high speed and precision are considered of special importance for the maintenance of transformers in localization of the origin of partial discharge. In this paper, the transformer winding is first modeled in a transient state by using RLC ladder network and multiconductor transmission line (MTL) models. The parameters of the two models were calculated by Ansoft Maxwell software, and the simulations were performed by Matlab software. Then, the PD pulses were applied to the models with different widths of pulses. With regard to the fact that the signals received after the application of PD had a variable frequency nature over time, and based on the wavelet transform and signal energy, a new method was presented for the localization of PD. Ultimately; the mentioned method was implemented on a 20 kV winding distribution transformer. Then, the performances of the models used in this paper, including RLC and MTL models, were compared in different frequency bands for the correct distinction of partial discharge location.

Effect of partial insulation winding scheme on discharge characteristics of GdBCO coils

D.G. Yang,최윤혁,D.H. Kang,Y.J. Park,이해근 한국물리학회 2015 Current Applied Physics Vol.15 No.2

In this study, sudden discharge tests were performed on partially-insulated (PI) GdBCO coated conductor single-pancake coils to investigate the effects of a PI winding scheme on the discharge characteristics. Three sets of PI coils were constructed with insulation at 3 different intervals: every 2nd, 4th, and 8th turn. Each set included coils with 4 different insulation-angles: 90˚, 180˚, 270˚, and 360˚. Discharge delay of the PI coils was alleviated by increasing the insulation-interval or insulation-angle due to increased insulated area, which partially hinders radial current flow. The results of the sudden discharge test were in fairly good agreement with simulations of the PI coils using an equivalent circuit model consisting of a single RL circuit in parallel. The characteristic resistance of the PI coils was reasonably estimated through the numerical approach with contact surface resistance and compensation for the current-bottleneck effect, which enables the PI coils to be utilized in practical superconducting magnet applications.

Cavity and Interface effect of PI-Film on Charge Accumulation and PD Activity under Bipolar Pulse Voltage

Shakeel Akram,Guangning Wu,GuoQiang Gao,Yang Liu 대한전기학회 2015 Journal of Electrical Engineering & Technology Vol.10 No.5

With the continuous development in insulation of electrical equipment design, the reliability of the system has been enhanced. However, in the manufacturing process and during operation under continues stresses introduce local defects, such as voids between interfaces that can responsible to occurrence of partial discharge (PD), electric field distortion and accumulation of charges. These defects may lead to localize corrosion and material degradation of insulation system, and a serious threat to the equipment. A model of three layers of PI film with air gap is presented to understand the influence of interface and voids on exploitation conditions such as strong electrical field, PD activity and charge movement. The analytical analysis, and experimental results are good agreement and show that the lose contact between interfaces accumulate more residual charges and in consequences increase the electric field intensity and accelerates internal discharges. These residual charges are trapped charges, injected by the electrodes has often same polarity, so the electric field in cavities increases significantly and thus partial discharge inception voltage (PDIV) decreases. Contrary, number of PD discharge quantity increases due to interface. Interfacial polarization effect has opposite impact on electric field and PDIV as compare to void.