KMITL

Permanent URI for this communityhttps://dspace.kmitl.ac.th/handle/123456789/1

Browse

Search Results

Now showing 1 - 10 of 20

Some of the metrics are blocked by your
consent settings
The Study of Partial Discharge of a Decommissioned 11kV Rotating Machine
(2024-01-01)
Waiwicha, Supisara
;
Monkolsatitpong, Suriya
;
Inwanna, Woranan
;
Vanijkirati, Parada
;
Jeenmuang, Siwakorn
Over time the insulation system of the stator winding in machinery will gradually lose electrical and mechanical strength due to factors such as thermal, electrical, ambient, and mechanical stressors. At a certain point, the material will deteriorate significantly to the extent that the insulation breaks down or cracks under normal operating voltages, due to transient electrical or mechanical situations. This paper presents a study of the stator winding insulation system of a decommissioned 11kV motor with the removed rotor, using offline PD measurement. The measurement results revealed PD signals in all three phases. The PRPD patterns indicate internal delamination discharge and discharge at stress control coating(S/C) and stress control grading which is occurring simultaneously. When the test voltage is increased to a certain point, the electric field stress in the stress control grading area becomes high enough to cause a gap-type discharge pattern, occurring between the press finger and the stress control grading area. Visual inspections also revealed spark discharge.
Some of the metrics are blocked by your
consent settings
Localisation of Partial Discharge in Power Cables Through Multi-Output Convolutional Recurrent Neural Network and Feature Extraction
(2023-02-01)
Yeo, Joel
;
Jin, Huifei
;
Mor, Armando Rodrigo
;
Yuen, Chau
;
Pattanadech, Norasage
This paper proposes an algorithmic approach constructed from a convolutional recurrent neural network (CRNN) iterated with examination of extracted features for partial discharge (PD) localisation; tests were conducted offline on medium voltage (MV) power cables. To evaluate the performance of the algorithm, a case study was performed on 7 cables deliberately selected to comprehensively illustrate the difficulties encountered in field testing. The experimental test results prove that the proposed concept is able to identify and localise discharges besmirched with significant quantities of noise. Main contribution of the methodology is the successful automated interpretation of measurements acquired under noisy challenging field constraints.
Some of the metrics are blocked by your
consent settings
Online PD Measurement by Detecting the Pulsed Compensating Current in High Voltage Equipment
(2022-01-01)
Srinangyam, Chissanupong
;
Pannil, Pittaya
;
Nimsanong, Phethai
;
Chuayin, Chaitawat
;
Thungsook, Kittisak
This paper discusses the pulsed compensating current caused by partial discharge (PD) phenomena that flows inside the electrical equipment installed in the power system. Such electrical equipment like to be the capacitive coupler in the partial discharge test circuit. In order to study the pulsed compensating current of the PD measurement, artificial PD source such as corona, surface, and internal was used in this experiment. The electrical equipment like surge arrester combined with HFCT sensor utilized to detect the PD pulse current. Furthermore, this proposed technique has been applied for online PD measurement in substations. It was found that the surge arrester could compensate for the pulse current arising from the PD source. This study will be helpful information for online PD measurement.
Some of the metrics are blocked by your
consent settings
Analysis and Comparison of Characteristics for Offline PD Measurements in Turbo-Generators at Different Test Time Intervals
(2022-01-01)
Dorkmai, K.
;
Pannil, P.
;
Tattiwong, K.
;
Maneerot, S.
;
Suksawat, D.
Partial discharge (PD) measurement is widely used for the condition assessment of high voltage equipments. It is a tool to detect the localized discharges occurring in the weakness point sites, which causes deterioration that can lead to failure. Hence, it is essential to diagnose the PD behavior to prevent the consequent failure which maybe takes place. This paper presents an analysis of the offline PD measurements performed on the stator winding insulation system of three turbo-generators which consist of a hydrogen-cooled generator rate of 211.75 MVA, 15.75 kV, and two air-to-water heat-cooled generators which the same rate of 50.8 MVA, 11.5 kV, which were located in the power plant. Firstly, the offline PD measurements of these generators have been energized to the star point side and the high voltage coupling capacitor is installed on the high voltage terminal side, according to IEC 60034-27-1. Additionally, the test voltages were applied to the test object with a step voltage profile. To analyze the PD behaviors of the stator winding insulation, the PD characteristics such as the PD pulses, PD magnitude, and phase-resolved PD (PRPD) patterns were monitored and recorded. Besides, the effect of applied test voltage-time, i.e., 1, 3, and 5 minutes, on such characteristics were reported and compared. Finally, the PD behavior of the stator winding insulation of these generators showed clearly different results for PD measured at different recording times. The highly fluctuating PD magnitude and PD pulse shape at the initial duration of the measurement, and then gradually decreases to convergence to a stable charge magnitude as the test-time increases.
Some of the metrics are blocked by your
consent settings
A locating diagnosis of partial discharge on cross-bonding ground system
(2021-05-19)
Inwanna, W.
;
Mongkolsatitpong, S.
;
Chancharoensook, P.
;
Pattanadech, N.
At the present, Thailand has turned the attention to Underground Cable (UC) systems and trends to use it more to safety, stability and reliability of electrical system. However, one problem that can affect to this electrical system is the Partial Discharge (PD) problem. Most of PD problems are caused by incomplete installation, maintenance reason and insulation degradation on the weakest part, especially cable joint. This paper proposes a method of analysis to locate the PD source in UC systems with Cross Bonding (CB) focus on cable joints. This work has carried out in laboratory on CB system model using 50ohm R58 coaxial cable instead of underground cable. The PD detection technique according to IEEE 400.3 standard with a RFCT sensor to refer the appropriate signal. This work uses a PD diagnostic device that can filter noise from the PD groups and separate groups of PD for greater analysis accuracy. To determine which cable joint is PD source and to be able to fix it on the spot. The PD signal analysis are performed by using time of arrival method considered together with the characteristics and the polarity of the PD pulse.
Some of the metrics are blocked by your
consent settings
Partial discharge characteristics of mineral oil immersed transformer compared with natural ester and palm oil immersed transformer under different periods of impregnation
(2020-09-13)
Maneerot, Sakda
;
Pattanadech, Norasage
This paper represents the partial discharge (PD) characteristics of mineral oil immersed transformer compared with natural ester, and palm oil immersed transformer under different periods of impregnation. Three identical three-phase transformers with 22kV/400V 50 kVA rated were designed and constructed. The first transformer was fully filled with mineral oil. The second transformer was fully filled with natural ester (FR3), and the third transformer was fully filled with palm oil. The partial discharge at 1.1Urated of these transformers with various conditions, i.e., non-impregnated paper, impregnated paper with 3 hours, and 6 hours was investigated. The impregnation process was done with 65 <sup>o</sup>C liquid temperature and 5 mmbar pressure. From the test results, it can be concluded that PD characteristics of the mineral oil immersed transformer was obviously different compared with these of the natural oil (FR3) immersed transformer and the palm oil immersed transformer. Moreover, the impregnation impacted PD characteristics of the tested transformers, which were analyzed and reported in this paper.
Some of the metrics are blocked by your
consent settings
Evaluation of UHF transfer function in a power transformer for real-time partial discharge detection
(2020-08-14)
Promwong, Sathaporn
;
Tiengthong, Thanadol
The UHF transfer function is significant for a short-range communication system, e.g., a real-time diagnosis of partial discharge (PD). Real-time diagnosis of the PD has become a challenging topic of improving the diagnosis of high voltage equipment, including a power transformer. Further, the PD detection in high voltage equipment is critical since the PD can cause severe damage to electrical systems. The PD detection methods are classified by a phenomenon of the PD. The PD detection by electromagnetic (EM) method is regulated by IEC TS 62478, which specified the UHF band for the PD detection in power transformers. Hence, an evaluation of frequency characteristics is essential to achieve an excellent diagnostic performance. In this paper, a complex form of channel analysis is applied with the PD detection method. The measurement model in a power transformer is proposed. The optimum receiver is introduced to maximize SNR and hence it is easy to analyze the results. The results were analyzed by using magnitude, phase, group delay, received waveform, and path loss parameters. The results show that the measured channel is affected by the structure of the power transformer. The contribution of this research is useful for improving the precision of the PD detection with EM method and building an accurate real-time partial diagnosis via a smartphone or laptop computer.
Some of the metrics are blocked by your
consent settings
Partial Discharge Phenomena in Power Capacitor Unit Insulation Under Harmonic Resonance Effects
(2020-01-01)
Boonseng, Chongrag
;
Boonseng, Rapeepornpat
;
Boonsaner, Nutthaphan
;
Kinnares, Vijit
;
Apiratikul, Promsak
The capacitor in the electrical system for power factor correction is always damaged when under voltage and current waveforms are distorted. There was a test found that the electrical insulation was damaged and destroyed. In order to learn this damage mechanism it requires a non-destructive inspection method. The partial discharge (PD) testing is a method that can detect deterioration and a defect in the electrical insulating material that is not visible. The purpose of this paper is to investigate the impact of harmonic resonance on power capacitor unit insulation. High voltage capacitor units consist of parallel and series connected elements. The rating of element of capacitor units applied in the power system is 6.67 kVAR/Phase, 400 V. Series resonance can lead to high voltage distortion levels at a low voltage side of transformer resulting in high harmonic current in the element of capacitors. The inspection and element of capacitor unit test are used to obtain power system resonance, a standard operating procedure, testing and measurement between phase to ground using the partial discharge model MPD 600 OMICRON, dielectric losses and capacitance model CPC 100 OMICRON. Finally, the scanning electron microscope (SEM) is used. The comparison of results between new element of capacitor and element under harmonic resonance are performed. The results convey that breakdown in insulating of capacitors under harmonic resonance can be used for considering capacitor voltage rating. The failure of insulation an increase in obtained and emphasized by photograph from SEM.
Some of the metrics are blocked by your
consent settings
Development of high-voltage testing system based on power frequency converter used in partial discharge tests of potential transformers
(2020-01-01)
Prombud, Tongpian
;
Yutthagowith, Peerawut
Some of the metrics are blocked by your
consent settings
Experiences in nonconventional partial discharge measurement for gas-insulated substation in Thailand
(2020-01-01)
Nganpitak, Tritod
;
Kunakorn, Anantawat
;
Klienhom, Sitthisak
;
Likhitsupin, Suwapich
;
Jariyawichai, Parinya
Nowadays, nonconventional partial discharge (PD) measurement has become essential for diagnosis the high-voltage insulation condition. The nonconventional PD measurement not only uses for periodic assessment but also uses for commissioning test after transportation and installation. This paper focuses on nonconventional PD test techniques using Ultra-high frequency (UHF) sensors, acoustic sensors and light detection sensors for gas-insulated substation (GIS) commissioning test. Fundamental defects found in GIS: (1) Hopping particles (2) Fixed protrusions (3) Floating potential and (4) Voids are described. Then, explanation about how to detect such defects by using UHF, acoustic and optical methods. Afterwards, PD commissioning tests were performed with three 230 kV electricity generating authority Thailand (EGAT) GISs, i.e., Phayao EGAT GIS, Lamphun 2 EGAT GIS and North Bangkok EGAT GIS. The PD signals due to hopping particle were found by using UHF sensors at Phayao and North Bangkok EGAT GISs. The acoustic PD test technique was used in Phayao EGAT GIS to locate such particles. In case of Lamphun 2 EGAT GIS, by using UHF measurement, PD signals were found due to tracking caused by flashover on the cone insulation surface. Later, light detection sensors were used to detect the PD location. As a result of studies, its clearly guarantee the powerful accuracy and efficiency of nonconventional PD measurement by the combination of UHF and acoustic technique including light detection sensors.

KMITL

Browse

Filters

Settings

Sort By

Results per page

Search Results