Review of Electrical - Power Transformer Responses to Fast Transients

2021 ◽  
Author(s):  
D. V. Giri ◽  
F. M. Tesche
Keyword(s):  
Power Transformer ◽  
Electrical Power ◽  
Fast Transients

The influence of ultrasound signal parameters on sonoluminescence light intensity

2013 ◽  
Vol 62 (4) ◽  
pp. 605-612
Author(s):  
Marek Szmechta ◽  
Tomasz Boczar ◽  
Dariusz Zmarzły
Keyword(s):  
Acoustic Emission ◽  
Acoustic Waves ◽  
Power Transformer ◽  
Electrical Power ◽  
Partial Discharges ◽  
Research Project ◽  
Insulation Systems ◽  
Secondary Phenomenon ◽  
New Research ◽  
The Relationship

Abstract Topics of this article concern the study of the fundamental nature of the sonoluminescence phenomenon occurring in liquids. At the Institute of Electrical Power Engineering at Opole University of Technology the interest in that phenomenon known as secondary phenomenon of cavitation caused by ultrasound became the genesis of a research project concerning acoustic cavitation in mineral insulation oils in which a number of additional experiments performed in the laboratory aimed to determine the influence of a number of acoustic parameters on the process of the studied phenomenona. The main purpose of scientific research subject undertaken was to determine the relationship between the generation of partial discharges in high-voltage power transformer insulation systems, the issue of gas bubbles in transformer oils and the generated acoustic emission signals. It should be noted that currently in the standard approach, the phenomenon of generation of acoustic waves accompanying the occurrence of partial discharges is generally treated as a secondary phenomenon, but it can also be a source of many other related phenomena. Based on our review of the literature data on those referred subjects taken, it must be noted, that this problem has not been clearly resolved, and the description of the relationship between these phenomena is still an open question. This study doesn’t prove all in line with the objective of the study, but can be an inspiration for new research project in the future in this topic. Solution of this problem could be a step forward in the diagnostics of insulation systems for electrical power devices based on non-invasive acoustic emission method.

scholarly journals Towards Precise Interpretation of Oil Transformers via Novel Combined Techniques Based on DGA and Partial Discharge Sensors

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 2223 ◽  
Author(s):  
Sayed A. Ward ◽  
Adel El-Faraskoury ◽  
Mohamed Badawi ◽  
Shimaa A. Ibrahim ◽  
Karar Mahmoud ◽  
...  
Keyword(s):  
Power Transformer ◽  
Partial Discharge ◽  
Electrical Power ◽  
Diagnostic Techniques ◽  
Gas Analysis ◽  
Economic Losses ◽  
Dissolved Gas ◽  
Electricity Transmission ◽  
Dissolved Gas Analysis ◽  
Precise Interpretation

Power transformers are considered important and expensive items in electrical power networks. In this regard, the early discovery of potential faults in transformers considering datasets collected from diverse sensors can guarantee the continuous operation of electrical systems. Indeed, the discontinuity of these transformers is expensive and can lead to excessive economic losses for the power utilities. Dissolved gas analysis (DGA), as well as partial discharge (PD) tests considering different intelligent sensors for the measurement process, are used as diagnostic techniques for detecting the oil insulation level. This paper includes two parts; the first part is about the integration among the diagnosis results of recognized dissolved gas analysis techniques, in this part, the proposed techniques are classified into four techniques. The integration between the different DGA techniques not only improves the oil fault condition monitoring but also overcomes the individual weakness, and this positive feature is proved by using 532 samples from the Egyptian Electricity Transmission Company (EETC). The second part overview the experimental setup for (66/11.86 kV–40 MVA) power transformer which exists in the Egyptian Electricity Transmission Company (EETC), the first section in this part analyzes the dissolved gases concentricity for many samples, and the second section illustrates the measurement of PD particularly in this case study. The results demonstrate that precise interpretation of oil transformers can be provided to system operators, thanks to the combination of the most appropriate techniques.

scholarly journals Enhancement of the Thermal Performance Characteristics of an Electrical Power Transformer

2020 ◽  
pp. 94-112
Author(s):  
Nawras Mohammed Azbar ◽  
Hayder Mohammad Jaffal ◽  
Basim Freegah
Keyword(s):  
Thermal Performance ◽  
Thermal Load ◽  
Model Comparison ◽  
Experimental Finding ◽  
Power Transformer ◽  
Electrical Power ◽  
Operational Parameters ◽  
3D Numerical Simulation ◽  
Cooling Performance ◽  
Three Phase

A 3D numerical simulation was conducted to test the effects of the geometrical and operational parameters on the cooling performance of a three-phase electrical distribution transformer (250 kVA oil natural air natural (ONAN)). The geometric parameters include the shape of the transformer (rectangular, circular, and hexagonal), fins shape (rectangular, semicircular, and trapezoidal) as well it arrangement (asymmetric fin heights and perforated fins). Both of oil temperature and thermal load have been used as boundary conditions. In order to verify the reliability of the numerical model, comparison between numerical results and experimental finding has been done. The results have indicated that the circular and hexagonal shapes reduced the average oil temperature by 3.4% and 4.7%, respectively, compared to the traditional transformer shape (rectangular). Furthermore, the lowest average oil temperature was observed for the trapezoidal fin, followed by the rectangular and semicircular fins. Additionally, it has been noticed that the asymmetric fin heights of the trapezoidal and perforated trapezoidal fins been contributed to the improvement of the cooling performance of the transformer. Furthermore, the best thermal performance was obtained with the trapezoidal perforated fin to compared other arrangement of fins. Finally, the highest reduction in oil has been obtained by the use of hexagonal transformer with a perforated trapezoidal fin approximately by 12% compared to traditional rectangular transformer. Hence, it can be concluded that the shape of the transformer and fins play an important role in thermal performance of such systems.

scholarly journals Investigation of the Effects of the Arc Fault Resistance and Transient Resistance on the Overcurrent Ground Relay Protection Setting in Medium Voltage Electrical Power Lines

2020 ◽  
Vol 4 (1) ◽  
pp. 67-72
Author(s):  
Plamen Antonov Stanchev ◽  
Mediha Enver Mehmed-Hamza
Keyword(s):  
Power Transformer ◽  
Electrical Power ◽  
Relay Protection ◽  
Power Grids ◽  
Power Lines ◽  
Medium Voltage ◽  
Fault Resistance ◽  
Ground Fault ◽  
Determining Factors ◽  
Transient Voltages

In the medium voltage electrical power lines, the most common fault is the phase to ground fault. The determining factors for selection of the neutral grounding mode of the medium voltage electrical power lines are the selectivity of the relay protection, the transient voltages during phase to ground fault, the magnitude of the fault currents, etc. The paper studies the influence of the transient resistance of phase to ground fault on the selectivity and sensitivity of the earth fault protection when the neutral of the power transformer is grounded through active resistance in medium voltage power grids.

scholarly journals Study on Descriptors of Acoustic Emission Signals Generated by Partial Discharges under Laboratory Conditions and in On-Site Electrical Power Transformer

2016 ◽  
Vol 41 (2) ◽  
pp. 265-276 ◽  
Author(s):  
Michał Kunicki ◽  
Andrzej Cichoń ◽  
Sebastian Borucki
Keyword(s):  
Acoustic Emission ◽  
Power Transformer ◽  
Electrical Power ◽  
High Sensitivity ◽  
Laboratory Research ◽  
Time Frequency ◽  
Laboratory Conditions ◽  
Set Up ◽  
Point To Point ◽  
Ae Signals

Abstract An acoustic emission method (AE) is widespread and often applied for partial discharge (PD) diagnostics, mainly due to its ease of application as well as noninvasiveness and relatively high sensitivity. This paper presents comparative analysis of AE signals measurement results archived under laboratory conditions as well as on-site actual AE signals generated by inside PDs in electrical power transformer during its normal service. Three different PD model sources are applied for laboratory research: point to point, multipoint to plate and surface type. A typical measuring set up commonly used for on-site transformer PD diagnostics is provided for the laboratory tasks: piezoelectric joint transducer, preamplifier, amplifier and measuring PC interface. During the on-site research there are three measuring tracks applied simultaneously. Time domain, time-frequency domain and statistical tools are used for registered AE signals analysis. A number of descriptors are proposed as a result of the analysis. In the paper, at- tempt of AE signals descriptors, archived under laboratory condition application possibilities for on-site PD diagnostics of power transformers during normal service is made.

scholarly journals Effects of VA Rating on the Fault Diagnosis of Power Transformer Using SFRA Test

2021 ◽  
Vol 23 (5) ◽  
pp. 381-389
Author(s):  
Khalid H. Ibrahim ◽  
Nourhan R. Korany ◽  
Saber M. Saleh
Keyword(s):  
Fault Diagnosis ◽  
Power Transformer ◽  
Electrical Power ◽  
Mechanical Damage ◽  
Response Analysis ◽  
Electrical Power System ◽  
Statistical Parameters ◽  
Functional Interpretation ◽  
Emission Analysis ◽  
Main Challenge

The electric power transformer is an essential part of an electrical power system since it is used to step up or down voltage levels to maintain the system performance as well as possible. Frequency response analysis (FRA) is one of the most widely used techniques for detecting various types of mechanical damage in transformers. The equivalent circuit of the transformer will be represented by a complex network of R, L, and C elements in the FRA technique. For transformer faults diagnosis, various calculation techniques and diagnostic techniques may be used, such as acoustic emission analysis, thermal images of electromagnetic radiation, transformer temperature, and humidity analysis. SFRA test is one of these techniques that could be used to determine the fault type based on its response over a wide frequency range. The main challenge of the SFRA test is that the functional interpretation requirement for this test is not universally accepted Also statistical features are defined for this SFRA response to be used in fault detection and classification. In this paper, the effect of the transformer rating on the fault diagnosis techniques using SFRA is tested. Also, the effect of the transformer VA rating on the statistical parameters and the classification rules of fault diagnosis is discussed. Finally, the features used in fault diagnosis are ranked according to its independence of the transformer rating resulting in a more accurate matching fault diagnosis technique.

scholarly journals The effects of drying time during manufacturing process on partial discharge of 83.3 mva 275/160 kv power transformer

2018 ◽  
Vol 218 ◽  
pp. 04008
Author(s):  
Siswanto ◽  
Agus Indarto ◽  
Radin Rahmatullah ◽  
Chairul Hudaya
Keyword(s):  
Manufacturing Process ◽  
Power Transformer ◽  
Partial Discharge ◽  
Electrical Power ◽  
High Standard ◽  
Electrical Power System ◽  
Drying Time ◽  
Standard Design ◽  
Cellulose Insulation ◽  
Discharge Test

Power transformer (PT), essential equipment in electrical power system proceeds complicated manufacturing process to meet high standard design. During manufacturing process of PT, the drying stage is of importance to remove excessive moisture contaminant on the solid insulation. This study investigated the effects of drying duration on partial discharge test of 83.3 MVA 275/160 kV PT. The partial discharge test measurements were carried out using IEC 60270 standards comprising of the capacitive network model based on the main quantity apparent charge concept. We found that the lowest partial discharge of 21 pC was achieved at 68 hours drying duration, while the highest value of 60 pC was reached at 81 hours drying time. The longer drying time may lead to initial degradation of cellulose insulation due to excessive heating. The amount of water extracted during drying effect to partial discharge also investigated. We conclude that the drying time at a higher and lower than 68 hours significantly contributes to the increased partial discharge values of PT.

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