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Dissertations / Theses on the topic 'Oil Immersed Transformers'
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1
Robalino, Vanegas Diego M. "Loss of life of medium voltage oil-immersed current transformers under thermal accelerated ageing a dissertation presented to the faculty of the Graduate School, Tennessee Technological University /." Click to access online, 2009. http://proquest.umi.com/pqdweb?index=0&did=1934058311&SrchMode=1&sid=2&Fmt=6&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1264684717&clientId=28564.
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Mohamed, Ali Mohamed. "ANALYZING THE IMPACT OF PHOTOVOLTAIC AND BATTERIE SYSTEMS ON THE LIFE OF A DISTRIBUTION TRANSFORMER." Thesis, Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-54952.
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This degree project presents a study case in Eskilstuna-Sweden, regarding the effect of the photovoltaic (PV) systems with battery energy storage system (BESS) on a power distribution transformer, and how they could change the transformer lifespan. For that, an extensive literature review has been conducted, and two MATLAB models were used to simulate the system. One model simulates the PV generation profile, with the option of including battery in the system, and the other one simulates the transformer loss of life (LOL) based on the thermal characteristics. Simulations were using hourly time steps over a year with provided load profile based on utility data and typical meteorological year weather data from SMHI and STRÅNG. In this study, three different scenarios have been put into consideration to study the change of LOL. The first scenario applies various levels of PV penetrations without energy storage, while, the other scenarios include energy storage under different operating strategies, self-consumption, and peak shaving. Similarly, different battery capacities have been applied for the purpose of studying the LOL change. Thus, under different PV penetrations and battery capacities, results included the variation of LOL, grid power, battery energy status, and battery power. Moreover, results concluded that the PV system has the maximum impact on LOL variation, as it could decrease it by 33.4 %, and this percentage could increase by applying different battery capacities to the system. Finally, LOL corresponding to the battery under peak shaving strategy varies according to the battery discharge target. As different peak shaving targets were used to control the battery discharge, and hence, study the impact on the transformer and estimate its LOL.
3
Marko, Robert Michael. "Thermal modelling of a natural-convection-cooled, oil-immersed distribution transformer." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/mq23407.pdf.
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Lin, Ying-Fu, and 林盈甫. "Study of Heat Dissipation on Oil-Immersed Power Transformers." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/93710812640798548840.
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碩士<br>中原大學<br>機械工程研究所<br>98<br>The main purpose of this research is to study the thermal dissipation by natural convection of oil-immersed transformer with flow channels. The 167kVA oil-immersed power transformer is installed inside the utility box. The only way to cool it down. Therefore, the flow channel is very important for thermal dissipation of transformer. Hence, this study from the thermal dissipation in different flow channels in order to understand the temperature distribution in the transformer.
This article uses CFDRC to simulate the velocity field as well as the temperature field in different flow channel types. The numerical experiment herein is proceeded by taking flow channels of 2mm~5mm width, flow channels 3, 4, 5 pcs, heights of coils 300mm, 400mm, 500mm, and the external layer of the low voltage coil windings with different materials. The main discussion will be on temperatures of high and low voltage oil-immersed transformer and velocity of flow channel. Result shows increase of the width of flow channels and Increase of flow channels provides more cooling channels, and accelerate oil cycling. Heights of coils influence velocity of oil flow. However, materials change on the external layer of the low voltage coil windings does not make significant differences on thermal dissipation.
5
Shu, Bor-Wen, and 許博聞. "Study of Temperature Rise on Oil-Immersed Power Transformers." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/32126061712116725621.
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碩士<br>中原大學<br>機械工程研究所<br>92<br>Abstract
The flow field inside the tank of a transformer has a major impact on the performance of the transformer. As a result, it is essential for the design of the device to have an in-depth understanding of the flow field. Transformer is an effective electrical device for the connection of tow power systems and a major power source for the industry.
In this study, the computational fluid dynamics (CFD) software Icepak, developed by the Fluent Company, was used to evaluate the thermal management of the various electronic devices. Icepak was based on the finite volume algorithm for the numerical simulation, with the capabilities for determining the transient, 2-D, and 3-D flow fields. It has a number of turbulence models with powerful, multi-grid and parallel numerical processing. In addition, it provides the unstructured grid generation capability to handle the complicated geometrical modeling. Furthermore, it has the easy-to-use modules for the users to choose.
This study investigated the temperature and flow fields of an oil-cooled power transformer with internally natural convection as the cooling means. The study used theoretical calculations and the numerical simulations; their respective results were compared with the experimental results. The purpose for this study was to evaluate the adequacy of the methodology and procedure by using the Icepak software package to determine the thermal management of a power transformer. The results obtained from the Icepak calculations indicated that the peak temperatures obtained for the core and the winding of transformer were in reasonable agreement with those obtained from the experimental results. In addition, the location for the peak temperature obtained from the Icepak calculations could be used for pinpointing the location of the temperature sensing devices. Furthermore, in-depth study of the arrangement of the cooling device used for the power transformer could predict valuable information of the temperature rise for the configuration under the tests. This could cut down the time and cost required for the development of the new product for the transformer.
The methodology and procedure established by this study can certainly be extended to determine the temperature and flow fields for a number of other power transformers different from the one studied in this thesis.
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Tsai, Ching-Chou, and 蔡青舟. "Partial Discharge Detection Technique for Oil-Immersed Transformers Diagnosis." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/16022588878998043260.
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碩士<br>崑山科技大學<br>電機工程研究所<br>103<br>With the electrical equipment insulation deterioration, during the breakdown period, the small-scale partial discharge will occur and leads to gradual decreasing of electricity insulation performance. With the increase of the applied voltage and duration, the frequency of occurrence of partial discharge intensity will increase, followed by arcing, result in outages of power system which is often the main cause of the failure. If the discharge phenomenon of intensity, position, patterns can be effectively monitoring, the loss of electrical equipment can be prevented. The partial discharge detecting technique is widely used for testing molded-type equipment. In this thesis the partial discharge detecting technique is used to diagnosing oil-immersed transformer is proposed.
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Wu, Sung-Chi, and 吳松錡. "Study of Partial Discharge on Oil-Immersed Power Transformers." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/95312056279254448971.
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碩士<br>健行科技大學<br>電機工程系碩士班<br>104<br>Partial Discharge phenomenon is a superior factor to influence quality of transformer, improvement of partial discharge frequency and location will be major solution to increment transformer life time and quality. Transformer is a kind of power connection system which link different power level to each in industrial environment today.
This research focus on Partial Discharge evaluation by new facility SPDA to observe phenomenon. We loaded relative data in mating software to simulate reality internal working situation then find electric discharge position out soon, moreover, reduce experiment cost and maintenance time when operation. In addition, raw data will be storage, classification and analysis, not only for research data fundamental but also evaluation informal discharge in the future.
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Chiu, Chen-Yi, and 邱正義. "Design of Full Range Current Limit Fuse for Oil Immersed Distribution Transformers." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/19380120564970797001.
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碩士<br>國立臺灣科技大學<br>電機工程系<br>95<br>Electric power fuses have been used for protecting equipments in electric power system for over hundred years. Although other new protecting equipments have been provided with much more complex functions, power fuses are still very important equipments in electric power system. The simple construction, high reliability and fastest current cutout properties make it be used widely of the world. Traditional power fuses are sufficiently used for breaking high current, such as fault current, but insensitvely for low overload current (i.e. less than five times the rate value). Full range current limit fuses are designed for both high breaking zone and low overload breaking zone protections.
The study for full range current limit fuse was beginning from rating requirements of fuse characteristics, electrical arcing and circuit modeling, then calculating and designing constructions and sizes of fuse element were investigated. The protocol samples were made and tested to check design performances including dielectric, interrupting, temperature rise, time-current, liquid tightness. This study provides the technical design theory above of full range current limit fuses for oil immersed distribution transformer. Three type fuses made according to this study, were tested according to IEEE Std C37.41-2000, which could be used in oil immersed transformer for external power distribution system.
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Tsai, Cheng-Yu, and 蔡承佑. "Fault Diagnosis of Oil-Immersed Power Transformers by Using Back-Propagation Neural Networks." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/a35j63.
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碩士<br>國立彰化師範大學<br>電機工程學系<br>106<br>The large power transformer is one of the most important and expensive equipment in the power system. The operating situation of transformer will directly affect the safety of the power system, and the fault of the transformer may cause the power interruption and the profit loss. Therefore, early detection of the initial fault of transformers, reduction and prevention of the fault can improve the reliability of power system.In this paper, we use the dissolved gas in transformer oil for fault diagnosis. The data of dissolved gas will provide an indirect basis for the internal hidden trouble of transformers. Dissolved Gas Analysis (DGA) is the most popular and effective method for diagnosing transformer’s initial failure; however, due to the variability of gas data and operation, it is not easy to identify the characteristic of transformer’s fault by traditional methods. Therefore, in this paper, we used the algorithm of BP (Back-Propagation BP) neural network to train and test to improve the efficiency and accuracy of system diagnosis.
The experimental results show that, using BP neural network to identify the transformer fault can improve the accuracy of about 40% than the traditional IEC ratio method, which can not only make up the error of traditional IEC ratio method, but also prove the reliability of this method in the initial fault detection of the transformer.
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HSU, CHIA-TAI, and 許嘉玳. "Applying Finite Element Analysis for Electromagnetic and Heat Thermal of Oil-immersed Pole Transformers." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/p7859h.
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碩士<br>國立臺北科技大學<br>電機工程系<br>107<br>This paper will be analyzed using the Finite Element Method to the pole 25 kVA oil-immersed transformer, and the type of sealed type have improved such as transformer, silicon steel and amorphous Alternatively other materials for the two types of cores are made, by COMSOL simulation analysis software Construction architecture Electromagnetic and Heat Thermal other transformer core and the outer electromagnetic intensity produced by the bucket analysis, and environmental impact study the changes in the hysteresis curve in the iron loss, while an analog loss to iron loss and copper temperature state of the transformer Heat Thermal.
Simulation of an electromagnetic and heat transfer analysis for the four types of transformers, after obtaining the maximum magnetic field strength in the electromagnetic simulation core, respectively, extend two types of simulated state and the tub around them analog modulation rated current of the magnetic field strength and the like, according to our substation around 1 meter field strength specifications, the four transformer tub are in compliant analog around them; magnetic core material density different impact when the rated current is adjusted to change, and thus a difference in hysteresis curve. Using COMSOL simulation software to obtain steady-state heat energy core and coil temperature and analyzed four styles in core and coil, confirming the results of Taipower than worth test report adopted.
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Chun-CheHsieh and 謝鈞哲. "A study on Artificial Neural Network Analysis based on Dissolved Gas in Oil-Immersed Distribution Transformers." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/74407874579404078315.
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碩士<br>國立成功大學<br>電機工程學系碩博士班<br>101<br>In this thesis, an oil-immersed distribution transformer dissolved gas analysis and diagnosis system are presented. The diagnosis adopts artificial neural network technique to evaluate the normality status of the oil-immersed type transformer. Three kinds of artificial neural network architectures, BPNN, RBFNN and PNN, were compared using 975 data, and then used trial and error method to find out the best model. After find out the best model using 20 data that is confirmed abnormal and 5892 historical data to observe and compare the ability of judgment along three kinds of network architectures. Test result discovers that the BPNN shows the best judgment accuracy, the next is RBFNN, the last is PNN. All three kinds show that their judgment accuracy are over 96%. Therefore, the feasible and accurate of the diagnosis system, ANN based on oil-immersed dissolved gas analysis are proved.
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Lin, Chien-Hung, and 林建宏. "Oil-Immersed Transformer Residual life Detector." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/x25393.
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碩士<br>中原大學<br>電機工程研究所<br>107<br>This study uses the temperature model algorithm and the equivalent aging factor algorithm to find the correlation between the load and temperature. The program is programmed in a single-chip microcomputer and combined with circuits to measure and analysis the operation of transformer. The detector is used to measure the load state and ambient temperature of the oil-immersed transformer, and then calculate the equivalent aging factor and residual life. Finally, the measured value and calculation result will show on the display. The actual value of the residual life is compared with the theoretical value, which proves the applicability of the measurement of the measuring instrument and the correctness of the calculated value.
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Shyu, Jin-Huei, and 徐進輝. "Research of Preventive Diagnosis for Oil-immersed Transformer." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/79p4m5.
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碩士<br>國立虎尾科技大學<br>電機工程研究所<br>95<br>The power transformer is designed to change the voltage of power system,
and have to face the burdens of long-term high voltage, large current, various
temperatures and impact of electromagnetic stress. Once a breakdown happens,
it always makes havoc and the outage will cause economic loss. Therefore, it is
important to keep the power transformer running smoothly and longer. On the
other hand, to predicate the breakdown events of the power transformer is
another main subject. Dissolved gas analysis technique is the most popular and
effective method for diagnosing the potential defects existing in oil-immersed
power transformer. To practice the technique can keep the power supply and
provide a higher reliability. The technique of dissolved gas analysis is adopted
to commence routine maintenance of the power transformer.
The main purpose of this thesis is to employ the dissolved gas analysis for
abnormal conditions diagnose. A fast and accurate synthesis diagnosis program
which based on six different existing theories is designed in this thesis. The
abnormal parts and fault types can be detected when the power transformer oil
dissolved gas data is applied to the program. An artificial neural network (ANN)
is employed to assist diagnosis program. The approach in this thesis is compared
with conventionally-used methods, gas pattern analysis (GPA) and dissolved gas
analysis (DGA), to investigate its feasibility. The practical data of faulted cases
from Taiwan Power Company has been utilized to test the proposed method.
From the simulation results, it has been shown the proposed approach in this
thesis can provide an alternative method to maintenance the power transformer
operating reliability and safety.
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Li, Ruei-Jhang, and 李瑞璋. "Life Assessment of Oil Immerged Power Transformer." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/69548780705928183693.
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碩士<br>臺北城市科技大學<br>資訊應用產業碩士專班<br>102<br>In general, the life expectancy of a power transformer is about 35 to 40 years. During operation of a power transformer, the various types of faults can be detected from gases in the insulating oil by using the dissolved gas analysis (DGA) diagnostic technology. The volume of these “fault gases” may effectively identify and represent the different conditions of transformer fault. Important information can be obtained after analysis of the integrated fault gases data. According to these data is helpful to draw out the life assessment curve of the transformer, and compare with the bathtub curve to obtain deterioration turning point. The results achieve the main purpose of this study to assess the life of oil immerged power transformer.
This paper uses historical data from the database of transformer gas and failure rate technology successfully drawn into a transformer failure curve. This curve compares with the bathtub curve clearly to depict the cracking turning point. Research confirms the correctness within three different periods such as debugging, occasional failures, and wears period. The result also quantifies the actual degree of aging power transformers
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Shun, Chun-Chi, and 單淳琪. "Estimation of oil-immersed power transformer insulation aging life." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/33pajt.
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碩士<br>國立臺北科技大學<br>電機工程系研究所<br>99<br>Oil-immersed power transformer needs to endure for an extended period of time high voltage, high current, temperature rise, and the impacts of electromagnetic and mechanical forces, and any malfunction may lead to large-scale power outages and other drastic losses. Oil-immersed power transformer is also highly expensive. It is therefore of crucial importance to keep the transformer in normal operation and to prolong its service life. Using effective maintenance mechanism and test-diagnostic techniques to measure the aging degree of a power transformer helps trace the current status of the power transformer and enables the operator to initiate proper responses to contingencies and irregularities.
The study accordingly aims at measuring the aging life of insulation paper by examining the elements and related parameters in transformer oil. The relationships between aging of insulation paper and major elements of transformer oil, notably furan, dissolved gases (CO2, CO), loading, hot-spot, temperature, moisture, and dielectric loss, are analyzed. Based on the standard and literature review, furan, moisture, and hot-spot temperature of oil help provide better diagnostic results. The study then proceeds to examine the methods frequently used to evaluate the aging life of transformer oil and compare the differences between the various methods. Obtained figures related to major affecting factors like furan, CO2, and CO are adopted to quantify the life loss of power transformer. Artificial neural network (ANN) is further applied to identify and examine the correlations between the aging of power transformer and affecting factors. Using two- and four-input-variable assessment models, the study has the functions of transformer life loss served as the ANN outputs to facilitate network training. The trained model is then used to measure and forecast the life loss of aging power transformers.
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KUO, YING-TE, and 郭英德. "Design Technology for Oil-Immersed Amorphous Metal Core Distribution Transformer." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/90706562329317847185.
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碩士<br>中原大學<br>電機工程研究所<br>97<br>The transformers with amorphous metal core have characteristics of very low core loss and moderate decreasing the copper loss. Therefore, they are compatible with environmental protection and energy conservation. They are widely used in the power systems. The design of amorphous metal core transformers can be divided into two major parts, namely electrical design and structure design. The electrical design, according to the specifications requested by the customers, is to calculate the core size, the conductor size and turn number of windings, and the required electrical characteristics which in general include efficiency, voltage regulation, excitation current, leakage impedance and voltage stress. Based on the electrical design parameters, the structure design is proceeded which mainly include the designs related to insulation span and strength of structure. This report mainly focuses on the electrical design of oil-immersed amorphous metal core transformers. The features of this type of transformer are first introduced, and their application situations on Taipower system and future tendency are described too. Then the considerations associated with electrical design are illustrated. Furthermore, the design method and related calculations are described in detail. Finally, a practical design case is presented for depicting the whole design procedure details.
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Yeh, Yuan-Chang, and 葉元彰. "Application of Fuzzy Theory to Oil-Immersed Power Transformer Fault Diagnosis." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/61711383343252925764.
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碩士<br>國立彰化師範大學<br>電機工程學系<br>98<br>Power transformer is an important equipment in power system. If a breakdown happens, it will cause huge economy loss. Therefore, it is important to keep the power transformer running smoothly. On the other hand, to predict the breakdown events of the power transformer is another main subject. Dissolved gas analysis technique is the most popular and effective method for diagnosing the potential defects existing in oil-immersed power transformers. This technique can keep the power system at high reliability. The technique of dissolved gas analysis is adopted to commence routine maintenance of the power transformer. Although these methods are widely used in the world, they sometimes give fault diagnose, especially when more than one fault exist in a transformer or the measured values locate on the boundary line of the diagnosis definition.
This thesis builds a fuzzy diagnosis system for transformer faults based on the IEC standard. The measured gas parameters are fuzzified, inferenced according rule base, and defuzzified to obtain the diagnosis result. The experiment result shows the fuzzy method has the improvement of 16.7% on the diagnosis.
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Hsieh, Hung-Wei, and 謝宏偉. "Fault Diagnosis of Oil-immersed Power Transformer Using Dissolved Gas Analysis." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/97404191408426757042.
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碩士<br>正修科技大學<br>電機工程研究所<br>101<br>Power transformers play an important role in power system operation. Their failure may lead to power supply interruption, or even cause a fire and a series of industrial safety accident, thus causing significant loss of social and economic development. Therefore, enhancement of the maintenance and predictive maintenance of the power transformers become a necessary trend to ensure that the power system can be securely, stablely, and efficiently operated.
Dissolved gas analysis is one of the vital and efficient diagnosis techniques for fault diagnosis of oil-immersed transformers because it can sample the oil on-line. This thesis primarily diagnoses the transformer faults by the total dissolved combustible gases, and the key gas method, gas ratio methods, and gas-ratio code methods are further used to diagnose the faults of the transformers. Finally, the suspected transformer has to do internal inspection if necessary. Compared with the results of internal inspection, this thesis has confirmed the feasibility and validation of the dissolved gas analysis.
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Wang, Fu-Chun, and 王福春. "The Study of Dissolved Gas Analysis and Oil Activation Recycling Treatment in the Oil-immersed Transformer." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/756873.
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碩士<br>崑山科技大學<br>電機工程研究所<br>97<br>According to the more and more high expectations of the power supply dependability followed by economic development and livelihood, makes the electricity to be more and more important from power plants to substations, and then from transformers to the customers of industry, commerce and family. The oil-immersed transformer can be regard as the heart of the power supply system. It has very important meanings for energy transmission, flexible distribution and safe manipulation. If it is out of order, it will create a serious effect. However, transformer insulating oil is one of the essential links for power supply protection. To certify the reliable operation of the transformer and decline the maintainable fee, there are several different monitoring and analytic methods that can examine the potential disordered information ahead to prevent from extending the accident. The dissolved gas analysis (DGA) can extract the oil sample on-line, and then separate and analyze the dissolved gas to determine the operation conditions and disorder styles of transformers. And it owns the positive action for protective equipment and safe operation of power system due to its high sensitivity and effectiveness.
This thesis is studied the dissolved gas analysis by using flammable gas elements, amounts, and ratios to determine the disorder types in oil-immersed transformers. If the disorder type does not occur from the transformer itself and the electric characteristics but occur from the inferior quality of the insulating oil, it can be improved by the oil activation recycling treatment to treat the transformer insulating oil. After the oil activation recycling treatment used to these two main transformers of the National Cheng Kung University, its results solidify the feasibility and effectiveness of the proposed method.
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FU, YANG YUNG, and 楊永福. "The internal temperature of the test for the oil-immersed transformer intelligent fibers." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/07919153454831200082.
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碩士<br>逢甲大學<br>資訊電機工程碩士在職專班<br>103<br>The purpose of this study semiconductor optic fiber temperature sensors for smart amount of oil-immersed transformer internal temperature measured in order to facilitate their maintenance and prolong the life of substation equipment, and asset management. The study found poorly installed transformer manufacturing process or lead to reduced life of the transformer and a major accident, causing the client no case of electricity available. When the transformer previously detected abnormal temperature rises, the engineer early response measures to reduce outage happens.
This study investigated the photoelectric temperature sensing technology, combined with the use of the characteristics of the semiconductor element fiber temperature sensing technology transformer internal temperature, the apparatus includes a source of radiant energy, radiant energy guiding device, device-oriented semiconductor radiation sensing device measuring element and a detector. A detector for detecting the intensity of radiation sensed by said semiconductor emission element. Radiant energy transmission device may use an optical fiber for directing radiant energy to the semiconductor and emitting return radiation to the detector. Semiconductor detection element made of a suitable semiconductor material, such as gallium arsenide, a semiconductor material can be manufactured as a mirror or reflective Prism as the sensing element, and an optical element portion of the radiant energy transmission means.
In use the intelligent optic fiber of temperature measurement and the PT100 temperature difference between two the largest following two points: the first is that the reaction time, intelligent optic fiber temperature probe is embedded in the transformer winding, can immediately measure the temperature inside the transformer full oil However the PT100 sensing element is a simulated winding temperature, the reaction rate will take longer time to show the internal winding temperature; the second measurement mode, the intelligent optical fiber temperature measurement is direct contact, can instantly and accurately measured volume the transformer winding temperature than traditional indirect measurement, the data read more reference value.
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Liao, Wei-Chen, and 廖偉辰. "The Research and Development of Oil Immersed Transformer by Using Pulsating Heat Pipes (PHP)." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/572249.
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Chun-Fu, Chang, and 張春富. "Development of a Sound Source Location and Identification Technique for Oil Immerged Power Transformers." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/09756315345316253531.
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碩士<br>國立臺灣大學<br>工程科學與海洋工程學系<br>92<br>In consideration of the imperious requirement in promoting efficiency and in-serve detection on load tap changers (OLTC) in large scale oil-immerged power transformers, an acoustic based on-line detection, failure source location and patterns recognition technique is developed in this article.
To determine the wave mode change, velocity and propagating path of acoustic wave which propagate from the source to the outer wall of transformers and the Lamb wave is dispersive phenomena have to confirm before, to take for source location technique a basis. In this article, further to confer on load tape changers action the circumstances, to correct the propagating paths to use the point detection to match up the wavelet transform based time-frequency analysis, source location is applied.
In part of source patterns recognition, first, using a hydrophone to measure different source waveform, to proceed the waveform autocorrelation coefficients, reflection coefficients, then to train and recognition based the Back Propagation Network (BPN), and to establish the database on the model. Second to reconstitute the source waveform, using a sensor and the source geometry relationship, to appoint the concept of Leaky Lamb wave to compute the dispersive curve, the relationship between the incident angle, wave velocity and frequency was found, then it’s easy to know the attenuation and time delay could be computed, and to invert waveform. Finally, use the inversion source waveform to compare the species with a hydrophone measure waveform database, to accomplish the source recognition module in transformers. From the result of experiments that input a hydrophone waveform, the recognition result to reach satisfied, AE signal measured outside the transformer wall to inversion source waveform to compare the database, wolfram peak to peak, a mechanism action have effect from inversion Source, and for classifying the source species in large scale oil-immerged power transformers. The study concludes that source location and patterns recognition is to confirm and verify from experiment simultaneously.
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Pan, Wen-Hua, and 潘文華. "Development of Partial Discharge Source Recognition and Identification Scheme for Oil Immerged Power Transformers." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/71866036236742649858.
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碩士<br>國立臺灣大學<br>造船及海洋工程學研究所<br>89<br>In consideration of the requirement of recognition of the partial discharge (PD) phenomena in large scale oil-immerged power transformers, a waveform inversion procedure based on elastic wave theory and digital signal processing is developed in this study. To diminish the influence of dispersion relation on waveform and to provide useful information for classifying PD in power transformers, leaky lamb wave theory was introduced. It was used to find out the wave propagation and velocity of different mode and different frequency, then the attenuation and time delay were known. Using attenuation and time delay , it is possible to inverse waveform from sensor to source. In this study, three methods were used to compute the inverse waveform, spectrum inversion, impulse response, and genetic algorithm. It is successful to recognize four differenct species of artificial electrodes from inverse waveform.
Through the experiment on actual 11kV power transformer, It was known that before electric breakdown, the small PD will happen, the scale and the number of times will increase if the voltage don''t descend below the critical voltage. It is very important and achievable to detect and recognition the small PD before it breakdown.
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Kao, Hao-Chiang, and 高豪強. "Study of On-line Dissolved Gas Monitoring System for Oil-Immerged Power Transformer." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/98380027750364626038.
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碩士<br>國立高雄應用科技大學<br>電機工程系博碩士班<br>101<br>In power companies and industries, oil-immerged power transformers are adopted to all large capacity transformers. Consequently, oil-immerged power transformer plays an extremely important role, also the key equipment in power system.
Power transformer failure could result to power supply interruptions that lead to equipment impact and damages, in worse cases, fire hazard. To monitor transformers operation, build up an early stage alarm system that allow measures taken when dysfunctions occur, and to bring power transformer back to normal operations are inevitable to meet people's expectations. Dissolved gas analysis is what served as one of the most effective off-line way to test transformers operation currently.
This thesis is meant to research on two categories of on-line dissolved gas monitors composite gas type and multi-gas type, and both installed to monitor oil-immerged power transformer at the same time. Compared to the monitoring data and oil sample analysis data of Taiwan Power Research Institute. The diagnostic methods of IEEE, IEC, and JEA Standard will be used to evaluate the fault type when transformers indicate abnormalities, and compare with the results of transformer interior inspection.
Finally, evaluations results will be given to choose which is the more suitable on-line dissolved gas monitor, and aim to achieve normal operation of the power transformer.
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Tsai, Wei-hsin, and 蔡偉炘. "The Application of Diagnosis Techniques of the in-Service Transformer and the Gases Analysis of the Insulated Oil to Prevent Oil-Immersed Power Transformer Failures." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/f2rbcp.
Full textAbstract:
碩士<br>國立高雄大學<br>電機工程學系碩士班<br>102<br>The oil-immersed power transformers are utilized to voltage transform and power dispatch in electric power systems. The power supply would interrupt while failures occurred in power transformers, and also caused the economic lost. The priority issue is to maintain the transformers operating safely and prevent the causing of the accident. This thesis integrated some diagnosis techniques and the gases analysis of the insulated oil. To detect and identity the possible types of fault and its location prior to breaking down.
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張育華. "Test Analysis of Oil Immerged Transformers Insulation Based on Fabrication Design of Pressure Relief Valve." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/44783072614459290089.
Full textAbstract:
碩士<br>國立彰化師範大學<br>機電工程學系<br>94<br>The insulated oil makes transformer deform based on the result of high temperature and power loading effects. At present, pressure relief valve (PRV) is one of the key solutions used to release the rising pressure inside the transformer. But, conventional PRV design is not only efficient at installation time but also in time consumption. The main purpose of this thesis is to decrease the time for PRV installation and power shutdown. The PRV is used to locate on the cover of transformer which causes moisturized easily. Aiming to overcome this shortcoming, this thesis designs a bended PRV copper connector. It can pass the pressurized gas limit with watering test. Measurement of insulation ohm value associated with turn ratio proves structural insulated resistance test. Besides, insulated oil passes the high voltage testing. Proposed bended PRV copper connector in this thesis is feasible. Experimental results illustrates that the solution of shorten installation time and least time of labor hour for conventional oil immerged transformer.
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Chang, C. T., and 張哲騰. "Fault Diagnosis of Oil-Immersed Power Transformer by Using Fuzzy Set and Artifical Neural Network Theories." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/80268197972265190688.
Full textAbstract:
碩士<br>國立中正大學<br>電機工程研究所<br>90<br>Dissolved gas analysis technique is the most popular and effective method for diagnosing the potential faults existing in oil type transformer. The technique of monitoring and sampling the dissolved gasses provides a higher reliability. Some advanced industrial countries adopt the technique of dissolved gas analysis to maintain the function of the transformer because it does not interrupt the power supply. However, the accuracy of dissolved gas analysis not high. So developing a available diagnosis technique for local oil type transformer propriety models is essential.
This study is based on the theory of neural network for discrimination. Which helps to gain higher accuracy, by means of self-adjusting, self-learning, and self-training. Further more, I collected the reports of the dissolved gasses analysis and some cases transformer fault from Taipower to set up a data bank. By the training structure of neural network in the data bank, the neural network discrimination system works not only in predicting the fault patterns but also in diagnosing the fault positions. This study effectively improves the technique to gain higher accuracy and precision in Taipower local oil immersed type transformer diagnosis.
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Chen, Kuan-Ju, and 陳冠儒. "An Intelligence Maintenance Recommendation Platform Based on Real-time Monitoring Information for Oil-immersed Transformer Case Study." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/8783g3.
Full textAbstract:
碩士<br>國立臺北科技大學<br>工業工程與管理研究所<br>99<br>In the power supply system, the transformer has been one of the most important components. If the transformer faults during the power supply, the economy and stability of the power supply will suffer huge impact and influence. Therefore, the transformer has become a critical factor for business operations in the power system asset management. It focuses on the real-time diagnosis and preventive maintenance to avoid unexpected accidents. In addition, the deterioration of insulating paper can be used to determine the degree of transformer depletion. Serious deterioration of the insulating paper would cause the transformer explosion, and the replacement price of the paper is equivalent to buy a new transformer. Therefore, using the degradation degree of the insulating paper to compute the remaining life of the transformer and determine time for replace or purchase a transformer becomes extremely important.
This research is for oil-immersed transformers case study, to propose an intelligence maintenance recommendation platform base on real-time monitoring information. The purpose is to help asset manager quickly compiled the data that collected by the real-time monitoring equipment and regular sampling into information reports. These reports not only give the diagnostic and maintenance advice to engineer but also evaluate equipment remaining life for reduces the incidence of unexpected events. The platform using dissolved gas-in-oil analysis (DGA) base on the three methods which is Doernenburg, Rogers (revised by Institute of Electrical and Electronics Engineers, IEEE) and Duval Triangle (described in the International Electrotechnical Commission (IEC) appendix document) to diagnose transformer internal potential, and provide Maintenance recommend. On the other side, this research proposed a prediction method base on Group method of data handling to estimate life of impairment. This algorithm let the dissolved gas-in-oil and furfural formation to be the input variables to form a new life of impairment assessment model. Using the new proposed model predicted result and another life prediction model proposed by IEC provided for the manager to evaluate life of impairment, compared with each other and reference.