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1
Karlsson, Svante. "Power Transformer Monitoring and Diagnosis using Transformer Explorer." Thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-280958.
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Power transformers are one of the most expensive and vital components in the power system. A sudden failure could be a very costly process for both the transformer owner and the society. Several monitoring and diagnostic techniques have been developed over the last decades to detect incipient transformer problems at an early stage, so that planned outages for maintenance and reparation can be carried out in time. However, the majority of these methods are only secondary indicators which do not address the transformers fundamental function: to transfer electric energy between different voltage levels with turn ratio, short-circuit impedance and power loss within acceptable limits. Transformer Explorer is a concept developed by ABB which utilizes ordinary current and voltage signals available in the substation to extract transformer fundamental parameters such as: turn ratio, magnetizing current, impedance and power loss, which has significant diagnostic value. By estimating these parameters the method should be able to detect a number of problems related to the windings and the magnetic circuit of the transformer. Transformer Explorer is expected to find it's application in two different versions, either as an permanent on-line monitoring and diagnostic tool or as a short-time version for temporary measurements. The thesis could be divided into three main parts. The first one focusing on a quantitative study trying to answer questions regarding the concepts feasibility when the temporary version is used. The second part is about optimizing and improving the procedure by which the fundamental parameters are estimated. In the last part, a new method for reducing the impact of errors introduced by the acquisition system on the estimated power loss is proposed. All the investigations related to the three topics covered in this thesis showed interesting and promising results.
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Zandberg, Hermanus Andries Jakobus. "Wireless transformer condition monitoring system." Thesis, Cape Peninsula University of Technology, 2013. http://hdl.handle.net/20.500.11838/1186.
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The Department of Electrical Engineering in fulfilment of the
requirements for the Magister Technologiae in Electrical
Engineering at the
Cape Peninsula University of Technology
November 2013Pole mounted transformers (PMT) in rural areas present an opportunity for local utilities to do current monitoring on these systems. These transformers are exposed to abnormal amounts of stress due to the vast power demand in these areas. The aim of this study is to develop a more cost-effective condition monitoring system. Transformer current monitoring can be a dangerous practice if not done by suitably trained utility electricians. Hence this study is partly aimed at the elimination of hazardous working environments associated with manual electrical measurements. An investigation to determine a safe and cost-effective way to obtain the electrical measurements required from PMTs is undertaken. Although current measurements can be done with a current clamp-on meter, these measurements still take place at the phases of the transformer and are unsafe. The possibility of implementing wireless data gathering on current clamp-on meters is therefore investigated. This is made possible by a wireless sensor node (WSN) which gathers information and transmits it wirelessly to a WSN base station. This wireless solution is battery powered, necessitating battery replacements, therefore leading to the investigation of magnetic fields, magnetic materials and magnetic induction. A current clamp able to generate a high voltage (HV) output with minimal magnetic field strength is developed. The magnetic fields produced by the transformer’s phase cables are used to generate an alternating voltage. With the help of a microcontroller and an energy harvesting circuit, this voltage is converted and used to charge supercapacitors. The magnetic fields are also used to determine the current flow in the transformer phase cables when the device is not in energy harvesting mode. The device will then undergo comprehensive laboratory testing to determine its accuracy and durability, and is then used to do ‘real life’ current measurements, the results of which are compared against an off-the-shelf current monitoring device.
3
Lavery, Grant. "A prototype transformer insulation condition monitoring system." Thesis, University of Canterbury. Electrical and Electronic Engineering, 1999. http://hdl.handle.net/10092/6037.
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A prototype data acquisition and processing system is developed for evaluating the insulation condition of a power transformer winding in real-time. The Transformer Insulation Condition Monitoring System (TICMS) evaluates the insulation condition by calculating the winding transadmittance function. The winding transadmittance function is used to fingerprint the insulation system and provides a means of monitoring its condition. The use of a transfer function for evaluating the insulation condition of a power transformer winding was proposed by Malewski and Poulin in 1988 [6, Chapter 1]. The work described in this thesis extends their work in a number of important areas and makes the following contributions to the state-of-the-art. Firstly, the TICMS is able to calculate the transadmittance function to 3MHz, which is sufficient to detect breakdown between individual turns in an Extra High Voltage (EHV) transformer. This is a key distinguishing feature of this work and is important as faults between individual turns can quickly snowball into a catastrophic failure. Previous attempts have been successful at determining the transadmittance function to around 1.5MHz, which only allows breakdown between discs to be detected in an EHV transformer. Second, the TICMS is able to determine the transadmittance function on-line and in real-time for a fully energised transformer. This is another key distinguishing feature of this work as it allows action to be taken to remove a faulty transformer from service prior to catastrophic failure. Previous attempts have calculated the transadmittance function in an offline situation over a period of minutes using pre-recorded data.
Recent advances in analog-to-digital converter (ADC) technology and the availability of high speed Digital Signal Processors (DSPs) have made it possible to extend the work of Malewski and Poulin as described above. This thesis describes the key design features of the TICMS which provide it with the ability to determine the transadmittance function over a 3MHz bandwidth in real-time. These features include the application of an excitation with tailored spectral characteristics, a novel transducer arrangement that allows the effective dynamic range of the digitizer to be extended and at the same time online measurements to be performed, a first-in-first-out (FIFO) memory arrangement that allows the high speed data acquisition section to easily interlace to the data processing section, and a powerful 32-bit floating point Digital Signal Processor (DSP) that enables the trans admittance function to be determined in real-time. The graphical user interlace to the laboratory prototype is also
presented.
Also described are the signal processing techniques, both applied and developed, that are used by the TICMS to determine the trans admittance function in real-time. These include the deconvolution of the voltage and current channel transducer output signals, a radix-2 decimation-in-time (DIT) fast Fourier transform (FFT) algorithm that transforms the voltage and current channel inputs into the frequency domain simultaneously, the calculation of the transadmittance function magnitude and phase from the recorded transients, and a zooming algorithm that is used to accurately determine pole height.
The transadmittance function of a 7.5kVA 11kV/230V distribution transformer is determined and compared with that obtained by performing a time consuming sweep frequency test. Artificial faults are inserted into a 2nd 7.5kVA 11kV/230V distribution transformer to establish relationships between the location and size of a fault and the corresponding changes in the transadmittance function. Sets of tests are conducted to evaluate the effect of fault size, fault location, the introduction of simulated partial discharges, and single turn faults. The ability of the system to detect single turn faults is a key feature as this allows faults to be detected before they can snowball into catastrophic failures.
The effect of temperature on the location and height of poles in the transadmittance function of a 7.5kVA 11kV/220V distribution transformer is established through the use of the TICMS. On-line testing of an energised transformer is performed to evaluate the effect of supply voltage magnitude, load current magnitude, and the point in the 50Hz AC cycle when the insulation test is initiated. This information allows the system to compare successive transadmittance functions and generate an alarm signal if insulation condition degradation is found to have taken place. This information will allow the system to eventually become a 'black box' that permanently sits beside a transformer continuously evaluating insulation condition.
4
Archer, Dale S. "An adaptive thermal module for transformer monitoring." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/11992.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1988.Includes bibliographical references (leaves 132-133).
by Dale S. Archer.
M.S.
5
Mouayad, Lama. "Monitoring of transformer oil using microdielectric sensors." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/39497.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1985.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.
Includes bibliographical references.
by Lama Mouayad.
M.S.
6
Guo, Dongsheng. "Power transformer condition monitoring with partial discharge measurement." Thesis, Glasgow Caledonian University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.443183.
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Zaretsky, Mark Carmeron. "Parameter estimation using microdielectrometry with application to transformer monitoring." Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/14722.
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Boyd, Mary Jane. "Intelligent on-line transformer monitoring, diagnostics, and decision making." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/9953.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1998.Includes bibliographical references (p. [231]-235).
by Mary Jane Boyd.
Ph.D.
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Liu, Jing. "Industrial Mobile Application Design and Development : Transformer Monitoring Mobile Application." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-208526.
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This thesis shows how mobile communication and information technology can be used on power industry domain. More specifically, the goal of this thesis is to design and develop a software concept demonstrator that gives operators a better possibility to check the status on ABB high voltage products, utilizing mobile devices, such as mobile phones and tablets. At the beginning of this thesis, user study and information gathering was conducted at ABB Corporate Research Center, Västerås, Sweden and VB Energi, Ludvika, Sweden. According to the result of interview with both transformer monitoring experts and operators, a preliminary use case of the concept demonstrator was defined. By using evolutionary prototyping, the use case was continuously refined and rewritten, and user interface was designed in from sketches to high-fidelity prototype. Finally, a fully functional prototype, which used as software concept demonstrator, was implemented on Android mobile phone platform and evaluated by both experts in ABB and end users in VB Energi.The result of this thesis illustrates the current state-of-the art technologies on mobile device can be used in power industry to help the operators and engineers with their daily work. Usability, accuracy, interactivity are the most significant characters for this kind of industrial used software
10
Edwards, Laura E. (Laura Elaine). "Optimization of data storage for the adaptive transformer monitoring system." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/12770.
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Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1992.Includes bibliographical references (leaves 150-151).
by Laura E. Edwards.
B.S.
11
Elzagzoug, Ezzaldeen. "Chromatic monitoring of transformer oil condition using CCD camera technology." Thesis, University of Liverpool, 2013. http://livrepository.liverpool.ac.uk/12233/.
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Power transformers are essential components within the power distribution system. Transformer failures having a high economic impact on the distribution operators and the industrial and domestic customers. Dielectric mineral oil is used in transformers for electrical insulation between live parts, cooling and protection of the insulation papers in the transformer. Oil contamination and changes in the chemical structure of the oil result in the decay of insulation paper and reduced insulation and cooling which can lead to a transformer failure. The general approach to oil monitoring has been for an operator to examine the colour index (ASTM) of the oil, electrical strength, acidity, water contents and dissolved gas analysis results and form an opinion as to the extent of oil degradation. Chromatic techniques enable data from di↵erent sources to be combined to give an overall evaluation about the condition of a system being monitored. One of the main goals for this work was to use chromatic techniques for integrating the oil data from the di↵erent sources and sensors. In addition the chromatic approach enables liquids to be monitored optically so a second aim was to apply chromatic optical oil monitoring using portable system by transmitting polychro- matic light through the oil sample, which is contained in a transparent cuvette and imaged using a mobile phone camera. A number of oil samples were optically analysed with portable chromatic sys- tem and the optical data was compared with the colour index and chromatically companied with the dissolved gas and other oil data to give overall evaluation of oil degradation. The chromatic optical result compared favourably with the colour index. It was also possible to classify the oil samples chromatically into categories of low, medium and high degradation. This enabled the chromatic data combination approach to be implemented as a prototype system in Matlab software that an operator could use to get a classification of an oil sample. Essential experiment was introduced to monitor di↵erent oil particles by obtaining the result of di↵erent filtered samples through the filter paper. Beside the ability to analyse data and distinguish between fresh and contam- inated oil samples the chromatic technique has the ability to track the history of di↵erent degraded oil samples which can give an indication about failure faults and it could give a prediction of any future faults. Therefore a commercially viable reliable system can be developed to extend the service life and extend the maintenance schedules. These monitoring systems could lead to extending the service life of the transformers, making the electricity supply more reliable and giving the consumer a better quality of life.
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Dong, Bo. "Fiber Optic Sensors for On-Line, Real Time Power Transformer Health Monitoring." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/77175.
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High voltage power transformer is one of the most important and expensive components in today's power transmission and distribution systems. Any overlooked critical fault generated inside a power transformer may lead to a transformer catastrophic failure which could not only cause a disruption to the power system but also significant equipment damage. Accurate and prompt information on the health state of a transformer is thus the critical prerequisite for an asset manager to make a vital decision on a transformer with suspicious conditions.
Partial discharge (PD) is not only a precursor of insulation degradation, but also a primary factor to accelerate the deterioration of the insulation system in a transformer. Monitoring of PD activities and the concentration of PD generated combustible gases dissolved in the transformer oil has been proven to be an effective procedure for transformer health state estimation. However current commercially available sensors can only be installed outside of transformers and offer indirect or delayed information.
This research is aimed to investigate and develop several sensor techniques for transformer health monitoring. The first work is an optical fiber extrinsic Fabry-Perot interferometric sensor for PD detection. By filling SF6 into the sensor air cavity of the extrinsic Fabry-Perot interferometer sensor, the last potential obstacle that prevents this kind of sensors from being installed inside transformers has been removed. The proposed acoustic sensor multiplexing system is stable and more economical than the other sensor multiplexing methods that usually require the use of a tunable laser or filters. Two dissolved gas analysis (DGA) methods for dissolved hydrogen or acetylene measurement are also proposed and demonstrated. The dissolved hydrogen detection is based on hydrogen induced fiber loss and the dissolved acetylene detection is by direct oil transmission measurement.Ph. D.
13
Fu, Le. "Voltage stability monitoring and enhancement in electrical power systems using transformer tap changers." Thesis, Imperial College London, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.506484.
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Overby, Alan Bland. "Dissolved Gas Analysis of Insulating Transformer Oil Using Optical Fiber." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/48598.
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The power industry relies on high voltage transformers as the backbone of power distribution
networks. High voltage transformers are designed to handle immense electrical loads in hostile
environments. Long term placement is desired, however by being under constant heavy load
transformers face mechanical, thermal, and electrical stresses which lead to failures of the
protection systems in place. The service life of a transformer is often limited by the life time of
its insulation system. Insulation failures most often develop from thermal faults, or hotspots, and
electrical faults, or partial discharges. Detecting hotspots and partial discharges to predict
transformer life times is imperative and much research is focused towards these topics. As these
protection systems fail they often generate gas or acoustic signals signifying a problem. Research
has already been performed discovering new ways integrate optical fiber sensors into high
voltage transformers. This thesis is a continuation of that research by attempting to improve
sensor sensitivity for hydrogen and acetylene gasses. Of note is the fabrication of new hydrogen
sensing fiber for operation around a larger absorption peak and also the improvement of the
acetylene sensor's light source stability. Also detailed is the manufacturing of a field testable
prototype and the non-sensitivity testing of several other gasses. The developed sensors are
capable but still could be improved with the use of more powerful and stable light sources.Master of Science
15
Catterson, Victoria M. "Engineering robustness, flexibility, and accuracy into a multi-agent system for transformer condition monitoring." Thesis, University of Strathclyde, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435150.
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Pieters, Willem Diederick. "Monitoring, protection, and voltage control of parallel power transformers based on IEC 61850-9-2 process bus." Thesis, Cape Peninsula University of Technology, 2019. http://hdl.handle.net/20.500.11838/3067.
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Thesis (MEng (Electrical Engineering)--Cape Peninsula University of Technology, 2019The purpose of an electrical power system is to supply electrical energy to the customers. Power transformers are required to transform the system voltage from generation to transmission and distribution levels. Protection and control systems must ensure that power system high voltage equipment such as transformers operate and deliver save, reliable and secure electricity supply. The aim of the project research work is to develop and implement a strategy, methods and algorithms for monitoring, protection and voltage control of parallel power transformers based on IEC 61850-9-2 process bus standard. NamPower is a power utility in Namibia. The IEC 61850 protocol for electrical substation automation system is used for the protection and control of 5 power transformers operated in parallel in an existing substation system. The IEC 61850-9-2 process bus standard is however not used in regards of Sampled Values (SV). Protection and control devices are connected to a substation communication network, routers and switches using fibre optic linked Ethernet. Inductive Current Transformers (CTs) and Voltage Transformers (VTs) secondary circuits are hardwired to Intelligent Electronic Devices (IEDs) and fibre optic links are not used for this purpose at process level communication. The research focuses on the implementation of the IEC 61850 standard with Merging Units (MUs) and sampled values to improve the existing implemented protection and control system at NamPower. This includes substation communication networks and MUs used for transformer protection, voltage regulator control and cooling fan control. At the present the CTs located at the transformer bushings and switchgear and the VTs located at the switchgear are hardwired to the inputs on protection and control IEDs. The research focuses on issues with the copper wires for voltage and currents signals and how these issues can be eliminated by using the MUs and the SV protocol. The MUs which are considered in this Thesis is to improve the voltage regulator control and the control of the cooling fan motors. The voltage regulator control IED is situated at the tap change motor drive of the On-Load Tap Changer (OLTC). The IED of each transformer is required to regulate the voltage level of the secondary side bus bar it is connected to. All the regulating IEDs are required to communicate with each other and collectively to control the bus bar voltage depending on the switching configuration of the parallel transformers. The control circuit for controlling the cooling fan motors is hardwired. Temperature analogue signal input into a programmable automation controller IED can be used for controlling the transformer cooling fans. A strategy, methods and algorithms for transformer protection, voltage regulator control and cooling fan motor control of parallel power transformers need to be developed and implemented based on IEC 61850-9-2 process bus. Power utilities and distributors can benefit from interpretation of the IEC 61850-9-2 standard and implementing MUs and SV in substations. MUs can be included in the power transformer protection, automation and control systems. A cost reduction in high voltage equipment, substation installation and commissioning costs and better performance of protection and control system are anticipated.
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Tee, Sheng Ji. "Ageing assessment of transformer insulation through oil test database analysis." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/ageing-assessment-of-transformer-insulation-through-oil-test-database-analysis(9d99e3a3-8795-4b85-a484-48fae2f02d2e).html.
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Transformer ageing is inevitable and it is a challenge for utilities to manage a large fleet of ageing transformers. This means the need for monitoring transformer condition. One of the most widely used methods is oil sampling and testing. Databases of oil test records hence manifest as a great source of information for facilitating transformer ageing assessment and asset management. In this work, databases from three UK utilities including about 4,600 transformers and 65,000 oil test entries were processed, cleaned and analysed. The procedures used could help asset managers in how to approach databases, such as the need for addressing oil contamination, measurement procedure change and oil treatment discontinuities. An early degradation phenomenon was detected in multiple databases/utilities, which was investigated and found to be caused by the adoption of hydrotreatment oil refining technique in the late 1980s. Asset managers may need to monitor more frequently the affected units and restructure long term plans. The work subsequently focused on population analyses which indicated higher voltage transformers (275 kV and 400 kV) are tested more frequently and for more parameters compared with lower voltage units (33 kV and 132 kV). Acidity is the parameter that shows the highest correlation with transformer in-service age. In addition, the influence of the length of oil test records on population ageing trends was studied. It is found that it is possible to have a representative population ageing trend even with a short period (e.g. two years) of oil test results if the transformer age profile is representative of the whole transformer population. Leading from population analyses, seasonal influence on moisture was investigated which implies the importance of incorporating oil sampling temperature for better interpretation of moisture as well as indirectly breakdown voltage records. A condition mismatch between dielectric dissipation factor and resistivity was also discovered which could mean the need for revising the current IEC 60422 oil maintenance guide. Finally, insulation condition ranking was performed through principal component analysis (PCA) and analytic hierarchy process (AHP). These two techniques were demonstrated to be not just capable alternatives to traditional empirical formula but also allow fast, objective interpretation in PCA case, as well as flexible and comprehensive (objective and subjective incorporations) analysis in AHP case.
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Jadim, Ramsey. "On the estrablishment of effective condition monitoring parameters for copper corrosion problems in mineral oil-filled electrical transformers." Licentiate thesis, Linnéuniversitetet, Institutionen för maskinteknik (MT), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-99899.
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The power transformer is a critical equipment in which the protection process is essential for modern societies where continuous electric power supplies are required. Copper corrosion problems due to the formation of sulfur deposits on the copper windings of mineral oil-filled power transformers are considered a major issue that can lead to sudden failures, and in some cases, to costly fire and explosion accidents in the power plants. These kinds of problems are still being reported regardless of available condition monitoring (CM) parameters applied in power transformers' maintenance strategy. The currently applied CM parameters are based on three different types of technologies. The first is oil analysis focuses more on measurable variables such as measuring the concentration of the corrosive sulfur compounds in the insulating oil, evaluating the oil's capability to form sulfur deposits, and measuring an increase in the concentration of specific gases. The second is on-site electrical testing focuses on the variation of the transformer's electrical properties due to the sulfur deposits. The measurable variables used in the electrical testing are Frequency Domain Spectroscopy test and Polarization/Depolarization Current test. The last is online sensor technology using Corrosive Sulfur Sensor, where the sensor's outcome data provide information about the oil's capability to form sulfur deposits. The research problem addressed is how to establish more effective CM parameters for early detection of copper corrosion problems. The research problem is divided into three concretized research problems: What are the strengths and weaknesses of the currently applied condition monitoring parameters? Which measurable variables could be utilized to improve the currently applied condition monitoring parameters to be more effective for early detection of copper corrosion problems? And how to establish a procedure for the condition monitoring for detecting copper corrosion? Two research methodologies were applied to answer these questions, literature review and experimental work. The literature review showed significant gaps in the currently applied CM parameters for early detection of copper corrosion problems due to incomplete data of the corrosion reaction mechanism. Therefore, qualitative and quantitative investigations in the experimental work were carried out. The most important result was finding new relevant measurable variables, i.e. hydrogen sulfide gas and toluene compound, which are by-products of corrosion reaction. These measurable variables are utilized to establish more effective CM parameters for early detection of copper corrosion problems. The main conclusion of this thesis is the importance of detection corrosion problems in the initial stage by implementing more effective CM parameters to prevent catastrophic and costly failures, reduce the negative impacts on human life and the environment, and save the economic losses. Another conclusion is the importance of regularly following the measurable variables' uptrend during transformer useful life to avoid incorrect evaluation of corrosion conditions.
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Jürgensen, Jan Henning. "Condition-based Failure Rate Modelling for Individual Components in the Power System." Licentiate thesis, KTH, Elektroteknisk teori och konstruktion, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-187701.
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The electrical power grid is one of the most important infrastructures in the modernsociety. It supplies industrial and private customers with electricity and supportsother critical infrastructures such as the water supply. Thus, it is significant that the power grid is a reliable system. However, the power system experiences a hugetransition from classical production methods such as coal and nuclear power plantsto distributed renewable energy forms such as wind energy and photovoltaic. This change to a more distributed system challenges the existing power grid as well as the traditional business models of electric utilities. Thus, cost minimization to increase profitability and improvement of the power grid to increase customer satisfactionare in the focus. One approach to increase the reliability of the grid and decrease maintenance costs is a condition-based maintenance approach which requirescondition monitoring techniques. This thesis introduces into failure rate modelling for individual power system components and develops a method to calculate individual failure rates based onthe average failure rate, failure statistics, and condition monitoring data. This approach includes the analysis of failure statistics to identify failure causes and failure locations which are population characteristics but can be utilized to describe the heterogeneity within the population. Thus, the thesis first introduces into the topic of failure analysis and heterogeneity in populations. Different factors are identified and categorized which describe the condition development of a component overtime. Then, the literature within failure rate estimation is reviewed to present the factors which are used within failure rate modelling and to outline the existingmethods which consider the individual. However, limitations are discussed which emphasize the demand for a new approach. Consequently, this thesis introduce intoa new approach for estimating the failure rate for individual components.QC 20160526
Energiforsk AB risk analysis program
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Girbino, Michael James. "Detecting Distribution-Level Voltage Anomalies by Monitoring State Transitions in Voltage Regulation Control Systems." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1550483383962611.
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Barbosa, Daniel. "Sistema híbrido inteligente para o monitoramento e proteção de transformadores de potência." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/18/18154/tde-25102010-092314/.
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Este trabalho apresenta um conjunto de métodos para a proteção e o monitoramento de transformadores de potência baseado em sistemas inteligentes e na aplicação das transformadas de Clarke e Wavelet. A abordagem inteligente utilizada permite analisar a condição operativa dos transformadores de potência e detectar a ocorrência de defeito interno, distinguindo-a de outras situações de operação, como, a energização, a energização solidária, a saturação dos transformadores de corrente e a sobreexcitação. As tomadas de decisão das técnicas desenvolvidas são realizadas pela lógica fuzzy após o pré-processamento dos sinais de entrada por meio de diversos métodos, os quais variam de acordo com o algoritmo que esta sendo executado. Os algoritmos propostos foram testados por meio de simulações realizadas através do software Alternative Transients Program (ATP). É importante salientar que nas simulações do ATP foram modelados diversos equipamentos que constituem o sistema elétrico de potência, incluindo um gerador síncrono com regulação de velocidade, linhas de transmissão com variação em frequência, transformadores de potência com suas respectivas curvas de saturação, transformadores de potencial e de corrente. Estas modelagens tiveram por objetivo gerar dados das distintas situações de operação para a verificação e análise da metodologia proposta. Os resultados da pesquisa mostram a aplicabilidade dos algoritmos propostos na proteção e no monitoramento dos transformadores de potência, mesmo nas condições mais adversas, como na ocorrência da saturação dos transformadores de corrente, uma vez que os sinais de entrada distorcidos pela saturação são corrigidos por uma rede neural artificial. Os resultados apresentados comparam as respostas obtidas pelas técnicas propostas em relação às saídas de um relé comercial, habilitado à proteção diferencial percentual.This work presents a set of methods for protecting and monitoring power transformers based on intelligent systems and the application of Clarke and Wavelet transforms. The intelligent approach allowed us to analyze the operating condition of power transformers and it discriminates between an internal fault and different operating conditions, as energization, sympathetic inrush, saturation of current transformers and overexcitation. Decision making is performed by fuzzy logic after the preprocessing of the input signals through various methods, varying according to which algorithm is running. It is important to point out that in the simulations using ATP many different power system equipment had been modeled, including a synchronous generator with speed regulation, transmission lines with variation in frequency, power transformers with their saturation curves, potential transformers and current transformers. The objective of these tests was to generate data for distinct situations for the verification and the analysis of the proposed methodologies. The results of the research show the applicability of the algorithms considered in protection and monitoring of power transformers, even in adverse conditions, such as saturation of current transformers, since the input signals are distorted by CT saturation corrected by artificial neural network. The results are compared to the ones presented by a commercial percentage differential relay.
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Han, Baojia. "Partial discharge monitoring of power transformers." Thesis, University of Southampton, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416467.
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Pradhan, Manoj Kumar. "Conformal Thermal Models for Optimal Loading and Elapsed Life Estimation of Power Transformers." Thesis, Indian Institute of Science, 2004. http://hdl.handle.net/2005/97.
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Power and Generator Transformers are important and expensive elements of a power system. Inadvertent failure of Power Transformers would cause long interruption in power supply with consequent loss of reliability and revenue to the supply utilities. The mineral oil impregnated paper, OIP, is an insulation of choice in large power transformers in view of its excellent dielectric and other properties, besides being relatively inexpensive.
During the normal working regime of the transformer, the insulation thereof is subjected to various stresses, the more important among them are, electrical, thermal, mechanical and chemical. Each of these stresses, appearing singly, or in combination, would lead to a time variant deterioration in the properties of insulation, called Ageing.
This normal and inevitable process of degradation in the several essential properties of the insulation is irreversible, is a non-Markov physico-chemical reaction kinetic process. The speed or the rapidity of insulation deterioration is a very strong function of the magnitude of the stresses and the duration over which they acted. This is further compounded, if the stresses are in synergy. During the processes of ageing, some, or all the vital properties undergo subtle changes, more often, not in step with the duration of time over which the damage has been accumulated. Often, these changes are non monotonic, thus presenting a random or a chaotic picture and understanding the processes leading to eventual failure becomes difficult. But, there is some order in this chaos, in that, the time average of the changes over short intervals of time, seems to indicate some degree of predictability.
The status of insulation at any given point in time is assessed by measuring such of those properties as are sensitive to the amount of ageing and comparing it with earlier measurements. This procedure, called the Diagnostic or nondestructive Testing, has been in vogue for some time now.
Of the many parameters used as sensitive indices of the dynamics of insulation degradation, temporal changes in temperatures at different locations in the body of the transformer, more precisely, the winding hot spots (HST) and top oil temperature (TOT) are believed to give a fairly accurate indication of the rate of degradation. Further, an accurate estimation of the temperatures would enable to determine the loading limit (loadability) of power transformer.
To estimate the temperature rise reasonably accurately, one has to resort to classical mathematical techniques involving formulation and solution of boundary value problem of heat conduction under carefully prescribed boundary conditions. Several complications are encountered in the development of the governing equations for the emergent heat transfer problems. The more important among them are, the inhomogeneous composition of the insulation structure and of the conductor, divergent flow patterns of the oil phase and inordinately varying thermal properties of conductor and insulation.
Validation and reconfirmation of the findings of the thermal models can be made using state of the art methods, such as, Artificial Intelligence (AI) techniques, Artificial Neural Network (ANN) and Genetic Algorithm (GA).
Over the years, different criteria have been prescribed for the prediction of terminal or end of life (EOL) of equipment from the standpoint of its insulation. But, thus far, no straightforward and unequivocal criterion is forth coming. Calculation of elapsed life in line with the existing methodology, given by IEEE, IEC, introduces unacceptable degrees of uncertainty. It is needless to say that, any conformal procedure proposed in the accurate prediction of EOL, has to be based on a technically feasible and economically viable consideration. A systematic study for understanding the dynamical nature of ageing in transformers in actual service is precluded for reasons very well known. Laboratory experiments on prototypes or pro-rated units fabricated based on similarity studies, are performed under controlled conditions and at accelerated stress levels to reduce experimental time. The results thereof can then be judiciously extrapolated to normal operating conditions and for full size equipment.
The terms of reference of the present work are as follows;
1. Computation of TOT and HST
Theoretical model based on Boundary Value Problem of Heat Conduction
Application of AI Techniques
2. Experimental Investigation for estimating the Elapsed Life of transformers
Based on the experimental investigation a semi-empirical expression has been developed to estimate the loss of life of power and station transformer by analyzing gas content and furfural dissolved in oil without performing off-line and destructive tests.
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Tang, Wenhu. "Intelligent condition monitoring and assessment for power transformers." Thesis, University of Liverpool, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.400134.
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Bennoch, Craig John. "UHF monitoring of partial discharges in high voltage transformers." Thesis, University of Strathclyde, 2006. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21681.
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The thesis considers using measurements of Ultra High Frequency (UHF) signals from Partial Discharges (PD) to detect and characterise defect signals in multi-source environments. PD is the result of partial bridging of the insulation medium between electrodes, and can be a precursor to eventual flashover. UHF monitoring techniques became predominant in monitoring Sulphur Hexafluoride (SF6) filled Gas Insulated Substations (GIS). There are some particular characteristics of a PD that make monitoring in this range of signals advantageous, such as fast propagation velocities and low attenuation. These attributes make the technique very suitable to determining the type of PD source and location of the defect with accuracy. The research presented in the thesis uses three UHF sensors to detect PD signals from defects. By simultaneously capturing the UHF signals on three channels of a high bandwidth oscilloscope the time of arrival and signal strengths at the three sensors can be used to form Partial Discharge Cluster Maps (PDCMs), which are one of the main contributions of this research. These enable multiple defect sources to be identified and the defect location to be accurately determined. The application that will be considered in most detail is the use of UHF techniques to characterise defects in High Voltage (HV) oil-filled transformers. This is a relatively new area of research and the thesis discusses the challenges the complex internal structure of a transformer presents. The capability to locate and characterise multisources is shown to be successful. An on-line system was developed for plant assessment. Using this system, the technique was successfully tested on operational transformers and these results are also presented in the thesis.
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MARANHAO, PAULO HENRIQUE COELHO. "CONTROL CHARTS ON TRANSFORMED VARIABLES FOR MONITORING MULTIVARIATE PROCESS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2012. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=21881@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROA maioria dos trabalhos que propõem esquemas de Controle Estatístico de Processos Multivariados (CEPM) e que analisam o desempenho desses esquemas considera alterações nas variáveis observadas. Alguns autores mostraram que, quando alterações no vetor de médias de um processo multivariado ocorrem tipicamente em direções previsíveis, a estatística mais eficaz para o monitoramento do processo é o valor da projeção do vetor de observações (ou de sua média amostral) em cada uma dessas direções. Este trabalho propõe um método para o monitoramento de processos multivariados nos quais alterações nos parâmetros do processo são devidas a causas especiais que afetam variáveis não observáveis e ocorrem em direções conhecidas (ortogonais), e compara seu desempenho com o de gráficos de Shewhart nas variáveis observadas, nas componentes principais, e com o de gráficos de T2 no vetor de variáveis observadas. Além disso, é proposto um esquema complementar de monitoramento para detectar alterações em novas direções fora do hiperplano formado pelas direções conhecidas. Resultados obtidos por simulação mostram que o esquema proposto, de gráficos de controle em variáveis transformadas (projeções do vetor de variáveis observadas nas direções conhecidas), tem melhor desempenho na maior parte dos casos analisados. A análise de desempenho é feita supondo deslocamentos da média nas direções conhecidas (já que estes é que são as alterações conhecidas, ocasionadas pelas causas especiais) e/ou aumentos da variância nessas mesmas direções. A comparação é baseada nas probabilidades de alarme falso e de alarme verdadeiro.
Most of the works that propose schemes of Multivariate Statistical Process Control (MSPC) and that analyze the performance of these schemes consider changes in the observed variables. Previous authors have shown that when the shifts in the mean vector of a multivariate process typically occur in predictable directions, the most effective statistics for process monitoring are the values of the projections of the vector of observations (or of the sample average vector) in each of these directions. This paper proposes a method for the monitoring of multivariate processes in which changes in the process parameters are due to special causes that affect non-observable variables and occur in (orthogonal) known directions, and compares its performance with that of Shewharts charts on the observed variables, on the principal components, and with that of T2 charts on the vector of observed variables. In addition, it is proposed a supplementary scheme of monitoring to detect changes in new directions outside of the hyperplane formed by known directions. Results obtained by simulation show that the proposed scheme, consisting of control charts on the transformed variables (projections of the vector of observed variables on the known directions), has better performance in most of the cases analyzed. The analysis of performance is done assuming shifts in the mean of the known directions (since these are the known changes associated to special causes) and/or increases of the variance in these same directions. The comparisons are based on the in-control and out-of-control probabilities of signal.
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Vilaithong, Rummiya [Verfasser]. "Models for Thermal and Mechanical Monitoring of Power Transformers / Rummiya Vilaithong." Aachen : Shaker, 2011. http://d-nb.info/1070150282/34.
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Crowley, Thomas Henry. "Automated diagnosis of large power transformers using adaptive model-based monitoring." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/13616.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1990.Includes bibliographical references (leaves 173-176).
by Thomas Henry Crowley.
M.S.
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Aburaghiega, Ehnaish Ali F. "Condition monitoring and evaluation techniques for extending power transformers' life cycle." Thesis, Glasgow Caledonian University, 2017. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.743901.
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Zumr, Zdenek. "Last Mile Asset Monitoring: Low Cost Rapid Deployment Asset Monitoring." PDXScholar, 2014. https://pdxscholar.library.pdx.edu/open_access_etds/1967.
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Installation and utilization of residential distribution transformers has not changed substantially over a long period of time. Utilities typically size their transformers based on a formula that takes into account broadly what types and how many dwellings will be connected.
Most new residential dwellings feature 200 Amp service per household with an anticipated energy demand of under 20,000 kWh per year. Average electrical energy consumption varies from state to state but averages to 11,280 kWh per year. Energy demand is expected to fall into a typical residential load curve that shows increased demand early in the morning, then decreasing during the day and another peak early to late evening. Distribution transformers are sized at the limit of the combined evening peak with the assumption that the transformer has enough thermal mass to absorb short overloads that may occur when concurrent loading situations among multiple dwellings arise. The assumption that concurrent loading is of short duration and the transformer can cool off during the night time has been validated over the years and has become standard practice. This has worked well when dwelling loads follow an averaging scheme and low level of coincidence.
With the arrival of electric vehicles (EV's) this assumption has to be reevaluated. The acquisition of an electric vehicle in a household can drive up energy demand by over 4000 kWh per year. Potentially problematic is the increased capacity of battery packs and the resulting proliferation of Level 2 chargers. The additional load of a single Level 2 charger concurring with the combined evening peak load will push even conservatively sized distribution transformers over their nameplate rating for a substantial amount of time. Additionally, unlike common household appliances of similar power requirements such as ovens or water heaters, a Level 2 battery charger will run at peak power consumption for several hours, and the current drawn by the EVs has very high levels of harmonic distortion. The excessive loading and harmonic profile can potentially result in damaging heat build-up resulting in asset degradation.
In this thesis I present a device and method that monitors pole mounted distribution transformers for overheating, collect and wirelessly upload data and initiate commands to chargers to change output levels from Level 2 to Level 1 or shut down EV charging altogether until the transformer returns into safe operational range.
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Lin, Shui-Town. "Gear condition monitoring by wavelet transform of vibration signals." Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318680.
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Paya, Basir Abdul. "Vibration condition monitoring and fault diagnostics of rotating machinery using artificial neural networks." Thesis, Brunel University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390220.
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Babnik, Tadeja. "Condition monitoring of transformers based on non-invasive measurements and characterisation of partial discharges." Thesis, University of Bath, 2005. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760860.
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Gavrilovic, Nenad. "VIBRATION-BASED HEALTH MONITORING OF ROTATING SYSTEMS WITH GYROSCOPIC EFFECT." DigitalCommons@CalPoly, 2015. https://digitalcommons.calpoly.edu/theses/1358.
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This thesis focuses on the simulation of the gyroscopic effect using the software MSC Adams. A simple shaft-disk system was created and parameter of the sys-tem were changed in order to study the influence of the gyroscopic effect. It was shown that an increasing bearing stiffness reduces the precession motion. Fur-thermore, it was shown that the gyroscopic effect vanishes if the disk of system is placed symmetrically on the shaft, which reduces the system to a Jeffcott-Ro-tor. The second objective of this study was to analyze different defects in a simple fixed axis gear set. In particular, a cracked shaft, a cracked pinion and a chipped pinion as well as a healthy gear system were created and tested in Adams. The contact force between the two gears was monitored and the 2D and 3D frequency spectrum, as well as the Wavelet Transform, were plotted in order to compare the individual defects. It was shown that the Wavelet Transform is a powerful tool, capable of identifying a cracked gear with a non-constant speed. The last part of this study included fault detection with statistical methods as well as with the Sideband Energy Ratio (SER). The time domain signal of the individual faults were used to compare the mean, the standard deviation and the root mean square. Furthermore, the noise profile in the frequency spectrum was tracked with statistical methods using the mean and the standard deviation. It was demonstrated that it is possible to identify a cracked gear, as well as a chipped gear, with statistical methods. However, a cracked shaft could not be identified. The results also show that SER was only capable to identify major defects in a gear system such as a chipped tooth.
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Grossman, Hy. "A NEXT GENERATION AIRCRAFT POWER MONITORING SYSTEM." International Foundation for Telemetering, 2007. http://hdl.handle.net/10150/604535.
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ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, NevadaHistorically, aircraft power monitoring has required the use of multiple signal conditioning functions to measure various parameters including voltage, current, frequency and phase. This information was then post processed to determine the characteristics of the 3-phase power quality on the aircraft. Recent developments in embedded DSP processors within signalconditioning systems provide the instrumentation engineer with expanded capabilities for realtime on-board power quality monitoring. Advantages include reduced space and bandwidth requirements and minimal wiring intrusion. For each phase, output data may include peak positive and negative voltages and currents, peak-to-peak, average and RMS voltages and currents, phase power (real and apparent), phase power factor, phase period (frequency), phase shift measurement from phase 1 (the reference phase) to phase 2, and from phase 1 to phase 3. In addition, a Fast Fourier Transform (FFT) is performed on each phase voltage to provide Total Harmonic Distortion measurements. This paper describes the methods employed in the implementation of these functions on a single signal-conditioning card in order to provide detailed information about the power quality of a three-phase aircraft power source.
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Dong, Jun 1971. "Quantitative condition monitoring of lubricating oils by Fourier transform infrared (FTIR) spectroscopy." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36915.
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Three new quantitative Fourier transform infrared (FTIR) spectroscopic methods were developed to measure key lubricant condition monitoring parameters; total acid number (TAN), total base number (TBN), and moisture (H2O). All methods employ a common sample-handling accessory and are based on the addition of specific reagents designed to react stoichiometrically with target species in oils, with quantification being carried out using differential FTIR spectroscopy. The combined use of a stoichiometric reaction and differential spectroscopy overcomes the need for a reference oil, which has traditionally hindered quantitative analysis of lubricants by FTIR spectroscopy. Potassium hydroxide, trifluoroacetic acid (TFA) and 2,2-dimethoxypropane (DMP) were the stoichiometric reagents used to develop the FTIR TAN, TBN and H2 O methods, respectively. Calibrations were developed using either peak height measurements or partial least squares (PLS) regression and the methods were validated using standard addition techniques, as the ASTM (American Society of Testing and Materials) standard methods were not sufficiently reproducible to make valid comparisons. Validation of the methods indicated that the TAN, TBN and H2O methods had accuracies of +/-0.095 mg KOH/g, +/-0.5 mg KOH/g and +/-32ppm respectively and corresponding reproducibilities of +/-0.05 mg KOH/g, +/-0.17 mg KOH/g and +/-22 ppm. The TAN, TBN and H2O methods were implemented on a Continuous Oil Analysis and Treatment (COATRTM) System, integrating instrumentation, software and sample handling so as to provide packaged, user and environmentally friendly analytical methods that are alternatives to conventional ASTM wet chemical methods.
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Hilton, Moira. "Passive emission monitoring of remote combustion gases using Fourier transform infrared spectroscopy." Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262592.
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Liang, Yishan. "Studies of Monitoring and Diagnosis Systems for Substation Apparatus." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/30791.
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Substation apparatus failure plays a major role in reliability of power delivery systems. Traditionally, most utilities perform regular maintenance in order to prevent equipment breakdown. Condition-based maintenance strategy monitors the condition of the equipment by measuring and analyzing key parameters and recommends optimum maintenance actions. Equipment such as transformers and standby batteries which are valuable and critical assets in substations has attracted increased attentions in recently years.
An automated monitoring and diagnosis tool for power transformers based on dissolved gas analysis, ANNEPS v4.0, was developed. The new tool extended the existing expert system and artificial neural network diagnostic engine with automated data acquisition, display, archiving, and alarm notification functions.
This thesis also studied substation batteries types and failure mode and surveyed the market of current on-line battery monitors. A practical battery monitoring system architecture was proposed. Analysis rules of measured parameters were developed. The above study and results can provide basics for further designing of a simple battery monitoring system in industry applications.Master of Science
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Shen, Chia-Hsuan. "Acoustic Based Condition Monitoring." University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1341797408.
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Holeš, David. "Vizualizace a on-line kontrola důležitých parametrů blokových a odbočkových transformátorů jaderné elektrárny Dukovany." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-413207.
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The thesis focuses on a design of visualization and setting limits of important parametres of power and own-consumption transformers at the nuclear power plant Dukovany. In the first part there is a description of a present technical state of oil power transformers at this power plant, including a description of a currently installed transformers monitoring system and electro monitoring system. The second part deals with a design of a visialization of parametrs and a diagram design of active-access displays of monitored parametrs of these transformers. In the thesis there is also a description of web interface with a new visualization. The last part of the thesis contains a design of setting the limits and criteria of important monitoring parametres of these transformers.
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Sandström, Tobias. "Condition Monitoring of Ceramic Ball Bearings in an Engine Testing Dynamometer." Thesis, KTH, Maskinkonstruktion (Inst.), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-183126.
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The choice of the topic addressed in this thesis aims to improve the service and maintenance on ceramic ball bearings in a specific test dynamometer and through an engineering approach develop tools for condition monitoring. The company connected to this thesis, AVL, is the world's largest privately owned company for development, simulation and testing technology of powertrains for passenger cars, trucks and large engines. Engine testing is a critical part of the business at AVL Sweden and unexpected bearing failure can result in long repair times and great economic losses due to loss of the testing time. In short terms, the methodological approach followed the following steps; first a thorough information retrieval regarding bearings and analysis was conducted. The search was deepened around areas such as hybrid ball bearings, bearing failure mechanisms, bearing defect frequencies, signal analysis and condition monitoring. After this a table for bearing damage detection was developed and a “step by step” guidance for condition monitoring. The tools where afterwards verified by simple testing to detect complications within the chosen system. The existing condition monitoring system that is used today revealed weaknesses as it lacked the feature of taking preventive measures. The system that is based on temperature measurements isn’t satisfactory enough, especially when it’s missing visual clarity. Service and maintenance according to specifications from the manufacturer should be scheduled to ensure operational and guarantees. Currently mounted accelerometers on the housing of the Dynas3 engine should be connected for collecting data and the total sum of energy should be calculated for simple monitoring of historical progression. This should be done by following the guidance in order to ensure proper data acquisition. The best way to implement condition monitoring showed to be by performing multi-parameter monitoring. The design of the condition monitoring system is highly connected to what to monitor and at what stage. One main consideration to keep in mind is that it’s very rare that manufacturing defects are the reason for bearing failure. Instead it derives from improper storage, transport, handling or dimensional errors and even in some cases by improperly implemented force analysis prior to bearing selection.Huvudämnet som behandlas i detta examensarbete syftar till att förbättra service och underhåll på keramiska kullager i en viss testdynamometer och genom ett ingenjörsmässigt tillvägagångsätt utveckla verktyg för tillståndsövervakning. Företaget som är ansluten till detta examensarbete är AVL som är världens största privatägda företag för utveckling, simulering och testteknik för drivlinor för personbilar, lastbilar och stora motorer. Motorprovning är en viktig del av verksamheten vid AVL Sverige, och ett oväntat lagerhaveri kan leda till långa reparationstider och stora ekonomiska förluster på grund av utebliven test tid. I korta termer följde den metod som använts följande steg, först genomfördes en grundlig informationssökning om lager och tillhörande analyser. Efter det fördjupades sökande kring områden som hybrida kullager, lagerskademekanismer, frekvenser kopplade till lagerskador, signalanalys och tillståndsövervakning. Efter detta framställdes en tabell för detektering av lagerskador, samt en ”steg för steg” guide för tillståndsövervakning. Verktygen för tillståndsövervakning kontrolleras efteråt, genom att enkla tester genomfördes för att upptäcka komplikationer inom det valda systemet. Det övervakningssystem som används idag avslöjade svagheter genom att sakna funktionen att vidta förebyggande åtgärder. System som är baserat på temperaturmätningar är inte tillräckligt tillfredsställande, speciellt när det saknar en visuell tydlighet. Den service och underhåll som enligt tillverkarens föreskrifter påvisas bör planeras för att säkerställa drift och garantier. Nuvarande monterade accelerometrar fästa vid motorhöljet bör anslutas för att insamla data, och den totala summan av energin bör beräknas för en enkel övervakning av det historiska utvecklingsförloppet. Detta bör göras genom att följa de riktlinjer som framställts för att säkerställa korrekt datainsamling. Det bäst passande sättet att genomföra tillståndsövervakning på i detta fall visade sig vara att utföra multiparameterövervakning. Framställningen av tillståndsövervakningssystemet är starkt förknippat med vad som skall övervakas och i vilket skede. En huvudsaklig bidragande faktor att komma ihåg är att det är mycket ovanligt att fabrikationsfel är orsaken till lagerhaveri. Istället härstammar haveriet från felaktig förvaring, transportering, hantering eller dimensioneringsfel och i vissa fall av felaktigt genomförd kraftanalys inför lagerval.
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Setayeshmehr, Alireza [Verfasser]. "Investigations of Off-Line and On-Line Monitoring and Diagnosis Methods on Power Transformers / Alireza Setayeshmehr." München : Verlag Dr. Hut, 2013. http://d-nb.info/1042307970/34.
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Bisht, Saurabh. "Methods for Structural Health Monitoring and Damage Detection of Civil and Mechanical Systems." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/33672.
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In the field of structural engineering it is of vital importance that the condition of an ageing structure is monitored to detect damages that could possibly lead to failure of the structure. Over the past few years various methods for monitoring the condition of structures have been proposed. With respect to civil and mechanical structures several methods make use of modal parameters such as, natural frequency, damping ratio and mode shapes. In the present work four methods for modal parameter estimation and two methods for have been evaluated for their application to multi degree of freedom structures. The methods evaluated for modal parameter estimation are: Wavelet transform, Hilbert-Huang transform, parametric system identification and peak picking. Through various numerical simulations the effectiveness of these methods is studied. It is found that the simple peak-picking method performs the best and is able to identify modal parameters most accurately in all the simulation cases that were considered in this study. The identified modal parameters are then used for locating the damage. Herein the flexibility and the rotational flexibility approaches are evaluated for damage detection. The approach based on the rotational flexibility is found to be more effective.Master of Science
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Jae, Chan Kim. "Investigation of flow signals for condition monitoring using time-frequency analysis and wavelet transforms." Thesis, University of Sussex, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405977.
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Kaewkongka, Tonphong. "Bearing condition monitoring using acoustic emission and vibration : the systems approach." Thesis, Brunel University, 2002. http://bura.brunel.ac.uk/handle/2438/7862.
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This thesis proposes a bearing condition monitoring system using acceleration and acoustic emission (AE) signals. Bearings are perhaps the most omnipresent machine elements and their condition is often critical to the success of an operation or process. Consequently, there is a great need for a timely knowledge of the health status of bearings. Generally, bearing monitoring is the prediction of the component's health or status based on signal detection, processing and classification in order to identify the causes of the problem. As the monitoring system uses both acceleration and acoustic emission signals, it is considered a multi-sensor system. This has the advantage that not only do the two sensors provide increased reliability they also permit a larger range of rotating speeds to be monitored successfully. When more than one sensor is used, if one fails to work properly the other is still able to provide adequate monitoring. Vibration techniques are suitable for higher rotating speeds whilst acoustic emission techniques for low rotating speeds. Vibration techniques investigated in this research concern the use of the continuous wavelet transform (CWT), a joint time- and frequency domain method, This gives a more accurate representation of the vibration phenomenon than either time-domain analysis or frequency- domain analysis. The image processing technique, called binarising, is performed to produce binary image from the CWT transformed image in order to reduce computational time for classification. The back-propagation neural network (BPNN) is used for classification. The AE monitoring techniques investigated can be categorised, based on the features used, into: 1) the traditional AE parameters of energy, event duration and peak amplitude and 2) the statistical parameters estimated from the Weibull distribution of the inter-arrival times of AE events in what is called the STL method. Traditional AE parameters of peak amplitude, energy and event duration are extracted from individual AE events. These events are then ordered, selected and normalised before the selected events are displayed in a three-dimensional Cartesian feature space in terms of the three AE parameters as axes. The fuzzy C-mean clustering technique is used to establish the cluster centres as signatures for different machine conditions. A minimum distance classifier is then used to classify incoming AE events into the different machine conditions. The novel STL method is based on the detection of inter-arrival times of successive AE events. These inter-arrival times follow a Weibull distribution. The method provides two parameters: STL and L63 that are derived from the estimated Weibull parameters of the distribution's shape (y), characteristic life (0) and guaranteed life (to). It is found that STL and 43 are related hyperbolically. In addition, the STL value is found to be sensitive to bearing wear, the load applied to the bearing and the bearing rotating speed. Of the three influencing factors, bearing wear has the strongest influence on STL and L63. For the proposed bearing condition monitoring system to work, the effects of load and speed on STL need to be compensated. These issues are resolved satisfactorily in the project.
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Zhou, Zen-Hong. "Real time in-situ monitoring and control of silicon epitaxy by Fourier transform infrared spectroscopy." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/12011.
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Subramanian, Anand Swaminathan. "Monitoring Flavor Quality, Composition and Ripening Changes of Cheddar Cheese Using Fourier-Transform Infrared Spectroscopy." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1243949818.
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Memedi, Mevludin. "Mobile systems for monitoring Parkinson's disease." Licentiate thesis, Örebro universitet, Akademin för naturvetenskap och teknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-20552.
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This thesis presents the development and evaluation of IT-based methods and systems for supporting assessment of symptoms and enabling remote monitoring of Parkinson‟s disease (PD) patients. PD is a common neurological disorder associated with impaired body movements. Its clinical management regarding treatment outcomes and follow-up of patients is complex. In order to reveal the full extent of a patient‟s condition, there is a need for repeated and time-stamped assessments related to both patient‟s perception towards common symptoms and motor function. In this thesis, data from a mobile device test battery, collected during a three year clinical study, was used for the development and evaluation of methods. The data was gathered from a series of tests, consisting of selfassessments and motor tests (tapping and spiral drawing). These tests were carried out repeatedly in a telemedicine setting during week-long test periods. One objective was to develop a computer method that would process tracedspiral drawings and generate a score representing PD-related drawing impairments. The data processing part consisted of using the discrete wavelet transform and principal component analysis. When this computer method was evaluated against human clinical ratings, the results showed that it could perform quantitative assessments of drawing impairment in spirals comparatively well. As a part of this objective, a review of systems and methods for detecting the handwriting and drawing impairment using touch screens was performed. The review showed that measures concerning forces, accelerations, and radial displacements were the most important ones in detecting fine motor movement anomalies. Another objective of this thesis work was to design and evaluate an information system for delivering assessment support information to the treating clinical staff for monitoring PD symptoms in their patients. The system consisted of a patient node for data collection based on the mobile device test battery, a service node for data storage and processing, and a web application for data presentation. A system module was designed for compiling the test battery time series into summary scores on a test period level. The web application allowed adequate graphic feedback of the summary scores to the treating clinical staff. The evaluation results for this integrated system indicate that it can be used as a tool for frequent PD symptom assessments in home environments.
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Shrestha, Dilesh Raj. "Bearing condition monitoring : An investigation on the possibility of monitoring aging of the lubricating grease by means of acoustic emission and temperature." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-87220.
Full textAbstract:
Grease is among the most widely used lubricants in rolling element bearings. Proper understanding of the effect of lubrication due to grease aging can provide a significant increase in the life of the engineering systems. However, at present, there is no sufficient understanding of the grease aging effect in rolling elements bearing. This restricts the optimal usage of the bearing and timely monitoring of the grease. The current research work tries to address this issue with an experimental investigation. This project studies the behavior of 4 types of greases in rolling elements bearings for various operating conditions by recording the temperature and acoustic emission data. The aged samples were prepared to keep in the oven at 150 °C for a series of time duration letting it go through the chemical changes and thermal degradation. Tests were carried out in a test rig with the different levels of oxidized greases for 5 hrs time. And the effects in bearing temperature, acoustic emission were recorded. This is an investigation to analyze the effects of grease composition and aging in rolling elements lubrication by means of acoustic emission and bearing temperature. The IR spectroscopy was carried from the samples collected from the oven in order to understand the change in lubricant composition. The results show that the grease with di-urea thickener and base oil of synthetic ether and polyolester gives the best bearing temperature and acoustic emission behavior compared to the other grease type. The possibility of using the acoustic emission and temperature data to monitor the grease aging is also presented. Along with this, the possibility of using the AE statistical methods, AE count method, and energy plot were also explored to relate with the degree of aging.
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Konchuba, Nicholas. "Temperature Compensation Improvements for Impedance Based Structural Health Monitoring." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/44455.
Full textAbstract:
Structural Health Monitoring is a useful tool for reducing maintenance costs and improving the life and performance of engineering structures. Impedance-Based SHM utilizes the coupled electromechanical behavior of piezoelectric materials to detect adverse changes and material and mechanical failures of structures. Environmental variables such as temperature present a challenge to assessing the veracity of damage detected through statistical modeling of impedance signals. An effective frequency shift method was developed to compensate impedance measurements for changes resulting from environmental temperature fluctuations. This thesis investigates how the accuracy of this method can be improved and be applied to a 100oF range of temperatures. Building up the idea of eliminating temperature effects from impedance measurements, this thesis investigates the possibility of using statistical moments to create a temperature independent impedance baseline.Master of Science