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2008, Electric Power Systems Research
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2012, International Journal of Electrical Power & Energy Systems
2000, IEEE Transactions on Power Delivery
SCADA base transformer maintenance
Diagnosis of electrical equipment, particularly distribution and power transformers, which are considered as the heart of the electric power grid, has been quite important for quite a long time. Transformer diagnosis methods have been introduced and employed to recognize transformer internal defects since many years ago. Turn to turn and disc to disc short circuit in transformer windings are considered as one of the main problems in transformer active part. Flux Division Measurement (FDM) technique is employed specifically to realize internal short circuit in transformer windings. This test is performed as an on-site, non-destructive, fast and simple method to detect turn to turn or disc to disc short circuits in transformer windings. In this study, a 360 MVA, 230 kV/20 kV five-limb step up transformer has been taken as a case in order to clarify the capability of Frequency Response Analysis (FRA) in internal short circuit detection of transformer. Also, FRA tests were performed to ...
The growing amount of information increases the size of the databases. To search the required information from these big data repositories we need some specially designed search techniques for a specific website. There are many searching techniques, but retrieving relevant information is difficult. To overcome these difficulties, semantic web technologies are playing a vital role. However, expansion terms are usually determined on “term co-occurrences†within records. This paper describes a method of implementing a semantic search using query expansion as well as retrieving relevant information by content ranking. These records are retrieved using query expansion and then they were ranked to provide users with the most relevant information. This proposed method helps the information retrieved maintain its relevance.
2011, International Transactions on Electrical Energy Systems
2011, Energy and Power Engineering
International Journal of Science Technology & Engineering
There are many methods of fault diagnosis of Power transformer but among all these FRA is the most suitable method for electrical and /or mechanical faults of a transformer. The concept of FRA has been successfully used as a diagnostic technique to detect the winding deformation of power transformer. In FRA measurement, the nine statistical indicators are used to detect the deviation in FRA signature. The effects of different winding parameters on FRA signature is described. The artificial neural network approach has been proposed to complement these nine indicators. ANN can be used to increase the efficiency and accuracy of diagnosis system. Neural network toolbox is used to train the multilayer feed-forward neural network. The Probabilistic neural network (PNN) approach and General Regression Neural network (GRNN) has been introduced due to its higher sensitivity and accuracy over the neural network. Neural pattern recognition toolbox is used to train the multilayer probabilistic neural network. Different practical case studies and their data are used to train and test the multilayer feed-forward neural network, probabilistic neural network and general regression neural network.Among all these AI techniques PNN gives the best accuracy result. In this work Matlab-2014 is to be used.
2013, Procedia Engineering
2016, Journal 4 Research - J4R Journal
The sweep rate response analysis is wide used technique for establish veiled fault and circumstance observance of power electrical device. The action is administrated by provide a coffee voltage signal of changeable frequencies to the electrical device windings and measures each the input and output signals. These 2 signals provide the specified response of the magnitude relation is named the transfer operate of the electrical device from that each the magnitude and section may be obtained. Frequency response is modification as deliberate by SFRA techniques might indicate a state change within the electrical device, so causes of fault recognized and examination is needed for root cause analysis.
The sweep rate response analysis is widely used technique for identify veiled fault and circumstance monitoring of power transformer. The action is carried out by supply a low voltage signal of changeable frequencies to the transformer windings and measures both the input and output signals. These two signals give the required response of the ratio is called the transfer function of the transformer from which both the magnitude and phase can be obtained. Frequency response is change as deliberate by SFRA techniques may indicate a physical change inside the transformer, and then causes of fault recognized and examination is required for root cause analysis.
2007
The paper presents a mathematical model of disc-type power transformer winding for frequency response analysis (FRA) based on traveling wave and multiconductor transmission line theories. Each disc of the model is described by traveling wave equations, which are connected to each other in a form of multiconductor transmission line model. The model is applied to FRA simulation in order to study winding axial and radial deformation and its delectability. Comparison of the simulated winding deformation cases with the reference FRA traces is given and discussed to explore the potentials of the proposed model for winding fault detection.
2012, Archives of Electrical Engineering
2019, Mantech Publications PVT LTD
Transformer is one of the most basic units in modern power system. The use of ferrite core gives an improvement in this direction since it has very high permeability because of which it can withstand higher voltages at reduced physical sizes. Attention has also been given to the fact that at which frequency the transformer works best, i.e. amplifies the input the most. This can be useful while using ferrite core in testing transformers. The transformer windings compose an electrical network in the space. This network must necessarily have a transfer function. By evaluating this transfer function, we can have a good understanding of the transformer windings and equivalent network which have several meshes depending upon order of transfer function. .When a fault occurs, the windings get displaced and in-turn the distribution of impedance parameters gets disturbed. Transfer function through analyzed by Sweep Frequency Response Analysis (SFRA) of power transformer characteristics.
2013, International Journal of Electrical Power & Energy Systems
2009, 2009 IEEE Electrical Insulation Conference
2000, IEEE Transactions on Power Delivery
2013, Archives of Electrical Engineering
2010, Iet Electric Power Applications
— Frequency response analysis (FRA) is a technique used to diagnose the mechanical integrity of a transformer winding; such diagnostic tools can be of enormous value since power transformers are a critical asset within any electrical network. To minimize the probability of an unexpected outage, or prevent a catastrophic failure, maintenance and monitoring of power transformers is essential for utilities. Over the past couple of decades, FRA has been utilized as an off-line diagnosis method. However, with the recent development in smart grid systems, there is now a growing interest in the development of on-line FRA techniques. This paper proposes a technique for in-service monitoring of power transformer winding deformation, which uses a broad frequency sine wave voltage excitation signal and high frequency Current Transformers (CT) in conjunction with the bushings test taps. Experiments using this system were conducted and then validated on a single-phase 22kV/110V voltage transformer.
2009, IEEE Transactions on Power Delivery
2014, Electric Power Systems Research
2010
The frequency response analysis (FRA) is a well-established method used for assessment of the mechanical and electrical conditions of power transformer windings. The evaluation of the winding condition is done by comparison between an actual FRA and a reference FRA, which are carried out previously. A deviation between both FRA curves can indicate a change of the winding condition of the tested transformer. According to the standard of knowledge, the connections between measuring device and transformer terminals, as well as the grounding technique are of main importance for a good repeatability. Additionally, a power transformer is a large construction that needs long cables and grounding lines for the signal transmission. Against this background, it is clear, that the geometric arrangement of the measuring setup may not be the same as it was at the reference measurement and this change can have an influence on FRA results. Therefore, an excellent repeatability of the measurements i...
2002, IEEE Power Engineering Review
2003, IEEE Transactions on Power Delivery
2015, Ieee Transactions on Dielectrics and Electrical Insulation
1992, IEEE Transactions on Power Delivery
Frequency response analysis (FRA) is a powerful and sensitive tool to assess the mechanical and geometrical integrity of core, windings and clamping structures within power transformers, by measuring their transfer functions over a wide frequency range. Despite a rapidly increasing number of users throughout the world and a significantly growth of knowledge about the application of the method, the only current, valid and obligatory national standard is in the Peoplepsilas Republic of China. Intensive work is being carried out in organizations such as Cigre and IEEE to create international guidelines for the use of FRA. The paper gives an overview about the status of this work.
2015, IEEE Transactions on Dielectrics and Electrical Insulation
Transformers is one of the key equipment of the power system. Power rating of the transformers varies from KVA to several hundreds of MVA. The transformer is expensive equipment of the power system. Failures of transformer usually lead to substantial profit loss to the utility, potential environmental damage, explosion and fire hazards and expensive repairing or replacement costs, thus, it is desirable that the maximum service life of transformer is required. Condition monitoring of transformer can help to increase the life of the transformer and reduce the maintenance cost. Online monitoring is the record of significant data of a transformer and analysis of data and including the history of the transformer. In this paper percent the different techniques adopted for condition monitoring of transformer.
2000, IEEE Transactions on Industrial Electronics
2012
Ingenieria e Investigación
El monitoreo en transformadores basado en la condición de operación (pruebas en línea) ha tenido un gran auge en los últimos años debido a que facilita detectar oportunamente situaciones de riesgo o limitaciones de utilidad que permita tomar decisiones oportunas, antes de que ocurra una falla. Una de las técnicas en la cual se viene investigando con fuerza para el desarrollo en línea es el análisis de la respuesta en frecuencia (FRA), la cual se basa en obtener la respuesta en frecuencia (admitancia, impedancia, o función de transferencia) del transformador en un ancho de banda determinado. El siguiente artículo presenta un método experimental para obtener la respuesta en frecuencia con el transformador en servicio, por medio de la inyección de pulsos controlados sobre la señal de voltaje, usando un circuito electrónico externo. Una vez registradas las señales de voltaje y corriente, se usó la transformada Wavelet mediante el análisis multirresolución (MRA) para el filtrado, lo que ...
2007, International Conference on Power Systems Transients (IPST’07) in Lyon, France
2012, 2012 IEEE International Symposium on Electrical Insulation
2007, COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering
2002, European Transactions on Electrical Power
Transient currents can cause the mechanical displacement of transformer windings. The transfer function method is presented as a tool to detect this displacement. In order to be able to evaluate the measurements, the correlation between the characteristics of transfer functions and possible damages must be known. Axial displacement of transformer windings has been studied in this research. As test object a transformer with a primary winding of 31 double inverted disk (approx. 1.3 MVA, 10 kV) and a secondary winding with four layer concentric winding was used. A detailed mathematical model was developed for the test object and a comparison was carried out between measured and calculated results. To compare the sensitivity of transfer functions, five different transfer functions with different terminal conditions are simulated. It is shown that the detailed model can present the behaviour of the transformer winding in case of sound and displaced windings.