Effect of the Asymmetrical Axial Displacement of Transformer Windings on Fra Characteristics (original) (raw)
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IEEE Transactions on Dielectrics and Electrical Insulation, 2015
Frequency response analysis (FRA) has become a widely accepted tool to detect power transformer winding deformation due to the development of FRA test equipment. Because FRA relies on graphical analysis, interpretation of its signature is a very specialized area that calls for skilled personnel, as so far, there is no reliable standard code for FRA signature identification and quantification. Many researchers investigated the impact of various mechanical winding deformations on the transformer FRA signature using simulation analysis by altering particular electrical parameters of the transformer equivalent electrical circuit. None of them however, investigated the impact of various physical fault levels on the corresponding change in the equivalent circuit parameters. In this paper, the physical geometrical dimension of a single-phase transformer is simulated using 3D finite element analysis to emulate the real transformer operation.
The Characteristics of Frequency Response on Winding Faults and Configurations of Transformer
Thesis, 2019
This research presents a study on the monitoring of several winding configurations of power transformers using Frequency Response Analysis (FRA). The frequency response provides indications of any mechanical and electrical changes in the transformer's active parts. Three three-phase transformers were tested with the aim to investigate their FRA responses due three case studies. They are due to vector group, three types of faulty winding and also the effect of coupling in the three-phase coretyped transformers. The tests were repeated to three transformers to carry out the desired condition scenario of the FRA responses. The first case is to investigate the characteristics of the FRA response due to different vector groups. It is found that it gives subtle to the response and mainly altering the medium frequency region. The second case study is the investigations of the effect of three types of faulty winding in the FRA response. They are performed by physically simulate the faults to the transformers. The faults are inter-turn short circuit (SC) fault, local overheating and radial deformation. The results show that the SC causes the starting magnitude to increase and the resonance at the low frequency region to shift towards higher frequencies. Meanwhile, during local overheating fault, the winding carries out additional resistance at the winding. It is found that it causes the alteration of the response at the very low frequency region. Lastly, the study found that radial deformation causes the responses to change in the mid-frequency region. The third case study is to investigate the effect of coupling in the three-phase transformers. This is performed by investigating the effect of fault at winding of other phases to the response of measured phase. It is found that faulty occurred in winding of other phases could actually affect the response of measured winding. The location of the fault determines how severe it is affecting the response. The findings from this research could be helpful in enriching the knowledge to evaluate the FRA response.
Ieee Transactions on Dielectrics and Electrical Insulation, 2015
Frequency response analysis (FRA) has become a widely accepted tool to detect power transformer winding deformation due to the development of FRA test equipment. Because FRA relies on graphical analysis, interpretation of its signature is a very specialized area that calls for skilled personnel, as so far, there is no reliable standard code for FRA signature identification and quantification. Many researchers investigated the impact of various mechanical winding deformations on the transformer FRA signature using simulation analysis by altering particular electrical parameters of the transformer equivalent electrical circuit. None of them however, investigated the impact of various physical fault levels on the corresponding change in the equivalent circuit parameters. In this paper, the physical geometrical dimension of a single-phase transformer is simulated using 3D finite element analysis to emulate the real transformer operation.
IEEE Power Engineering Review, 2002
Short circuit currents or forces during transport can cause mechanical displacements of transformer windings. The transfer function method is presented as a tool to detect these displacements. 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 and radial deformation of transformer windings have been studied in this research work using two test transformers. The primary winding of the first transformer for axial displacement has 31 double disk coils (1.3 MVA, 10 kV) and the secondary winding is a four layer winding. The second transformer for the study of radial deformation has 30 double disk coils (1.2 MVA, 10 kV) as primary winding and a one layer winding as secondary winding. The detailed mathematical models were developed for the test objects and a comparison was carried out between measured and calculated results. It is shown that this model can present the behavior of the transformer windings in the frequency domain in the case of sound and displaced conditions.
Fault location of transformer winding deformation using frequency response analysis
2001
FRA (frequency response analysis) is the best effective method that can successfully detect transformer winding deformation. This paper tries to diagnose the fault by the winding's physical parameter changes. At frequencies lower than critical frequency, the transformer winding may be modeled as a lossless transmission line that the series capacitance could be easily neglected. The parameters of inductance and grounding capacitance may be determined respectively. Any change in these parameters then should reflect the probable position of transformer winding deformation
Modeling of frequency response of transformer winding with axial deformations
Archives of Electrical Engineering, 2014
One of important methods used for diagnostics of a transformer’s active part is Frequency Response Analysis (FRA). It allows to determine the mechanical condition of windings, their displacements, deformations and electric faults, as well as some problems with internal leads and connections, core and bushings. Still pending problem is interpretation of measurements results. One of approaches is application of computer modeling to simulate various failure modes and connected with them changes in FRA response. The paper presents two types of models, one based on lumped parameters with RLC elements, and one based on distributed parameters with TLM method. Both methods give similar results, comparable to real measurements of simulated coil
Investigations on sensitivity of FRA technique in diagnosis of transformer winding deformations
2004
This work studies the sensitivity of frequency response analysis (FRA) method in detecting different types of deformations on a 6.6 kV plain disc type transformer winding. Winding deformations such as axial displacements and inter-turn faults are experimentally simulated and the measured FRA results are presented. A high frequency transformer-winding model is developed to investigate the sensitivity of the FRA method for these winding deformations. A comparison is carried out and a good agreement is shown between measured and calculated FRA results.
Characterization of transformer FRA signature under various winding faults
2012 IEEE International Conference on Condition Monitoring and Diagnosis, 2012
Frequency response analysis (FRA) is gaining global popularity in detecting power transformer winding and core deformations due to the development of FRA test equipment. However, because FRA relies on graphical analysis, interpretation of its signatures is still a very specialized area that calls for skillful personnel to detect the sort and likely place of the fault as so far, there is no reliable standard code for FRA signature classification and quantification. This paper aims to initiate the establishment of standard codes for FRA signature interpretation through comprehensive simulation analysis on a detailed transformer distributed parameters-based model. Various mechanical faults such as axial displacement, buckling stress, disk space variation and bushing fault are simulated on the model to study its impact on the FRA signature. The main contribution of this paper is the comprehensive table it presents for FRA signature sensitivity to winding and core deformations that can be used for classification and quantification of the transformer FRA signature.
Ability of transfer function method to diagnose axial displacement of transformer windings
European Transactions on Electrical Power, 2002
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.