Improved power transformer winding fault detection using FRA diagnostics – part 2: radial deformation simulation (original) (raw)
Related papers
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.
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.
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.
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
2007
This paper discusses the possibility of utilizing power transformer modelling for interpretation of frequency response analysis (FRA) measurements. FRA is a reliable technique for power transformer winding distortion and deformation assessment and monitoring. A lumped parameter model of a three phase power transformer is briefly presented and applied to simulate frequency responses at various winding fault conditions such as short-circuited turns, axial displacements and radial deformations. Simulations and discussions are presented to explore the potentials of the model to transformer fault detection based on FRA measurements.
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.
Effect of the Asymmetrical Axial Displacement of Transformer Windings on Fra Characteristics
Journal of critical reviews, 2020
Frequency response analysis (FRA) is one of the most reliable and useful methods for mechanical fault detection in transformers. The winding axial displacement is one of the mechanical fault types that can occur in transformers. Axial displacements causes the detailed model parameters changing, in response to which FRA characteristics will also change. Numerous researchers have considered winding axial displacements as a symmetrical movement of disks. However, one of the most prevalent types of winding axial displacements is asymmetrical axial displacement which has not been considered by any prior studies. In this paper, physical asymmetrical and symmetrical axial displacements of the first disk of the LV winding were simulated and FRA characteristics were obtained for these cases. Finally, experimental tests were performed on an experimental transformer to validate the simulation results.
Recognition of power transformer winding movement and deformation using FRA
COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, 2007
Purpose -The purpose of this paper is to present a frequency domain technique for the recognition and location of winding movements and mechanical deformations in power transformers. Both, axial and radial coil movements, as well as changes in clamp pressure will be studied. Design/methodology/approach -The developed algorithm is based on using a distributed s-domain parameter equivalent network, which is cascaded with other sections to constitute a generalized model. The frequency domain transfer admittance is used as the main criterion to recognize, identify and locate the winding movement and deformation. Findings -In order to reduce the number of failures due to winding movements and deformations, it is suggested to measure and store the transfer admittance over frequency range 0-10 MHz region at normal operation as saved data for comparison with the corresponding data during failure. With the proposed technique, the type and the location of eventual displacement, as well as the number discs involved can be identified. Research limitations/implications -Although the simulation was based on real experimental data adopted from the literature, the algorithm should be tested for real transformers. Several checks have been conducted in order to validate the mathematical model. Originality/value -A relatively simple mathematical model has been presented. It can be used for any transformer, to check the integrity of the winding in order to meet certain degree of equipment safety and reliability.
Detection of minor winding deformation fault in high frequency range for power transformer
2010
This paper presents a simplified distributed parameter model for minor winding deformation fault analysis of power transformers on the basis of frequency response analysis (FRA). The FRA data of an experimental transformer is employed as a reference trace, which are compared with the simulations of the simplified distributed parameter model concerning minor winding deformation faults. In order to perform quantitative analysis when a deformation fault occurs, three statistical indicators are used to analyze the FRA simulation data. It is suggested in the results that minor winding deformation faults can be detected at the frequency range above 1 MHz.
IET Science, Measurement & Technology
One of the main drawbacks of the frequency response analysis (FRA) technique that is widely accepted as the most reliable tool to detect transformer internal mechanical deformations is the inconsistent interpretation of the measured signature because of its reliance on personal expertise more than standard codes. Moreover, conventional FRA signature has a very low accuracy in detecting incipient and low mechanical fault levels. In order to avoid inconsistent interpretation for the transformer FRA signatures and improve its accuracy to detect minor fault levels, a reliable automated technique has become essential. This paper investigates the feasibility of utilizing FRA polar plot to detect minor radial deformation levels within two, 3-phase power transformers of different ratings and winding configurations simulated using three-dimensional finite element analysis software. Simulation results are validated through experimental measurements. Results of this paper are also compared with the results obtained for other types of transformer winding deformations that are published in the literature in order to identify unique impact for each fault type on the proposed method. Findings reveal the superiority of the proposed approach over existing conventional technique in terms of accurate identification and quantification for minor transformer winding deformations.