Condition Monitoring of Power Transformer by using SFRA Test (original) (raw)
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Procedia Engineering, 2013
Distribution transformer is the key element in the electricity transmission throughout the nation. Hence, serious attention for the transformer condition monitoring is a crucial. With an occurrence of short-circuit in the power system, the transformer active parts such as core and winding will experience a mechanical movement created by the electromagnetic forces. There are various types of transformer condition monitoring measurement in market, but the monitoring of the mechanical movement in transformer is still lacking. Therefore, Sweep Frequency Response Analysis (SFRA) has been introduced to assess any mechanical movement especially of the transformer's core and winding. The frequency response of the transformer provides mechanical information of core and winding conditions. The SFRA measurement results were validated using the actual transformer untanking process.
Application of Sweep Frequency Responnse Analysis (Sfra) Method to Detect Transformer Fault
Journal of emerging technologies and innovative research, 2021
Power transformer is the most important device for reliable power system. While working with it, many faults may occur in it. Diagnosis of these faults can be done with lot of techniques. Here in this paper, transformer fault detection by Sweep Frequency Response Analysis (SFRA) technique has been introduced. The SFRA is nothing but monitoring the change occur in the transformer R-L-C network parameter. SFRA measurement can be done by using sweep frequency of the range of 20 Hz to 20 MHz range. These sweep frequencies applied to transformer in healthy and faulty condition. SFRA gives the results in the form of signature curve in both healthy and faulty cases. This obtained signature curve confirms the exact location of fault. This paper presents simulation study of transformer equivalent circuit with implementation of SFRA technique and shows the SFRA results with both healthy and faulty condition.
Condition Assessment of Power Transformers by Swift Frequency Response Analysis
Monitoring the health of power transformer is important for the reliability of electrical power supply. Conventional tests carried out on power transformers can only detect damage of permanent nature. Frequency Response Analysis (FRA) is found to be a useful tool for reliable detection of incipient mechanical fault in a transformer. There are various methods of evaluating the frequency spectrum to confirm the presence of an incipient fault. This paper aims to present the signature of single phase autotransformer 33MVA based on FRA data using signal processing techniques, taking into consideration the recommended frequency range specified by Doble Engineering Company. Thus, it is found that the proposed technique is very efficient and effective in analyzing and detecting accurately the type of mechanical fault existing in a power transformer. This paper presents technical details regarding Sweep Frequency Response Analysis (SFRA) and the role it plays in transformer test and maintenance. SFRA is an electrical test that provides information relating to transformer mechanical integrity. This paper details the use of sweep frequency response as a diagnostic tool to detect winding deformation and core displacement in power transformers. Practical case studies are presented that demonstrates the effectiveness of this technique.
SFRA, Detect Of Winding Deformation in Power Transformer
IOSR Journal of Electrical and Electronics Engineering, 2014
The sweep frequency response analysis is extensively used technique for detect hidden fault and condition monitoring of power transformer. The operation is carried out by supply a low voltage signal of varying frequencies to the transformer windings and measuring 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 measured by SFRA techniques may indicate a physical change inside the transformer, and then causes of fault identified and investigation is required for root cause analysis.
Electric Power Systems Research, 2008
The sweep frequency response analysis (SFRA) is an analysis technique for detecting winding displacement and deformation (among other mechanical and electrical failures) on power and distribution transformers. Nowadays, there is an increasing interest in SFRA method because of its sensibility in detecting mechanical faults without opening the unit. SFRA as a diagnostic technique must integrate both the off-line measurements and the interpretation of the data in order to provide an assessment of the condition of the windings. However, guidelines for the measurement and record interpretation are not available. The evaluation is presently done by experts in the topic through the visual inspection or with the help of statistical parameters such as the correlation coefficient and the standard deviation. However, criteria like the limits of normal variation of the parameters, and the features observed in the records in the presence of a determined type of fault could not to coincide. Although, there are some proposals for making the interpretation more objective, neither of them integrate human expertise along with the different kind of parameters obtained from the evaluation of the records in a diagnostic model. This paper presents a survey on the alternatives in the measurement techniques and interpretation of SFRA measurements, describing some sources of uncertainty in applying this methodology.
Sweep Frequency Response Analysis (SFRA) has turned out to be a powerful and sensitive method to evaluate the mechanical integrity of core, windings and clamping structures within power transformers by measuring their electrical transfer functions over a wide frequency range. The contribution summarizes various aspects of the practical application of SFRA. After a short introduction of SFRA basics a survey of existing standards and guides on FRA is given. The different sources of reference data and their significance are discussed. Uncertainties are shown and tips for dealing with them are presented. The choice of test types is discussed for measurements without existing reference data. Information about the handling of test data is mentioned. Finally a summary of guidelines derived from a large number of successful measurements is given to put the reader in a position to achieve a good degree of repeatability, too.
Effects of VA Rating on the Fault Diagnosis of Power Transformer Using SFRA Test
European Journal of Electrical Engineering, 2021
The electric power transformer is an essential part of an electrical power system since it is used to step up or down voltage levels to maintain the system performance as well as possible. Frequency response analysis (FRA) is one of the most widely used techniques for detecting various types of mechanical damage in transformers. The equivalent circuit of the transformer will be represented by a complex network of R, L, and C elements in the FRA technique. For transformer faults diagnosis, various calculation techniques and diagnostic techniques may be used, such as acoustic emission analysis, thermal images of electromagnetic radiation, transformer temperature, and humidity analysis. SFRA test is one of these techniques that could be used to determine the fault type based on its response over a wide frequency range. The main challenge of the SFRA test is that the functional interpretation requirement for this test is not universally accepted Also statistical features are defined for...
A Review of Frequency Response Analysis Methods for Power Transformer Diagnostics
Energies, 2016
Power transformers play a critical role in electric power networks. Such transformers can suffer failures due to multiple stresses and aging. Thus, assessment of condition and diagnostic techniques are of great importance for improving power network reliability and service continuity. Several techniques are available to diagnose the faults within the power transformer. Frequency response analysis (FRA) method is a powerful technique for diagnosing transformer winding deformation and several other types of problems that are caused during manufacture, transportation, installation and/or service life. This paper provides a comprehensive review on FRA methods and their applications in diagnostics and fault identification for power transformers. The paper discusses theory and applications of FRA methods as well as various issues and challenges faced in the application of this method.
Study on locating transformer internal faults using sweep frequency response analysis
Electric Power Systems Research, 2017
As an extensive network of resistances, capacitances, and inductances, a transformer has inherent characteristic parameters that are functions of frequency. The form of these functions is predicated on the geometric design of the transformer and materials that comprise it. Any change in the structure of a transformer will be reflected in its frequency response characteristics. Of the possible changes that can take place in a transformer structure, an internal short circuit is one of the far-reaching incidents that has been recently reported for many wind-farm transformers. Detecting the location of an internal short circuit that has occurred in a transformer winding is therefore beneficial in the repair process and also in improving future designs. In an effort to identify trends with inter-turn fault locations and frequency responses, this research investigates the effect of the location of deliberately initiated internal faults on parameters such as transfer voltages and input impedances by means of sweep frequency response analysis (SFRA). The analysis of three different model transformers with different core and winding designs shows several trends in frequency response patterns, depending on the location of the internal short circuits. The paper discusses such trends as a potential use of SFRA in locating inter-turn winding failures that may result in noticeable short circuits.
Transformer Fault Diagnosis Using Frequency Response Analysis - Practical Studies
2011
Any failures in these equipments directly reduce network reliability and increase maintenance costs. Consequently, the preventive maintenance techniques are increasingly developed. In this regard, frequency response analysis is an appropriate method in order to diagnose any change which occurs in transformer physical construction.