Experimental data-based transient-stationary current model for inter-turn fault diagnostics in a transformer (original) (raw)
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A Sensitive Method for Identifying winding turn to turn faults in Power Transformer
2011
This paper presents the development of a new approach for diagnosing the occurrence of turn to turn short-circuits in the windings of three-phase power transformers. The main problems of the current differential relay are short circuits of one or more turns of a transformer winding. Hence a new approach using' power differential' is developed to discriminate turn to turn faults by the sum of active power flowing into transformers from each terminal. The proposed scheme is tested using EMTP/ATP as well as an internal fault simulation program and gave reliable and accurate results.
International Journal of Electrical and Electronic Engineering & Telecommunications
The transformer is critical equipment in electrical power systems as it is continuously exposed to various failures. Inter-turns fault in the transformer reduces the turns of the winding, thus it can be detected using a transformer-turns-ratio (TTR) test. On the other hand, the Frequency Response Analysis (FRA) method is used for assessing the mechanical condition of the transformer winding and core. In this paper, the TTR, and FRA methods are proposed to detect the inter-turns fault in the transformer winding. The winding inter-turn fault was investigated using FRA inductive inter-winding measurement and compared with the TTR test. Findings from the statistical analysis showed that FRA inductive inter-winding can detect the inter-turn fault. Finally, acceptance limits for the absolute sum of logarithmic error and standard deviation were proposed. The limits were established based on TTR’s acceptance limit from the IEEE standard. This finding proves that the FRA test can be used to ...
2021
Inter-turn short circuits within the transformer winding are diagnosable through the impulse voltage based frequency response analysis (IFRA). If the diagnosis is made Online, interruption to the power network can be avoided. However, the transformer’s load may influence the frequency response based diagnostic process, and this aspect has not yet been investigated. Motivated by this research gap, experimental investigations were carried out on a three-phase 5 kVA, 440 V/440 V Star/Delta transformer and a three-phase 315 kVA, 11 kV/433 V, Dyn11 distribution transformer, when they were supplying power to loads of different magnitudes and power factors. The influence of the load current and its power factor on the IFRA was observed under the transformer’s healthy condition and with inter-turn short circuits in one of the windings. Investigations under these different loaded conditions revealed that a signature FRA plot developed at a particular load condition cannot be directly used fo...
2016
Power transformers are designed to transmit and distribute electrical power. Depending on the size of a transformer, replacement costs can range from a few hundred dollars to millions of dollars. Performing invasive tests also add to the replacement cost. Hence, there is an increasing need to move from traditional schedule-based maintenance programs to condition-based maintenance. A focused approach is required for diagnostics. Considering the long service life of a power transformer and prevalent use of human judgment (expert), there is a need to develop a knowledge base expert system. This paper proposes a noninvasive approach, using digital signal processing wavelet-based artificial neural network technique for monitoring non stationary variations in order to distinguish between transformer inrush currents and transformer inter-turn faults. The performance of this algorithm is demonstrated on custom-built three-phase transform. Keywords— Transformer, Inrush, Interturn fault, Wave...
Frequency and time fault diagnosis methods of power transformers
Measurement Science Review, 2018
The authors describe experimental and theoretical analyses of faults of power transformer winding. Faults were caused by mechanical effect of short-circuit currents. Measurements of transformer were carried out in high-voltage laboratory. Frequency and time diagnostic methods (method SFRA - Sweep Frequency Response Analysis, impact test) were used for the analyses. Coils of transformer windings were diagnosed by means of the SFRA method and the time impact test. The analyzed methods had a significant sensitivity to a relatively small deformation of coil. In the analysis a new technique for analyzing the effects of short-circuit currents is introduced. This technique is developed for high-voltage transformers (different types of power). The proposed analyses show that it is necessary to analyze the value of short-circuit current. Short-circuit current represents a danger for the operation of the power transformer. The proposed approach can be used for other types of transformers. Mor...