Search results for: Ferroresonance

Authors: G. Mokryani, M. R. Haghifam, J. Esmaeilpoor

Abstract:

Happening of Ferroresonance phenomenon is one of the reasons of consuming and ruining transformers, so recognition of Ferroresonance phenomenon has a special importance. A novel method for classification of Ferroresonance presented in this paper. Using this method Ferroresonance can be discriminate from other transients such as capacitor switching, load switching, transformer switching. Wavelet transform is used for decomposition of signals and Competitive Neural Network used for classification. Ferroresonance data and other transients was obtained by simulation using EMTP program. Using Daubechies wavelet transform signals has been decomposed till six levels. The energy of six detailed signals that obtained by wavelet transform are used for training and trailing Competitive Neural Network. Results show that the proposed procedure is efficient in identifying Ferroresonance from other events.

Keywords: Competitive Neural Network, Ferroresonance, EMTP program, Wavelet transform.

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Authors: Sezen Yildirim, Tahir Çetin Akinci, Serhat Seker, Nazmi Ekren

Abstract:

Ferroresonance is an electrical phenomenon in nonlinear character, which frequently occurs in power system due to transmission line faults and single or more-phase switching on the lines as well as usage of the saturable transformers. In this study, the ferroresonance phenomena are investigated under the modeling of the West Anatolian Electric Power Network of 380 kV in Turkey. The ferroresonance event is observed as a result of removing the loads at the end of the lines. In this sense, two different cases are considered. At first, the switching is applied at 2nd second and the ferroresonance affects are observed between 2nd and 4th seconds in the voltage variations of the phase-R. Hence the ferroresonance and nonferroresonance parts of the overall data are compared with each others using the Fourier transform techniques to show the ferroresonance affects.

Keywords: Ferroresonance, West Anatolian Electric Power System, Power System Modeling, Switching, Spectral Analysis.

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Authors: Chun-Wei Huang, Jyh-Cherng Gu, Ming-Ta Yang

Abstract:

Non-synchronous breakage or line failure in power systems with light or no loads can lead to core saturation in transformers or potential transformers. This can cause component and capacitance matching resulting in the formation of resonant circuits, which trigger ferroresonance. This study employed a wavelet transform for the detection of ferroresonance. Simulation results demonstrate the efficacy of the proposed method.

Keywords: Ferroresonance, Wavelet Transform, Intelligent Electronic Device, Transformer.

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Authors: M. H. Mohammadi Sanjani, A. Oraee, M. Fotuhi-Firuzabad, A. Amirnia, A. Taheri, M. Arabi

Abstract:

Ferroresonance effects cause overvoltage in medium voltage transformers and isolators used in electrical networks. Ferroresonance effects are nonlinear and occur between the network capacitor and the nonlinear inductance of the voltage transformer during saturation. This phenomenon is unwanted for transformers since it causes overheating, introduction of high dynamic forces in primary coils, and rise of voltage in primary coils for the voltage transformer. Furthermore, it results in electrical and thermal failure of the transformer. Expansion of distribution lines, design of the transformer in smaller sizes, and the increase of harmonics in distribution networks result in an increase of ferroresonance. There is limited literature available to improve the effects of ferroresonance; therefore, optimizing its effects for voltage transformers is of great importance. In this study, comprehensive modeling of a medium voltage transformer is performed. In addition, a model is proposed to improve the performance of voltage transformers during the occurrence of ferroresonance using damping oscillations. Also, transformer design optimization is presented in this study to show further improvements in the performance of the voltage transformer. The proposed model is experimentally tested and verified on a medium voltage transformer in the laboratory, and simulation results show a large reduction of the effects of ferroresonance.

Keywords: Optimization, voltage transformer, ferroresonance, damper.

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Authors: George Eduful, Yuanyuan Fan, Ahmed Abu-Siada

Abstract:

This paper investigates the dynamic behaviour of a 200 kVA, 11/0.433 kV cable-fed transformer under ferroresonance conditions using an analytical approach. The objective is to gain insight into the characteristics of ferroresonance and identify potential solutions for mitigating its effects in power distribution networks. To achieve this, a simplified mathematical model was developed, incorporating the transformer's inductive reactance and the capacitance of the cable. The nonlinear magnetic characteristics of the transformer were represented using a typical magnetising curve for a transformer of this capacity. MATLAB simulations were employed to validate the accuracy of the mathematical model. Frequency analysis of both the model and the simulation confirmed the occurrence of fundamental-mode ferroresonance. It was found that ferroresonance in cable-fed transformers can lead to severe voltage oscillations with increased amplitudes. While the mathematical model provides a valuable framework for understanding the circuit's behaviour, the simulation results emphasise the importance of considering nonlinearities and real-world component variations for accurate predictions.

Keywords: Ferroresonance, cable-fed transformer, Poincaré maps, MATLAB Simulation.

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