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Layered Shielding Structure in Oil-Immersed Transformers for Suppressing Resonances Caused by Non-Standard Lightning Waveforms
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Keyvan Rostampour1   , Mohammad Tolou Askari *2 , Mahdi Izadi3 , Mohammad Sadegh Younesian4 |
1- Department of Electrical Engineering, Se.C., Islamic Azad University, Semnan, Iran, Department of Electrical Engineering, Se.C., Islamic Azad University, Semnan, Iran.
2- Department of Electrical Engineering, Se.C., Islamic Azad University, Semnan, Iran. , m.askari1980@iau.ac.ir
3- Department of Electrical Engineering, Shahr.C., Islamic Azad University, Shahriar, Iran., Department of Electrical Engineering, Shahr.C., Islamic Azad University, Shahriar, Iran.
4- Department of Electrical Engineering, Sha.C., Islamic Azad University, Shahrood, Iran., Department of Electrical Engineering, Sha.C., Islamic Azad University, Shahrood, Iran. |
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Abstract: (18 Views) |
This paper presents a novel internal shielding structure for the winding of oil-immersed transformers, aimed at mitigating insulation stress caused by non-standard lightning waveforms. Unlike conventional approaches that rely on standardized test models (such as µs10/350 or µs8/20), this study utilizes a set of real-world data including multi-peak waves, high amplitudes, and long-duration pulses representative of natural lightning observed in dry and mountainous regions of Iran. A detailed winding model, along with a multilayer shielding design optimized for placement between critical winding disks, has been developed using a hybrid EMTP and FEM simulation framework. The results show that the proposed shielding structure significantly improves voltage distribution along the winding and reduces frequency resonances—which are responsible for local voltage spikes—by up to 65%. A comparative analysis of the transformer’s response under three conditions—no shield, conventional shield, and the proposed shield—demonstrates the superior performance of the proposed design in suppressing transient overvoltages. These findings can contribute to the enhanced design of distribution transformers in lightning-prone areas and serve as a basis for revising electrical equipment testing standards. |
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| Keywords: Oil-immersed transformer, non-standard lightning waveform, internal protective shield, frequency resonance, EMTP, FEM, resilient design. |
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Full-Text [PDF 896 kb]
(10 Downloads)
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Type of Study: Research |
Subject:
Special
Received: 2025/10/26 | Accepted: 2026/01/14 | Published: 2026/03/1
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| * Corresponding Author Address: Department of Electrical Engineering, Se.C., Islamic Azad University, Semnan, Iran. |
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