Short-Circuit Performance Analysis of a Distribution Transformer Using Coupled Field-Circuit Approach

Abstract

The inability of power transformers to resist a short-circuit (SC) fault significantly impacts the safety of power systems. During SC faults, the leakage field undergoes significant distortion, resulting in large SC electromagnetic forces (EFs), which results in critical mechanical stresses. The finite element method (FEM) might be one of the best non-destructive numerical methods that enable designers to assess the transformer SC performance. Using the FEM, most SC performance analysis studies assume either the three-phase (LLL) or the single-phase-to-ground (LG) SC fault. Moreover, the existing studies use an excitation method that provides a high error rate due to the sensitivity of transient solvers. Furthermore, no considerable attention has been given to analyzing the influence of grounding the wye-connected windings on the SC performance. In this work, a non-linear-transient field-circuit coupled 3-D finite element model is created to analyze the SC performance of a delta-wye connected distribution transformer under various SC fault conditions. Results show that grounding the secondary windings significantly impacts the performance when a LG fault is applied. Except for the LG fault with wye configuration of the secondary windings, the windings SC current and EFs decay/rise over time with an exponential trend till reaching steady state.

Keywords:

• electromagnetic force (EF)
• finite element analysis (FEA)
• non-linear transient
• short-circuit (SC) current
• short-circuit forces

DISCLOSURE STATEMENT

The authors declare that they have no conflict of interest.

Additional information

Notes on contributors

Osamah Al-Dori

Osamah Al-Dori received his BS degree (with honors) in electrical and electronics engineering from Aydın Adnan Menderes University, Aydın, Turkey, in 2021. He is currently working toward the MS degree in electrical and electronic engineering with Gaziantep University. His current research interests include power electronics, design and optimization of electrical machines, and renewable energy.

Atilla Dönük

Atilla Dönük received B.S. degree in electrical and electronics engineering from Inönü University in 2000, and Ph.D. degree in electrical and electronics engineering from Middle East Technical University in 2012 where he has been a Research Assistant between 2002 and 2013. He worked as a guest researcher in the Research Group of Power Systems in Electrical and Computer Science at University of Southampton (UK) between November 2010 and October 2011. He has worked in Department of Electrical-Electronics Engineering at Atatürk University between February 2013 and July 2013. Since July 2013, he has been working as assistant professor in Department of Electrical and Electronics Engineering at Aydın Adnan Menderes University. His research interests include electrical machine design, power electronics, and renewable energy applications.