An Investigation Into the Impact of Typical Defects on Transformer Oil Pressure: Unveiling the Potential for Fault Localization

Abstract

Large oil-filled transformers are integral components of power systems, but internal arc faults during operation can lead to catastrophic failures, including explosions, which have occurred globally in recent years. These incidents pose significant risks to the stable operation of power systems and, in some cases, endanger the safety of operational and maintenance personnel. This study focuses on a 220 kV transformer, and develops a multiphysics model to investigate the propagation of pressure waves generated by internal arcs in transformer oil. The model analyzes the influence of several factors on pressure wave characteristics, including the iron core, fault point location, arc energy, and the blockage of the oil flow at the lower end of the oil storage tank. Notably, the iron core is a critical factor that must not be overlooked in the modeling process. When compared to models that ignore the iron core, the oil pressure in the upper housing is found to decrease by nearly 40%. Furthermore, the study suggests that deploying more than three distributed sensors within the transformer could enable effective fault source localization. To ensure a sensitive and reliable response to faults, key recommendations for sensor selection are provided: the response threshold should not be less than 0.1 MPa, and the response time should be under 20 ms. The findings of this paper offer essential data and insights for advancing distributed oil pressure sensing technologies in transformers and contribute to enhancing the safe operation of transformer equipment.

Keywords

• Fault localization
• oil pressure characteristics
• pressure wave model
• distributed oil pressure sensors