Evaluation of Power Transformer Thermal Performance and Optical Sensor Positioning Using CFD Simulations and Temperature Rise Test

Abstract

The internal temperatures and the ability to dissipate the heat from active part influence the windings insulation deterioration and determine how long power transformers are able to remain in operation. Due to the great importance of these equipments for the electrical system, studies to avoid failures and early ageing are needed. This paper presents an evaluation of thermal performance of power transformers and the optical fiber sensors positioning to temperature monitoring. For this is performed an experimental and numerical methodology, comparing the measurements during the temperature rise test of single-phase prototype power transformer, under ODAN cooling system conditions equipped with 20 optical fiber sensors along its windings, to the obtained results of computational fluid dynamics (CFD) simulations performed in ANSYS® Fluent software. It was verified that the punctual temperature measured by optical sensors may not accurately represent the critical temperatures along transformers windings and the windings arrangements impact on oil flow and temperature distribution, as the number and positioning of block washers, being necessary to be considered in previous studies for a better positioning of the sensors and temperature monitoring.