Research on the Electric Field- Temperature Coupling Characteristics of Insulating Oil-Paper Materials for Converter Transformers

This study focuses on the electric field-temperature coupling characteristics of converter transformer oil-paper insulation materials, aiming to establish a characteristic database for oil-paper insulation materials to support the development of a multi-physics coupling model for converter transformers. First, the dielectric constant and electrical conductivity models of oil-paper insulation materials under different electric and temperature fields are analyzed, revealing the nonlinear characteristics of the material under multi-field coupling. Next, a testing platform for the dielectric constant and electrical conductivity of insulation materials is established to provide data support for modeling the nonlinear characteristics of oil-paper insulation materials. Finally, experimental results show that the conductivity of insulating oil decreases and then increases within the 1–3 kV Imm electric field range, while the conductivity of insulating oil increases by approximately one order of magnitude as the temperature rises to 90°C. The conductivity of the insulating paper changes by nearly two orders of magnitude with temperature variation. The relative dielectric constant of insulating oil decreases by approximately 3.2% from 30°C to 90°C, while the insulating paper increases by approximately 4.3%, with no significant pattern observed for electric field intensity variation. The findings of this study will provide significant references for the digital transformation of electrical equipment and contribute to the development of smart grids.