High-thermal-conductivity GFRP for dry-type air-core reactors: thermal-electrical performance and trade-off analysis

Dry-type air-core reactors suffer from localized overheating due to the limited thermal conductivity of conventional glass fiber reinforced polymer (GFRP) insulation. Enhancing the thermal conductivity of GFRP provides a potential approach for improving reactor heat dissipation; however, excessive incorporation of thermally conductive fillers may compromise electrical insulation reliability. This study establishes an integrated material-to-equipment evaluation framework to investigate the thermal-electrical trade-off of high-thermal-conductivity GFRP (HTC-GFRP) for dry-type air-core reactors. HTC-GFRP samples with different alumina contents were prepared, and their thermal conductivity, dielectric properties, AC flashover voltage, and breakdown strength were experimentally characterized. The results demonstrate that increasing alumina loading effectively enhances thermal conductivity by promoting the formation of thermally conductive pathways, whereas excessive filler incorporation leads to deterioration of insulation performance. Considering both thermal enhancement and electrical insulation reliability, a favorable thermal conductivity range of approximately 0.75–0.95 W/(m·K) was identified. Furthermore, multiphysics simulations of a 10 kV dry-type air-core reactor reveal that increasing the GFRP thermal conductivity from 0.35 to 1.3 W/(m·K) reduces the maximum operating temperature by approximately 3 °C. These results demonstrate the thermal-electrical trade-off of HTC-GFRP and provide quantitative guidance for balancing heat dissipation capability and insulation reliability in dry-type air-core reactors.