Research on engineering selection methods for electromagnetic lines and insulation materials of UHV converter transformers under extreme margin conditions

As the transmission capacity of the ± 800 kV ultra-high voltage project is increased to 10 GW and the ± 1100 kV project capacity is increased to 12 GW, the requirements for the flow level of various equipment have been improved. Due to the limited overall design size, the design margin of the converter transformer is approaching its limit. Due to the weight of a single converter transformer reaching hundreds of tons and the huge amount of material used, the physical property testing for a single electromagnetic wire and a single insulating cardboard in the existing IEC standards can no longer meet the requirements for engineering use. This study focuses on the main materials of converter transformers and researches material selection methods for the operating conditions of ultra-high voltage equipment. The selection scheme for electromagnetic wires, insulating cardboard, and insulating screws of ultra-high voltage converter transformers has been determined. The results of this study can be used to select converter transformer materials in ultra-high voltage engineering and improve the reliability of power equipment operation.