Method for welding door frame of ultra-low-temperature high-power wind turbine tower

The invention discloses a method for welding a door frame of an ultra-low-temperature high-power wind turbine tower. The method comprises the following five main steps: preparing materials of the door frame; cutting a door hole; mounting an anti-deformation tool; welding corner weld of the door frame and the tower; and carrying out stress relief treatment after welding. Stress concentration of a welding region of the door frame and the tower under the working condition of ultra-low temperature and the condition of high-power generation requirements can be eliminated, defects of welding cracks and lamellar tearing are avoided, and requirements of impact energy at the low temperature of minus 40 DEG C are met; influences of stress concentration to yield of flatness and ovality of a flange of the tower is avoided; and first-pass yield of inspection and acceptance of the tower is improved.