For example: a desktop computer is 270~300w, a fast heating 1000w, and an electric kettle1000 W.

Power rationing is not power rationing. As long as the system detects a heating device, such as a heating wire, it will be cut off directly. The six computers in our dormitory can get up and down at least 2000W, but the other hair dryer can't, so as long as there is no DC equipment.