The invention discloses an economical operation control method for distribution transformers with a spare power automatic switching function. A distribution network
system has three operation
modes. When the distribution network
system is in the
control mode, power failure conditions of low-
voltage sides of two transformers are detected first, and a
relay is used for collecting on-off states of three phases of breakers on the low-
voltage sides of the transformers; when any two phases are powered off or the three phases are all powered off, it is judged that the transformers are in a power failure state; then, switching is conducted according to different power failure conditions. In the switching process, firstly, a load is removed from the
low voltage side of an original
system; secondly, the
high voltage on the other side is put into use, then the
low voltage is put into use, and finally the
high voltage on the fault side is removed. According to the economical operation control method, 10 KV-0.4 KV power distribution devices are combined to be an integral whole and controlled, so that the control difficulty is reduced; switching of the distribution transformers is automatically achieved according to built-in logical functions, so that no-
load loss of the transformers is reduced, and economical operation is achieved. The reliability of no-
voltage judgment is improved through multi-phase voltage detection, no-voltage faults can be detected more effectively, the quality of
electric energy is improved, and the security of
electric equipment is protected.