Method for automatically switching between DC ice melting three-phase AC line

The invention relates to a method for automatically switching a DC ice-melting three-phase AC circuit. A DC ice-melting main loop comprises a rectifier, a control protection device, and DC side switches. A three-phase AC power supply is connected to a three-phase input of a valve group of the rectifier, namely a current converter. An anode output and a cathode output of the rectifier are connected to the three-phase AC circuit needing the ice-melting respectively through two groups of DC side isolation switches in a DC ice-melting mode to form the DC ice-melting main loop, and DC ice-melting is carried out on the three-phase AC circuit. The DC side isolation switches are controlled to automatically switch a three-phase conducting wire to connect the rectifier for the ice-melting by operating the control and the DC side isolation switches according to the operation state of ice-melting equipment. The operation of the rectifier and the DC side switches is controlled by an automatic sequence in the switching process. The method makes the three-phase conducting wire evenly heated, reduces the switch transferring operation of switching on or switching off the switches and the wire connecting work in ice-melting sites at the same time, and greatly improves the safety and reliability of systems.