Voltage loss protection judgment method for transformer with open-phase function

The invention provides a transformer no-voltage protection judgment method with an open-phase function, which is combined with a transformer principle and RTDS simulation test data. The method comprises the following steps: 1, simulating a traction substation power supply mode through a real-time data simulation system RTDS, and modeling a transformer wiring mode; 2, testing changes of line voltages and phase voltages of the high-voltage side and the low-voltage side of the transformer when A, B and C three-phase voltages of the high-voltage side of the transformer are open-phase respectively; 3, deducing a voltage loss protection judgment condition of the transformer with the open-phase function in combination with the transformer principle and the data obtained in the step 2. The method lists the change of the voltage of the high-voltage side and the influence on the voltage of the low-voltage side when the open-phase of various transformers occurs; therefore, whether phase loss occurs in the transformer ca