Method for judging transformer connection group based on external characteristics

The invention relates to a method for judging the connection group of a transformer based on external characteristics, and the method specifically comprises the steps: building a three-phase vector conversion relation between a high-voltage side and a low-voltage side of the transformer according to an equivalent circuit of a 10kV transformer, and calculating the amplitude of each phase voltage after offset correction, a voltage included angle and a phase offset angle; according to the three-phase vector conversion relation of the high-voltage side and the low-voltage side of the transformer and the voltage amplitude and the voltage included angle of each phase after offset correction, zero-sequence voltage and current of the xy axis are calculated; calculating zero-sequence voltage, zero-sequence current and a voltage-current included angle of the transformer according to the xy-axis zero-sequence voltage and current, and further calculating zero-sequence impedance of the transformer; fitting all transformer