Abstract：In order to solve the circuit checking problem of zero-sequence differential protection of main transformer in power system, a method based on phase-angle discriminant is proposed to judge the polarity of zero-sequence differential protection circuit of main transformer. On the basis of this method, a self-calibration device for zero-sequence differential protection circuit of main transformer is developed. The self-calibration device can realize timely, accurate and automatic calibration of zero-sequence differential protection circuit and improve the reliability of zero-sequence differential protection operation. Finally, the proposed method is verified by dynamic simulation and field experiment. The self-calibration device can calibrate the zero-sequence differential protection circuit timely, accurately and automatically, and improve the reliability of the zero-sequence differential protection operation. Finally, the reliability and correctness of the proposed method are verified by the simulation of the dynamic simulation unit and the field experiment.
2019, Vol. 20 
