A novel direction protection principle for power transformer

The transformation of instantaneous value symmetry component applied, the positive space vector of voltage and current fault component can be derived .This paper deduce the determinant criterion of fault direction based on the positive space vector. The algorithm is proved to determine fault direction in short date window by theory analysis and simulation experiment, then to determine internal fault or not. The algorithm can shorten time to judge internal fault or external fault greatly, and can enhance the velocity of clearing up all internal faults of transformer assisted by the fast inrush criterion with high reliability and sensibility.