Novel design of a fast phase selector using correlation analysis

This paper proposes a novel phase selector using superimposed sequence currents in conjunction with the correlation analysis. The vector ratio between superimposed positive-sequence current and negative current for various types of faults especially the double-phase-earth fault is investigated. As a result, the appropriate criterion of phase selection is put forward. The correlation analysis is introduced to implement the fast phase comparison to improve the operating speed. The multibase relative comparison is performed on the correlated coefficients evaluated from the three different base phases to adapt to this type of phase selecting scheme. Additionally, a magnitude-comparison-based subsidiary criterion is applied to address the problem of possible malphase selection in the event of double-phase-earth faults. The reliability and fast operation of this scheme was proven by the Electromagnetic Transients Program-based simulation tests.