HIGH-SPEED IMPEDANCE PROTECTION TECHNOLOGY WITH RESPECT TO DYNAMIC ERROR OF CAPACITIVE INSTRUMENT TRANSFORMER

摘要

PROBLEM TO BE SOLVED: To provide an impedance protection technology that discriminates in-band failures from out-of-band failures, based on digitally-induced instantaneous signal and polarized-distance comparator signal.;SOLUTION: The method for protecting an impedance utilizes a pair of high-speed orthogonal filter for improving D and Q components of input voltage and current. Two sets of a dynamic signal and a polarizing signal are induced to improve passage of power signal at a peak and zero point. Three comparison steps are utilized between the dynamic impedance and the polarization impedance. A half-cycle equation window and a three-quarter window are used in these comparison steps. A first comparison step is based on an energy comparator responsive to both information on a magnitude within signal and information on a phase. A second and a third steps are of as a phase comparison type that respond mainly to phase information and ignore magnitude information for improving immunity against noise and signal distortions.;COPYRIGHT: (C)2009,JPO&INPIT