Patent ID: 6115675
Filing Date: 2000-09-05
Classification: G01R,H02H

Abstract:
A system for obtaining a digital representation at a time t of one of an analog voltage and current associated with one or more conductors of an electric power generation, transmission, transformation, or distribution system, said system comprising:a multiplexor having a plurality of channels wherein each channel has one of an analog voltage or current signal from said conductors, said multiplexor selectively outputting a selected signal from one of said channels;an analog-to-digital convertor in electrical communication with said multiplexor for converting said selected signal to a digital sample y, said multiplexor and analog-to-digital converter introducing a time-skew equivalent to the difference between the actual sample time t.sub.a and the time t into at least some of said samples; andmeans in communication with said analog-to-digital convertor for deriving time-skew corrected sample data p' from said digital sample y;wherein said means for deriving time-skew corrected sample data from said digital sample y comprises means for determining the value of a point p' at time t from a sample y.sub.k taken at time t.sub.a wherein p' is derived from three consecutive time skewed samples y.sub.k, y.sub.k-1, and y.sub.k-2 such that p' is determined as the weighted average of two estimates p.sub.1 and p.sub.2 of the corrected sample data, wherein p.sub.2 is estimated from a straight line intersecting two skewed samples y.sub.k-1 and y.sub.k-2 and p.sub.1 is estimated from a straight line intersecting two time skewed samples y.sub.k and y.sub.k-1.