Removal of DC offset using digital mimic filtering technique

The paper describes a method which is used for removal of DC offset from fault current and can be recovered to its originality sinusoidal waveform. Basic Digital filtering approach relates with protection algorithms which are becoming more complex since the cost of computational equipment's continues to decrease in present era. The concept based on the FIR type of digital mimic filter which is described here, it is shown that, those filters which are exhibiting a none response at frequency zero on their frequency response, in which the addition of a digital mimic circuit, results in tuning to the middle of the range of time constants to be suppressed, so it will almost completely eliminate the effect of an exponentially decaying component. During fault unwanted distortions on power system network are created which could adversely affect discrimination and the reliability of protective relays. The digitalized concepts based on new modern multistate digital mimic filtering approach to minimize such kind of problems are principally concerned with this paper.