Independent Time-Delay Signal Cancellation for Fast Harmonic-Sequence Filters Targeting Arbitrary Sequences and Frequencies

A new type of filter/extractor named independent time-delay signal cancellation (itDSC) method is proposed in this article. Unlike conventional harmonic sequence filter (HSF) designs, the phase modifying and vector recovering stages of the proposed itDSC are separately set with single targets to make time-delays independent from the targeted HS indices and fundamental period. Consequently, the proposed HSF is more flexible in design, more robust and accurate in performance as well as faster in dynamic response compared to the conventional ones. A new phasor representation of an arbitrary order and sequence is first introduced for three-phase signals by using only a single integer-index-number (
h
). Then, a generalized principle of filtering/extracting arbitrary HS is proposed where the conventional time-dependent methods are specific cases. Last, new designs with independent time-delays are proposed to avoid the drawbacks of dependent time-delays and improve the filter performance in the applied systems. Comparative performance and extended applications on fundamental-frequency positive-sequence extraction used in power converter control areas are presented. The experiments show the superiority, application potentials, and challenges of the proposed method in the power converter control area.