A method to detect three-phase fundamental positive-sequence active current based on single-phase cascaded delayed signal cancellation

It is very important for power quality control to detect fundamental positive-sequence active current rapidly and accurately. In traditional detection approaches many techniques such as phase locked loop (PLL), low pass filter (LPF) or  and dq coordinate transforms are often integrated, however there are certain limitations in these approaches, for this reason, a novel detection method is proposed. Firstly, by means of fan-in vector transformation a three-phase system is normalized into single-phase system; then through constructing cascaded-delayed signal cancellation module, the fundamental positive-sequence voltage and current are extracted rapidly; finally, positive-sequence active current can be obtained by simple calculation. In the proposed method nor PLL neither LPF are needed, besides the complex computation during  and dq coordinate transformation can be omitted. The effectiveness of the proposed detection method is validated by simulation results.