Novel complex filter with recursive algorithm for phasor computation in power-quality monitoring

Accurate on-line tracking of the instantaneous phasor in power-disturbance waveforms is a key element for power-quality monitoring, power-system metering, relaying, control and fault diagnosis in electric power systems. The performance of the measurement techniques in common use or newly developed is briefly reviewed by using three criteria, namely measurement accuracy, dynamic response and real-time capability. Further, a novel complex filter and the associated recursive algorithm for phasor computation are presented, which can achieve both high measurement accuracy in various service conditions and low computational complexity. The proposed method can suppress well signal components other than that selected and is not sensitive to frequency deviation. Its effectiveness and superiority over the Fourier algorithm and the continuous wavelet transform are also ascertained using both simulated and practical power-disturbance waveforms.