A nonlinear adaptive filter for online signal analysis in power systems: applications

This paper presents various applications of a nonlinear adaptive notch filter which operates based on the concept of an enhanced phase-locked loop (PLL). Applications of the filter for online signal analysis for power systems protection, control and power quality enhancement are presented. The proposed scheme can be applied for signal analysis both under stationary and nonstationary conditions. Based on digital time-domain simulations, applications of the filter for (a) sinusoidal waveform peak detection, (b) harmonic identification/detection, (c) detection/extraction of individual components of a signal, (d) instantaneous reactive current extraction, (e) disturbance detection, (f) noise reduction in zero-crossings detection, and (g) amplitude (phase) demodulation for flicker estimation, are presented.