Modified Second-Order Generalized Integrators With Modified Frequency Locked Loop for Fast Harmonics Estimation of Distorted Single-Phase Signals

• Published in: IEEE transactions on power electronics Vol. 35; no. 3; pp. 3298 - 3309
• Main Authors: Hackl, Christoph M., Landerer, Markus
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.03.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Adaptive filters; Amplitude estimation; Estimation; Frequency estimation; Frequency locked loops; Frequency locking; frequency-locked loop (FLL); Harmonic analysis; Integrators; Internal model principle; Notch filters; phase estimation; Pole placement; Power system harmonics; Resonant frequencies; second-order generalized integrator (SOGI); Tuning
• ISSN: 0885-8993; 1941-0107
• DOI: 10.1109/TPEL.2019.2932790

This article proposes modified second-order generalized integrators (mSOGIs) for a fast estimation of all harmonic components of arbitrarily distorted single-phase signals, such as voltages or currents in power systems. The estimation is based on the internal model principle leading to an overall observer consisting of parallelized mSOGIs. The observer is tuned by pole placement. For a constant fundamental frequency, the observer is capable of estimating all harmonic components with prescribed settling time by choosing the observer poles appropriately. For time-varying fundamental frequencies, the harmonic estimation is combined with a modified frequency locked loop (mFLL) with gain normalization, sign-correct antiwindup, and rate limitation. The estimation performances of the proposed parallelized mSOGIs with and without mFLL are illustrated and validated by measurement results. The results are compared to standard approaches such as parallelized standard SOGIs (sSOGIs) and adaptive notch filters (ANFs).