Modified second-order generalized integrators with modified frequency locked loop for fast harmonics estimation of distorted single-phase signals (LONG VERSION)
For power systems engineers, this work provides an improved method for real-time harmonic estimation with faster convergence, though it is an incremental improvement over existing SOGI-based approaches.
This paper proposes modified Second-Order Generalized Integrators (mSOGIs) with a modified Frequency Locked Loop (mFLL) for fast estimation of all harmonic components in distorted single-phase signals. Experimental results show that the proposed method achieves faster settling time and better accuracy compared to standard SOGIs and adaptive notch filters.
This paper 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 system 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 anti-windup 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).