A unified method for signal parameter estimation of arbitrarily distorted single-phase grids with DC-offset

Abstract

A unified method is presented which allows to<br>estimate all harmonic components, DC-offset and fundamen-<br>tal frequency in arbitrarily distorted single-phase grids us-<br>ing a frequency-adaptive observer (FAO) consisting of modi-<br>fied Second-Order Generalized Integrators (mSOGIs), a DC-<br>Integrator (DCI) and a modified Frequency Locked Loop<br>(mFLL). DCI and mSOGIs are tuned by pole placement which allows for an arbitrarily fast detection of DC-offset and harmonic components if the fundamental frequency is known. If the fundamental frequency must be estimated as well, a mFLL with Gain Normalization (GN), Rate Limitation (RL), Anti-Windup (AW) strategy and low-pass filters (LPF) must be employed. The effectiveness of the proposed FAO is validated by experimental results and its enhanced performance is shown by comparisons<br>to existing estimation methods.