Hybrid Estimator-Based Harmonic Robust Grid Synchronization Technique

Abstract Harmonic robust grid synchronization technique has been studied in this paper. This implies the estimation of phase and frequency of single-phase grid voltage signal. Motivated by recent developments in linear harmonic oscillator based technique, this paper first propose an adaptive observer based solution that has the potential to speed-up the dynamic performance with respect to other generalized integrator type techniques. However, this may decrease the robustness of the proposed technique in the presence of harmonics and or DC bias. To overcome this issue, a hybrid estimator is proposed. This estimator is comprised of a band-pass type pre-loop filter and the initially proposed adaptive observer. Local stability and tuning of the adaptive observer are provided for the nominal case. In the presence of harmonics, small-signal modeling and tuning of the hybrid estimator are provided as well. Finally, hardware-in-the-loop (HIL) comparative experimental results are provided with similar other recently proposed techniques in the literature. Experimental results demonstrate the suitability of the proposed techniques.