Adaptive observer-based grid-synchronization and sequence extraction techniques for renewable energy systems: A comparative analysis

Abstract

Various faults and disturbances often make the grid unbalanced and distorted. To make the grid-connected converters resilient to unbalanced and distorted grid, real-time estimation of grid voltage sequences are essential. Adaptive-observer based grid-synchronization techniques are very suitable for this purpose. In this paper, a comparative analysis of three recently proposed adaptive observer-based grid-synchronization technique are presented for frequency estimation and sequence extraction. The considered techniques are: global adaptive observer, gain normalized adaptive observer, and second-order generalized integrator type adaptive observer. Following a fair and systematic gain tuning process, the performances are verified through extensive numerical simulation and experiments. Experimental results demonstrate the merits and demerits of the individual techniques. Academic researchers and industrial practitioners will find the results useful for the selection of adaptive observer-based grid-synchronization and sequence extraction techniques.