A Nonlinear Observer for Self-Synchronizing Grid-Tied Feeding Inverters

This paper proposes a solution for the self-synchronization of grid-tied feeding inverters. Since the proposed algorithm allows the self-synchronization, it avoids using a voltage sensor for measuring the Point of Common Coupling (PCC) voltage. The algorithm is based on an adaptive non-linear observer that uses the measurement of the output inductor current. Unlike synchronization schemes based on the virtual synchronous generator, which is often used in control strategies based on power synchronization, when combined with a non-linear control strategy, the proposed algorithm allows obtaining an excellent dynamic performance, even in presence of large PCC voltage disturbances and fast varying references. The performance of the proposed observer when combined with a non-linear control strategy, designed by considering the non-linear model of the converter, is illustrated through experimental results.