Análise de DSOGI-PLL e DTOGI-PLL Aplicados em um VSC Quatro Fios Conectado à Rede Elétrica com Desequilíbrio de Tensão e Harmônicos

Abstract

The three-phase four-wire voltage source converters are the equipment used in the connection of alternative sources to the distribution system where the loads are predominantly single-phase. Three-phase unbalanced neutral distribution system has unwanted components of negative and zero sequence. Under these conditions, the synchronism between the VSC and the electrical grid that is done using the PLL (Phase Locked Loop) is affected. Traditional PLLs such as SRF-PLL (Synchronous Reference Frame-PLL) is widely used, however they do not guarantee synchronism in unbalanced conditions. The PLLs DSOGI-PLL (Dual Second Order Generalized Integrator-PLL) and DTOGI-PLL (Dual Third Order Generalized Integrator-PLL) ensure accurate synchronization between the VSC and the mains under unsafe conditions. ideals. Thus, the objective of this article is to evaluate the effect of voltage unbalance and voltage harmonics on the ac currents of the VSC using DSOGI-PLL and DTOGI-PLL.