The Current Sequence Components Extraction for Dual Synchronous Rotation Frame Current Control in Unbalanced Grid Conditions

The positive and negative sequence components of the line current are coupled with each other in unbalanced grid conditions. It raises a problem of sequence components extraction (SCE) for the line current. The extra filter is usually applied for SCE in the traditional scheme, which deteriorates the dynamic performance of the current control loop. For addressing the problem, this article proposed a fictitious quadrature SCE scheme, which can decompose the current sequence components without using any filter, and the dynamic performance of the current control thereby is not affected by this SCE method. Furthermore, the well-known dual synchronous rotation frame (DSRF) current control with the proposed SCE is applied in three-phase rectifiers under unbalanced grid conditions for different power control demands, which include input power control, output power control, and input and output power control. Finally, the proposed method is tested by the experimental prototype and the experimental results verify the correctness of the proposed SCE scheme.