Dual sequence current control scheme implemented in DSRF with decoupling terms based on reference current feed-forward

Injecting negative sequence current into the grid can improve the operating performance of grid-connected voltage source converters under unbalanced grid voltage conditions. In this paper, a dual sequence current control scheme was proposed to quickly track positive- and negative-sequence sinusoidal currents with zero steady state error, implemented in double synchronous reference frames and without requiring current positive- and negative-sequence component decomposition. The proposed method applied a proportional integrator controller in positive synchronous reference frame and only a integrator in negative synchronous reference frame. A reference cross transformation was introduced to avoid extracting current sequence components. Moreover, decoupling terms based on reference current feed-forward were used to realize decoupling control for both positive- and negative-sequence currents. Experimental tests were implemented on a laboratory prototype with 2kHz switching frequency to demonstrate the performance of the proposed dual sequence current control scheme.