A Dual Loop Current Control Structure With Improved Disturbance Rejection For Grid Connected Converters

A Dual Loop Current Control Structure With Improved Disturbance Rejection For Grid Connected Converters.

Abstract:

 This paper introduces and analyzes a dual loop current control structure which utilizes two independent controllers, one for reference tracking and the other for disturbance rejection in the dq frame. However, the PI controller by itself, may not suffice for adequate disturbance rejection, especially when the utility grid voltages contain other harmonics in addition to the fundamental component.  A small signal model of the dual loop current control has been presented an  its robustness under grid impedance variation, examined. Extensive simulation results are presented to validate the dual loop control strategy for improved disturbance rejection capability and filtering action during the presence of grid voltage disturbances and grid impedance variations, without compromising the reference tracking performance.