Multiloop Current Control Strategy for a Grid-connected VSI with LCL Filter Using Backstepping and Proportional+Resonant Controller

Abstract

This paper presents a multiloop current control strategy for grid-connected converters through an LCL filter, based on an integrator backstepping and proportional+resonant controllers, in order to achieve robustness toward the uncertainties of the grid. The proposed strategy demonstrates robust stability and performance with the third order filter, which can cause difficulties to implement for the most types of controllers. Moreover, the uncertainties present on the grid can lead the system to operate inappropriately. Thus, an inner loop with a backstepping technique is used to ensure the tracking of the current from the converter side. In addition, on the outer loop, a proportional+resonant controller was designed to track grid-side current. The performance of the control strategy is verified using the software PSIM.