Design of a Current Controller Based on a Two Step Procedure for Grid-Connected Converters

Abstract

This paper provides a two step procedure for current control design of grid-connected converters with LCL filter. The proposed procedure is based on: i) an internal loop with state feedback, aiming on active damping of the LCL filter resonance; ii) an external loop with resonant controllers, aiming to ensure tracking of sinusoidal grid current references. The state feedback gains are computed based on pole location and the resonant control gains are computed based on the minimization of a closedloop tracking error index. A case study is shown to illustrate that the proposed control design procedure leads to grid-injected currents with suitable steady state and transient performances.