PI-PBC Cascade Control Tuning For Active Power Filter Application

Abstract

Because of the non-linear load increase in the electrical grid, the use of active power filter has gone increasing, this last is in order to improve the power quality. In the study of control applied to the active power filter, cascade control is the most used; this control scheme consists of two control loops: one external dc voltage control loop and one internal current control loop.  For this work, in the external loop a proportional-integral (PI) control is used, whereas in the inner loop a passivity-based controller (PBC) is used. The main objective of this work is presenting a proposal for tuning PI and PBC controllers. This tuning methodology allows computing the gain k of the PBC based on two parameters: switching frequency and a convergence criterion, which is given by an error bound. PI parameters are obtained from step response analysis. This tuning proposal is simple and has shown to be consistent for different switching frequency values. Through the measurement of the active power filter performance, the tuning proposal has been corroborated. Simulation and experimental results are presented.