Projeto de controladores robustos para conversores fonte de tensão conectados à rede elétrica através de filtros LCL

Abstract

This dissertation presents a methodology to design robust controllers to regulated the currents synthesized by a voltage source converter connected to the grid through a LCL filter. The system's mathematical model was developed using the state-space methodology. The equations that describe the model were initially written in abc coor-dinates before they are refered on the a,30 frame by using the Clarke transformation. Basic concepts regarding the state-space control, as well as, the systematic inclusion of controllers were presented and discussed. The control law based on pole placement using full-state feedback was employed. The poles were placed applying the integral of time multiplied by absolute error criterion, Bessel polynomials and robust regional pole placement via linear matrix inequalities. Time and frequency domain analyses for each aforementioned method were performed. Finally, a comparison among the methods regarding the grid's inductance parametric uncertainty was done. The analysis of the results have shown that neglecting parametric variations may lead the systems to insta-bility. Consequently, the regional robust pole placement via linear matrix inequalities is the only method which is suitable under parametric variations.