Comparison of controllers for a three-phase Phase Locked Loop system under distorted conditions

Abstract

The analysis and design of a three-phase Phase Locked Loop system to synchronize to the electrical grid is presented. The whole phase locked loop model is obtained and a Proportional Integral, a Proportional Integral Derivative and a novel Fractional Proportional Integral controllers in continuous time domain are proposed to solve the phase tracking by improving time response, phase error and overshoot. The performance of the three controllers is analyzed under distorted utility conditions, such as imbalance, harmonics and phase and/or frequency variations. The phase locked loop is totally implemented by software, and tested by simulation via SIMULINK and experimentally via xPCTarget, in a three phase Autoadjustable Synchronous Reference Frame application. A comparison in the dynamic and steady state of the phase locked loop parameters like accurate, robustness and fastness is carried out for the three different controllers.