Operation of a phase locked loop system under distorted utility conditions

Operation of a three phase-phase locked loop-system under distorted utility conditions is presented. A control model of the PLL system is developed and and used for time and frequency domain analysis, and recommendations are made on tuning of this model specially for operation under common utility distortions as: line notching, voltage unbalance/loss, frequency variations. The PLL is completely implemented in software. All analytical results are experimentally verified.