Operation of a phase locked loop system under distorted utility conditions

Abstract

Operation of a phase locked loop (PLL) system under distorted utility conditions is presented. A control model of the PLL system is developed and recommendations are made on tuning of this model specially for operation under common utility distortions such as line notching, voltage unbalance/loss, and frequency variations. The PLL is completely implemented in software without any filters. All analytical results are experimentally verified.