Analysis of linear Phase-Locked Loops in Grid-Connected Power Converters

Fast and accurate synchronization capability of grid-connected converters is becoming more and more important to ensure proper performance during transient events, such as grid faults. The higher requirements during the operation, as Fault-Ride-Through with reactive current injection, cause higher requirements on the operation during severe system conditions. This paper analyzes an addition to Synchronous-Reference-Frame Phase-Locked Loops for power electronic converters, that is linearizing the input signal. This enhances the tracking capabilities during abnormal transient events in the power grid. The improved control is analyzed and its increased performance is validated through simulations and experimental results.