Phase-locked loops for grid-tied inverters: comparison and testing

Abstract

The increasing number of power electronic inverters connected to the utility grid means their synchronization to the utility grid plays an increasingly key role. Typically a phase-locked loop (PLL) is used, however limited information is still only available on PLLs in the public domain comparing them for power system applications. This paper presents quantified analyses and comparisons of the main PLL techniques based on different structures for both single phase and 3-phase systems. A more comprehensive comparison than previous work is made by introducing the robustness to geomagnetically induced current effects and islanding.