Performance of a phase locked loop as affected by power system dynamics

Implementation of vector control for a VSC-based equipment installed in a power system relies on the accurate and fast tracking of the phase of voltage at the point of common coupling (PCC) by a phase locked loop (PLL). This paper investigates the influence of power system dynamics on the performance of the PLL by connecting the PLL to a power system. Results of power system simulation demonstrate that the PLL´s performance is significantly affected by power system dynamics, which is not observable under the normal test condition with the PLL being connected to a three-phase voltage source. In the paper, three representative design schemes of the PLL are examined and tested with various simulation results presented.