Parameter tuning of the PLL to consider the effect on power system small‐signal angular stability

Abstract

A phase locked loop (PLL) tracks the phase of the terminal voltage of a grid-connected permanent magnetic synchronous generator (PMSG) for wind power generation. Phase tracking by the PLL is used by the vector control for the grid connection of the PMSG. This study investigates the impact of phase-tracking performance of the PLL on power system small-signal angular stability. Damping torque analysis conducted in this study explains why the impact of the PLL is normally small. The analysis indicates that under the special condition of open-loop modal resonance, however, the effect of the PLL may become significant. It is very likely that the open-loop modal resonance may reduce the power system small-signal angular stability. Hence, in tuning the parameters of the PLL, the open-loop modal resonance should be avoided. In this study, the procedure about the parameter tuning of the PLL to consider the effect of open-loop modal resonance is proposed and demonstrated in an example multi-machine power system integrated with a PMSG. Analysis and conclusions made in this study are evaluated using the example power system.