Prefiltered Synchronization Structure for Grid-Connected Power Converters to Reduce the Stability Impact of PLL Dynamics

Grid-connected converters under weak grid conditions could present instabilityassociated with the synchronization elements and not directly current control loop. The impedance-based stability criterion is an effective tool to address problem. To solve negative effect of synchronous reference frame phase-locked loop (SRF-PLL) on conditions, a structure prefilter, based filtered quadrature signal generator (FQSG), proposed in this article improve dynamics controller’s performance. small-signal impedance model, implemente as multiple-input multiple-output system dq -frame, characterizes FQSG-PLL From it, analysis shows reduction issues converter. results were verified by time-domain simulations experimental tests full-scale 2-MW converter test bench.