Parallel operation of common PLL-based synchronverters under transient conditions

Generally, a parallel connection of generators is required to meet the power need to supply the load demand. As a preferable replacement for typical generation units, a topology based on three-phase voltage source converters has been proposed. This paper proposes an approach based on virtual synchronous generator-based synchronverters for parallel operation of alternators. This approach automatically exchanges active and reactive power between parallel operated inverters of the same kind. Furthermore, to serve the purpose of synchronization, a Phase Locked Loop (PLL) is used. To avoid the tuning complexities and stability margin issue, a common PLL is used for both the converters. The PLL detects the grid voltage angle and helps with initial synchronization of the synchronverter in an easier way. The simulation studies are carried out to validate the performance and control of the proposed system. In addition, stability analysis has been performed using a state space approach to prove the efficacy of the system.