Synchronverter (SV) control or also known as virtual synchronous generator (VSG) control has emerged as a popular method for distributed energy resources (DERs), to emulate the response of a synchronous generator. The process of synchronizing DER voltage to grid voltage, before connecting DER to the grid is known as pre-synchronization and this process must be done for SV controlled DERs. In earlier works, pre-synchronization was done by virtual current methods which had drawbacks of trial and error parameter design, restriction of local load connection, etc. Taking into account the limitations of virtual current methods, a gradient descent based pre-synchronization control for SV scheme is presented in this talk. Transient response analysis is presented, based on small signal transfer functions derived from the proposed method. From the theoretical analysis of proposed pre-synchronization control, a simple process for design of the parameters is presented. Thus, there is no trial and error basis for parameters tuning in the proposed method, as compared to virtual current based methods. Simulation and experimental validation of transient response analysis, effectiveness of proposed pre-synchronization and grid integration are presented in this talk.



SV or VSG controlled DERs during an unbalanced grid condition is another problem that will be slightly addressed in this talk. In order to solve issues regarding unbalanced grid connected DERs, an integrated control combining an Enhanced-PLL for unbalanced voltages and a standard SV control will be touched upon in this talk.