Single-phase synchronverter for a grid-connected roof top photovoltaic system

This study proposes a grid supportive control scheme for a single-phase photo-voltaic (PV)-based inverter to mimic the behaviour of a synchronous generator during grid voltage/frequency variations. The converter embedded with the proposed controller, termed as a single-phase synchronverter', transforms a large segment of rooftop PV, which is, in general, single phase, to an ancillary service provider in compliance with the grid code (i.e. if the grid code allows rooftop PV to provide inertial/primary frequency/voltage response). Owing to fluctuations in incident solar irradiation, a battery has been connected at the dc link to take care of the variability in PV output power. The challenges involved in extending the three-phase synchronverter philosophy to a single-phase converter have been discussed and the performance of the resultant single-phase synchronverter to different values of virtual inertia and droop/regulation has been analysed. An experimental setup is developed and the system behaviour for different operating conditions has also been studied.