Residential photovoltaic and battery energy system with grid support functionalities

This paper presents the design of a control system for a grid connected residential photovoltaic (PV) system with battery energy storage (BES). The control methods for the power electronic converters are presented and the potential of utilizing BES for participating in primary frequency regulation of the grid is investigated. The charging/ discharging rate of the battery is controlled based on the frequency droop characteristic. The performance of the control system is validated in a simulation study, in which fast response and perfect tracking of the set points are observed in (i) normal operating condition and (ii) a case where the grid frequency varies. The amount of the battery´s capacity that can be utilized for this purpose depends on the quantity of power generated by the PV system, as well as the load level. The study shows that sometimes the rated capacity of the battery could be fully utilized for serving the primary frequency regulation purposes.