A novel ramp-rate control of grid-tied PV-Battery systems to reduce required battery capacity

Abstract

This paper proposes a novel ramp-rate control of PV-battery systems in microgrids, including the coordination and control of time-varying loads. The power consumed by the loads is part of regulation strategy and participates in mitigating the overall ramp-rate of the controlled PV system and the loads. The control strategy is grid-friendly as the power fluctuation of the loads is also considered besides that of the PV system. Furthermore, this control strategy economizes on the number and size of auxiliary batteries that tipically are considered combined with PV system, since a part of the required active power is now borrowed from the loads. Combined to the load control a ramp-rate control, based on the virtual synchronous generator technology, is originally proposed to further reduce the use of the batteries and to provide innovative ancillary service. Finally numerical simulations on a test microgrid indicate the effectiveness of the proposed ramp-rate control. The test cases also demonstrate that this control strategy succeeds in reducing the battery capacity and the number of (dis)charge cycles as well as in offering frequency support to the microgrid.