| Achieving a high-level of stability represents one major concern in autonomous microgrids (MGs) with high penetration levels of renewable energy sources. The aim of this paper is to study how photovoltaic (PV) power plants can provide dynamic frequency support in MGs, in order to obtain an improved stability for the entire power system. On the PV side an energy storage subsystem is added, with the main purpose of better control and higher power reserve of the PV power plant. By this way the necessary input power is provided by the PV system along with the battery block. The required output power is supplied by a three-phase voltage source converter (VSC). The VSC control is implemented in a rotating dq reference frame, including a harmonic compensation loop for the output current. To improve the dynamic frequency stability of the MG, specific functions are implemented within the PV inverter control. To highlight the performance of the proposed system, a comparative analysis is provided, which cover four cases of interest depending on the status of the storage system and dynamic support (i.e. with/without storage and with/without dynamic support). Simulation results are included to validate the power control system, showing that the dynamic frequency control can be improved by the proposed solution. |
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