Improving the autonomy of islanded microgrids through frequency regulation

摘要

In stand-alone operation, microgrids are susceptible to potential shortages in generation capacity, requiring a consideration of all technically feasible opportunities to conserve energy in order to keep the islanded grid operational for as long as possible. In this sense, the network autonomy capacity must be considered in the islanded microgrid frequency control formulation, alongside the traditional concern related to the accomplishment of the dynamic frequency regulation requirements. This paper proposes a new outlook for secondary frequency regulation in islanded microgrids denoted as conservation frequency reduction (CFR). The proposed approach exploits the frequency dependency characteristics of microgrids by intentionally reducing the reference setpoint of the islanded network frequency in a controllable way in order to decrease the network's demand and improve the autonomy duration of islanded microgrids, i.e., availability to supply demand in islanded mode; while ensuring the system operation within permissible limits. The results indicate that the proposed approach is able to significantly enhance islanded microgrids autonomy capacity while guaranteeing its frequency of operation within satisfactory dynamic and steady-state limits.