Multitier decentralized control scheme using energy storage unit and loadmanagement in inverter-based AC microgrids

Abstract

The use of renewable energies, such as wind and solar, is rising in microgrids. However, because of theirintermittent nature, achieving a stable system in spite of the uctuations of generation and demand is very difficult.Aiming to increase the stability margin of AC islanded microgrids comprising nondeterministic resources, properly sharereal power (P), and keep the network frequency (f) at nominal value, this study exploits the presence of energy storageunits (ESUs) along with a load-shedding scheme. To this end, this study proposes a multitier decentralized controlstrategy that is based on frequency and includes three control schemes, distributed generation unit (DGU) control,ESU control, and local loads control (LLC). These controllers operate simultaneously. The DGU controller shares theloads among DGUs in accordance with the frequency droop method. On the other hand, the ESU controller controlsthe production of ESUs and also the LLCs manage the loads and dump-load of the microgrid. This method ensuresthe proper operation of AC microgrids that comprise intermittent resources under stand-alone conditions and despitenumerous events. The time responses of P andfprove the high performance of the method. The simulations areperformed and coded in m- le of MATLAB.