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1. A multilayer control framework for a power system, comprising: a hybrid storage system (HSS) to store energy using a plurality of energy storage devices; a local controller coupled to the HSS to smooth output power of wind or photovoltaic energy sources while regulating a State of Charge (SoC) of the HSS;
wherein the local controller provides a four-mode control scheme, each mode activated based on a state of charge of the energy storage devices; wherein for each mode, different action sets are used to regulate the SoC of the energy storage devices and maintain system performances; wherein the HSS comprises a battery and an Electric Double-Layer Capacitor (EDLC) or supercapacitor or ultracapacitor, each one equipped with a direct current/direct current (DC/DC) converter, and HSS is connected to the grid through a DC/AC converter; and wherein the HSS operates in Mode I with the DC/DC converter of the EDLC to regulate the DC-link voltage of HSS (Vdc), the DC/DC converter of the battery to keep the SoC of the EDLC (SoCsc) in a predetermined range; and the DC/AC converter controlling an output active power of the HSS (Phss) to smooth the output power of renewable energy and a reactive power of HSS (Qhss); wherein the HSS operates in Mode II with a DC/DC converter of the EDLC charging or discharging the EDLC based on the SoC of EDLC to bring the SoC of EDLC back to predefined range, the DC/DC converter of the battery to regulate the DC-link voltage of HSS (Vdc), and the DC/AC converter controlling an output active power of the HSS (Phss) to smooth the output power of renewable energy and a reactive power of HSS (Qhss); wherein the HSS operates in Mode III with the DC/DC converter of the EDLC to regulate a DC-link voltage of HSS, the DC/DC converter of battery charges/discharges the battery based on the SoC of battery in order to bring the SoC of battery back to a predetermined status, and the DC/AC converter controlling an output active power of the HSS (Phss) to smooth the output power of renewable energy and a reactive power of HSS (Qhss); wherein the HSS operates in Mode IV with the DC/DC converter in the EDLC to charge/discharge the EDLC based on the SoC of EDLC in order to bring the SoC of EDLC back to a predetermined status, the DC/DC converter of battery charges/discharges the battery based on the SoC of battery in order to bring the SoC of battery back to a predetermined status, and the DC/AC converter regulates the DC link voltage; and a system-wide controller coupled to the HSS activated upon an occurrence of one or more energy disturbances with a control strategy designed to improve system dynamics to address the one or more energy disturbances. |
