Voltage Responses of Tomia Island Microgrid under Load Variations

Constraints on the microgrid, such as demand-supply balance and small inertia on the synchronous machine, require an in-depth study to connect Distributed Energy Resources to the microgrid. Additionally, the power electronic converters that connect the DERs to the microgrid must be regulated and operated differently than the conventional power system. Hence further study has to be made, especially during load variations. Several methods improve a microgrid's stability, such as introducing an energy storage system to the microgrid, a proper control strategy, droop control, load shedding, etc. These methods work best depending on their application and the system scenarios. Tomia Island is one of the islands in Wakatobi Regency, situated in the East of Indonesia. The electricity's high production cost causes the electricity only to be available from 3 pm to 6 am. The limited access of Tomia Island from the nearest power grid caused Tomia Island Microgrid to be isolated from the main grid. The Tomia Island government built four photovoltaic power plants spread across the island to reduce the costs required for Diesel Generators' operation. Thus, this paper analyzes the microgrid behavior, especially the diesel generator's function in maintaining voltage stability during load variations. A 5% Q-V droop control was applied to two out of four PV plants in the Tomia Island microgrid. The result shows that the localized droop control improved the voltage responses on all the PV system points of interconnection due to load loss.