Power Management Strategy for Islanded Operation Using Wind Power, Solar PV, and Battery Storage

Abstract

As electricity demand grows and renewable energy becomes a larger part of the power system, maintaining a reliable supply during grid interruptions becomes increasingly important. Microgrids that combine wind power, solar photovoltaics and battery storage can supply local loads independently of the main grid. However, operating these systems in islanded mode requires careful coordination to balance changing generation and demand. This thesis investigates the islanded operation of a wind–solar–battery microgrid based on the Chalmers research wind turbine at Björkö, Sweden. A battery-connected grid-forming converter provides the voltage and frequency reference, allowing wind and solar generation to operate alongside it through grid-following converters. The main objective was to develop a power balance controller and evaluate its ability to work with the grid-forming converter during different operating conditions. The control logic was developed in MATLAB/ Simulink to manage power surpluses and deficits while respecting battery state-of-charge and power limits. When renewable generation exceeds demand, the controller directs the surplus to the battery and curtails generation when necessary. When generation is insufficient, the battery supplies the shortfall, with load shedding used when the available power cannot meet demand. EMTP-RV simulations were then used to evaluate the interaction between the power balance controller and the grid-forming converter. The simulation results demonstrate how coordinated control of generation, storage and demand can support islanded operation within the system’s operating limits. The work provides a basis for developing renewable microgrids that can maintain local electricity supply when disconnected from the main grid.