Inverter-Based Nanogrid Design with Integration of Primary, Secondary and Tertiary Controls – A Case Study

This paper investigates the performance of a hierarchical control framework in an inverter-based Nanogrid (NG) serving a building. The NG integrates a 21 kW Photovoltaic (PV) array and two 40 kWh Battery Energy Storage Systems (BESS1 and BESS2). Firstly, a Mixed-Integer Quadratically Constrained Programming (MIQCP) Energy Management System (EMS) was implemented in MATLAB/YALMIP and solved with Gurobi, executing a dayahead optimization to minimize cost. Secondly, a simulation was carried out to test the behavior of the NG when undergoing a load increase contingency during islanded mode operation. To this purpose, the NG was implemented in MATLAB/Simulink Simscape. The EMS results highlighted that PV selfconsumption through BESSs is the best solution to minimize the operating costs of the facility. Dynamic simulation showed that the BESSs, by increasing the power output, are able to stop the frequency variation in the NG to 49.8 Hz, efficiently providing a frequency containment action.