Simulation of Control Strategy for Microgrid System Frequency Recovery

In the microgrid system, the system frequency is maintained at the nominal frequency (50Hz) by compensating the power change in the system through the power set point change of the generator or battery. The existing control system on the bidirectional battery inverter requires power data from all generators and loads via wireless network communication. Communication interruptions can cause the battery to supply/absorb large power suddenly, which can damage the bidirectional inverter. For this reason, a control strategy is developed for the microgrid system to maintain frequency stability at nominal frequencies without communication to the generator and load. This control strategy is referred to as recovery control (which is identical to secondary and tertiary control in large power systems) and works using Decision Tree (DT) and Artificial Neural Network (ANN) methods. Based on the simulation results, the DT and ANN methods can recover the system frequency to the nominal frequency. It works through predicting the amount of power that must be absorbed or generated by the battery system only based on system frequency data. In addition, the DT and ANN methods are also able to identify the inertia value of the microgrid system.