Enhanced droop control for off-grid and grid-tied scenarios in renewable energy systems

The control methods of Grid-forming (GFM) inverters are discussed and reviewed. Then, the droop control method’s weak points are modified to have better load sharing performance and improving the lifetime of the inverters when the system has light load situations. Also, the effects of the coupling reactance on stability and reliability are investigated. This control method is applied to three different scenarios in order to see frequency and voltage stability and load sharing between three Inverter Based Resources (IBRs) and the grid. The first case is that the voltage and frequency regulation control algorithm is presented when the IBRs have equal power ratings during the off-grid. Then, the second case is also performed in islanding mode where the load sharing control algorithm is determined based on the different power ratings of the IBRs. Lastly, this setup examined the load sharing status during the grid-tied scenario when the IBRs are not capable of supplying enough power to the load. In all cases, loads are added to and removed from the system to ensure that the frequency and voltages are in the range of continuous operation.