Cascade Droop-Virtual Synchronous Generator Control Approach to Improve Frequency Deviation

The concept of “system inertia,” “system droop,” and system frequency response to disturbances, are widely discussed and used to limit the frequency deviation in a microgrid. To remedy this, the concept of cascade droop-virtual synchronous generator (VSG) is increasingly integrated, based on the imitation of the very popular synchronous generator (SG), which enhances the inertia and damping of the system, making it robust with better frequency stability. The droop task estimates the active power needed to reduce the frequency deviation from the battery energy storage system (BESS) and the VSG controls the inverter through the PLL (Phase Locked Loop) angle to inject this active power at the PCC (Point Common Coupling). The proposed cascade droop-Vsgcombined is greatly improved with the power sharing using droop for the two diesel generators and the increase/decrease the transient voltage at the PCC during load variation and PV solar power transfer to the load. Finally, the simulation results obtained correspond to our expectations and demonstrate the viability of the approach, reducing frequency deviation, ensuring stability of the voltage at the PCC and improves power sharing.