PI Controller Based Operational Scheme to Stabilize Voltage in Microgrid

This paper presents an innovative control scheme for the operation of parallel three multilevel diode clamped inverters to supply some loads in a microgrid. The distributed energy resources are the PV panels connected to batteries at the DC side of these inverters. The presented control scheme depends on PI controllers, which operate two cascaded control loops to stabilize the voltages and frequency at the load side. The adopted scheme coordinates the operation of the parallel inverters such that the instantaneous loads' currents are equally shared among the inverters. Also, the presented scheme accommodates the modular structure of parallel inverters and it is robust in the case any one of the parallel inverters is disconnected/reconnected. The performance of the proposed scheme is validated using simulation results.