Nested Multiband Hysteresis Current Control of Master-Slave Scheme for Reliable Microgrid

The master-slave control/operational scheme proves to be very efficient for operating any microgrid in different modes: Islanded and grid-connected modes. The master-slave schemes prove to be competitive compared to the droop control schemes because of their admirable characteristics for the control/operation of AC microgrids. This presented paper employs the master-slave scheme as a control scheme for the operation of the microgrid. The adopted microgrid contains three multilevel (five-level diode-clamped) inverters. Two of them are operated as slave units, and the remaining unit is employed as a master unit. The slave units are operated in a current-controlled mode using developed multiband hysteresis current control. At the same time, the master inverter is operated in a voltage-controlled mode, which is responsible for maintaining both frequency and voltage at a certain level. In addition, the redundancy of the slave units is checked in case one slave unit is disconnected. The simulation results prove that master control and hysteresis current control perform well at different operating conditions.