Comparative Analysis of Direct and Indirect Current Control of Master-Slave Scheme for Microgrid

Abstract

The master-slave control is an important scheme to control the microgrid in both islanded and grid-connected modes. It has been proved that it is competitive to the droop control schemes. This presented paper shows two techniques to control the current/power of the slave inverters to precisely adjust the injected output power of the slave inverters. The adopted microgrid contains two multilevel (five-level diode-clamped) inverters. One inverter is operated as a slave inverter and the remaining inverter is operated as a master inverter. The slave inverter can be operated using two techniques. The slave inverter is operated in a direct current control (DCC) mode using nested multiband hysteresis current control. While the second technique is the indirect current control (ICC) mode through the cascaded structure of power and current loops. Simulation results show a comparative analysis, which affirms that the DCC gives much better performance for current/power control, while the ICC gives a slightly better performance for voltage stabilization at loads.