Distributed Secondary Control in DC Microgrid for Voltage Restoration and Current Sharing

In comparison to an AC system, a DC microgrid is becoming highly popular on account of its ease of connecting renewable energy resources, high reliability, and high efficiency. The primary goals of a DC microgrid are to retain a constant voltage on a DC bus and ensure appropriate current distribution amongst all converters. Proper current sharing can be accomplished with the traditional droop technique at the primary level of control. However, the DC output voltage of a converter decreases linearly with an increase in output current. It is a limitation of primary control. So, this work presents a secondary control approach based on the Low-Bandwidth Communication (LBC) network to enhance the function of the DC microgrids. It is implemented by using a local-level controller and the LBC link to transmit information. A secondary current controller is used in each converter module to increase the accuracy of current sharing, while a secondary voltage controller is used to retain the DC bus voltage at its nominal voltage. Every controller is implemented locally, and the LBC channel is just utilized to transmit DC current values. Because of this, the approach is appropriate for distributed microgrid control. Finally, MATLAB/Simulink software is utilized to validate the efficiency of a proposed distributed secondary control technique.