On-line stability monitoring for power converters in DC microgrids

This paper presents the application of an online stability monitoring technique (MT) for droop controlled power converters in DC microgrids. This method is based on Middlebrook's loop-gain measurement technique, adapted to digitally controlled switched-mode power supplies (SMPS). In particular, the MT is used to evaluate the stability margin in control loops of droop-controlled distributed energy resources in DC microgrids. An experimental microgrid prototype composed of two droop-controlled converters is reported and discussed to validate analytical and simulation results and to evaluate the improvements attained in the digital implementation of the monitoring technique. The MT used in this paper, can be extended to any other control loop existing in power converters within dc microgrids