  This work explores the usage of a supplementary controller for improving the
transient performance of inverter$\unicode{x2013}$based resources (IBR) in
microgrids. The supplementary controller is trained using a reinforcement
learning (RL)$\unicode{x2013}$based algorithm to minimize transients in a power
converter connected to a microgrid. The controller works autonomously to issue
adaptive, intermediate set points based on the current state and trajectory of
the observed or tracked variable. The ability of the designed controller to
mitigate transients is verified on a medium voltage test system using
PSCAD/EMTDC.
