Online Exciter Controller Tuning for a Synchronous Condenser in a Weak Grid

The point of connection of an inverter-based resource (IBR) experiences low fault currents due to the limitation of power electronic converters. This decreases the strength of the power system as measured by short circuit ratio (SCR). In addition, an IBR does not have mechanical inertia unlike a synchronous generator, which reduces the total inertia of the power system. Lack of strength and inertia in the power system causes challenges, such as subsynchronous resonance and undamped oscillations in the case of contingencies, e.g., short circuit faults. Synchronous condensers (SC) can be used to address these challenges as an SC can provide inertia and voltage control by injecting reactive power. In this paper, an exciter controller is proposed for an SC based on an unscented Kalman filter (UKF) in a weak grid. The effectiveness of the proposed exciter controller is verified for fault scenarios in a single-machine infinite bus (SMIB) case in PSCAD/EMTDC software.