Auto-Tuning of Droop Controllers for Grid-Forming Inverters

This article proposes an auto-tuning control strategy for the power loop of grid-forming inverters to compensate the dynamic performance degradation caused by the variation of unknown variables (e.g., grid impedance, inverter parameter values) under grid-connected operating conditions. The auto- tuning is achieved by online monitoring the crossover frequency and phase margin of the power control loop, and adjusting key parameters of the droop controller according to these performance indices. It is shown that the crossover frequency and phase margin can be maintained at desired values, thus the expected dynamic control performance can be achieved and maintained. Simulation and experimental results are presented to demonstrate the effectiveness of the proposed approach.