Reactive Power Sharing in Islanded Microgrids Using Adaptive Voltage Droop Control

In this paper, a strategy that employs an adaptive voltage droop control to achieve accurate reactive power sharing is investigated. Instead of controlling the output voltage of the inverter directly, the voltage droop slope is tuned to compensate for the mismatch in the voltage drops across feeders by using communication links. If the communication channel is disrupted, the controller will operate with the last tuned droop coefficient, which is shown to still outperform the controller with the initial fixed droop coefficient. Also, the net control action of the adaptive droop terms is demonstrated to have a negligible effect on the microgrid bus voltage. Since communication is not used within the tuning control loop, the strategy is inherently immune to delays in communication links. A small-signal model of the proposed controller is presented, and the effectiveness of the proposed strategy is demonstrated on a 1.2 kVA prototype microgrid.