Adaptive Droop Controller for a Hybrid 375 Vdc/48 Vdc/400 Vac AC/DC Microgrid

This article studies the sharing control scheme for a hybrid 48 V/375 V/400Vac ac/dc microgrid, based on classical droop control and a novel approach for secondary control. In this article, both the dc and ac grids are controlled by a
$P/V$
droop strategy. At the ac grid, this assumes a main resistive component in the distribution line impedance. The droop control voltage error in steady state is compensated by a novel and simple secondary control approach. The proposed control strategy is based on the calculation of the optimum power flow in each operating point and the real-time modification of the droop characteristics of the converters involved in the power flow calculation. The proposed control is also capable of eliminating the induced voltage drop when using virtual impedance and incorporating any power sharing criteria for the converters contributing to the power production, being this flexibility one of its more important characteristics.