Improved reactive power sharing with adaptive droop control in islanded microgrids

Appropriate control strategies for power sharing between multiple generation units operating in parallel are required to create a stable AC microgrid bus. In this paper, we explore the droop control strategy, implemented by power electronics units, to maintain a stable AC bus voltage without the need for a separate (central) communication layer. In particular, our suggested control method is based on adaptive control. Fundamentally in microgrids, due to the effects of feeder and line impedance, the droop control method is subject to real and reactive power coupling and steady-state reactive power sharing errors, and in particular for complex microgrid configurations, the reactive power sharing poses certain challenges. To improve the reactive power sharing equalization, an enhanced adaptive strategy has been utilized to calculate a droop coefficient for reactive power control, where the reactive power error has been compensated through the injection of small real power disturbances. Root locus analysis of a representative microgrid has been undertaken to confirm that stable solutions are feasible.