An Adaptive Piecewise Droop Control Strategy for DC Microgrids

In DC microgrids, the piecewise droop control is an advanced coordinative control strategy, realizing plug-and-play capability of parallel converters and improved DC bus voltage regulation. However, it is difficult to realize smooth and accurate switch among different droop curves. The traditional hysteresis-based piecewise droop control fails to switch droop curves when difference among line resistances of parallel converters is not negligible. To handle this issue, this paper proposes an adaptive piecewise droop control strategy to switch droop curves reliably. First, the control architecture and basic principle of the proposed strategy are illustrated. Then, the transition process among different droop curves is analyzed. Furthermore, the practical implementation of the proposed control strategy is presented. Finally, the effectiveness and advantages of the strategy are verified, based on the laboratory-scale DC microgrid prototype.