Authors: A.C. Braitor; G. C. Konstantopoulos; and V. Kadirkamanathan
Published in: IEEE Transactions on Control Systems Technology ( Volume: 29, Issue: 1, Jan. 2021) https://doi.org/10.1109/TCST.2019.2951092
Date Published: 03 January 2020
In this brief, a novel current-limiting droop controller for paralleled dc-dc boost converters loaded by constant impedance Z, constant current I, or constant power P loads in a dc microgrid is proposed to guarantee closed-loop stability and power sharing. Using an improved version of the recently proposed nonlinear current-limiting controller, an inherent current-limiting property is guaranteed for each converter independently of the load type or magnitude variations. Then, sufficient conditions to ensure closed-loop stability for the entire dc microgrid system with a constant Z, I, or P load are analytically obtained. Hence, compared with existing droop control methodologies, the proposed controller ensures accurate power sharing, tight voltage regulation, and closed-loop stability with a current limitation when connected to Z, I, or P load, for multiple paralleled boost converters, which introduce nonlinear dynamics. To verify the effectiveness of the proposed controller and the stability analysis, simulation results for the three parallel operated dc-dc boost converters with Z, I, and P loads and experimental results for two parallel operated dc-dc boost converters with a P load are performed under several changes of the load power demand.
Keywords: Constant power load; current-limiting property; dc microgrids; droop control; stability.
Insights for EnergyREV:
Unifying control approaches at the primary control layer, in DC microgrids, can guarantee both nominal operation and microgrid protection. Enabling the use of combined methodology and theoretical strategies leads to the theoretical proof of the closed-loop stability for both physical and control layers.