Modeling and Stability Analysis of Islanded DC Microgrids Under Droop Control

• Published in: IEEE transactions on power electronics Vol. 30; no. 8; pp. 4597 - 4607
• Main Authors: Nobrega Tahim, Andre Pires, Pagano, Daniel J., Lenz, Eduardo, Stramosk, Vinicius
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-08-2015; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Analytical models; bifurcation analysis; constant power load (CPL); Construction; DC microgrid; Differential equations; Direct current; droop control; Electric currents; Electric potential; Electric power; Electric power grids; Electricity distribution; Integrated circuit modeling; Load modeling; Mathematical models; nonlinear stability analysis; Nonlinearity; Power transmission lines; Resistance; Stability analysis; Voltage; Voltage control; nonlinear stability analysis; DC microgrid; constant power load (CPL); Bifurcation analysis; droop control
• ISSN: 0885-8993; 1941-0107
• DOI: 10.1109/TPEL.2014.2360171

The stability of dc microgrids (MGs) depends on the control strategy adopted for each mode of operation. In an islanded operation mode, droop control is the basic method for bus voltage stabilization when there is no communication among the sources. In this paper, it is shown the consequences of droop implementation on the voltage stability of dc power systems, whose loads are active and nonlinear, e.g., constant power loads. The set of parallel sources and their corresponding transmission lines are modeled by an ideal voltage source in series with an equivalent resistance and inductance. This approximate model allows performing a nonlinear stability analysis to predict the system qualitative behavior due to the reduced number of differential equations. Additionally, nonlinear analysis provides analytical stability conditions as a function of the model parameters and it leads to a design guideline to build reliable (MGs) based on safe operating regions.