Analysis and Control of High-frequency Oscillation for DC Distribution System with Droop Control

Aiming at the phenomenon of high-frequency oscillation in DC distribution systems, the frequency domain models of the voltage source converter, DC line and constant power load are established regarding radial DC distribution system with droop control as the research object. And the frequency domain reduced-order model of DC distribution systems is further established. The analytical expression of the influence of system parameters on high-frequency oscillation frequency in frequency domain is derived. The influences of the droop control coefficient, DC line and load parameters change on the system oscillation frequency are analyzed. It is found that the negative damping characteristics of the droop controller and constant power load tend to cause the high-frequency oscillation. Based on this, the droop control method of feedforward compensation based on line parameters and the controller design method of the improved virtual resistance are proposed, and the stability of the system before and after compensation is compared. The correctness of the theoretical analysis and the effectiveness of the proposed method are verified by the simulations in frequency domain and time domain. © 2021 Automation of Electric Power Systems Press.