A reduced-order model for high-frequency oscillation mechanism analysis of droop control based flexible DC distribution system

•A high-order mathematical model of a flexible DC distribution system.•Integral coefficients have little effect on high-frequency oscillation frequency.•Sensitivity analysis is used to obtain a second-order system for mechanism analysis.•The analytical expression of the oscillation frequency in the time domain.•The rule of how parameters affecting the high-frequency oscillation. High-frequency oscillation (HFO) is easy to occur in a flexible DC distribution system, due to the influence of the interaction of multiple time scale control links and physical circuits. This paper studies the mechanism of HFO and establishes a reduced-order mathematical model of a flexible DC distribution system based on droop control. Sensitivity analysis has been used to obtain a second-order system for mechanism analysis. The analytical equation of HFO is deduced in time domain considering the system parameters’ influence. This paper summarizes the influence law of the filter capacitor, equivalent inductance, and controller parameters on HFO. Finally, a simulation model of a low-voltage flexible DC distribution system is built based on Matlab/Simulink, and the simulation result verifies the validity of the theoretical analysis.