Oscillation Coupling Analysis of MVDC Distribution System Based on Impedance Measurement

Abstract

For medium-voltage DC (MVDC) distribution system, the MVDC bus voltage is prone to instability owing to the dynamic interaction among source, constant power load and cable. Based on the equivalent model of MVDC distribution system, the input and output impedance considering the cable are established in detail. In addition, the voltage closed-loop transfer function of the equivalent model is also established. Then, the instability mechanism of system oscillation caused by cable can be revealed intuitively. To address this oscillation issue, the input filter capacitor of constant power load is further increased, thus the oscillation instability of the system is suppressed effectively. Finally, PLECS based simulation verification have been provided.