Stability Analysis and Control of DC Distribution System with Electric Vehicles

Abstract

The DC distribution network system equipped with a large number of power electronic equipment exhibits weak damping characteristics and is prone to low-frequency and high-frequency unstable oscillations. The current interpretation of the oscillation mechanism has not been unified. Firstly, this paper established the complete statespace model of the distribution system consisting of a large number of electric vehicles, characteristic equation of the distribution network system is derived by establishing a state-space model, and simplified reduced-order equations describing the low-frequency oscillation and the high-frequency oscillation are obtained. Secondly, based on eigenvalue analysis, the oscillation modes and the influence of the key system parameters on the oscillation mode are studied. Besides, impacts of key factors, such as distribution network connection topology and number of dynamic loads, have been discussed to suppress oscillatory instability caused by inappropriate design or dynamic interactions. Finally, using the DC distribution example system, through model calculation and time-domain simulation analysis, the correctness of the aforementioned analysis is verified.