Small-Signal Stability of a DC Network Planned for Electric Vehicle Charging

摘要

This study sets out to investigate the small-signal stability of a DC network being planned for electric vehicle chargingstations (EVCSs). The aim of this investigation is to reveal how the interconnection of EVCSs may affect the stability of the DC network so as to provide general guidance for the planning of the network. An analysis based on an equivalent model clearly reveals that two key factors impact network stability when EVCSs are interconnected: 1) the dynamic interaction between an individual EVCS and the remainder of DC network; 2) the topology and parameters of the DC network. In the worst case, the integration of a large number EVCSs can result ingrowing oscillations in the DC network, which is related to the high-frequency filter oscillation modes of EVCSs. Based on the results, a computationally simple, reduced-order modal analysis method for approximately assessing the small-signal stability of a DC network, as affected by the interconnection of EVCSs, is proposed for planning. An example of the planning of a DC network for about 40 EVCSs is used to evaluate the conclusions andto demonstrate how driving factors can be considered in the planning process by using the proposed reduced-order modal analysis method.