Utilisateur:Majid Khalili Dermani/Brouillon

The transient stability conditions for an Electrical Vehicle (EV) charger power stage connected to the weak grid are investigated. An index based on a Lyapunov approach has been used to highlight possible stability issues. An EV charger generally includes Voltage Source Converters (VSCs), which may face difficulties in synchronization leading to their instability in the case of weak grids. The non-linear behavior of the Phase Locked Loop (PLL) is generally the main source of stability issues. The derived Lyapunov conditions are thus defined based on a well-known nonlinear model of the PLL VSC. For this purpose, the nonlinear state space model of the system composed of the grid and the PLL, is presented. Consequently, the stability and domain of attraction of the system equilibrium point is studied. Finally, an application has been performed on a 100kVA EV charger connected to the Grid, showing that instabilities may occur for some values of the parameters of the upstream network, especially in the case of LV long cables.