Design of an Asymmetrical LCL Filter for Stability Enhancement in Multi-Electric Vehicle V2G Systems

With the increasing integration of inverter-based resources (IBRs) into modern power systems, the operational strategies of inverter-based facilities under grid faults have become a critical concern owing to oscillations and limited fault current. This study proposes an asymmetrical LCL filter for vehicle-to-grid systems connected with multiple electric vehicles to suppress power injection oscillations and ensure stable operation. Based on an m-first design framework, the method was validated through MATLAB/Simulink-based simulations. The proposed design methodology assigns distinct values to the grid-side and inverter-side inductances to simultaneously improve steady-state power quality and post-fault recovery stability. By maintaining a relatively low modulation index m to secure control headroom, the grid-side inductance is reduced to facilitate recovery to a stable operating point after fault clearing, whereas the inverter-side inductance is increased to enhance power quality and mitigate steady-state oscillations. The proposed asymmetrical LCL filter provides a noticeable ripple-mitigation benefit, achieving up to 34.21% and 33.63% reductions in ripple RMS and MAE, respectively, compared with conventional configurations. The evaluation considered a five electric vehicles V2G system under the standard 22.9 kV distribution conditions in South Korea. Simulation results demonstrate that the proposed asymmetrical LCL filter achieves superior power quality and maintains a stable operating point following grid faults compared with conventional LCL filters, without unnecessary tripping after fault clearance. Therefore, the proposed approach improves the grid stability during large scale EV integration and ensures reliability and resilience in V2G systems.