Impact of Electric Vehicle Charging Stations on Distribution Grid: Voltage Stability, Harmonic Analysis and Optimal Placement using Grey Wolf Optimizer (GWO)

The rapid proliferation of Electric Vehicles (EVs) introduces significant challenges to existing distribution networks including voltage instability, excessive power losses, transformer overloading, and harmonic injection. This paper presents a comprehensive simulation-based analysis of EV charging station (EVCS) impacts on the IEEE 33-bus radial distribution system under four scenarios: (1) Base Case, (2) Uncoordinated Charging, (3) Smart Coordinated Charging, and (4) GWO-Optimized Placement. Detailed power flow calculations, Voltage Stability Index (VSI), Total Harmonic Distortion (THD) analysis, and load profile studies are performed. The proposed Grey Wolf Optimizer (GWO) approach minimizes a multi-objective function combining active power loss (ΔPLoss), voltage deviation (ΔVDev), and THD. Results demonstrate that GWO-optimized placement (at Buses 13, 24, 29, 31) reduces power losses by 46.5% (from 287.6 kW to 153.8 kW), improves minimum bus voltage from 0.9124 p.u. to 0.9782 p.u., and constrains THD within IEEE 519-2014 limits (≤5%). Comparative benchmarking against PSO, GA, and WOA confirms GWO’s superiority in convergence speed (11.3 s) and solution quality.