An Effective Fault Detection Technique for Grid-Connected Electric Vehicle Charging Station

The widespread integration of electric vehicle (EV) charging stations (CS) into the existing utility grid is giving rise to numerous power quality and protection challenges, significantly impacting load performance at both large and small consumer ends. This phenomenon is escalating as the transition from internal combustion engine (IC) vehicles to EVs gains momentum, driven by their inherent advantages. EV chargers utilize power electronics to convert AC power into DC power for battery charging from the grid. However, this conversion process, facilitated by high-frequency switching converters, introduces harmonics into the grid, consequently deteriorating the power quality of grid line currents. These injected harmonics lead to electrical and thermal overloading of distribution transformers, thereby compromising their lifespan. Additional issues include excessive current draw from the grid, imbalance between demand and supply, and voltage fluctuations. Apart from power quality issues, there is a need to develop a fast fault detection algorithm to protect the charging station supply equipment when a fault occurs either grid side or on the downstream DC side. This paper presents an instantaneous power-based fault detection algorithm to detect the fault in grid-connected EV charging stations for Grid vehicle (G2V) and vehicle-to-grid (V2G) mode of operation.