Upstream Fault Detection Technique in Grid-Connected EVCS Using Negative Sequence Components

The widespread integration of electric vehicle (EV) charging stations into the existing utility grid is causing significant power quality and protection challenges. These challenges are notably impacting load performance for both large and small-scale consumers. As the transition from internal combustion engine (ICE) vehicles to EVs accelerates, driven by their numerous benefits, these issues are becoming increasingly severe. EV chargers rely on power electronics to convert AC power from the grid into DC power for battery charging. However, this conversion process, which involves high-frequency switching converters, generates harmonics that degrade grid current quality. This degradation leads to electrical and thermal stress on distribution transformers, ultimately reducing their operational lifespan. Additionally, there are concerns about increased grid current demand, supply-demand imbalances, and voltage fluctuations. Beyond power quality issues, there is a pressing need to develop fast fault detection algorithms to safeguard EV charging station equipment against faults, whether on the grid side or within downstream DC components. This paper introduces a Q-sum (cumulative sum) of the rate of change of a negative sequence (RCNS) power-based fault detection algorithm designed specifically for grid-connected EV charging stations operating in both G2V and V2G modes.