Investigation of the effects of energy storage systems and high-power electric vehicle charging units in distribution grid with renewable energy sources

Today, the increasing energy demand has made the integration of renewable energy sources into power systems and the stable operation of distribution networks more critical. Although renewable resources such as solar and wind energy are environmentally friendly, their variable production characteristics may cause technical issues in distribution systems, including voltage fluctuations, irregular power flows, and increased line and transformer loading. Additionally, with the rapid growth in electric vehicle adoption, the connection of high-power charging stations to the grid has further amplified existing loading and stability problems due to sudden and intensive power demands. This study investigates the annual and seasonal impacts that arise when renewable generation units, high-power charging stations, and energy storage systems operate simultaneously on a realistic distribution network model representing the load of a small district. Within the model, a 100 MVA power transformer, a 23.6 MW wind power plant, a 57 MW solar power plant, a 6 MW electric vehicle charging station, a 10 MW heavy-vehicle (truck) charging unit, and two 10 MW energy storage units connected to the renewable plants were used. Seven different operating scenarios were constructed, and the system behavior under each scenario was examined in detail. The findings reveal that energy storage units reduce transformer loading, balance line power flows, and significantly enhance the overall operational stability of the distribution network.While scenarios involving only high-power charging units resulted in notable peak load increases, the inclusion of energy storage systems effectively mitigated these adverse effects. Overall, the results demonstrate that energy storage units are a critical component for modern distribution networks with high renewable penetration.