Assessing the Impact of Transport Electrification on Distribution Networks - A Case Study of the Croatian Region of Istria

The increasing number of electric vehicles (EVs) introduces significant challenges for distribution networks planning and operation, including higher loading levels, voltage deviations, and potential transformer and line overloads. These challenges are amplified by the requirements of European Union Directive 2014/94/EU on alternative fuels infrastructure and Croatia’s National Energy and Climate Plan for the period 2021–2030. This paper analyzes the impact of transport electrification on the distribution network of the Croatian region of Istria, selected due to its pronounced seasonality and specific geographical conditions. The analysis is based on a detailed network model consisting of nearly 2,500 medium to low voltage substations and more than 170,000 end users, incorporating real data on existing and planned charging stations, tourism related load variations, and EV growth projections. The methodology applies a k-medoids approach to identify representative low voltage networks, enabling the assessment of load increases and the identification of necessary grid reinforcements. The results show that EV growth combined with uncoordinated infrastructure deployment leads to voltage and current congestion. Based on these findings, the paper proposes a timeline of required investments, including conductor replacements and the construction of new transformer stations, to ensure reliable and efficient network operation as transport electrification progresses.