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RESEARCH PRODUCT

Impact of High Penetration of Electric Vehicles on Low Voltage Network Stability and Role of Managment Programmes for Electric Vehicle Charging

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Masteroppgave fornybar energi- Universitetet i Agder, 2015 The number of electric vehicles (EVs) have increased in Norway over the last couple of years. Low emissions and reducing petroleum dependence are some of the advantages achieved by using EVs. This master thesis presents the impact of high penetration of EVs on a low voltage distribution network. Uncontrolled charging patterns of EVs will likely stress the distribution network and could cause power outages, voltage fluctuations, thermal stress on the lines and harmonic pollution. As an alternative to grid reinforcement, smart load management (SLM) and demand side management (DSM) were introduced for coordinating the charging of large numbers of EVs. Simulations of uncoordinated and coordinated charging of EVs were conducted with the power grid calculation software DIgSILENT PowerFactory and the proposed management algorithms written in MATLAB. The network was simulated using none, two and eight EVs connected. The Nissan Leaf battery specifications were used as a reference, where 3,3 kW and 6,6 kW charging power were tested. The impact of the original scheduled EV loads were compared with the results from applying the management programmes to the system, and discussed with respect to network stability and user satisfaction. The transformer was the main bottleneck for the system, but also overloading of overhead lines limited the charging of the EVs. Of the programmes tested, the minute-based SLM programme gave the best results. The constraints were adhered, and the delay of the charging was reasonable. Increased charging power was also possible for this programme during the most power demanding periods with similar results.