Impacts and solutions on vehicle to grid (V2G) infrastructure.
Mkhize, Savious Mduduzi.
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To deal with the problem of global warming and dependency on oil, the need for emmissionfree transport has brought electric vehicles to life. The main aim of this thesis is to investigate, analyze and propose solutions to the impact of electric vehicles (EVs) on the smart grid. Before investigating the impacts of electric vehicles to smart grid, it is important to have a better understanding of EVs, power grids and vehicle to grid (V2G) infrastructure. The fundamentals of V2G technology are provided in the thesis to understand V2G infrastructure. A power demand study for domestic customers is carried out which asseses the best period for charging electric vehicles at home. Several domestic customer distribution feeders are studied and common observations are drawn. The number of EVs that can be connected to the distribution transformer per phase is calculated and discussed. This calculation considers three home charging levels and types of distribution transformers used by the South African utility company ESKOM together with common observations from demand studies. The electric vehicle is modelled and simulated using MATLAB. The aim of this work is to understand EV power requirements, energy requirements and EV charging times. The electric vehicle is simulated travelling at different road gradients and travelling at different speeds for each road slope. The study results in terms of the impacts of V2G infrastructure are provided and discussed systematically. It is observed that the main impacts include: overloading, under-voltage, imbalance and network instability. Possible solutions to the impacts are provided and discussed. The solutions include overnight charging, constructive charging, balanced charging, distributed controlled charging and centralized controlled charging. After careful analysis, it is observed that the charging impacts are further minimized when these solutions are combined together. Overall results, discussion and conclusion are provided. The challenges faced in this study are outlined and recommendations for future studies are given. In this thesis, it is found that EVs can be safely integrated into a power grid with intelligent charge control through V2G. V2G provides significant benefits to all stakeholders. V2G has many additional applications in the smart grid and microgrids.