Electric Vehicle Charging Integration in Buildings: Local ChargingCoordination and DC Grids

Electric vehicle (EV) charging in buildings has a non-negligible impact on the in-building and low-voltage (LV) distribution grid. It is widely accepted that the coordination of EV charging may reduce this grid impact, allowingnbsp;EVsnbsp;be charged through the power system, without grid infrastructure investments. The literature mainly focuses on (large-scale) optimization coordination fornbsp;certain objective (technical and/or economical), which requires a relative high penetration rate of EVs to be beneficial. However, local clustering of EVs in buildings or LV distribution grids might already occur in the nearfuture, requiring local charging solutions. Therefore, in order to reduce thisnbsp;charging grid impact, this dissertation focuses on the following local EV charging solutions: (a) local EV charging strategies (rule-based control) in large buildings (multiple EVs charging), which require minimal local or EV internal knowledge, and minimal or no communication in and outside the building, and (b) the use of DC grids to connect and charge the EVs in buildings. The objective is to assess how these solutions can alreadynbsp;the grid impact, in order tonbsp;a higher penetration rate of EVs and others, such as a heat pumps and PV systems, innbsp;system. The following local EV charging strategies have been assessed: (a) EV based peak shaving, which reduces the EV charging power in order to maximally use the available charging time, i.e. load shifting and load reduction, (b) delayed charging delays the charging as long asnbsp;(c) renewable self-consumption, i.e. matching local electricity demand and production, (d)nbsp;voltage droop mechanism adapts the EV charging power as anbsp;of the grid voltage, and (e) a building peak shaving mechanism reduces the EV charging powernbsp;a function of the total building load. All local EV charging strategies succeed in their objectives, i.e. reducing the demand and/or injection peak powers, increasing the local self-consumption, and/or reducing the voltage deviations. The results show that these local EV charging strategies, which do not require any optimizations and any communication outside the building, decrease the grid impact and allow to charge more EVs in the building, postponing or avoiding the needs to invest in grid infrastructure reinforcements. The use of DC grids also reduces the grid impact of EV charging in buildings. The results show that DC grids arenbsp;interesting regarding the voltage unbalance an