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E-Mobility starts to become an important part of our live. Germany plans to bring 1 million cars into the market until 2020. Nowadays the cars mostly use single phase charging with charging currents up to 32A and sometimes even more. 2-phase charging is also in discussion. Unbalanced charging of electrical cars differs from the operation of other single phase domestic loads (e.g. water cooker) due to the long charging times and the higher coincidence. Therefore unbalanced charging may lead to an increase of unbalance in LV grids, especially in the weaker rural ones. Starting with some theory and an overview of the relevant standards the paper discusses the charging behaviour of 5 different electrical cars and presents measurements of actual unbalance levels in selected LV grids. The main part of the paper illustrates a stochastic simulation of unbalance caused by an increased penetration of single phase charging electrical cars. The ratio of grid utilization depending on the magnitude of charging current is discussed for different scenarios and is compared to the case that equivalent 3-phase charging would be used. The paper concludes with some recommendations.
Date of Conference: 17-19 Oct. 2011