Harmonic distrortion caused by EVs on the LV distribution grid

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Dr. Farkas Csaba
Department of Electric Power Engineering

Electric vehicles need AC/DC conversion in order to power their DC power supplies from the AC grid. That conversion is granted by a non-linear unit, the inverter. Therefore they inject harmonic currents into the grid. In the future the popularity and the penetration of the EVs are very likely to grow significantly. By some estimation they can replace the traditional combustion engine cars. If that happens almost every household will have an EV. Alongside with the growing popularity of the non-linear household devices, massive amount of harmonic currents will be injected into the grid.

The distortion caused by those harmonic currents can affect the power quality on a large scale. The distributor system operators should be prepared for this. Thus it is very important to investigate the impacts of the harmonic currents on the power quality.

In order to examine the exact effects of the problems listed above I ran simulations on a real-life based network model. For creating the model I used measurement results and estimations where needed. The effects of various variables were tested, the importance of the harmonic profiles of the households, the numeric calculation method of the modelling software, the harmonic injection of the background grid and the penetration of the EVs in particular. For more accurate results I also ran stochastic simulations on a network model.


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