In the frame of this thesis, unintended interruptions of electric vehicle charging processes were detected while the power quality was within normative limits. This indicates that poor power quality could impose a significant risk for the successful integration of electric vehicles into the distribution grids. Particularly higher frequency harmonics in the range from 2 to 150 kHz (Supraharmonics), generated by modern power electronic applications, raise concerns among the scientific and standard setting communities. There is limited knowledge and experience about the long-term behavior of Supraharmonics in the field. The main reasons are the lack of suitable measurement equipment and data analysis methods, able to overcome the challenge of processing the large amounts of generated data in an efficient manner. This work proposes a new monitoring approach for the continuous long-term measurement and characterization of Supraharmonics, which are rarely measured in the field.