Determining the Impacts of Fast-Charging of Electric Buses on the Power Quality Based on Field Measurements

In the last few years more electric vehicles (EV) are being connected to the electricity network. Fast charging EVs is of paramount for the smooth transition of mobility from conventional oil/natural gas-based infrastructure towards electricity-based infrastructure. In the Netherlands, some pilots have started to understand the impacts of EV charging on the electricity networks. One such pilot case has taken place in a major city of the Netherlands, where every day many fast and slow charging of electric buses takes place in the same bus depot. As the EV chargers contain converters (power electronics-based components), these are considered as potential sources of harmonics (<2 kHz) and supraharmonics (2 kHz-150 kHz). Presently, there is no specific standard that gives limit values for supraharmonic emissions at a network connection point. It is anticipated that both harmonics and supraharmonic disturbances can have adverse impacts on the lifetime of connected devices. Theses emission can also disturb the quality of the supply voltage and may therefore affect the operation of other equipment in the same installation. The power quality measurement (PQM) results at this bus depot show harmonics and supraharmonic emissions from the EV charging points. In this paper various PQM results are summarized and their implications towards the present grid voltage quality are discussed.