Frequencies above the harmonic range - challenge of the future?

During the last two decades, the main topic in respect to power quality (beside voltage dips and outages) was and still is harmonic distortion. However, following the development in power electronics with an increasing use of self-commutated converters, problems are shifting slowly to higher frequencies. Voltages with frequencies above the “classical” harmonic range create new challenges and require new solutions. With the large-scale introduction of electric vehicles, solar power, wind turbines or similar applications, the level of voltages with frequencies in the kHz range are most likely to increase in the next years. For the operator of a network, by now there exists no sufficient guidance yet in respect to tolerable disturbance levels. Effects of significant voltage levels of higher frequencies are known only to some extent. Such, there seems to be a lot to do in order to ensure a trouble-free operation of electric distribution networks in the future. The paper tries to give an overview on the current status of voltages above the harmonic range and to identify critical points which require some efforts in the future.