With the increase of switching frequency of semiconductor devices connected to the power grid

the harmonics injected into the power grid by converters are extending towards the high frequency direction.Super-harmonics is one of the one of the new problems of power quality due to electronization of distribution power grid. In view of non-intentional emission of ultra-high harmonics

its generation cause and frequency distribution feature are analyzed on the basis of the principle of pulse width modulation

a method of preferred aggregation band to reflect typical characteristics of ultra-high harmonics is proposed. The influence of different factors on the ultra-high harmonics are studied further

which provides the theoretical base for detection and identification of ultra-high harmonics

formulation of related standards as well as the management methods.