A New Approach to Account for the Risk of Partial Discharge Inception in the Design of Insulation Systems Fed by Power Electronics Waveforms

Design of insulation systems is generally performed resorting to intrinsic aging laws. The design field for life and reliability specifications is calculated and insulation thicknesses are derived. Little thoughts are mostly devoted to the risk of partial discharge (PD) inception especially in energy sectors that, as electrified transportation, are only now escalating toward MV from LV designs. PD are one of the prevailing causes of premature breakdown of organic insulation. Hence, developing tools for minimizing the risk of PD inception at the design stage seems to be a must for the development of highly reliable design concepts, as required in many electrified transportation applications. This paper focuses on a new paradigm for PD-free insulation system design, called the three-leg approach, applied here to components supplied by power electronics waveforms (PWM). It is shown that also under the most common type of voltage supply in electrified transportation, i.e. AC modulated, the proposed three-leg approach effectively estimates the partial discharge inception voltage for simple capacitive objects, thus providing the limit nominal voltage for a design with minimal PD risk.