Power losses analysis of two-levels and three-levels PWM inverters handling reactive power

Reactive power handling by distributed power generation systems (DPGS) was prevented in the past in order to avoid additional power losses in the distribution feeders, however several new national grid codes request reactive power generation/absorption by the converters of active users. Actually almost no literature is focused on power losses analysis in case of reactive current circulation from the DPGS converter point of view. In the reactive power management, it has to be considered that the amount of the power losses varies on basis of the converter topology and the related modulation strategy. In this paper an accurate power losses evaluation is provided in case of two-levels and three-levels single-phase PWM inverters in grid-connected operation. The H-Bridge converter and the Neutral Point Clamped (NPC) half-bridge converter are compared. Reactive power handling feasibility is demonstrated up to low power factors (leading and lagging) involving a very limited increase of the power losses.