Effect of non-unity power factor operation in photovoltaic inverters employing grid support functions

The high penetration of utility-interconnected photovoltaic systems is causing heightened concern over the effect that variable renewable generation will have on the electric power system (EPS). These concerns have initiated the need to amend the utility interconnection standard to allow functionalities, so-called advanced inverter functions, to minimize the negative impact these variable distributed energy resources may have on EPS voltage and frequency. Unfortunately, advanced functions, in particular volt-VAr, will result in non-unity power factor (PF) operation[3]. The increased phase current results in additional conduction losses and switching losses in the inverter power electronics. These power losses have a direct impact on real power delivered to the grid at the point of common coupling (PCC) and an impact on inverter service life. This report provides analysis, simulation, and experimental evidence to investigate the effect of advanced inverter functions on non-unity PF operation.