Provision of Phase Balancing and Reactive Power Compensation with Junction Temperature Control by Photovoltaic Inverters

The provision of reactive power compensation and phase balancing by photovoltaic (PV) systems is considered as an essential component for enhancing the power quality and efficiency of distribution grids. However, phase balancing and reactive power compensation can increase the power losses of PV inverters in an asymmetric way. This can cause a different temperature rise in each switching device, leading to a reduction of the overall lifetime of the inverter. This paper investigates the potential improvement of PV inverters reliability with a junction temperature control while providing phase balancing and reactive power compensation. The PV inverters can provide either full compensation to asymmetric loading and reactive power or a limited compensation considering the thermal stresses at the switching component level. With the latter option for ancillary services provision, the junction temperature is always kept bellow a desired value, limiting the degradation of the inverter lifetime. Simulations and experimental tests are carried out to demonstrate the performance of the junction temperature control during ancillary services provision.