Improvement of electric power quality using a unified power-quality conditioner integrated with a PV system and a supercapacitor

This paper proposes a unified power-quality conditioner (UPQC) integrated with a PV system and a supercapacitor (SC) energystorage system (ESS) to achieve power-quality improvement of nonlinear loads connected to a power source. The perturbation and observation (P&O) method joined with the maximum power point tracking (MPPT) scheme is used for the PV system with a PV array connected with a DC-DC boost converter to offer maximum power to the grid and the SC-ESS. The SC-ESS with an SC and a bidirectional DC-DC converter can operate in either charging mode or compensation mode. The proposed UPQC joined with the combined PV system and the SC-ESS scheme can effectively compensate for severe voltage sag and short-term power outage, which the traditional UPQC cannot offer.