Performance Enhancement of PV-UPQC With Integration of Battery Energy Storage System at the DC-Link to Support Sensitive Consumer Loads

The proposed work illustrates an adaptive and coordinated control of battery energy storage system (BESS) supported photovoltaic fed unified power quality conditioner (PV-UPQC) to satiate the power quality requirements of sensitive consumers for their unperturbed and unpenalized operation under non-ideal grid and load condition. For grid synchronised unity power factor operation at point of common coupling (P.C.C), cross-coupled cascaded integral action (CCIA) based filter is used to accurately generate grid in-phase unit templates, magnitude of fundamental component of non-ideal voltage and current. Also, efficient regulation of DC-link voltage under grid voltage sag and PV intermittency is a significant concern. As per system configuration, power required for in-phase grid voltage sag compensation depends upon the amount of grid current flowing through injection transformer. Here, the objective is to reduce the grid current during sag to lessen the sag compensating power. Hence, incorporation of BESS across the DC-link with PV minimizes the burden on the grid subsequently reduces sag compensating power and also facilitates optimum utilization of PV power with smooth regulation of DC-link voltage under varying PV characteristics. To harness the benefits effectively under such dynamic scenario, an adaptively updating factor is introduced in the evaluation of battery feed-forward component and battery reference current for UPQC (shunt) and BESS controller respectively. The effectiveness of proposed improvisations are verified through simulation study and experimental implementation on a developed prototype of proposed system under all possible system dynamics.