ABSTRACT
This work assesses the feasibility and performance of an enhanced Unified Power Quality Conditioner (UPQC). A UPQC configuration has been developed which incorporates Photo voltaic (PV) cells and Battery Energy Storage System (BESS) in the DC link of the UPQC. The BESS is connected using a bi-directional DC-DC converter. The system operates in two modes namely: Interconnected and Islanding. This arrangement enabled the reliable and efficient compensation of interruption, and the amelioration of the effects of loss of supply. A pre-defined power management strategy has been determined in which the combination of the PV/BESS takes care of a maximum of 1.4940MW of load active power demand during interruption and loss of supply. This value is such as to ensure active power balance in the system. A detailed model of the system has been developed in the two modes of operation. Data for the hourly demand on the 11kV Gaskiya feeder of the Power Holding Company of Nigeria (PHCN) Zaria and that for the hourly solar insolation in Zaria (Latitude 11.067 and Longitude 7.7) have been obtained. A thorough evaluation of the feasibility and performance of the system on the 11kV Gaskiya feeder is presented using the developed models, m-files and the embedded function of MATLAB/Simulink. Results show that at a solar insolation level of S = 0.07 representing the least insolation, S = 0.45 representing the most prevalent solar insolation other than the least and S = 0.85 representing the highest insolation, there is real time collaboration, based on the determined power management strategy, between the batteries and PV cells in meeting system demand. In the islanding mode, a part of load active power (1.4940MW) demand is met by the combination of the PV cells and batteries. Thus, interruption and loss of supply is mitigated by the system. Also, the capabilities of the UPQC to regulate load voltage and supply power factor remains uncompromised.