Performance Enhancement of Grid-Off Photovoltaic Pumping System-Quasi Z Source Inverter by Hybrid Battery-Supercapacitor Energy Storage

Abstract

in this paper, a scheme of standalone off-grid solar photovoltaic water pumping system based on quasi z source inverter and battery/supercapacitor hybrid energy storage is proposed. The most challenge in photovoltaic pumping system is how to ensure a higher sufficient useful power in all really meteorological and daily water conditions. The main objective of this study is to improve the reliability of the conventional photovoltaic pumping system by appropriate hybrid combination of battery-supercapacitor energy storage. The quasi z source inverter used in this structure make it possible to establish the simultaneous control of the photovoltaic maximum power and real time motor speed regulation. Also, their structures give the opportunity to integrate several storage systems in parallel with the capacitance in the impedance network. For that, the batteries are used to compensate the long time power lack can be occurred in the installation because it has a high energy density. In other hand, supercapacitors are used to improve the battery lifetime and reduce the life cycle cost of the photovoltaic pumping system, hence, they are integrated to reimburse the transitory moments time produced by fast climatic and pump speed variations because it has a high power density and a large cycle life. The analysis is carried out through simulation in the Matlab™ environment, the results obtained clearly depicts the robustness of the proposed control system and the power flow performance enhancement.