Novel Control of Photovoltaic based Water Pumping System without Energy Storage

Abstract

Abstract Photovoltaic (PV) based water pumping systems are used for irrigation and drinking water. PV based pumping systems without battery can provide a cost-effective solution. In this paper an integrated controller is proposed for the operation of a stand-alone PV based water pumping system without battery storage. To incorporate PV based water pumping system, two schematics and corresponding controllers (i.e, power and voltage based) are proposed. In voltage based control scheme, inverter not only controls the voltage but also acts as maximum power point tracker for PV. Hence no extra dc-dc converter is required to extract maximum power from solar. The proposed integrated controller requires only measurements of dc-link voltage and load currents, no need to measure the PV and load powers. Under light load condition, dc-link voltage will go up, hence, in order to protect dc bus resistive type of dump load is connected so that it will consume the surplus power from PV. Effective control coordination is developed to switch ON/OFF the induction motors so that negligible power wasted in dump load under scenario of PV power is more than load. Results are presented based on different cases of irrigation pumping application and availability of solar irradiance. Extensive simulation is carried out using Matlab/Simulink and through simulation results it is shows that the performance of proposed controller is quite satisfactory.