Modeling Hydraulic Performance of a Drip Irrigation Network Directly Coupled to a Photovoltaic Pumping System

Abstract

Drip irrigation network coupled to photovoltaic pumping system presents an alternative solution that can efficiently improves use of water and energy by small and medium irrigated farming systems compared to conventional energy use for water pumping. Standalone photovoltaic water pumping systems (PVWPS) coupled to drip irrigation network constitute the best technico-economical solution compared to PVWPS using electrical or water storage demanding additional cost for the storage device. However, the standalone PVWPS need adequate process control to optimally be coupled with a drip irrigation network as adaptation between variable irradiance inputs and hydraulic outputs are needed to overcome problem of emission uniformity instability that can affect the hydraulic network performance. This study aims to improve the performances of a drip irrigation network coupled to a standalone photovoltaic water pumping system by evaluating the impact of irradiation variation on the hydraulic performances of microirrigation networks based on the calculation of emission uniformity coefficients (5 indicators). A Matlab/Simulink hydraulic model was developed to simulate a drip irrigation network confronted to variable hydraulic behaviours due to irradiance change. Evaluation of the hydraulic performances showed that irradiance change affects water distribution uniformity of the irrigation network. Emission miss uniformities up to 10 % were showed when lower irradiance input occurs. This problem can be solved by proposing hydraulic point tracking that adjust the network impedance with the photovoltaic generator input and irradiance occurrence.