Novel Pumping System based on Micro-Hydro Turbine and Centrifugal Pump coupled using EVT Induction Machine. Application in Rural Area Irrigation

Abstract

In this article, a topology for energy conversion oriented to water pumping for irrigation in remote areas is proposed. A micro-hydraulic turbine working at fixed speed, in a "run-off-river" configuration, drives a centrifugal pump through a variable electric transmission (EVT). An EVT based on induction machines was selected, with the stator directly connected to a weak AC grid but the internal rotor fed by a variable frequency drive, allowing an adjustable pump speed. The grid supplies a base power for residential consumption, while the hydro turbine increases the available power for irrigation and thus augmenting productivity of the land uphill and beyond the vicinity of the watercourse. The grid also provides an assistance function, absorbing/delivering a reduced amount of power in case the hydraulic resource is excessive/insufficient for the requested water pumping. As the turbine delivery is constant, the water pumping requirement establishes the power exchanged between turbine, AC grid and pump. For this reason, an analysis to quantify the power flow in the system components for different pump speeds has been carried out. The system modeling is described and computer simulations, using a specific pump speed profile, are presented to validate the performed theoretical analysis.