Abstract:
Many developing countries including my country Ethiopia are following rainfall based agricultural economic system. The product collected from agricultural crops is not satisfactory due to the variation of the rainy season by climatic changes. Water pumping using a renewable solar PV energy for irrigating agricultural areas can be a solution to improve the products collected from the crops. Two-stage standalone solar PV power feed speed sensorless induction motor drive (IMD) water pumping system using a centrifugal pump for irrigation purpose is proposed in this dissertation report. Perturb and Observe (P&O), Incremental Conductance (IC) and fuzzy logic based maximum power tracking (MPPT) algorithms are assessed and compared for Solar PV power generation. Soft starting and speed control of IMD is achieved by speed sensorless V/f constant control scheme. The input reference frequency to the V/f constant speed controller is generated from the available solar PV power and regulating DC-link voltage. DC-link voltage is regulated by using a PI controller to make sure the V/f of induction motor supply constant for all conditions. Pump affinity law is used for the proposed control system which relates the speed and power by using pump constant (Kpump) as a proportionality factor. The pump constant is used to show pump load estimation. MATLAB Simulink is used to verify the performance of the proposed water pumping system. Starting, steady state and dynamic performance of the proposed system under different environmental condition is evaluated. Effect of the wrong pump constant (Kpump) estimation and load torque variation in the proposed control system is also presented.
