Improved Estimation of Photovoltaic Water Pumping System Variables Using a Non-Linear Observer

This study presents an innovative method for estimating the state variables of a photovoltaic pumping system using a nonlinear observer. This approach is based on accurate system modeling and the use of an observer designed via optimization based on linear matrix inequalities (LMI). The observer was used to accurately estimate five key variables: the voltage and current of the photovoltaic array, the current in the DC/DC converter coil, and the voltage and rotational speed of the DC motor. Simulation results, carried out using MATLAB/SIMULINK, show rapid convergence of the estimated variables towards their actual values, even in the presence of variations in climatic conditions, such as irradiance and temperature. The effectiveness of the proposed estimation method is further validated through numerical performance indices, with the root mean square error (RMSE) for the estimated states remaining below 0.005 and a maximum estimation error under 0.45%, ensuring a high estimation accuracy of over 99.55%. This method offers a reliable and cost-effective solution for controlling PV systems by reducing the number of sensors required for single measurements. The performance obtained validates the robustness and efficiency of the proposed observer under different conditions.