Nonlinear CTMV Control of a Solar Photovoltaic Water Pumping System

This paper is focused on the development of a nonlinear controller of a solar photovoltaic water pumping system (SPVWPS) using continuous time minimum variance control (CTMVC). This approach is combined with the indirect rotor field oriented control (IRFOC). This controller assures the maximum power point tracking, the rotor flux orientation, the pursuit of rotor speed of the induction motor and the estimation of load torque and rotor speed. In order to design the control laws of the DC-DC and the DC-AC converters and to estimate the unknown mechanical variables, the mathematical models of the whole system are proposed. These estimators are used to replace mechanical sensors that may cause high oscillations, instability of the system and decrease system reliability. Stability study is performed. The validity of the nonlinear predictive control strategy is tested on a Matlab/Simulink environment. Satisfactory results are guaranteed regarding trajectory tracking, disturbance rejection and constraints to quickly climatic conditions variations.