Small-signal modelling and control of photovoltaic based water pumping system

- The small-signal modelling of a photovoltaic based water pumping system is obtained.
- PI controllers are designed to meet peak-overshoot and settling time specifications of the response.
- The PI controllers also ensure desired loop robustness.
- Simulations show that the linearized system obtained closely represents the nonlinear system dynamics.

This paper studies small-signal modelling and control design for a photovoltaic (PV) based water pumping system without energy storage. First, the small-signal model is obtained and then, using this model, two proportional-integral (PI) controllers, where one controller is used to control the dc-link voltage and the other one to control the speed of induction motor, are designed to meet control goals such as settling time and peak overshoot of the closed loop responses. The loop robustness of the design is also studied. For a given set of system parameters, simulations are carried out to validate the modelling and the control design.