Design of a robust PID controller used in PV systems

Improving photovoltaic systems in terms of time response and reducing the ripples in steady state, under varying conditions, becomes of high interest. In this work, a PID controller synthesis is presented. The PID is designed to work with a MPPT technique to track the target voltage. In order to outline the controller, a linearized representation (model) of the PV system is essential. This representation can be achieved by replacing, in the first place, the PV generator with its linear equivalent circuit, and then averaging the PV system equations over one switching cycle. The obtained system model is then used to synthesise the controller by means of Q-parameterization. This approach is an easy to use tool to design linear controllers and can guarantee at the same time closed-loop stability. After the design step, a stability analysis is conducted to measure the system robustness. The obtained results bear witness to the effectiveness of the designed PID in the improving the photovoltaic system performance.