Photovoltaic System Regulation Based on a PID Fuzzy Controller to Ensure a Fixed Settling Time

Abstract

The main objective of the controllers in photovoltaic systems (PV) is to ensure the maximum extraction of the available power. Those controllers usually combine the action of a maximum power point tracking algorithm (MPPT) with a voltage regulator, which has the function of rejecting disturbances at the panel terminals. Such controllers are commonly based on PI and PID structures, it requiring linearized models at an operating point. But, due to disturbances generated by the environment and the load, the operating point of the system changes drastically, which hinder to obtain the desired system performance. This paper proposes to regulate the PV system using a Fuzzy PID controller, which adapts to changes in solar irradiance and load oscillations. This characteristic guarantees a constant settling time, which is required to precisely define the period of the MPPT algorithm. In the case of classical linear controllers, the period of the MPPT algorithm is set to the worst case (longest period) which generates additional power losses by slowing down the tracking of the optimal operating point. Therefore, the solution proposed in this paper improves the overall system efficiency. Finally, such a solution is validated through simulations in Matlab®.