Adaptive PID Controller with P&O MPPT Algorithm for Photovoltaic System.

In order to extract maximum power from a Photovoltaic (PV) panel different Maximum Power Point Tracking (MPPT) algorithms have been developed, among which Perturb and Observe (P&O) MPPT algorithm is widely used. The P&O algorithm can be executed either by direct duty ratio or by voltage reference control. Both have drawbacks in tracking time and oscillation around MPP. In the latter case, the reference voltage generated by the algorithm is fed to a controller (PI/PID) to generate the corresponding duty ratio. The gains of PID controller are calculated under the standard test conditions (STC) (1000 W/m2, 25°C) of PV panel and the same values are used for other operating conditions too, which does not provide satisfactory performance under varying operating conditions. In this paper, an adaptive method is proposed to calculate the controller gains for different operating conditions without using any additional sensors. The proposed method establishes a linear relation between the PID gains calculated for the STC and those for other operating conditions, and this relation adaptively changes the PID gains for different operating conditions. It is observed from the simulations and experimental results that the proposed adaptive method precisely tracks the maximum power and optimizes the perturbation characteristics. [ABSTRACT FROM AUTHOR]