Stability analysis of photovoltaic systems driven by advanced MPPT controllers

An advanced maximum power point tracking (MPPT) control method, namely the ripple correlation control (RCC) MPPT method, is applied on a dc/dc boost converter used to interface a photovoltaic (PV) system with the electrical grid. An extensive nonlinear stability analysis is conducted in which the nonlinear model of both the PV source and the dc/dc boost converter dynamics are taken into account. Using this accurate nonlinear model and exploiting the singular perturbation theory and Lyapunov techniques, it is proven in the paper that for appropriate gain values of the RCC-MPPT controller, asymptotic stability to the desired equilibrium is guaranteed. The RCC-MPPT controller performance is finally evaluated by simulating an extreme case of rapid irradiance changes on a complete PV system.