An improved adaptive perturb & observe maximum power point tracking technique

To increase the energy harvest of photovoltaic (PV) module, a converter/inverter with maximum power point tracking (MPPT) is needed as the interface between the PV array and the load. The purpose is to adjust the effective load resistance presented to the PV modules so that the system operates at the maximum power point (MPP). As such, two requirements must be met by an effective MPPT controller: first, converge to the MPP quickly especially during dynamic weather conditions; second, exhibit small oscillation around the MPP under steady state. Knowing that oscillation will adversely affect the system stability and continuous power generation, many MPPT propose to adaptive change the variation step according to the power variation. For example, a second PI controller is implemented before the MPPT controller to minimize the perturbation size. These methods still do not suppress the steady sate oscillations around MPP effectively. As such, this paper proposed an improved adaptive MPPT technique by adding a steady state MPP determination algorithm after the adaptive perturb & observe method, which helps harness more renewable energy with reliable and high-efficiency tracking capability. The method is also independent with the environmental conditions and has smaller oscillation around the MPP compared to other adaptive P&O methods proposed. The proposed method is verified by both simulations and experiments under different irradiance levels and dynamic weather conditions.