An Improved Adaptable Step-Size P&O MPPT Approach for Stand-Alone PV Systems with Battery Station

Abstract

This study proposes and discusses a single-stage off-grid PV system to supply power to DC loads. A single-buck converter interfaces a 2 kW PV array and DC load and ensures a good operation of the maximum power point tracking (MMPT) and battery charge control, simultaneously. For the MPPT side, an improved adaptable step size P&O approach is suggested to reach the real maximum power point (MPP) of the solar PV array under varying weather conditions with reduced steady-state oscillation and less power loss. Furthermore, a three-stage charging controller (TSCC) is used in the battery charge control side to charge a 200 Ah lead-acid battery. MATLAB/Simulink environment tool is used for the implementation of the overall PV system. The simulation results under different scenarios of weather conditions prove the highest tracking performances of the improved approach over the conventional P&O method. In this respect, the developed P&O approach can capture the MPP in a time less than 2 milliseconds, which is 10 times faster than the conventional P&O method. In addition, it can mitigate the power losses and reduce the oscillations around the MPP to half compared with the basic P&O method. Furthermore, the improved P&O approach with TSCC can significantly enhance the BS charging operation with good stability in the output power, voltage, and current of the battery.