Variable step size P&O MPPT algorithm for optimal power extraction of multi-phase PMSG based wind generation system

Abstract

To eradicate limitations of conventional fixed step-size perturb and observe (P&O) maximum power point tracking (MPPT) based on the variable speed - wind energy conversion system (VS-WECS), this article proposes a fast and an efficient MPPT modular sectors algorithm. The variable-step perturb and observe (VS-PO) MPPT algorithm is implemented to divide the power-speed (P-ω) curve into modular sectors each with specific step-size. The modular sectors are established by comparing a special synthesized ratio, that associates with the theoretical power, with a specified ratio corresponding the required power accuracy. Hence, the proper step-size is selected according to the operating sector location. For the sectors near the maximum power point (MPP), a small step-size is applied. Otherwise, a large step-size is used. To calculate the theoretical power, a wind speed estimation algorithm is utilized for evaluating the wind speed. The system configuration involves a 1.5 MW five-phase permanent magnet synchronous generator (PMSG), and a back-to-back frequency converter with the dc-link capacitor for the grid integration. The simulation results illustrate the VS-PO superiority over both the conventional P&O (CPO) and modified P&O (MPO) techniques. The VS-PO improves the initial speed tracking and minimizes the steady state oscillations. The performance of the proposed control schemes is validated using MATLAB/SIMULINK environment.