A Direct Maximum Power Point Tracking Method for Single-Phase Grid-Connected PV Inverters

A direct maximum power point tracking (MPPT) method for PV systems has been proposed in this work. This method solves two of the main drawbacks of the Perturb and Observe (P&O) MPPT, namely: i) the tradeoff between the speed and the oscillations in steady-state, ii) and the poor effectiveness in dynamic conditions, especially in low irradiance when the measurement of signals becomes more sensitive to noise. The proposed MPPT is designed for single-phase single-stage grid-connected PV inverters, and is based on estimating the instantaneous PV power and voltage ripples, using second-order generalized integrator-based quadrature signal generator (SOGI-QSG). We analyzed the global stability of the closed-loop control system and validated the proposed algorithm through simulation and experiments on an advanced test platform according to the EN 50530 standard. The experimental results confirm the performance of the proposed method in terms of both speed and tracking efficiency.