An irradiance condition detection–based two-stage MPPT algorithm for photovoltaic systems

This study proposes a novel two-stage maximum power point tracking (MPPT) method, termed I3VM (Improved Inflection Voltage Method with Irradiance Condition Detection), for photovoltaic (PV) systems operating under both uniform irradiance conditions (UIC) and partial shading conditions (PSC). The algorithm incorporates two key innovations: (i) a first-stage irradiance condition detection (ICD) mechanism that identifies whether the PV array operates under UIC or PSC using only two current samples, preventing unnecessary scanning of local maximum power points under UIC and ensuring high-speed tracking; and (ii) a second-stage Pythagorean-based adaptive perturb and observe (P&O) method that guarantees fast convergence with significantly reduced power oscillations around the maximum power point (MPP). The proposed method was validated through PSIM simulations and experimental studies, and compared with the 0.8Voc and I2VM methods under varying irradiance scenarios. Simulation results demonstrate convergence rates exceeding 99% under both PSC (99.89%) and UIC (99.99%), with tracking times of 1.2 s and 0.6 s, respectively, representing an approximately 50% reduction compared to the benchmark algorithms; power and voltage oscillations were reduced to 0.20 W and 0.30 V under PSC. Experimental validation confirms these findings, achieving 99.59% convergence within 0.8 s under UIC with lower oscillations than both benchmarks.