A Novel Sensorless MPPT Control Technique for Grid-Connected PV System Operating on Internal Signals

Maximum power point tracking (MPPT) is essential for maximizing energy extraction from photovoltaic (PV) systems under varying operating conditions. This paper investigates a Sensorless control scheme (SCS) for grid-connected PV systems that eliminates the need for additional PV-side voltage and current sensors for MPPT by utilizing the internal power-factor-correction conductance signal GP. The SCS regulates the PV operating point through a piecewise-linear reference-voltage ramp whose direction is determined from successive variations in the internal control variables, with the objective of maximizing the average grid-injected power PAc. The proposed formulation is systematically evaluated against the conventional perturb-and-observe (P&O) algorithm using PSIM simulations under static and dynamic irradiance conditions and across multiple perturbation magnitudes ΔV. The results show that SCS maintains high MPPT efficiency over the operating range investigated, achieving up to 99.96% under static irradiance and 98.91% under the dynamic irradiance profile. The influence of ramp magnitude on tracking dynamics, steady-state oscillation, grid-side power transfer, and grid-current total harmonic distortion (THD) is also assessed. Under the investigated low-irradiance condition of 300 W/m2 with ΔV = 21 V, SCS produced a grid-current THD of 0.144%, compared with 0.22% for P&O, corresponding to an approximately 34.5% relative reduction. The SCS framework is applicable to both single-stage (SS-GPVS) and dual-stage (DS-GPVS) grid-connected PV architectures and provides a low-complexity MPPT approach based on existing converter control signals.