Optimum MPPT Control Period for Actual Insolation Condition

Solar power generation systems require maximum power point tracking (MPPT) control to get maximum power using low efficient and high cost PV modules. Most of the conventional MPPT algorithms are based on the slope-tracking concept. One of a typical slope-tracking method is Perturb and Observe (P&O) algorithm. The two factors that determine the MPPT performance of P&O algorithm are the MPPT control period and the magnitude of the perturbation voltage. When the perturbation voltage is set to large, the MPPT controller quickly moves to the new maximum power point at insolation change, while the error of output power will be huge in the steady state even when insolation is not changing. When the MPPT control period is set for short, the dynamics of the MPPT controller can be accelerated even though the perturbation voltage is set for small. However, too short MPPT control period does not contribute improvement of the MPPT performance but consumes the MPPT controller resources. Therefore, in order to determine the optimum MPPT control period and the magnitude of the perturbation voltage, it is necessary to analyze the performance of the MPPT controller for actual insolation conditions in real weather environment. This paper proposes an optimum MPPT control period that maximizes MPPT efficiency by measuring and analyzing actual insolation profiles in typical clear and cloudy weather in central Korea.