A probabilistic approach to size step-up transformers for grid connected PV plants

Step-up transformers are exploited to connect large PV plants to the utility network, their sizing being often accomplished only taking into account the PV plant peak power. In the present paper a general design methodology is proposed to optimally select the size of these transformers on the basis of the statistical distribution of the solar irradiation in the selected site and the mathematical model of the plant. It is based on a probabilistic approach based on the evaluation of the so called LPPP (Loss of Produced Power Probability) index. Taking into account full life costs the proposed approach is exploited to find the optimal transformer size for a grid connected 2 MW PV plant located in different geographical sites. Moreover, the effect of the introduction of energy storage systems in the PV plant is also evaluated.

► Methodology for optimal selection of the rated power of step-up transformers in PV plants.
► Approach based on the evaluation of the LPPP probabilistic index.
► Design of the step-up transformer for a grid connected 2 MW PV.
► Three geographical locations and the introduction of energy storage systems are considered.