DC CABLING REDUCTION IN A PV ARRAY THROUGH SECOND STAGE OF COMBINER BOXES FOR VERY LARGE SCALE PV POWER PLANTS

摘要

This paper aims to highlight the potential for reduction of the photovoltaic array cabling, in order to reduce the initial cost of a large scale PV power plant. We use a custom MATLAB tool to calculate the optimized configuration of the cabling for a PV array unit, which includes PV modules, combiner boxes, cables and one inverter station. In order to further optimize the cabling we investigate whether a second stage of combiner boxes (mentioned in this work as recombiner boxes) could lead to PV cabling reduction. Thus, we develop a method, which groups together a number of combiner boxes in various alternative ways and by using a recombiner connects them with the inverter. Afterwards, a comparison between the cases of using one and two stages of combiner boxes is performed for various PV array power ratings and for two different types of PV modules. It has to be mentioned that for the comparison, the cable conductor mass has been considered as a cost index, so that in all cases the optimization is focused in total conductor mass reduction. Recently, there have been discussions for increasing the maximum permissible voltage level in the PV array from 1000V to 1500V, mainly to allow longer PV strings. Thus, this study is performed for systems of both 1000V and 1500V maximum voltage ratings.