A supercapacitivite-storage based substation or the compensation of resistive voltage-drops in transportation networks is proposed. It allows to feed as a current-source in any voltage conditions of the line. The system has been desgned as a compensation-substation to be placed at weak points like end-of-line stations, instead of additional feeding substations. A dedicated power-electronic converter with an associated control system for the stabilization of the voltage level at the point of coupling in case of strong perturbations is proposed. Pratical results are also presented, which have been recorded from a reduced-size prototype.