Supercapacitor represent one of the newest innovations in the field of electrical energy rtorage, and are subject of several developments in the industry for many different and news applications. Supercapacitors, which can supply a high instantaneous power, offer a solution to define new supply able to provide both energy and power. This leads to severl studies, in the industry and also in research laboratories, because supercapacitors and their applications require new developments. The way supercapacitors can be used is presented in this paper, as complementary energy storage devices for voltage drop compensation at the end of supply lines for trolley-buses. Two main axes on a real bus overhead-supply and the developments also needed for the associated power converter. The simulation tools that have specialoly been developed will be also presented, taking into account the specifities of a DSP-bord for the implementation.