The power supply system of a contact network using a longitudinal line with points of communication without transformer is considered. The approach allowing to facilitate power filters and the way of switching of in-series connected semiconductor switches with fixing a voltage on them are offered.

The combined system of active filtration of target voltage of the rectifier using an added voltage converter as an in-series link and a high-frequency current inverter as parallel one is offered. Its application allows reducing weight of a choke of the passive filter.

The structure of the insert of direct current on the traction substation, which makes it possible to remove a number of deficiencies in the acting feeding scheme of the overhead electric transport power line of alternating current, is proposed. Additional possibilities on improvement in the use of electrical equipment by change in the form of voltage in the overhead electric transport power line are analyzed.