The work purpose is to estimate and investigate processes of the regenerative braking impact upon a voltage level on object buses of the system of traction power supply at electricity storage systems. In the investigation there are used methods of imitation modeling and analytical ones allowing the fulfillment of calculations for different conditions of the electric traction load formation within the limits of inter-substation areas under consideration. The work novelty consists in the approach to the estimation of the working mode impact of electricity storage systems upon the voltage level on buses of the objects of traction power supply under conditions of regenerative braking and charge characteristics changes. In the course of the investigation there are obtained the following results: the work cyclicity change estimation of a storage system is carried out; the dependence of a charge depth change upon rated power consumption is defined; charge characteristics for conditions of charge predominance in the diagram are calculated; the character of voltage changes on object buses of the system of traction power supply is defined; the necessity of charge characteristic adaptation depending on conditions of regenerative braking use is defined. The regenerative braking use makes an impact upon charge characteristics formed from the condition of charge predominance in the diagram of a charge degree at the rated interval and allows increasing currents of the second stage of the charge characteristics allowing the decrease voltage loss at charge realization caused by adjacent traction substations at the first stage.