Vol 89, No 10 (2018)

Regenerative braking with return of energy to an aerial contact wire in principle makes it possible to reduce the energy consumption for traction needs, but in real conditions the effectiveness of this braking type as a means of reducing the consumption of energy resources is often limited. The electric braking of rolling stock is more effective and independent of the external conditions in which the generated energy is stored in onboard energy storages. The largest reduction of consumption of energy resources for traction needs when using onboard energy storages composed of traction the electric drives can be achieved for rolling stock operating with frequent starts and stops. These types of rolling stock include suburban electric trains, subway trains, and urban electric transport, to the specific operation of which capacitive energy storages based on supercapacitors correspond best. This work considers the processes of energy exchange in traction drive systems with onboard capacitive energy storages during acceleration and electric braking of rolling stock. The energy exchange processes are considered in relation to resistive charging–discharging circuits and circuits with reactors, and the main attention is devoted to the effectiveness of energy exchange processes. The energy consumer in an energy-storage discharging circuit and the source of energy in the charging circuit are represented by an EMF source, which in general can change with time. The dependences of energy effectiveness of charging and discharging processes of capacitive energy storage on its initial voltage and on the rate of change in the EMF of energy consumer are obtained.

The important problem of increasing the energy effectiveness of traction rolling stock of railways and urban electric transport can be solved using onboard energy storages in traction electric drive systems. Onboard energy storages can perform a number of important functions promoting the efficient use of energy resources: storage of energy during cessation of electric braking, equalization of the schedule of power consumption from the prime heat engine, and storage of excess energy of regenerative braking. The main characteristics of electromechanical, inductive, capacitive, and electrochemical energy storages are considered from the point of view of effectiveness of their use as onboard energy storages in traction rolling stock.

Increasing the performance of electric traction of rail transport is a long-term priority. At present, the reserves for increasing the block speed of freight trains only by reducing downtimes at technical stations have been exhausted. An increase in speed will bring a synergistic effect in production activities. The 8-year long-term development program of the Russian Railways holding company (2018–2025) considers the premises of mutually advantageous cooperation of the railway industry and transport engineering and industrial enterprises ready to work for the long term. The implementation of this program should be based on next-generation industrial technologies. This article considers cutting-edge technologies, including competitive high-performance high-voltage direct current traction power supply systems and universal traction rolling stock with increased quality of outfeed from all kinds of electric traction networks by current type and voltage level.

The magnetic rotor flux in synchronous compensators with two excitation windings can be rotated by force, which makes it possible to achieve a more favorable effect of the compensator on the generator in emergency modes. This option has to do with the additional electromagnetic capacity formed in the machines by triggering the excitation along the compensator’s second axis. The control must ensure a relatively stable and possibly larger value of the compensator-induced component of the generator’s electromagnetic capacity. Other things being equal, the peak value of this capacity of the generator will be the same as in the standard generator. In terms of improving the dynamic resistance of the power line, the second excitation winding will make it possible at best to use the positive peak of the indicated capacity component in the required period of time. The control of the compensator excitation according to the laws of the sine and cosine of the relative angle between the compensator rotor and the generator rotor, as well as the derivative longitudinal and transversal components of the stator currents, can increase the electromagnetic generator capacity by a relatively constant value. The process of control according to the laws of the sine and cosine of the compensator angle relative to the voltage vector of the receiving system, their derivatives, and the derivatives of the stator current components increases the amplitude of the generator angular characteristic as in the case of the reducing mutual reactivity between the generator and the receiving system. The voltage in the compensator contact rings depends mainly on the time constant of the compensator excitation winding and slide and can reach a fairly high level; in this case, the dynamic stability limit reaches the postemergency mode limit.

The high harmonics of voltage and current that are generated by traction transformers mounted on ac electric rolling stock have a negative influence on systems of electrical power distribution and their components. The exact interrelation between harmonics and losses is too complicated to generalize, and, therefore, the influence of the form of current and voltage is determined as a rule using the power factor. The fundamental disadvantage of ac electric locomotives is a low power factor. To improving energy indices, methods were developed that make it possible to increase the power factor. The effectiveness of the proposed methods as a rule is estimated by means of determining the power factor. A calculating algorithm for the power factor is proposed in this work, which takes into account the influence of distortion power.