Control of recuperative braking of a locomotive under limitation of the energy recovery to a contact system

Abstract

Recuperative braking of electric rolling stock in railway transport provides energy recovery of the braked train to a contact system. However, during dc electric operation, this possibility is not exploited to the full extent. This is due to the fact that the contact system is not always ready to receive excess energy, because the diode rectifiers of the traction substation do not allow recovering electrical energy of the recuperating train from the contact system into the primary three—phase alternative current network. Thus, if a substation performs this function, it has to be equipped with a thyristor rectifier—inverter unit, which adds to its cost. Recuperative braking provides energy saving but rheostat braking is included for extra safety of trains. When energy recovery to the contact system is not possible, this break unit completely substitutes for recuperation. This principle is used for an electric dc train, but, with a high power electric train (up to 6 MW), the energy recovery is not more than 3%, i.e., much less of the potential. This happens because other electric rolling stock located in this feeder zone cannot receive the recuperation energy. Therefore, switching to the rheostat braking takes place; i.e., the recovering energy is damped in rheostat braking. A principle of comanagement of recuperating and rheostat brakes is proposed. According to this principle, recuperative braking comes first and current is increased gradually to the maximum possible value, with the rest of the energy being damped in rheostats. This method of regulating streams of energy provides energy savings by 12—15%, which is proven by a computer simulation for a Moscow railway junction.