Modeling of Processes When the Pantograph of a Shaft Electric Locomotive with a Frequency Electric Drive Is Disconnected

Abstract

The article presents the results of the study of phenomena in the short-term shutdown of the pantograph of a mine electric locomotive with a frequency electric drive of a voltage inverter system - an asynchronous motor, from a DC network.The relay contactor control system of a DC electric motor of a 14KA mine electric locomotive under the conditions of mines in Krivbass is by far the most common variant of electric drive. But it is already physically and morally obsolete, so a transition to modern drive systems is necessary. One option is to transition to a voltage inverter drive system - an asynchronous motor. At the same time, the power supply network remains unchanged - an outlying DC source. This raises the problem of a comprehensive study of the processes that can occur in the specified electromechanical complex, under various conditions. In particular, in practice, the pantograph is sometimes disconnected from the trolley for a short time, which is accompanied by sparking and arcing. This phenomenon most often occurs when the body of a locomotive with a single pantograph shakes at the rail junctions.Researches of the processes when the pantograph was turned off were carried out by the simulation method using the Matlab software package. The power supply system was taken into account as an unmanaged rectifier, which receives power from a voltage source with trolls, which are considered to be a series connection of inductive and active resistances. Rails are also counted as low active resistance. When modeling, the inverter of an electric locomotive in the model (together with the filter input capacitor) was disconnected from the trolley two times in a row at random intervals of 0.05 s. At the same time, a detailed and realistic sparking process for breaking an inductive current was not taken into account due to the complexity of its modeling. It was found that at the first moment in time when the pantograph is turned off, significant high-frequency voltages up to 40 kV occur in the network. Obviously, such high voltage values under favorable conditions can lead to the formation of an arc. Moreover, it can lead to malfunction of other electrical equipment connected to the same line, as well as disruptions in the operation of automation and communication in the power supply system. The simulation also found that when contact to the network is restored, significant switching currents (which are more than 100 times the rated current) and peak electromagnetic moments, which are more than 4 times the nominal motor torque, occur. The latter circumstance may contribute to the loss of controllability of an electric locomotive due to the loss of grip of the wheel with the rails. The obtained research results lead to the need for further improvement of the frequency drive in the case of its use in a mine electric locomotive in order to minimize negative phenomena in the event of an accidental short-term disconnection of the pantograph.Bibl. 10, pic. 5.