Search results

The purpose of this article is to analyze the voltage drop in the contact network caused by poor-quality operation of an alternating current electric locomotive when passing heavy trains. Heavy-haul traffic is considered today as a valid and necessary tool for increasing weight norms and increasing the throughput of railway sections. The article provides statistics on the passage of heavy and connected trains on the Krasnoyarsk railway for 2019 and 2020. For the effective use of heavy traffic, it is necessary to solve a number of problems, one of which is to reduce the voltage in the overhead network when passing heavy trains, this negatively affects the speed of the train along the haul, the conditions for cooling the power equipment of the electric locomotive deteriorate, etc. As a result of the analysis of the operation of the thyristor rectifier-inverter converter, a number of disadvantages were revealed. The reason for the low power factor of the electric locomotive lies in the use of an outdated element base based on thyristors, their closure is carried out only in the next voltage half-cycle, long-term switching and a large opening angle of thyristors leads to a significant reactive current in the contact network. Based on the analysis the voltage losses at the current collector, it was concluded that it is necessary to reduce the duration of the switching process of the arms of the rectifier-inverter converter, in which a short circuit occurs in the secondary winding of the traction transformer. An alternative version of the converter based on fully controlled semiconductor devices - IGBT transistors is proposed. The ability to open and close at any time of such elements allows you to minimize the phase angle and increase the power factor. Due to the almost instantaneous switching of transistors, the distortion in the contact network is minimized.

An urgent issue is to increase the power factor of electric rolling stock. One of the ways to increase the power factor in the traction and regenerative braking modes was proposed by the scientists of IrGUPS - this is the use of a rectifier-inverter converter on IGBT with modified control algorithms. This solution allows to significantly reduce the consumption of reactive current from the contact network, increase the capacity of railway sections, increase the technical speed, increase the efficiency of the traction power supply system, and also increase the amount of electricity returned to the contact network in the regenerative braking mode. The study of the performance of this converter is of interest. The transported volumes of goods on the railway lines of the Russian Federation continue to increase. One of the key links in ensuring the specified growth rates of tonne-kilometer work is the availability of powerful traction rolling stock equipped with an appropriate traction drive. A powerful traction drive is characterized by the consumption of significant current. To ensure its flow over the arms of the converter, a parallel connection of power semiconductor devices is used. For modern converters of electric locomotives, 4 parallel branches of power switches are used in the arm. The features of the parallel operation of the arm branches affect the performance of the converter on IGBT transistors. This article proposes to consider one of these features, namely the influence of parasitic inductances on the distribution of currents in the parallel branches of the converter, depending on the connection point of the AC power bus. The study was carried out using the Matlab Simulink software package. The article discusses various options for the topology of connecting power buses and presents diagrams of the distribution of currents in the parallel branches of the arm for each connection method. An assessment was made of such parameters as the spread of the peak current of switching on the branches of the arm, the time of current equalization during the conduction period, and the difference in the magnitude of the current in specific branches. Based on the results of the study, as well as taking into account the existing dimensions for the equipment of AC electric locomotives, a conclusion was made about the most optimal option for connecting power buses.