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The subject of the research is the power thyristor converter of AC electric locomotives and its influence on the power factor of the locomotive. A new method for increasing the power factor of AC electric locomotives with thyristors power converters is proposed and analyzed. These electric locomotives include locomotives of the 2ES5K, VL85, EP1 series, etc. At the initial of the paper, the existing methods of increasing the power factor are briefly considered and their disadvantage in comparison with the proposed method is indicated. The drawback of existing converters is also analyzed, which consists in the presence of a thyristor opening delay at the beginning of the supply voltage half-cycle. The proposed method implies the modernization of the control circuits of the thyristors of the converter, due to which, at the beginning of the half-period, a control current is spontaneously created on the control electrode by means of the supply voltage. As a result, the thyristors open with a minimum delay after the start of the half-cycle. To verification the effectiveness of the proposed solutions, a computer simulation of the operation of the power circuit of an electric locomotive in the ORCAD program was carried out. Simulation was carried out for two options: a power circuit with standard converters and a power circuit with converters upgraded in accordance with the proposed method. During the simulation, the change in the value of the power factor of an electric locomotive was investigated at different currents of traction motors, zone and angle of regulation. Analysis of the oscillograms of converter various arms currents the revealed that when using the modernized converters, the moment of the end of the network switching occurs earlier than in the standard circuit. There is also no area with negative voltage at the output of the converter at the beginning of the half-cycle. At the end of the paper, the values of the electric locomotive power factor are given under various conditions. These results show that the use of the proposed method increases the power factor of an electric locomotive by an average of 1.2 percentage points.

This article describes the standard field reduction system of traction electric motors of a contactor-resistors type using inductive shunts, its drawbacks are revealed. An improved field reduction system of traction electric motors of an AC locomotive based on IGBT transistors has been developed and proposed. The proposed solution will allow to exclude the copper-containing inductive shunt from the power circuit, while providing reliable protection in non-stationary operating modes of the electric locomotive, as well as reduce electricity consumption for train traction. To prove the advantages of the proposed the field reduction system of traction electric motors, a method of comparative analysis of electromagnetic processes of the mathematical model of the standard and proposed systems of the field reduction of traction electric motors of an electric locomotive obtained in the MatLab Simulink environment was applied. As a result, it is proved that the implementation of the field reduction systems of traction electric motors using IGBT transistors with the developed control algorithm provides an increase in the power factor of an electric locomotive on average by at least 4%, and also significantly reduces the ripple current of the traction electric motor.

In general, improvement of methods for electrical calculations aimed at increasing the accuracy of the results. One of the ways to improve the methods of calculation is the account in the calculation of the various factors that affect the accuracy of calculation of the traction power system parameters. This article describes an approach aimed at improving the method of calculation in the electrical part to improve the accuracy by changing the algorithm for calculating and accounting for a number of additional factors.

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.

In the paper the device for reactive power compensation for the electric locomotives based on passive adjustable compensator was described. This configuration of the compensator improve the power factor of the electric locomotive in all operational modes and raise value of the power factor to its maximum possible value. The management of the compensator unit is based on the extremum seeking control autonomous voltage inverter. Mathematical modeling of electric locomotive showed increase the power factor to a value of 0,98.

The article considers one of the ways of improving the energy efficiency of AC electrical system railways 25 kV, 50 Hz. The proposed approach allows to determine the optimal location and capacity of an unregulated device for compensation reactive power according to the criterion of minimum active power losses in a traction electrical system. Modeling of trains on the site was made using instant schemes. Description of the traction power supply system implemented by the node potential method and Steinmetz’s symbolic method. Optimal value of reactive power for all possible locations of a compensating device was calculated numerically by an optimization method of Hooke-Jeeves according to the criterion of minimum active power losses in the traction network. The mathematical model allows to consider the elements of the traction network, schedules of trains, change of traction loads of electric locomotives, schemes of overhead network. The proposed approach was considered on the example test problem, which solution allowed to determinate the optimal location and required value of reactive power of an technical device. The placement of a compensating device in a certain place will allows to minimize the power loss in the contact network, track circuit and traction transformers from the flow of the reactive component of the current in average for all instant schemes with various traction loads. An unregulated technical device for compensating reactive power which is located between two traction substations reduces energy consumption for traction of trains on the 1 - 2 %.

The paper deals with benefits of a new rectifier-inverter converter of an electric locomotive based on IGBT-transistors. Main directions of heavy haul traffic's development are considered for Siberia and Russian Far East electrified railways. Throughput and carrying capacity of power supply devices extremely depends on the voltage level in the catenary network of electrified sections of railways. Objects of our research are electric parameters of the 25 kV, 50 Hz AC traction power supply system. Operation parameters of two different types of the electric locomotive’s rectifier-inverter converters are calculated and discussed. We investigated operation parameters for thyristor-based and IGBT-transistors- based rectifier-inverter converter. Current and voltage curves for the thyristor and the transistor type of the rectifier-inverter converter are given and discussed. Similarity factor of current curves for electric locomotives was calculated by equivalent sinusoid’s .method. Quantitative assessment of the voltage level, currents and voltage losses in the AC catenary network is given. The graph-analytical method was used for constructing currents and voltages vector diagrams. It is proved that electric locomotives with a new rectifier-inverter conversion based on IGBT transistors provides a reducing of the total voltage losses in three times in the traction network comparing the thyristor conversion's operation.