The Study of VFTO Distribution in the Insulation System of IOCT Used in Traction Network

The FDS (Frequency-domain Dielectric Spectroscopy) of oil-immersed insulation paper, and semi-conductive paper with different moisture content, has been measured. The data measured are fitted as a function of frequency and moisture content using the amendatory Cole–Cole model utilizing the least square technique. Then, the broadband MTL model of the insulation system of IOCT (Inverted-type Oil-immersed Current Transformer) is established considering the capacitive electrodes thin layer, and the distribution parameters consider the moisture and frequency dependence. A new method for VFTO (Very Fast Transient Overvoltage) distribution calculation of insulation systems is proposed.

INCREASING THE ENERGY EFFICIENCY OF THE AC ELECTRIC LOKOMOTIVE TRACTION DRIVE

The study of the energy characteristics of the active traction converter with pulse-width modulation as part of the traction electric drive of an AC electric locomotive was held during the research. Active traction converter provides pulse-width control of the collector DC traction motors voltage and belongs to the basic AC / DC circuit. The transient process when switching transistor switches is accompanied by significant voltage surge, due to the scattering inductance reaction of the traction transformer. Studies have shown that the diode discharge buffer circuits do not provide discharge of the electromagnetic energy accumulated in the winding of the transformer. An active traction converter control algorithm has been developed, which implies the use of pulse-width and phase regulation of rectified voltage. Switching of transistor switches occurs in the presence of a parallel current circuit. This creates the conditions for the discharge of electromagnetic energy accumulated in the secondary winding circuit of the traction transformer. The developed mathematical model allows to investigate the electromagnetic processes that occur during the switching of transistor switches and to evaluate the energy efficiency of the electric locomotive with active traction converter. In the simulation process, the influence of active traction converter parameters and control algorithms on the power rate of the converter, the total THD distortion rate of current and voltage and the relative values of the rectified voltage were investigated. Measures to increase the power rate and to reduce the emission level of higher current harmonics into the traction network were proposed.

Determination of short circuit location in the electric railway traction

This article discusses the problem of improving the accuracy of determining the location of a short circuit in the AC railways traction networks. Finding a short circuit can take several hours. An urgent task is reducing the time to search for a fault location. The purpose of the study is to develop a method that increases the accuracy of determining the location of a short circuit in AC traction networks. The method is based on computer modeling of inhomogeneities in the structure of the traction network and the arc. The proposed method makes it possible to take into account the arc resistance. The method was tested on the traction network active section. The error of the method is 200-300 meters. The method can find practical application in the work of dispatchers.

Model of the traction and external power supply system joint operation

The paper presents a description of mathematical model designed to study the joint operation of 25 kV alternating current traction power supply systems and 110 - 750 kV power supply systemsThe design concept of three-phase and single-phase PU-generators on the basis of the EMF source behind inductive resistance as well as three-phase and single-phase loads is considered. Based on the above mathematical expressions, a computer model has been developed to analyze the joint operation of three-phase networks of external power supply and single-phase traction networks. The model is implemented in the software package MATLAB -Simulink. Using this computer model the influence of power overflows in the 110 - 330 kV network of PJSC “Karelenergo” and PJSC “FGC UES” on the equalizing currents in the traction network of the Knyazhaya-Idel’ section of the October railroad was analyzed. Brief analysis of modeling results is presented.

Determination of Electromagnetic Influence of 25 kV AC Electric Traction Network on 10 kV High-Voltage Overhead Line

Electrified railways include a system of cable and overhead lines. An analysis of the operation of alternating current (AC) electrified railways sections shows that the value of the induced voltage caused by the operation of the traction network can significantly exceed the permissible level on adjacent disconnected high-voltage overhead lines. As a consequence, this leads to serious injuries to operating personnel, including deaths, failure of electrical equipment. From this point of view, 1x25 kV 50 Hz AC railway system networks are considered the most dangerous. The electromagnetic influence of the traction network of a double-track section of an AC railway on an adjacent 10 kV high-voltage overhead line for power supply of automatic block signalling is investigated in the offered paper. Emergency cases of traction network operation are considered: short-circuit situation and forced state. The calculations of short-circuit currents in the influencing inter-substation zone, as well as estimation of the induced voltage on the wires of the 10 kV disconnected high-voltage overhead line for various schemes of grounding, have been performed. The investigations were carried out on models built using the ATP-EMTP program.

Rational reconstruction of sectioning posts of AC catenary at disconnectors

Operation of sectioning posts of the AC catenary at the disconnectors on the Gorkovskaya railway for a period of more than 60 years has shown its reliable operation, and the maintenance was reduced to a minimum. However, due to the growth of heavy haul and high-speed traffic on a number of sections, their reconstruction was required. In accordance with the current regulatory documents, such a reconstruction provides for the transfer of the operation of sectioning posts from disconnectors to circuit breakers. In connection with the reliable operation of the sectioning posts on disconnectors and the simplicity of their maintenance, it is proposed to expand the options for the reconstruction of the sectioning posts on the disconnectors and to introduce three reconstruction options into the regulatory documents. The first option provides for the reconstruction of the sectioning post with disconnectors by transferring it to the classic scheme with four switches, as indicated in the current regulatory documents. The second option provides for leaving the sectioning post at the disconnectors, but adding a fast-acting automatic reclosing device in the inter-substation zone in case of passing short circuits. The third option provides for the reconstruction of the sectioning post on disconnectors with the introduction of a vacuum circuit breaker into the bus of the post and a device for high-speed automatic reclosing and opening of the disconnector, in the zone of which a short circuit has occurred. The schemes of automatic devices for determining a stable (passing) short circuit in a traction network and a device for determining the location of damage are considered. The operation of the sectioning posts, reconstructed according to the indicated options, has been tested practically at the existing sections of the power supply of the traction network of the Gorkovskaya railway. All of them have shown high reliability.

A simulation model of a traction network taking into account the variable resistance of the contact line and a given power profile of the electric vehicle in MatLAB Simulink

The article describes an approach to the development of a simulation model of an electric transport traction network, taking into account the change in the resistance of the contact wire when the vehicle is moving. The advantage of the model is that it is executed using the building blocks of Simulink, visually reflects the topology of the traction network, and can be used for modeling both trolleybus and rail transport networks. As the initial data for the model, both standardized drive cycles and experimentally obtained modes of vehicle motion can be used.