The SIMSPOG simulation tool: a web-based implementation

The main problems of stray current and the low availability of the regenerative braking energy widely exist in DC traction power supply system which is currently widely used in China. The AC traction power supply system for Urban Rail Transit based on negative sequence current compensator is proposed as a kind of novel power supply scheme to solve these problems in DC system. And the construction of the AC traction power supply system is designed in detail. In the meantime, the system of negative sequence compensator based on three - phase three - level rectifier parallel is designed to compensate for the negative sequence generated by the proposed system in the paper. The negative sequence current compensation algorithm of the AC traction power supply system and the control method of the negative sequence current compensator are deeply analyzed and designed, and the proposed system is feasible to connect with three-phase power grid. Meanwhile, the equalization of the AC traction power supply system was also achieved. Finally, the performance of the power electronic compensator to eliminate the negative sequence current was verified by simulations and experiments.

Aim. Improving the efficiency of AC traction power supply systems. Solving challenges in testing technical and technological solutions using simulation modeling of their operating modes. Methods and Materials. The research is based on a simulation model designed to test algorithms for regulating the operation of electric power storage devices within the traction power supply system. The tasks are solved using the following methods: system method, analytical method, and statistical modeling method. Results. The proposed simulation model enabled the testing of an algorithm regulating an electric power storage device. The simulation provided results for active power regulation using the voltage levels in the contact network. The results included calculated oscillograms and voltages, along with their effective values for both charge and discharge modes. Conclusion. The results obtained can be used to compare the effectiveness of different methods for regulating electric power storage devices in AC traction power supply systems.

Objective: To study the problems and possible solutions in the introduction of an alternating current traction power supply system with catenary supports without rail grounding. Methods: To solve the set tasks, we used the statements and methods of the theory of power supply, experimental planning, mathematical and system analysis, and the theory of electrical measurements. In the experimental studies, the Trans-AURA Emergency Process Recorder and the Tektronix TDS 2014 Digital Oscilloscope were used, and the Aura2000 and MS Excel 2010 software products were used to process the experiment results. Results: The basic requirements for the AC traction power supply system grounding are presented. The flaws of the traditional grounding system of the catenary supports on the rail network are revealed. Two possible directions are described, which allow eliminating issues during the operation of the AC traction power supply system. The first direction requires the introduction of an additional stage into the traction network protection system, which makes it possible to identify short circuits through a high rail-to-earth resistance. The second suggests the need to revise the relay protection system itself, which includes changing the approach to grounding the catenary structures, the methodology for calculating the relay protection settings, a more detailed analysis of electrical safety conditions, etc. An equation has been formulated to determine support-groupto-earth resistance taking into account the group grounding cable and the existing requirements for ensuring the sensitivity of the main protection means, which allows ensuring reliable operation of feeders’ relay protection. The results of experimental tests of electrical safety conditions and electromagnetic influence are presented. The tasks are identified being the essential prerequisite to the widespread introduction of a system with supports without rail network grounding. Practical importance: The developed methodology for selecting the protection settings will make it possible to operate the AC catenary system without the supports’ rail grounding, as well as introduce the proposed additions to the instructions for grounding traction power supply devices at “Russian Railways”

Modeling and stability prediction for the static-power-converters interfaced flexible AC traction power supply system with power sharing scheme

Increased freight turnover on railway transport inevitably leads to increased traction current in DC and AC traction power supply systems. The increase in traction current is already causing problems related to the normal operation of the 25 kV AC traction power supply systems. One of the adverse consequences of the increased traction currents is the increased rail-to-ground potential. This has already caused a number of accidents and related traffic interruptions on the Far Eastern Railway of Russia and other railway sections powered with alternating current. The study considers the problem of increased rail-to-ground potentials and provides basic formulae for calculating the wave parameters of the rail network and rail-to-ground potentials. Various methods are given for calculating rail-to-ground potentials for a 25 kV AC traction power supply system. Since in an alternating current system, expressions for calculating the potential are functions of a complex variable, the calculation of such expressions requires the use of special programs. Adaptation of existing methods to modern software and computing systems allows you to optimize and significantly speed up the process of calculating the “rail-to-ground” potentials, either considering the use of certain potential-reducing measures or not. A calculation method includes an algorithm developed for calculating the rail-to-ground potentials in the 25 kV AC traction power supply system for an inter-substation zone of any length with any number of electric locomotives within the zone.

Purpose. The aim of the work is to increase the electromagnetic compatibility of track circuits with the traction power supply system of railways under the influence of reverse traction current disturbances. Conducting research and analysis of the causes of malfunctions of rail circuits on electrified sections of the railway, existing means and methods of increasing the interference resistance of track circuits and ensuring the electromagnetic compatibility of signaling, centralization and blocking devices with the traction power supply system, and the development of effective technical solutions for normalizing the operation and rail circuits in the conditions influence of traction current interference. Conducting a study of the electromagnetic characteristics of the DT-1-150 track choke-transformer in normal mode and under the influence of external factors on the magnetic system. Methods. During the research, methods of comparative analysis, theories of electric and magnetic circuits, methods of spectral analysis of signals, as well as mathematical, schematic and physical modeling were used. Findings. Situations in which the traction current significantly affects the operation of the rail wheel equipment have been analyzed in the work. The effect of the traction current constant component on the normal operation mode of the track circuits is considered. The coefficients value of the choke-transformer DT-1-150 with traction current asymmetry was determined. A comparative analysis of resistance to reverse traction current disturbances of track receivers of station rail wheels used at the docking station was conducted. The principle-structural scheme of the protective unit for blocking the leakage of direct traction current interference on the section of alternating current traction was developed. The scientific novelty. The scientific novelty of the work consists in identifying and justifying the causes of some specific failures of track circuit; in confirming the integral effect of choke-transformer steel core saturation, created by the constant component of the traction current in the railway power supply system. Practical significance. Based on the conducted research, the interference resistance of the 25 Hz track circuit with the DSSH-16 track relay and DT-06-500S was confirmed. A protective valve block was developed, which prevents the flow of the first periods of the largest amplitude transient current in the track circuit its protects and ensures, thereby, normal operation of track circuit.

The flexible AC traction power supply system can solve the power quality problem and realize flexible power supply of the whole line, which is an important direction of railway development. First, this paper introduces a flexible AC traction substation based on three-phase to single-phase MMC structure, which provides stable voltage support for train operation. Then, the influence of the filter capacitor on the output side is analyzed, and a damping control strategy for substation is designed to suppress potential oscillations. Aiming at the problem that the voltage amplitude and frequency deviate from the rated value in the traditional droop control, a droop control strategy with voltage amplitude and frequency recovery without communication for substation is designed, and the feasibility and effectiveness of the control strategy are verified by simulation.

The article considers the problem of reactive power compensation in AC traction power supply systems, which is of particular importance in the context of the energy crisis caused by military actions, which is relevant for Ukraine. Reactive power is an important component of electric networks, which significantly affects the stability and quality of power supply. The article highlights the impact of reactive power on the efficiency of traction substations serving railway transport. Special attention is paid to the technical aspects of the problem and the analysis of the effectiveness of existing compensation methods, which is critically important for reducing electricity losses and increasing the overall efficiency of power supply systems. In conditions of outdated equipment and limited resources, the problem becomes more complicated, which requires the implementation of modern technological solutions. The paper analyzes main methods and devices for compensation of reactive power, in particular, such as capacitor units and synchronous compensators, as well as the use of modern technologies of flexible alternating current transmission systems (FACTS). Particular attention is paid to experimental studies conducted at a real traction substation, where reactive power was measured and the effectiveness of compensating devices was shown. Research results show that reactive power compensation allows to significantly reduce energy losses, improve the quality of electricity and increase the stability of the network. The article also discusses the prospects of implementing FACTS systems for dynamically regulating reactive power and improving the operation of electrical networks. The use of these systems can significantly increase the reliability and efficiency of the power system, especially in the context of the integration of renewable energy sources such as solar and wind power plants. This will ensure reliable power supply in critical conditions and increase the efficiency of Ukraine’s energy infrastructure.

The article is devoted to the experiment, what was performed on the local distribution networks with poor power quality. As a rule, these networks are subsystem of AC traction power supply system, and their design causes voltage unbalance and other power quality problems in consumers. Often, the network is powered by transformers with different vector groups, therefore their parallel operation is impossible. The purpose of the experiment is to assess the effect on energy quality of a regime with sources on both sides. The quality of electrical energy was estimated, considerable attention is devoted to unbalance voltage. Using the statistics methods measurement data are studied. During the experiment, the energy quality improved when the parallel mode was used. The concept of smart grid has been proposed to reduce energy losses for dynamic power management.

The study aimed to quantitatively assess the effectiveness of neural network-based control of dynamic reactive power compensation in the traction network of Ukrzaliznytsia. The methodology involved high-frequency monitoring of 118 substations (≈16 trillion measurements), aggregation of 52 million Supervisory Control and Data Acquisition records, Theil-Sen trend estimation, Seasonal-Trend decomposition using Loess, the Brown Forsythe test, and a deep neural network with 64-32-16 layers optimised through a Tree-structured Parzen Estimator, validated in 120 Monte Carlo scenarios in Simscape. The results demonstrated that the average daily Q increased from 309.8 to 367.2 Mvar (18.5%) with a trend of 0.95 Mvar/month (95% CI 0.82-1.08; p < 0.001). Winter peaks reached 520 Mvar, while variance after February 2022 increased 1.5-fold (F = 34.9; p < 0.001). The neural network achieved Mean Squared Error = 184 Mvar² and R² = 0.982; in testing, R² = 0.975, Mean Absolute Error = 11.2 Mvar, and the median error of winter peaks did not exceed 3%. In simulations, the algorithm maintained cos φ between 0.985 and 0.991 for loads ranging from 0.3 to 1.2 p.u., reduced daily losses by 6.1-9.4% (≈1.2 MWh/day), and decreased the number of Static Var Compensator switchings by 38%. Under failure of 20% of Insulated-Gate Bipolar Transistor modules, the duration of cos φ < 0.98 was 0.7%, compared with 19% for the Proportional Integral-Derivative controller. Quantitative comparison of compensation strategies confirmed that the simulated STATCOM-DL system achieved the lowest average cos φ deviations (0.015 vs. 0.030-0.048 for competitors) and minimal annual losses (≈ 430 MWh), outperforming all alternative approaches. The findings confirmed that the combination of deep learning and statistical validation enhances network stability and improves energy efficiency. The practical significance lies in the fact that the resulting algorithms may be employed by railway dispatch centres and energy integrators for real-time optimisation

Aiming at the problem that the existing relay protection of traction power supply system mis-operates when an out-of-phase fault occurs, based on the sum of two phase impedance, a novel distance protection method is proposed. In addition, the characteristic and settings of the proposed protection are derived in detail. Simulation results verify the effectiveness and superiority of the proposed protection method.

The problem of railway transport electromagnetic compatibility automation systems in recent years has been aggravated by the use of power frequency converters in electric transport drives, which significantly increase the efficiency of traction characteristics of 3-phase electric engine. However, estimate relevant harmonic levels in the frequency range used in track circuits of railway automation and telemechanic systems. The paper provides theoretical justification for practical measurements of interference. It is shown, that the interference coefficients monotonically increase in the following cases: 1) increase in the value of the harmonic frequency; 2) increase in the propagation constant, taking into account the supports resistance of the contact network; 3) increase in the circuits track length. Operating frequencies of tonal track circuits up to 800 Hz, the interference increase rate in given length of the rail circuit slows down. The increase in interference coefficients depending on the mentioned factors is explained by the fact that with current part growth of the harmonic flows from the traction substation through the earth increases and thereby creates currents asymmetry of the track circuits.

Track circuit reliability assessment for preventing railway accidents

All-parallel autotransformer (AT) traction power supply system is widely applied to China high-speed railways. The traction feeding network of this kind is more complicated than traditional AT networks. It contains more current loops and the current distribution become more complex. This paper proposes a novel and efficient method to analyze its characteristics. On the basis of the analysis of the autotransformer characteristics, the current distribution can be obtained. Then, several typical short-circuit faults are analyzed by loop analysis method. The proposed current distribution results are compared with the simulation using PSCAD/EMTDC as well as the field test recorded wave data. Through analyzing the characteristics of the all-parallel AT traction feeding system, the short circuit behavior of the traction network can be identified. At the same time it can be indicated to provide theory guide for the relay protection and fault location for this power supply mode.

KTX산천 고속차량에서 사용하는 전력변환시스템은 전력전자기술, 고속 대용량 반도체소자 및 마이크로프로세서의 기술발달에 힘입어 높은 성능과 효율, 안전성, 에너지 소비측면에서 뛰어난 제어능력을 갖추게 되었다. 하지만 고속스위칭소자인 IGBT를 사용함에 따라 발생하는 고조파로 인해 전기차량은 물론 변전소, 신호시스템, 데이터전송 및 감시시스템 등 선로변 신호설비에 문제를 야기시켰다. 특히 전력변환장치의 정수배 부근 주파수에서 발생하는 귀선전류고조파의 영향으로 TI-21 무절연AF궤도회로가 부정 동작하는 사례가 발생되었다. 본 논문은 고속전기차량과 궤도회로간 귀선전류고조파 이동경로 분석을 위하여 실제 현장에서 측정 및 분석방법을 제시하였다. 이러한 분석결과는 향후 신규로 도입되는 고속전기차량, AF궤도회로, 공동접지망 설계 시 폭넓게 반영될 것으로 기대된다. The power transformation system of High Speed rolling stocks like KTX-Sancheon has shown excellent control capacities in the areas of riding comfortability, switching efficiency, safety and energy consumption due to technical developments in power-electronics, high speed & large scale integrated semiconductors and microprocessors. However, harmonics from IGBT, a high speed switching device used in the Convertor & Invertor equipment of rolling stocks have given rise to various problems in transformer substations, signaling systems, data transmission systems and facility monitoring systems. Especially, TI21 non-insulated track circuits have malfunctioned due to the influence of returning current harmonics which were generated at around of integer times of the number of power transformation equipment in the frequency domain. This paper, measures and analyzes various schemes to analyze the traveling path of the returning current harmonics generated due to the relationship between the rolling stocks and track circuits on site. Ultimately, theseschemes will be used to design high speed rolling stocks, AF track circuits and a common grounding network.