Перспектива внедрения системы тягового электроснабжения переменного тока с опорами контактной сети, не заземленными на рельс

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.

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.

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

Predicting the system behavior of traction power supply systems, earthing systems and track circuits have become of vital importance to the railway community. The availability of computer based tools is a precondition in engineering studies in the field of electrical systems compactibility (ESC) and electromagnetic compatibility (EMC). Also, the sharing of information among multiple parties involved in activities on a single segment of infrastructure has become more and more important. Multiple cases have demonstrated this need for cooperation. Since 1994 simulations and measurements on the behavior of AC traction power supply systems have been made by Holland Railconsult. Also, its influence on signaling and telecommunication systems as well as on existing railway infrastructure and third parties are studied. In the course of this process the necessity to have a dedicated simulation tool available became clear. After several years of development, a useful simulation tool is now available. The newly desgined web-implementation makes it possible to access the SimspoG tool through the Internet by a common Internet Browser. The SimspoG User application interface implementation allows for inputting or modifying different simulation model parameters and starting of simulation processing.

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.

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 object of the study is the process of operation of traction and external power supply systems as objects of inextricable interconnection while reducing energy costs in the cost of railway transportation in real time. One of the most problematic areas is the technology for choosing energy-efficient power supply schemes for railway traction networks in real time. The methods of forming and transforming graphs of complex schemes of traction and external power supply systems and building expert control systems for the implementation of energy-saving technologies of electrified railways were further developed in the work. In the course of the study, to increase the efficiency of simulation modeling of electric traction networks, the statistical characteristics of the loads of feeders that supply the final boundary sections, stations, depot access tracks, railway junctions and idle voltages on the traction substation tires were obtained. Methods of calculation and modeling of traction power supply have been developed, which take into account the inseparable relationship with power systems and allow choosing rational modes with minimal power flows and energy losses. Proposed methods of managing the modes of operation of the traction power supply system based on a vague description of their states and an expert system that allow solving new problems. Including, the choice of energy-saving power supply schemes in the case of power flows, economic modes of network operation in case of intensification of the transportation process. Thanks to this, ways of reducing power consumption and minimizing energy losses of traction power supply systems are proposed, which allow minimizing power flows and power losses by adjusting load flow parameters and voltage levels of traction substations. And also to increase the energy efficiency of electrified railway lines. The technique of technical and economic feasibility of power supply schemes of traction networks and evaluation of the possibility of switching to cantilever or loop power supply schemes with parallel connection points has been developed. The implemented recommendations save about 25 thousand kWh per 1 km of two-track section.

Adequate protection scheme is an important defense mechanism for traction power supply system (TPSS), and the reliability of its operation could affect the normal operation of the system. Therefore, in order to maintain the system in safe operation, it is of great importance to quantify the influence of protection scheme on traction power supply system. This paper presents a risk assessment method for traction power supply system considering the reliability of system protection. A risk probability model for system protection is established. Based on Markovian state-space method, the reliability of the protection system is evaluated; the misoperations of the protection system and their possible consequences are analyzed by FMEA method. Three types of economic loss indices are defined to establish the quantitative risk consequence model; the risk of traction power supply system is thereby quantified by integrating risk probability and risk consequence. Practical traction power supply system is taken as an example to prove the effectiveness of the proposed method. The evaluation results can help formulate corresponding measures, and provide guidance for maintenance strategies, thus reducing system risk.

The operation strategies of high-speed trains are influenced by variable gradients, speed limits and the neutral sections of a single phase alternating current (AC) traction power supply system. This paper aims at finding energy-efficient strategies for the punctual operation of High-speed trains. The train trajectory is divided into multiple phases based on start and end points of the neutral sections, variety points on gradients and speed limits. A basic optimization model is converted into a multiple phases model with the consideration of regenerative braking energy. Furthermore, the model is discretized and solved by a multiple phases pseudo spectral method, energy saving speed profiles and optimal modes were obtained. The correctness and effectiveness of the method are verified by comparing the simulation results with the operational data of the Guiyangbei-Kailinan High-speed Railway.

Electric railways use a single-phase system, with the line comprising a trolley wire (TF) that supplies power to the load with a neutral wire and an autotransformer (AF) feeder to absorb the return current of the rail. Testing the performance of the protective relay that detects the fault of the traction power-supply system (TPSS) and operates the circuit breaker is very important. Until now, the performance test of protective relays for the TPSS has been conducted via a simple-steady test or using an expensive real-time simulator. However, under a fast-moving environment in which the load consumes a large amount of power, the protective relay must always detect faults and operate properly. This paper proposes a digital simulator that enables the dynamic testing of protective relays without using any steady test and expensive real-time simulators. This simulator includes both external waveform import and internal waveform generation functions. Users can test the operation of the protective relay by entering the waveform generated externally or internally into the protective relay. Additionally, it has the ability to monitor the operating protection elements and pickup time when the protective relay detects a fault and orders the circuit breaker trip.