AC Traction Power Supply System Research Articles

Increasing the Energy Efficiency of DC Traction Power Supply Systems

In this paper, we consider means to develop and improve a dc traction power supply systems and its adaptation for high-speed mine lines. One way to improve and increase the efficiency of the traction power supply system is to increase the rated voltage in the dc traction grid up to 24 kV. This allows increasing the throughput and carrying capacity of railways, increasing the distance between substations, and reducing the cross section of the traction grid wires and electricity losses in power supply devices. All this, as well as the absence of supply voltage unbalance under dc, inductive losses, and a significantly lower electromagnetic effect on the infrastructure, is more efficient than all ac traction power supply systems. We determined the directions of numerical modeling and proposed nonlinear numerical models that allow analyzing the interaction of sources of electromagnetic fields of traditional and superconducting electrical equipment under the conditions of an unlimited region of magnetic field propagation and the absence of symmetry of the field distribution in space. To determine the effect of electromagnetic fields on the integral parameters of traditional and superconducting electrical equipment, an algorithm and a package of applied programs were developed. We performed studies and substantiated the parameters and dimensions of superconducting inductive reactors of smoothing traction substation filters at which the volume of occupied space is minimized and the best use of superconducting material is ensured at a specified energy intensity.

Modelling and control of a novel AT-fed co-phase traction power supply system for electrified railway

A large unbalanced current injected into the power gird and the neutral sections at the exits of traction substations have been the outstanding obstacles in conventional single-phase 25 kV AC traction power supply systems (TPSS). In order to meet the requirements of high-speed and heavy haul transportation systems, a novel autotransformer (AT)-fed co-phase TPSS is proposed, which can provide continuous power for the trains with high power quality (PQ). In this research, the electrical configuration of the new TPSS is presented, which is structured with Vx-connection traction transformer (TT) and power flow controller (PFC) adopting the modular multilevel converter (MMC) topology. Furthermore, the mathematic model of the novel system is built. The unbalanced current and the reactive power caused by traction load can be compensated effectively based on power balance principle. Moreover, a hierarchical control strategy is designed including upper optimized PQ compensation algorithm and low-layer PFC control, which can coordinate dynamic characteristics between different working patterns. Finally, the validity of the control method and the performance of the system are demonstrated by case studies. The results indicate that compared to the conventional co-phase TPSS, the proposed co-phase TPSS is able to reduce the compensation capacity by up to 59%.

A Control Method of Phase Angle Regulator for Parallel-Feeding Operation of AC Traction Power Supply System

A Control Method of Phase Angle Regulator for Parallel-Feeding Operation of AC Traction Power Supply System

VU limit pre‐assessment for high‐speed railway considering a grid connection scheme

Single-phase 25 kV AC traction power supply systems (TPSSs) are widely used in high-speed railways, leading to an increasingly prominent problem of voltage unbalance (VU) in the power grid. To fairly regulate the system VU level, implementing VU limit pre-assessment is an urgent need. A grid connection scheme including traction transformer selection and exchange phase connection design is a vital part of TPSS design that obviously affects the VU factor of power systems. A uniform mathematical model is established using Thevenin's theorem, which reveals the impact of multiple grid connection schemes on the VU propagation behaviour of a three-phase grid. Afterwards, under the requirements of IEC/TR 61000-3-13, an improved VU limit pre-assessment process is proposed, which correlates mapping between the grid connection scheme and VU limit. The unbalance compensation calculation is given, adopting the allocation limit; furthermore, the optimal design of the grid connection scheme with minimised compensation capacity as an object is presented. The correctness of the model and the rationality of the pre-assessment process are verified by a case study.

ANALYSIS OF ENERGY EFFICIENCY OF OPERATING MODES OF ELECTRICAL SYSTEMS WITH THE TRACTION LOADS

Innovative scenarios of reliable energy supply of transportation process aimed at reducing the specific energy consumption and increase energy efficiency of the systems of electric traction. The paper suggests innovative energy saving directions in traction networks of railways and new circuit solutions accessing traction substations in energy systems networks, ensure energy security of the transportation process. To ensure the energy security of rail transport special schemes were developed to propose the concept of external power traction substations, which would increase the number of connections to the networks of 220 – 330 kV, as well as the creation of transport and energy corridors, development of its own supply of electric networks of 110 kV substations and mobile RP-110 kV of next generation. Therefore, the investment program of the structures owned by the Ukrainian Railways (Ukrzaliznytsia) need to be synchronized in their technological characteristics, as well as the criteria of reliability and quality of power supply with the same external energy investment programs. It is found that without any load on left or right supplying arm one of two less loaded phases of traction transformer begins generating specific modes in the supplying three-phase line. Thus, modes of mobile substation cause leakage in one of the phases of the supply line of traction transformers of active-capacitive current, and as a result generating energy in the main power line of 154 kV, which is fixed and calculated by electricity meters. For these three phase mode supply network is necessary to use 1st algorithm, i.e. taking into account the amount of electricity as the energy in all phases. For effective application of reactive power compensation devices in the AC traction power supply systems it is proposed to develop regulatory documentation on necessity of application and the order of choice of parameters and placement of compensation systems taking into account operation mode of power systems and the use of software systems with imitation of instantaneous interrelated schemes of transport loads.

Industrial frequency single-phase AC traction power supply system for urban rail transit and its key technologies

To avoid stray current and maintain the benefit of no phase-split in the DC traction power supply system, an AC traction power supply system was proposed for the urban public transport such as metro and light rail transit. The proposed system consists of a main substation (MSS) and cable traction network (CTN). The MSS includes a single-phase main traction transformer and a negative-sequence compensation device, while the CTN includes double-core cables, traction transformers, overhead catenary system, rails, etc. Several key techniques for the proposed system were put forward and discussed, which can be summarized as (1) the power supply principle, equivalent circuit and transmission ability of the CTN, the cable-catenary matching technique, and the selection of catenary voltage level; (2) the segmentation technology and status identification method for traction power supply network, distributed and centralized protection schemes, etc.; (3) a power supply scheme for single-line MSS and a power supply scheme of MSS shared by two or more lines. The proposed industrial frequency single-phase AC traction power supply system shows an excellent technical performance, good economy, and high reliability, hence provides a new alternative for metro and urban rail transit power supply systems.

A comprehensive control strategy of railway power quality compensator for AC traction power supply systems

A comprehensive control strategy of railway power quality compensator for AC traction power supply systems

Transition and verification of ground fault protection method in Hokuriku Shinkansen line

The electrical discharge gaps called S type horn are applied to the ground fault detection and protection in AC traction power supply system for high speed railway called Shinkansen. In this method, the earth resistance of the steel pipe pillar is an important factor for the ground fault protection by the electrical discharge. In this study, the analyses of the transient characteristics of grounding fault are carried out by using EMTP, and the ground resistance value required to trigger discharge at S type horn was calculated. Moreover, the protection effect of a discharge gap called GP the substation equipment that is a discharge gap which is inserted between rails and substation mesh is evaluated.

Energy effectiveness and electromagnetic compatibility of DC traction power supply systems with 24-kV grid voltage

A new DC traction power supply system is advanced with a grid voltage of 24 kV, which would enable one to reduce significantly the distance between substations, the power grid wire cross section, and the power losses in supplying devices. This makes the new system superior to the AC traction power supply systems taken together with the absence of the supply voltage asymmetry, weaker electromagnetic influence and induction losses.

Development of Integrated Simulator for AC Traction Power Supply System

This paper describes the development of integrated simulator with GUI(Graphic User Interface) for traction power supply system. This simulator consists of a lot of calculation modules such as TPS, train time schedule, line constant, and power supply system analysis. Each module has input and output structure respectively. The algorithms of all modules have confirmed the validity to comparison with field test that is performed on both high speed railway line and conventional line.

The SIMSPOG simulation tool: a web-based implementation

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.