Showing papers on "Traction substation published in 2001"

Recent advances in power electronics technology for industrial and traction machine drives

Abstract: This paper presents a review of the state of the art of power electronics technology in both industrial and traction drive application. Key development trends include the dominance of AC adjustable-speed drives in new applications, with the squirrel-cage induction machine as the preferred machine in most cases. Particularly striking has been the rapid ascendance of the insulated-gate bipolar transistor (IGBT) as the predominant power switch in both industrial and traction applications ranging from fractional kilowatts to multimegawatts. Key current issues such as industrial drive input power quality and the effects of fast IGBT switching transients on the machines and electromagnetic interference (EMI) production are reviewed. Developments in electric traction for both rail and road vehicles are discussed, including the increasing modularity of new traction inverters in all sizes and the market introduction of new hybrid vehicles using advanced power electronics. The paper concludes with a discussion of expected future trends in power electronics technology that will likely expand the markets for industrial and traction drives during coming years.

Integrated traction inverter module and bi-directional DC/DC converter

Abstract: Integrated power systems and methods for use in an electric vehicle having a fuel cell and an electric motor, the integrated power systems and methods including a common casting, a traction inverter module operable for converting DC current generated by the fuel cell into AC current capable of powering the electric motor, and a DC/DC converter operable for stepping-down the voltage of the fuel cell. The traction inverter module and the DC/DC converter are disposed within the common casting.

Analysis of stray current, track-to-earth potentials and substation negative grounding in DC traction electrification system

Abstract: In the first part of the paper, we look at a stray current model under the ideal conditions with uniformly distributed track-to-earth resistances and develop the track-to-earth potentials and stray current relationships within a segment of track. We then expand the model to include buried metallic structures in the vicinity of the track using field theory to calculate the potential gradients generated due to flow of rail current and show that a potential difference experienced by a crossing or paralleling underground structure that traverses these gradients could cause stray current corrosion. We discuss the limitations of these models with the actual conditions such as nonuniform back-to-earth resistances, nonuniform soil resistivities. In the second part, we look at the stray current model when there are inadvertent breakdowns in the track insulation. The points of rail insulation breakdown may be approximated using the spherical ground electrode model and equipotential lines to illustrate the flow of stray current. Common grounding of the substation negative bus, substation AC ground mat and electric utility neutral are examined and discussed.

FACTS: powerful means for dynamic load balancing and voltage support of AC traction feeders

Abstract: With increasing focus on economical as well as environmentally friendly means for mass transit, rail transport is getting renewed momentum in many countries. This means investing in novel rail infrastructure as well as upgrading and electrifying of existing facilities. The feeding of heavy rolling stock from AC grids will in many cases cause unacceptable voltage drops as well as unsymmetry between phases of the feeding grid FACTS devices offer means of remedy, restoring grid symmetry as well as voltage stability. The paper treats dynamic load balancing of grids supplying power to rail transport, as well as dynamic voltage support, by means of thyristor-controlled VAr compensation (SVC) as well as voltage source converters (VSC).

Control strategy of advanced 25 kV-50 Hz electrified railway systems

Abstract: Technological innovation has been largely involved in the general modernisation of electrified railway systems in the last few decades. Better quality performances of supply and electrification subsystems are thus expected, which have until now made less recourse to electronic and automation techniques than other technological sections of the system. A method is proposed for compensating voltage and current unbalances in single-phase 25 kV-50 Hz railway power supply, based on a new configuration of the traction substation. Two Scott-connected transformers are coupled with an impressed voltage two-phase inverter, to obtain stabilisation of load voltages to rated values. Satisfactory power factor and reduction of network disturbances, as well as nonlinear load effects of the load, can also be reached. The full compensation of load unbalances and a substantial inherent protection against disturbances, even under changing conditions of power parameters, are obtained through a nonlinear control system, based on the variable structure system theory. Numerical simulations confirm the high performance of the compensation method with respect to fast response time, steady-state accuracy, and very low sensitivity to disturbances.

Parameters that influence power quality on industrial frequency AC traction systems

Abstract: It is proposed that power quality In AC railway systems should consider low voltage, high voltage form factor and resonant overvoltage rather than the parameters normally considered for public utilities. Each of the 3 system aspects has a conventional means of compensation and a solution using power electronic systems. The paper describes the potential power quality problem areas on AC traction systems and possible means of compensation. The conclusion Is drawn that disturbance levels on AC traction systems are likely to remain higher than disturbance levels within public electricity supplies to achieve lower capital cost for railway networks.

Development of new drive system of diesel electric multiple unit (DEMU) for Indonesia railway

Abstract: To resolve the fast growth of passenger demand, a new diesel electric multiple unit (DEMU) train set powered by an under-floor diesel-genset is designed The train set is powered by vector controlled asynchronous traction motor drives Each train set consists of 2 trailer cars at the both end of the train, 4 motors cars and 2 trailers cars that are placed in the middle In this paper, the calculation of the required traction power and braking effort, the choice of traction motor numbers, and the design of VVVF inverters and static auxiliary inverters are described

The Effects of Traction Load on the Quality of Electric Energy

Abstract: In this paper, the negative sequence current and harmonics current generated by the electric traction load are analysed through the example of Y/Δ-11 transformer The measured data is listed Some ideals of improvement are put forward, which include the rationally dispatching capacitors of the two power supply sections, the comprehensive compensation of reactive power and negative sequence current by means of the Steinmetz principle, the filters or the static var compensators installed in the low voltage sides of traction substation