Showing papers on "Traction substation published in 1995"

An integral battery charger for four-wheel drive electric vehicle

Abstract: In this study, an integral battery charger is proposed, which fully uses the hardware of the four-wheel drive electric vehicle. It has no extra component except a mechanical transfer switch. The inverters and the traction motors for the propulsion of the vehicle are transformed to a battery charger. It is verified by a prototype experiment that the charger can be operated at unity power factor and can match any kind of charging mode, such as constant voltage or constant current. >

Network modelling of traction substation transformers for studying unbalance effects

Abstract: The paper presents network mathematical models of traction substation transformers for simulation of the unbalance effects, due to railway demands, on the power supply system. The admittance models consider winding connections and phase-angle displacement between primary and secondary voltage. The proposed models are presented for the single-phase, V- and Scott connections of transformers used in, among other places, high-speed railway stations.

Inverting DC traction substation with active power filtering incorporated

Abstract: A new type of reversible traction substation is proposed and a small test of concept model was built and investigated. The test of concept consists of a 10 kVA three-phase IGBT inverter placed in anti-parallel with a 75 kVA three-phase diode rectifier. The inverter is not only capable of pumping energy back into the AC power supply during excessive regeneration, but also acts as dynamic power filtering (DPF) during normal traction load conditions. The total control algorithm for the inverter/DPF is implemented on a TMS320C31 digital signal processor (DSP). >

A frequency domain model for 3 kV DC traction DC-side resonance identification

Abstract: Frequency-dependent effects in railway traction power systems arise from the impedance of substation and locomotive line filters and the traction line. Harmonic noise from traction drives and substations can excite resonances and produce overcurrent or overvoltage conditions at critical points in the network. In this paper, the harmonic feeding impedances of a 3 kV DC traction system seen from the rectifier substation, locomotive drive converter and pantograph terminals are presented. Several substation and locomotive filters are considered with a frequency-dependent traction line. Resonances attributed to the substation filter, locomotive filter and traction line are separate and distinct, the line introducing poles and zeros in the audio frequency (AF) range which vary in frequency and magnitude with locomotive position. >

Control of stray currents for DC traction systems

Abstract: On a DC electrified railway system, low resistance between the traction return rails and the ground allows a significant part of the return current to leak into the ground. This is normally referred to as leakage current or stray current. The problems of these stray currents are briefly discussed and measures to combat them described. These include: maintaining rail-to-ground insulation, so far as is consistent with touch voltage requirements; implementing an effective earthing and bonding strategy-connect all rails in parallel, with adequate rail continuity bonding and cross-track bonding; installing a stray current collection system where appropriate; selecting a running rail that provides a low-resistance path for the traction return current; spacing the feeding substations at short distances; isolating all structural steelwork from the track-in particular from the under-track collection system when this is used; and ensuring effective drainage of water from the track, whether slab track or ballasted track.

Analysis on the voltage unbalances due to high-speed railway demands

Abstract: This paper introduces the analysis of the voltage unbalances caused by the demands of a high-speed railway on a public power system. A powerful three-phase power-flow program with simplified traction substation models is used to evaluate the voltage unbalances in detail. The evaluations consider the interactions between neighboring substations in which large unbalanced traction loads are connected. All of the bus voltages, line currents, system power flows and losses are calculated rigorously. The effects of unbalanced traction loads on a public power system and interactions between neighboring substations are discussed. The simulation results show that the system unbalances are affected by common balanced loads as well as the unbalanced traction loads. The balanced loads amplify the degrees of the voltage unbalances that are caused by the traction loads or other unbalanced loads, such as furnaces. The results also indicate that the degree of voltage unbalances at the point of common coupling is not necessarily the maximum in the entire power system. This fact is of value to consultants and engineers involved in related work and should be emphasized.

Load sharing with thyristor controlled rectifier substations

Abstract: Thyristor controlled rectifier substations (TCRS) accomplish energy management objectives by controlling load flow. Voltage sources connected in parallel to a common grid share load dynamically in a complex relationship between the DC output voltage sources at fixed traction power substation locations and time variant loads at moving vehicle locations. Conventional diode rectifier sources with inherent voltage regulation produce a load profile that cannot be changed at will. The load profile, and thus the load sensitive cost component of electrical demand is impacted only by train operating policies. Voltage control capability allows the load profile of TCRS to be adjusted within the constraints of train operating practices, and demand-control energy management may be achieved. Efficient solutions to the problems of energy management design require an understanding of the relationships between networked sources and dynamic loads. This paper presents the relationships between demand sensitive electric utility costs, traction power source energy management, and train operations and provides simplified quantitative expressions in support of the basic principles. >

Modelling for electromagnetic interference assessment in electric railway traction systems

Abstract: Electromagnetic field and circuit simulation models are described which enable a railway traction system with substations, traction drives, track signalling equipment, track and traction line to be assessed for low and audio frequency electromagnetic interference. The novel features are the derivation of frequency-dependent track and traction line impedance by the finite-element method of electromagnetic field analysis and the representation of the frequency dependency in circuit simulation by current-dependent voltage sources. Example interference spectra are given for cab signal current with audio frequency track signalling on a 3 kV DC traction system with 12-pulse rectifier substations and an inverter-fed traction drive.< >

Traction power-driven power generator

Abstract: A traction power-driven power generator including a power drive driven by a traction cable (2), an one-way rotary transmission mechanism coupled to the power drive, a power generating device (6) driven by the power drive through the one-way rotary transmission mechanism to generate electricity, and a casing (1), which holds the power drive, the one-way rotary transmission mechanism, and the power generating device (6) on the inside.

A comprehensive analysis of a locomotive traction system including main alternator, bridge rectifiers, contactor, and DC traction motors

Abstract: In the present traction system environment, the development of simulation models of traction equipment is a crucial task. This paper presents a novel dynamic modeling and digital computer simulation of a locomotive traction system in practical problems such as saturation of the magnetizing and leakage inductances in the generator equivalent circuits are included in the proposed method. An equivalent circuit including the eddy current losses of the DC traction motor is presented. A simple and fast model for simulating diodes is used to simulate the rectifiers dynamic behavior during parallel to series and series to parallel transitions. The required contactor for parallel or series operation of the two rectifier bridges is modeled as a nonlinear resistor. The simulation results follow the test results closely. >