Abstract
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.
Highlights
From worldwide application point of view, DC system, low-frequency single-phase AC system, and industrial frequency single-phase AC system are three main power supply systems for trunk railways, metros, and light rails
When the traction transformers (TT) primary voltage is 35 kV, its turn ratio would be no less than 10 if the chosen overhead catenary system (OCS) voltage does not exceed 3.5 kV, and the impedance modulus value of twocore cable (TCC) loop will be less than 1 % of the impedance modulus value of OCS-R loop imputed to TCC loop side
This paper has presented and discussed an AC traction power supply system that has the following salient features:
Summary
From worldwide application point of view, DC system, low-frequency single-phase AC system, and industrial frequency single-phase AC system are three main power supply systems for trunk railways, metros, and light rails. Metros and light railways in urban transit systems have prominent features of large traffic density and frequent starts and stops Their DC traction power supply systems have the advantage of no phase-split along the overhead catenary system (OCS), so that trains can run smoothly. The train, powered by AC traction motors and composed of an electric locomotive or electric multiple units (EMUs), is called an AC–DC–AC train, which is developed mainly for trunk railways and high-speed railways It is easy for AC–DC–AC trains to store the brake energy back to the grid, it is simple, convenient, safe and reliable to operate. A brief discussion on system’s economy and reliability, etc. is given
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