RU2258994C2 - Railway ac power distribution system using three-phase balancing and single-phase transformers - Google Patents

Abstract

FIELD: power distribution systems for railways.

SUBSTANCE: proposed system designed to supply railway equipment with ac power at 27.5 kV has pole-mounted traction substations spaced 200 - 240 km apart. These substations supply with power intermediate substations incorporating single-phase transformers and shorting-out switches through two-wire lines installed on contact-system poles. Two three-phase balancing transformers with grounded common point are installed in each pole-mounted traction substation; one of these transformers is operating and other one is stand-by transformer. Two-wire line is sectionalized trough one intermediate substation by means of two switches. Single-phase transformer is connected to each wire of two-wire line either side of sectionalizing switches through tee-junction of disconnecting switches which ensures parallel connection of all pole-mounted traction substations and intermediate substations to traction mains.

EFFECT: reduced number of pole-mounted traction substations and power loss in traction mains.

1 cl, 1 dwg

Description

The invention relates to power supply systems for railways with alternating current of 27.5 kV, 50 Hz and is a set of devices that provide an increased symmetrical effect of traction loads with respect to three-phase general-purpose networks with a voltage of 220 (110) kV, cheapening and simplifying traction power supply at increased reliability of traction load power.

Known power supply systems for AC railways with three-phase and single-phase transformers [1,2], characterized by complex traction substations 220 (110) kV / 27.5 kV with each connecting to general-purpose networks 220 (110) kV after 40-55 km [ 1] or a 2 × 25 kV system - after 60-90 km [2] and installation of 50/25 kV single-phase autotransformers on the inter-substation zones.

In both systems, to limit voltage asymmetry, traction substations are connected to phase-alternating power networks (“screw” circuit), which eliminates the parallel operation of several substations for loads located on adjacent inter-substation zones.

In terms of technical nature, the proposed system is a composition of both systems [1,2] and uses the principle of balancing traction loads described in [3]. These three technical solutions are the prototypes and the basis of the proposed system.

The technical result of the proposed system is to reduce the number of reference substations (one per 220-250 km) with two three-phase balancing transformers on each and five to six intermediate simplest substations with single-phase transformers, powered by transformers of adjacent reference substations on one two-wire line, which makes it possible parallel operation of all substations in the area between adjacent supporting substations, reduces energy losses in the traction network and construction costs odstantsy, simplifies, improves the effect of balancing the thrust loads on the supporting substations having access to the general purpose network.

The essence of the claimed invention lies in the fact that traction networks are supplied with power from general purpose networks with an interval of 220-250 km through supporting substations at a voltage of 220 (110) kV, on which special balancing three-phase transformers with Scott effect reduce the voltage to 91 kV by each shoulder nutrition. The transformer windings supplying voltage to the left and right shoulders are connected at a common point with each other, and this point is connected to the ground in such a way that the voltage of the terminals of each arm with respect to the ground (rails) is one 27.5 and the second 63.5 kV . The device of such a transformer is described in the accompanying application for the invention “A transformer for a distributed power supply system for a railway electrified with alternating current (27.5 + 63.5) kV, 50 Hz with a balancing effect”.

The use of such a transformer makes it possible to power a 91-kV two-wire transmission line with a system of substations each with a single-phase transformer, and at the same time, all transformers, at all intermediate substations at each inter-substation zone, are connected in parallel to each other.

The drawing shows a connection diagram of traction substations of the proposed power supply system.

A key element of the system is a balancing transformer 1. At each supporting substation 2, two transformers 1 are installed, one of which is a working one, and the second is a backup one.

The entire area between the two reference substations is a special-purpose network. From it, power is supplied to the substation with single-phase transformers 3 via a two-wire line 4 with a voltage of 91 kV applied along the supports of the contact network. Line 4 is a magnetically balanced element of this system. The connection to the ground of a common point 5 of the windings of the transformers of the supporting substations fixes the insulation level of wire 6 with respect to the ground at a voltage of 27.5 kV, and the second supply wire at a voltage of 63.5 kV.

Transformers 3 of intermediate substations receive power at a voltage of 91 kV from a two-wire line 4, and the line 4 itself is partitioned by switches 8 and 9, switches 8 to 27.5 kV are used as switches 8, and 110 kV as switches 9.

Section 4 is partitioned through one substation in such a way that any damage on the line leads to shutdown of only one substation. Saving parallel work on the contact network of all other substations facilitates the failure of one substation. At substations where the sectioning of line 4 is carried out, a transformer 3 is connected to each wire of line 4 through a fork of disconnectors 10 and 11 connected to the wires of line 4 on both sides of the sectioning switches, which makes it possible to switch the power of substations from damaged to a healthy section of the line. Disconnectors 10 are 27.5 kV, disconnectors 11 110 kV, circuit breakers 12 110 kV, switches 13 27.5 kV. In case of failure of the transformer 3, a shunt switch 14 is provided at each of the intermediate substations, which allows supplying power to the contact network through the substation buses with the transformer falling out from wire 6 of line 4. The switch 14 is operated at a voltage of 27.5 kV.

Implementation of the proposed power supply system will allow:

- reduce capex on the power supply system by 1.5-1.6 times;

- to increase the effect of balancing traction loads by changing new balancing transformers at the reference substations and increasing the distance between them by 1.6-2.0 times, eliminating penalties for violations of the quality of electricity at the points of common connection according to the voltage symmetry coefficient, which is based on one substation can amount to 1.5-2.0 million rubles. in year;

- reducing the power of transformers at intermediate substations to 10-16 MB-A and simplifying the schemes of substations will allow you to abandon the mode of their constant maintenance;

- the power of all intermediate substations from a common two-wire line will allow, like with a 3 kV DC system, to take advantage of the parallel operation of all substations on a contact network with the best use of the power of transformers of all substations;

- provide a modular simplified system for the manufacture of substations and minimize the territory occupied by them.

Sources of information

1. K.G. Marquardt. Power supply of electrified railways. M., Transport, 1982, p. 36-39.

2. R.R. Mamoshin, A.N. Zimakova. Power supply of electrified railways. M., Transport, 1980, p.146-149 (prototype).

3. Copyright certificate No. 1377930, SU1377930 A1, H 01 F 33/00, 1987 (prototype).

Claims (1)

A railway distributed AC power supply system containing traction support substations located at a distance of 200-240 km, from which intermediate substations with single-phase transformers and bypass switches are powered by a two-wire line laid on the contact network supports, on each support traction substations are equipped with two three-phase balancing transformers with a common point connected to the ground, one of which is a working one, and the second is a reserve one, while A two-wire line is partitioned through one intermediate substation with two switches, and a single-phase transformer is connected to each wire of the two-wire line on both sides of the sectionalizing switches through a fork of disconnectors, which ensures parallel connection of all traction support and intermediate substations to the traction network.