JPH0142852B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a DC feeding device for supplying DC power to electric trains.

Conventional electric railways use the running rails as a return path for the main operating current. However, the insulation properties of sleepers and trackbeds are extremely imperfect, and even though the conductor resistance of the rails is low, leakage current to the ground occurs. In other words, the insulation resistance between the rail and the ground is affected by the weather, and in rainy weather, especially during storms, the insulation resistance drops significantly and the leakage current from the rail to the ground increases significantly, reaching hundreds of amperes or more.
It can reach 1000A. Leakage current from the rails is determined by two factors: train load current, return resistance, and substation spacing.
and is inversely proportional to leakage resistance. Therefore, in principle, the leakage current can be reduced by reducing the former and increasing the latter.

FIG. 1 and FIG. 2 are diagrams showing a conventional power feeding configuration. In the diagram, 1 is a substation, 2 is a contact line, and 3 is a substation.
indicates a rail, and 4 indicates a train. In Figure 1 a, train 4 is located at a distance of DKm from substation 1.
Suppose that the operating current IP is taken. in this case,
The ground potential of the rail 3 near where the train 4 is present becomes a positive potential. On the other hand, the ground potential of the rail 3 near the substation 1 becomes a negative potential. In the vicinity where the train 4 is present, current leaks from the rail 3 to the ground, and in the vicinity of the substation 1, the current leaked to the ground returns to the rail 3. FIGS. 1b to 1d show the relationship between the currents I _L , I _N , I _E and the positions at that time.

The negative effects of this leakage current are usually known to be electrolytic corrosion of underground metal objects such as rails, their accessories, cables, water pipes, gas, etc., but they can also cause inductive damage to communication lines. There is also the problem of disturbances to geomagnetic observatories.

Regarding ground current, please refer to Electrical Equipment Technical Standards No. 257.
As stipulated in Article 1, it is necessary to ensure that there is no obstruction to observation of geomagnetic observatories or geoelectrical observatories.

As shown in FIG. 2, the conventional DC feeding circuit of a DC electric railway usually performs parallel feeding, and both the positive and negative poles are electrically connected in parallel. Therefore, leakage current leaking from the rails to the ground flows toward each substation, and the magnetic force generated over a wide area by this leakage current affects the earth's magnetism in the natural world. It is calculated by the Biot-Savart law that spreads from electric railways, but since the current directions in the overhead contact line and the rail are opposite, most of the magnetic fields cancel each other out in the distance, and the difference current and leakage current are caused by the geomagnetic field. affect.

Possible ways to suppress leakage current from railway substations include reducing return resistance, shortening the distance between substations, increasing the insulation resistance between the rails and the ground, or adopting a fourth rail system or AC electrification system.

If it is a new line plan, it is possible to increase the insulation resistance between the rail and the ground by adopting the fourth rail system, and it is possible to increase the insulation resistance between the rail and the ground. If so, it will be possible to adopt an AC electrification system. However, the above method cannot be applied to electrification of wheel transportation networks in urban areas or suburbs, extensions of DC sections, or sections where DC trains are to be run, and in the end, conventional DC electrification is used.

In order to suppress leakage current and reduce return resistance, it is theoretically possible to install a feeder line alongside the rail, but the size of the attached feeder line becomes extremely large, making it uneconomical, and the spacing between substations increases. Leakage current can be suppressed to some extent by shortening the current, but in cases where the train load current is large or the running intervals are short, the ground current will be scattered over a wide area because the rails are connected all the way, and this will not be very effective. I had a problem that I couldn't solve.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and it provides an insulated section on the rail and lays a feeder line for each rail unit divided by the insulated section, and connects the feeder line and substation. It is an object of the present invention to provide a DC feeding device capable of suppressing leakage current by connecting a thyristor device that becomes conductive when a train is present between corresponding rail units.

An embodiment of the present invention will be described in detail below with reference to FIG. In the figure, 1 is a substation, 2 is a contact line, 3 is a rail, 4 is a train, 5 is a rail insulation section, and 6 is a substation.
is a thyristor device, and 7 is a feeder line. The effects of the present invention in such a configuration will be explained below. The figure shows feeder wires 7a1 _to 7a1 to the center of rails _3a1 to _3b2 divided by rail insulation sections 5a to 5c.
7b ₂ is installed and the anodes of the thyristor devices 6a ₁ to 6b ₂ are connected to the feeder lines 7a ₁ to 7b ₂ . The feeder wires 7a ₁ and 7a ₂ from the connection point of the rails 3a ₁ and 3a ₂ are connected to the anodes of the thyristor devices 6a ₁ and 6a ₂ , and the cathodes of the thyristor devices 6a ₁ and 6a ₂ are connected to the negative electrodes of the substations 1a and 1b. are connected to each other. Thyristor device 6
b ₁ and 6b ₂ are similarly connected to substations _1a and 1b through feeder lines 7b ₁ and 7b ₂ from the contact points of rails 3b 1 and 3b ₂ . In the figure, the current of train 4 is at substation 1a
It is supplied from the substation 1b through the overhead contact line 2a, and from the substation 1b through the overhead contact line 2b. At this time, the thyristor devices 6b ₁ , 6b ₂ connected to the rails 3b ₁ , 3b ₂ where no train is present are in the blocking state, and the thyristor devices 6a 1 , 6a connected to the rails 3a ₁ , 3a ₂ where the train is _present . ₂ is kept in a conductive state. Therefore, the current that has passed through the train 4 flows through the rails 3a ₁ and 3a ₂ and returns to the substation 1b via the feeder line 7a ₁ and the thyristor device 6a ₁ through the substation 1a and the feeder line 7a _{2 and the thyristor device 6a 2} , and then returns to the substation 1b via the feeder line 7a ₂ and the thyristor device 6a 2. It is possible to prevent current from flowing to the rails 3b ₁ and 3b ₂ where no current exists.

Therefore, the leakage current from the rails caused by the electric train 4 occurs only in the rails 3a ₁ and 3a ₂ .

As a result, the leakage current can be reduced compared to the conventional method, and the earth current does not spread over a wide area.
The flow only flows within the area of the rail 3b, which has the advantage of greatly minimizing the influence of the magnetic field on the earth's magnetism.

Note that the present invention is not limited to the embodiment described above and shown in the drawings; for example, the drawing shows a case where the polarity of the overhead contact line is positive and the polarity of the rail is negative;
It goes without saying that the same effect can be obtained even if the overhead contact line is made negative and the rail is made positive, and that modifications can be made as appropriate without changing the gist.

To further increase the effect, as shown in Figure 4,
Leakage current can be further suppressed by connecting feeder lines not only to the center of the divided rails but also to several locations on the rails.

As described above, according to the present invention, an insulating section is provided on the rail, a feeder line is laid for each rail unit divided by the rail insulator section, and a train exists on a corresponding rail unit between the feeder line and the substation. Since a thyristor device is connected which is conductive when a leakage current is generated, leakage current can be economically suppressed.

[Brief explanation of drawings]

Figure 1 is a diagram showing the principle of leakage current generation, Figure 2 is a diagram showing a conventional DC feeding system, Figure 3 is a diagram showing a DC feeding system according to an embodiment of the present invention, and Figure 4 is a diagram showing the present invention. It is a figure which shows another Example of. In the diagram, 1...substation, 2...telephone line, 3
...Rail, 4...Train, 5...Rail insulation section, 6...Thyristor device, 7...Feeder line.
Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] 1. In a DC feeding device that supplies DC power to trains, an insulating section is provided on the rail, a feeding line is laid for each rail unit divided by the insulating section, and a corresponding rail unit is installed between each feeding line and a substation. A direct current feeding device characterized by connecting thyristor devices which conduct when a train is present.