JPS638694B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a protection scheme for electric railway distribution systems,
In particular, this paper relates to a power receiving system protection system for feeding substations of medium-duty rail transportation systems, which has been attracting attention recently.

Recently, new transportation systems that are not bound by conventional methods are being developed as a means of transportation to overcome traffic congestion caused by the concentration of population in cities and to cope with the expansion of urbanized areas. There are various methods being considered for new transportation systems, but one that has been attracting particular attention recently is a medium-sized rail transportation system between buses and suburban trains. This is used as a means of transportation between, for example, a housing complex, etc. and the nearest subway station, etc., instead of a bus, etc. It is a relatively light electric vehicle with a dedicated track and several cars connected together, and is unmanned by computers etc. Often driven. One feature of this system, unlike full-scale systems such as subways, is that it can be easily used by citizens as a substitute for geta, and the route length is relatively short, about several kilometers.
Moreover, safety and economy are strongly required above all for this system. Hereinafter, we will refer to this kind of medium-capacity rail transportation system as the "new transportation system."

Unlike general electric railways, the feeding system used in new transportation systems is often a low-voltage three-phase feeding system. The reason for this is that safe low voltage is desirable for unmanned operation, and high voltage requires equipment insulation, which increases the weight of the equipment.
This is because it would not only undermine the characteristics of the new transportation system, which is light and compact, but also be disadvantageous in terms of price.
Direct current feeding may also be considered, but alternating current feeding is often more advantageous because the chopper device used to control the vehicle becomes heavier. In the case of AC feeding, a three-phase feeding system is often used to reduce energy loss due to voltage drop in feeder lines when transmitting the same energy, which is different from one-phase feeding in normal electric railways.

Figure 1 shows an example of a conventional electric railway _AC feeding system _.
Power receiving transformers receive power from power company transmission lines via CB _a to CB _c , 1a to 1c are feeder lines connecting each transformer and the trolley wire 2, and 3a to 3c are for convenience of maintenance etc. Air section provided. On regular AC electrified railways, power receiving substations are often set up every 30 to 50 km as shown in Figure 1 to directly receive electricity from the power company. For this reason, it is necessary to prevent multi-system power supplies from matching up on the trolley wire, and dead sections 4,
It is normal to provide 5. Since the length l of the dead section (Fig. 2a) is set to be sufficiently longer than the length of one train set, switching and disconnecting switches 33S ₁ , 3 are used for feeding power in this section as shown in Fig. 2a.
3S ₂ will be provided. Each switch or disconnect is interlock controlled by a track relay (not shown), as is well known. For example, if a train is moving from the left side of the figure as indicated by arrow R, the lower switch 33S ₁ is initially closed and the lower switch 33S ₂ is open, and when the train has advanced to an appropriate point in the dead section section, 33S ₁ is opened. , 33S ₂ are switched closed. In addition, a system has been adopted in which the train passes through the dead section section by coasting without using switches or disconnectors, but even in this method, it is necessary to prepare for feeding power in the event that the train stops within the dead section section. Figure 2b
It is necessary to provide a feeder switch 94S and to operate it by remote control or the like.

On the other hand, in new transportation systems, the total track length is approximately several kilometers, and in order to emphasize economic efficiency, a method is adopted in which one power receiving substation is established and power is then distributed to multiple feeding substations, as described below. be done. The power distribution system also uses multiple busbars to reach each substation.

Figure 3 is a system diagram showing an example of a new transportation system.
T _r is the power receiving transformer, CB ₁ and CB ₂ are the power receiving transformers,
T _ra to _{T rc} are feeding transformers, A and B are double busbars for distribution, CB ₃ to B ₈ are lead-in and disconnectors, and CB ₉ to CB ₁₁ are feeder and disconnectors. ASS, BSS, and CSS represent the respective feeding substations. As mentioned above, since the single power receiving system is adopted in Figure 3, the phase difference between the feeding voltages of each feeding substation is small.
Further, from the viewpoint of emphasizing economic efficiency, the feeding section is not divided into dead sections, and only simple sections 3a to 3c are often provided for ease of maintenance.

In Fig. 3, the wire breakers CB ₁ , CB ₂ , CB ₄ ,
Since CB ₅ , CB ₈ to _{CB 11} are closed, and the rest are open, substations ASS and CSS are connected to bus B, and BSS is connected to bus A, supplying power to each section of the same trolley wire 2. is being carried out. If a short circuit accident occurs at point F of the busbar, then for point F,
A fault current I _F flows through the shield breaker CB ₁ and the bus bar A. At the same time, the breaker CB ₂ → CB ₈ →
CB ₁₁ → Feeding wire 1c → Trolley wire 2 → Feeding wire 1b
A wrap-around current I′ _F flows through →Shin breaker →CB ₁₀ →CB ₅ . Due to the fault current I _F , the
The overcurrent relay installed in CB ₁ operates to disconnect the shield breaker CB ₁ . However, as is clear from FIG. 3, if this is done alone, the wrap-around current _I'F will continue to flow toward the fault point. This I′ _F does not cause an overcurrent because the impedance of the feeding system is generally quite large. Therefore, it cannot be detected by the overcurrent relay in the substation CSS. Therefore, the accident at point F cannot be completely eliminated.

The present invention provides reliable and economical fault section removal means for the above-mentioned sneak current.

For this reason, in the present invention, for example, depending on the trip condition of the power receiving line disconnector CB ₁ connected to the bus line A, the lead-in lines and disconnectors connected to the same bus line A are connected and disconnected. That's what I do. This ensures that the sneak current _I'F is immediately cut off.
After the shingle is disconnected, it is possible to continue operating as a substation by drawing in the bus B side and turning on the disconnect switch.

FIG. 4 shows an example of connection and disconnection circuits for carrying out the present invention. Three connecting and disconnected busbars L1 to L3 are installed between each substation ASS and NSS. As shown in the diagram, each substation has a receiving relay 8 on this bus.
5R _i A and 85R _i B (i=1 to n) are connected. Something like a telephone line is sufficient as a contact or disconnection bus line. 5 and 6 are sequence circuit diagrams of the transmitting side and receiving side of FIG. 4, respectively. If there is a short circuit accident at point F, _51D1 is activated, so contact 85SA closes, and at that time, the line disconnector receiving relay 85R _i A connected to the A bus bar corresponds to the line disconnector auxiliary contact 52'. _iA , and issues a trip command to the corresponding shield breaker _52iA .
Note that 85SA in FIGS. 4 and 5 is a time-limited return relay to ensure that the disconnection command continues to be transmitted until the corresponding disconnector trips. By the above operation, all the leads and disconnectors connected to the bus A side are opened, so the wrap-around current I′ _F
will definitely be removed. After that, if the bus B side is pulled in or the disconnector is turned on, normal power feeding can be performed. In addition, if a short circuit accident occurs on the bus B side, 51D ₂ is activated, so contact 85SB closes, and at that time, the receiving relay connected to bus B connects the corresponding disconnector auxiliary contact 52' _i B. It is energized through the circuit breaker 52 i B and issues a trip command to the corresponding shield breaker 52 _i B. As a result, all the feeding substations connected to bus B are disconnected from bus B, and the fault section is completely removed.

Although the feeding system has been described above as a three-phase low-voltage feeding system, it goes without saying that it may be one-phase or a general n-phase system. Further, although the power distribution bus is a double A and B bus, it goes without saying that a general n-multibus may also be used.

As described above, according to the present invention, an accident can be eliminated by reliably cutting off the sneak current by simple and economical means such as connecting and disconnecting.
It is ideal for systems that place emphasis on economic efficiency, such as new transportation systems.

[Brief explanation of the drawing]

Figure 1 is a diagram showing an example of a conventional AC feeding system.
Fig. 2 is an explanatory diagram of a dead section, Fig. 3 is a diagram showing an example of a feeding system for an new transportation system, Fig. 4 is a wiring diagram of an embodiment of the present invention, Figs.
The figure is a sequence circuit diagram of the transmitting side and receiving side of FIG. 4. T _r ...receiving transformer, T _ra , T _rb ...feeding transformer,
A, B... Bus bar, ASS, BSS... Feeding substation,
L1 to L3...Connection or disconnection bus, 85R _i A...Reception relay, 52 _i A, 52 _i B...Lead-in or disconnection.

Claims (1)

[Scope of Claims] 1. Distribution of power from a common power receiving substation to a plurality of AC feeding substations is performed by multiple busbars, and the lead-in to each of the feeding substations is branched from these buses. In a protection system for an electric railway power distribution system having a configuration, when a short-circuit accident occurs on the busbar, the transmitting point or disconnector of the power receiving substation is opened, and in response to the opening of the transmitting point or disconnector. , an electric railway power distribution system characterized in that the wrap-around current from the feeder line is cut off by connecting and breaking the lead-in lines and disconnectors connected to the faulty busbar of each feeder substation. Protection method. 2. The protection system for an electric railway distribution system according to claim 1, characterized in that the feeding system is not provided with a dead section.