KR101007889B1 - Protecting System for Parallel Power Supply System of Electric Railway - Google Patents

Abstract

Parallel feed system protection system of the electric railway according to the present invention can not only stabilize the line voltage and improve the regenerative braking ability by the parallel feed method, but also adjusts the protection direction, protection distance, operating time, and the like of the distance relay. In the case of an accident of a tram line, only the corresponding tram line is blacked out, and even in the case of a fault in a parallel feed station and a feed station, an uninterruptible operation of the entire system is possible.

Electric Railway, Parallel Feeding System Protection System, Substation, Parallel Feeding Station (PP), Feed Division (SP), Distance Relay, Breaker

Description

Protection System for Parallel Power Supply System of Electric Railway

1 is a schematic diagram of a conventional power feeding system of a separate power feeding method.

2 is a schematic diagram of a parallel feed system applied to Gyeongbu High Speed Train.

3 is a schematic diagram of a parallel feed station according to the present invention.

4 is a schematic diagram of a feed section according to the present invention.

5 is a disconnected diagram of a parallel feed system protection system according to the present invention.

6 is a schematic diagram showing an operation procedure of the parallel feed system protection system according to the present invention.

Brief description of the main symbols in the drawing

SS: Substation SSP: Auxiliary Feeder Division

PP: Parallel Feed Station SP: Feed Division

AT: Single winding transformer AS: Air section

a, b, c, d, e, f, g, h, I, j, k, l, m, n: distance relay

PT: Instrument transformer, 27: Low voltage relay

Breaker: 52A, 52B, 52C, 52D, 52E, 52F, 52G, 52H, 52I, 52J, 52Z
GIB1, GIB2: Gas Insulated Bus

Field of invention

The present invention relates to a power supply system protection system of electric railway. More specifically, the present invention is to supply to the failure point according to the location of the failure point The present invention relates to a parallel feed system protection system for an electric railway capable of selectively interrupting power.

Background of the Invention

The power feeding system of the existing electric railroad in Korea was a separate power feeding system partially modified by modeling the power feeding method of the Japanese railway. As shown in FIG. 1, the separate feeder is composed of a substation (SS), a sub-sectioning post (SSP), and a sectioning post (SP), and compensates for voltage drop. And a Sub Sectioning Post (SSP) with a single winding transformer (AT) to reduce communication induction disturbances.

In this separate feeding method, since the ascending and descending lines are not connected to each other, voltage unevenness occurs in the up and down tram lines, and as a result, when the electric vehicle crosses the up and down lines, a large arc occurs in the tram line and descends on the slope section of the tram line. There is a problem that the regenerative braking ability to increase the power usage efficiency by supplying the electric power generated from the tank to the ascending tank is insufficient. Therefore, the up and down line is connected to the feeder division (SP) by tie line in parallel. It was. This is distinct from Japanese style.

On the other hand, the high-speed trains introduced from Europe in the early 2000s could overcome various problems such as the improved regenerative braking capability of the separate feed system by applying the parallel feed system, which is the French fed-in railway (SNCF). The parallel feeding method as shown in FIG. 2 applied to the train has various problems in completely protecting the high-speed train because it is a form of mixing the Japanese parallel feeding method with the European parallel feeding method.

That is, when a ground fault occurs in a portion of an electric railway up and down tram line, for example, the F1 point of FIG. 2 is broken or an icicle is running, a relay adjacent to the F1 point operates to operate the breaker 52A. When breaker 52A is activated, the current to the up line is cut off. However, even if the breaker 52A is blocked, the fault current flowing from the down line cannot be blocked through the parallel feed station (PP1: Parallel Post) connected with the up and down lines, so the breaker 52B, which is the down line parking short circuit, also operates, so all current supplied to the up and down lines As a result, the system is shut off at the same time, causing the entire system to lose power. In addition, the entire system is interrupted without determining whether a failure point is a line or a single winding transformer, and thus the circuit breakers 52C to 52H for the single winding transformer are also blocked by the voltage relay 27, so that all breakers in the system are blocked.

Afterwards, when the parking short circuit 52A and 52B are re-introduced to re-operate the train, the breaker 52A which supplies electricity to the up line with the breakdown point F1 is not put into operation, indicating that the up line is broken. Therefore, there is a problem that the only operation of the down line by re-injecting only the breaker 52B, the breaker of the down line single winding transformer 52D, 52F, 52H to drive the down line, and find and remove the fault point on the up line.

In addition, when a single winding transformer installed to prevent voltage drop and maintain a normal voltage of a train line (for example, a single winding transformer AT5) fails in spite of the presence of a backup transformer AT6 connected in parallel in case of a transformer failure, As there is no relay to detect and protect the fault of the system, all breakers of the whole system operate in the same way as the line failure, and the whole system is completely outage.

At this time, if the circuit breaker of all system is re-injected as in the case of the line breakdown, unlike the line breakdown, all the breakers operate again and complete power failure, so that the fault occurs in the single winding transformer. You must go through the screening process again.

As mentioned above, the parallel power supply system of the electric railway currently used is the entire system of power failure regardless of whether the failure point is a line or a single winding transformer.In the case of the single winding transformer with the highest probability of failure, even though a single single winding transformer is provided, There is a problem in that the operation of the tank is stopped due to the power outage for two times. Due to such problems, it may take a considerable time to restore the operation due to a failure, which may cause a delay in restarting the operation.

In addition, it is necessary to repeat the opening and closing times of breakers and operating mechanisms several times in order to check which line of up and down line is broken or which transformer of single winding transformer is broken. It takes time.

In addition, there is a problem in that a failure point expression device that costs billions of won to install a facility to determine where the failure occurs in the entire system.

In order to solve the above problems, the present applicant cuts only a line in case of a line failure, and removes only a single-stage transformer in case of failure of a single-circuit transformer having the highest probability of failure. It has begun to develop a parallel feed system protection system for railways.

It is an object of the present invention to provide a parallel feed system protection system for an electric railway.

Another object of the present invention is to provide an electric railway parallel feed system protection system that can easily improve the conventional Korean electric railway system susceptible to line accidents and single winding transformer failure.

Still another object of the present invention is to provide a parallel feed system protection system for an electric railway, which is capable of operating a train without a power failure on an opposite tank line in which an accident does not occur in the case of a track accident.

Still another object of the present invention is to provide a parallel feed system protection system for an electric railway capable of bi-directional operation of trains by disconnecting only the faulty single transformer from the system in the case of a single winding transformer failure in a parallel feed station or a feed section. will be.

It is still another object of the present invention to provide a parallel feed system protection system for an electric railway capable of roughly grasping a fault location even by a distance look device of a distance relay without a break point look device by selectively blocking according to the position of each break point. It is for.

Still another object of the present invention is to provide a system for protecting a parallel feed system for an electric railway, which can reduce a system installation cost by not providing a failure point expression device.

It is still another object of the present invention to provide a system for protecting a parallel electric feed system for an electric railway, which can reduce the cost and time required for maintenance by reducing the number of openings and closings of breakers and operating mechanisms that have been conventionally required to find a point of failure. .

The above and other objects of the present invention can be achieved by the present invention described in detail. Hereinafter, the content of the present invention will be described in detail.

Summary of the Invention

The electric railway feed system protection system according to the present invention includes at least one substation (SS), a parallel feed station (PP) and a feed section (SP).

In the electric feed system protection system of the electric railway, the parallel feed station of the present invention, the first winding transformer (AT3) connected between the up and down tram line of the electric railway, the first and second breakers for respectively disconnecting the connection between the single winding transformer and the up and down tram line 52C and 52D, first and second air sections AS1 and AS2 that disconnect the up and down tram lines, and first and second current transformers CT1 between the front and rear tram lines of the first air section and the first breaker 52C. And a gas insulated bus (GIB-gas insulated bus) or a catenary direct line connecting the front and rear tank lines before and after the first air section by using a CT2, the front and rear tank lines of the second air section and the second breaker 52D. Equipped with the third and fourth current transformers CT3 and CT4 respectively installed between the gas insulated bus lines or the tank line direct lines directly connecting the front and rear tank lines before and after the second air section, respectively, connected to the first and second current transformers, respectively, and protecting in opposite directions. Direction and fault current The first and second distance relays c and d for operating the first circuit breaker 52C and the third and fourth current transformers are respectively connected to each other and have protection directions opposite to each other. A third and fourth distance relay (e, f) for activating 52D) and an instrument transformer (PT) for supplying voltage components to the first and second distance relays and the third and fourth distance relays; The protection direction of the first to fourth distance relays is characterized in that the direction from the parallel feed station to the outside.

In addition, the feed section of the present invention is symmetrically positioned two sections connected to the center breaker (52Z) for extending the feed to the left and right of the disconnected up and down tram line portion (NS) and one section, up and down the electric railway Single winding transformer (AT7) connected between the tram lines, third and fourth breakers (52G, 52H) to cut off the connection between the single winding transformer (AT7) and the up and down tram line, respectively, the fifth current transformer (CT9) and the down tram line connected to the up tram line A sixth current transformer CT10 connected to the fifth current transformer and a fifth current transformer each connected to the fifth current transformer CT10 and a fifth current transformer CT10, each of which has a protection direction from the power supply division toward the outside and detects a fault current and the third circuit breaker and the third or fourth circuit breaker. And a fifth and sixth distance relay (k, l) for activating and an instrument transformer (PT) for supplying a voltage element to the fifth and sixth distance relay.

The substation of the present invention is connected to the substation breakers 52A and 52B, current transformers CT11 and CT12, single winding transformers AT1 and AT2, which are connected to each of the connection lines connected to the up and down tram lines, to cut off the electricity supply to the tram lines. And a substation distance relay (a; b) for operating the substation breaker upon detecting a fault current, and an instrument transformer (PT) for supplying a voltage element to the substation distance relay.

In the present invention, the distance relays a to l are located between the substations SS, the parallel feeder PP, or the feeder branch SP that are adjacent to each other in the protection direction, and the parallel feeder or feeder branch to which they belong. In the case 1), if the fault current flows, it operates within the first operating time, and if the fault current flows in the same lane (Zone 2) deviating from it, it operates within the second operating time longer than the first operating time, and the substation distance relay (a). , b) is to operate within the third operating time longer than the second operating time when the fault current continues to flow even after the first and second operating time has elapsed in the opposite tank line, it is possible to selectively block according to the accident location In addition to this, it is configured to increase the pick protection function in the system against failure.

At this time, the first to third operating time preferably has a time difference of the breaker operation time or more, and in the case of a failure of the single winding transformer AT3 of the parallel feed station, it is preferable to have a spare single winding transformer AT4 that can be replaced in parallel. desirable.

Hereinafter, the specific contents of the present invention will be described in detail.

Detailed Description of the Invention

The electric railway parallel feed system protection system according to the present invention, in the event of a failure in one of the up and down tram lines, only black out the failed tank line, when the single winding transformer of the parallel feed station (PP) and feed section (SP) failure up and down tram line To provide a power supply system protection system that enables all trains to operate without a power outage.

To this end, In the feed system protection system, as shown in FIG. 3, a single winding transformer AT4 and a single winding transformer connected in parallel so that the parallel feed station PP can be immediately inserted in the event of a failure of the AT3 and AT3 connected between the up and down tram lines of the electric railway. And first and second breakers 52C and 52D for respectively disconnecting the connection between the up and down tram lines, the first and second air sections AS1 and AS2 for disconnecting the up and down tram lines, and the front and rear tram lines of the first air section. A gas insulated busbar (GIB) and a direct connection between the first and second current transformers CT1 and CT2 between the first breakers 52C, respectively, to directly connect the front and the rear of the first air section (in parallel with the first air section). A gas insulated busbar that directly connects the front and rear tank lines before and after the second air section by equipping third and fourth current transformers CT3 and CT4 respectively installed between the front and rear tank lines of the second air section and the second breaker 52D. 4 connected to each of the current transformers It comprises a re-relay (c~f).

Instead of the gas insulated bus (GIB), a similar catenary direct connection line may be used, and an instrument transformer (PT) is installed to supply a voltage element to the distance relay.

In the case of the conventional parallel feed station applied to Gyeongbu high-speed trains, air sections AS1 and AS2 are installed in the up and down tram lines, respectively, and gas insulated switchgear (GIS) is retrofitted to convert the current transformers (CT1 to the front and rear tram lines). Newly installed gas insulated bus (GIB) with CT4) is connected directly, and can be easily converted into parallel feed station of the system according to the present invention by connecting distance relays (c to f) to current transformers. The instrument transformer (PT) for supplying the voltage element to the power supply may utilize an existing installation.

The first to fourth distance relays c to f provided in the parallel feed station of the present invention have a protection direction of the relay from the parallel feed station to the outside as indicated by the solid arrows in FIG. That is, the distance relay c sets the protection direction to detect the fault current flowing up the upside (left side in the drawing) based on the air section AS1 in the upcoming tram line, and the distance relay d is down the side (in the drawing) based on the air section AS1. The protection direction is set in the opposite direction to the distance relay c so as to detect the fault current flowing to the right), and the distance relay e protects to detect the fault current flowing upwards (left in the drawing) with respect to the air section AS2 in the downcomer tramline. Direction is set, and the distance relay f sets the protection direction in the opposite direction to the distance relay e so as to sense a fault current flowing downward (right in the drawing) with respect to the air section AS2.

Therefore, by installing the air section and the current transformer on the tram line, if the accident occurs on the substation (SS 1) side around the air section AS1 on the up line, the distance relay c operates to block the breaker 52C and the accident on the feed section (SP) side. If distance relay d is activated, breaker 52C is interrupted. In case of an accident in the substation (SS 1) on the down line, the distance relay e operates to block the breaker 52D. In the event of an accident on the feed branch (SP) side, the distance relay f operates to break the circuit 52D. To block. In other fault zones, the distance relays that detect fault currents operate to cut off the corresponding circuit breakers, thereby preventing the entire system from power failure by flowing fault current from the faultless train line toward the faulted train line.

In the event of a fault in the single winding transformer (AT3), the distance relays c and e or d and f detect the fault current (disconnect with the rear reach-back reach of the adjustable distance relay and send out a blocking signal) to shut off the breakers 52C and 52D. Let's do it.

In the parallel feed system protection system of the electric railway according to the present invention, in the case of the Gyeongbu high speed train, which has been conventionally installed, the configuration of the feed section (SP) is used to correct the distance relay in order to minimize the cost of system modification by utilizing existing facilities as much as possible. Other than that, the feed section of the conventional Gyeongbu high-speed train and its structure are kept the same.

In other words, the SP-sectioning post is installed in the middle of the substation and the substation, and the main purpose is to distinguish the supply range by cutting off both electricity. However, when one substation stops, it also serves as a facility to extend these two sections. Each section is powered by a different substation, centered around the disconnected up-and-down trajectory section (NS-Neutral Section). Central breaker (52Z) for up-and-down tramline (NS) that disconnects power to receive power from other substations, and for extension feeders that connect different feed sections to maintain rail service before and after NS even in the event of a power outage at another substation 2 sections are connected symmetrically, and each section (for example, an uphill section) includes a single winding transformer (AT7) connected between up and down tram lines fed from substation SS1 of an electric railway, the single winding transformer and an up and down tram line. Circuit breakers 52G and 52H respectively blocking the connection between the current transformer CT9 connected to the upcoming tramline, the current transformer CT10 connected to the downcomer tramline, and the current transformer are respectively connected to the central circuit breaker and the circuit breaker when a fault current is detected. It consists of a distance relay (k, l) that activates 52G or 52H (see Figure 4).

Instrument transformer (PT) is installed to supply a voltage element to the distance relay, in the present invention, the instrument transformer may be installed for each of the distance relay or one instrument transformer for two or more distance relays. .

The centrally-extended feeder breaker 52Z is normally open, but when electricity is not supplied from one substation due to an accident, the two sections can be connected to extend electricity to electricity supplied from the other substation.

The distance relays of the feed section also all have a protection direction outward from the feed section. Therefore, if there is an accident on the upstream line (on the left side of Fig. 4) centering on NS1, the distance relay k blocks the breaker 52G (when the center breaker 52Z is connected and is feeding the extension, it also blocks the center breaker 52Z). In case of an accident from the downcoming lane to the upstream of NS2, the distance relay l cuts the breaker 52H (when the central breaker 52Z is connected and in the case of extended feeding, the center breaker 52Z also cuts off). In the event of an accident on the downstream side centering on NS1 and 2, the distance relays m and n block the circuit breakers 52I, 52J and 52Z in accordance with the above description to prevent the other tank line from powering off at the same time by an accident occurring in one tank line.

In addition, if the single winding transformer AT7 fails, the distance relays k and l cut off the breakers 52G and 52H, respectively, to eliminate the single winding transformer AT7, so that neither the up or down tram line would be out of power due to the failure, and the distance relay m, n The corresponding breakers 52I and 52J are cut off to isolate only the fault section AT8.

The distance relay of the parallel feed station (PP) and the feed section (SP) configured as described above can constitute a more rational and efficient protection system by varying the correction distance and the settling time.

As an embodiment of the power supply system according to the present invention, reference is made to FIGS. 5 and 6 in which two parallel feed stations (PP1, PP2) and one feed branch (SP) are installed in a feed system in charge of one substation. The protection system according to the invention will be described in more detail.

5 and 6, the parallel feed station PP1 and the parallel feed station PP2 and the feed section SP are the same as the parallel feed station and the feed section according to the present invention described above, and the substation SS1 is connected to the up and down tram lines, respectively. The substation breakers 52A and 52B, current transformers CT11 and CT12, single winding transformers AT1 and AT2, and the current transformers are respectively connected to the connection line, and the current transformer substation is detected when a fault current is detected. Substation distance relays a and b are provided for activating the breaker.

The substation distance relays a and b have an outward protection direction from the substation, and operate the substation breakers 52A and 52B, respectively, when a fault current is detected.

As described above, a total of 12 distance relays a to l provided in the system supplied with electricity by the substation SS1 are located between the substations (SS), the parallel feed station (PP), or the feed branch (SP) adjacent to each other in the protection direction. Zone 1) and when the fault current flows (back reach) inside the parallel feeder (PP) to which it belongs, operates within the first operating time, and when the fault current flows out of the range (Zone 2), longer than the first operating time. And to operate within a second operating time. In this case, Zone 1 or Zone 2 means the zone that the distance relay is in charge of the distance from the PP or SP to the failure point, and at the same time Zone is the software-protected zone in the distance relay corresponding to these zones. Refers to both protected areas by these real distances and those defined within the distance relay. Local zones are in km or m, but distance relays recognize them as electrical units [Ω].

In addition, when a fault occurs inside a parallel feed station, that is, when a fault current flows due to a failure of a train line or an AT in a parallel feed station, the distance relay operates within the first operating time of the back reach, and in the same train line in the protection direction. In the case where a fault current flows, it may be configured to operate within a second operation time longer than the first operation time.

In the case of substation distance relays a and b, if a fault current flows to the opposite line, it will not operate until the second operating time, but some distance relays or breakers will not operate, ie if the main protection device fails to protect the system, When the fault current continues to flow because the fault has not been eliminated in the catenary, it is preferable to configure the after-protection for power failure of the entire system by configuring to operate at a third operation time longer than the second operation time.

The first to third operating time, that is, the correction time of the distance relay can be set by a person skilled in the art to determine the appropriate time, the first operating time is within 0.05 seconds to help understand the correction distance, correction time, etc. of each relay described above For example, the second operation time is 0.25 seconds, and the third operation time is 0.45 seconds as shown in the following table (see FIGS. 5 and 6).

In general, when the distance relay operates, the breaker operation is completed after 0.08 seconds, and thus the break is completed. Therefore, the relay, the breaker, and the operation completion time when the failure occurs in the F1 to F3 positions of the ascending lane in FIG. 6 are applied. Etc. are as follows.

As shown in the table above, in the event of a failure in the ascending line, all breakers 52A, 52C, 52E, and 52G connected to the ascent line are blocked in 0.33 seconds, and the settling time (0.45sec) for the distance relay b connected to the breaker 52B. ) Is later than the operation completion time (0.33 sec), the circuit breaker 52B which substantially cuts off the supply of electricity to the downcoming tramline does not operate. That is, the down line is not interrupted. Through this, if only the up line is blackout, it is immediately known that the up line is broken.

In addition, in FIG. 6, a relay, a circuit breaker, and an operation completion time (clear time) that operate when a failure occurs in the F4 to F6 positions of the downcoming tramline are as follows.

As can be seen from the table above, even in the case of downline track failure, all breakers (52B, 52D, 52F, 52H) connected to the downcoming tramline are blocked in 0.33 seconds, and the settling time (0.45sec) for the distance relay a connected to the breaker 52A Since it is later than the operation completion time (0.33 sec), the circuit breaker 52A which substantially blocks the supply of electricity to the ascending lane does not operate. In other words, the upcoming tramline is not powered off.

As described above, it is preferable that the third operation time is set to be longer than the second operation time (generally 0.08 s) than the second operation time in order to prevent the other vehicle from power failure due to a failure of one of the vehicle lines.

In addition, the relay, circuit breaker, and operation completion time (clear time) which are operated when a fault occurs in a single winding transformer are as follows.

As can be seen above, in case of failure of single winding transformers AT1 and AT2 directly connected to up and down tram lines, only the up tram line will be outage when AT1 fails, and only down tram line will be outage when AT2 fails.

On the other hand, in case of failure of the single winding transformers (AT3 to AT7) of the parallel feed station and the feed section connected in parallel with the up and down tram lines, the breakers connected to both of the failed single winding transformers are cut off in 0.13 seconds, and the breaker cuts off the electric supply to the up and down tram lines. In the case of the distance relays a and b connected to 52A and 52B, since the settling time (0.25sec) is later than the operation completion time (0.13sec), the circuit breakers 52A and 52B which substantially block the supply of electricity to the up and down tram lines do not operate. That is, the up and down tram lines are not blackout.

In case of failure of single winding transformers (AT3 to AT7) of parallel feeder and feeder division, both up and down tram lines are not interrupted.For this purpose, the second operation time is more than the first operation time (especially back reach operation time). s) It is preferable to set so that it may become later than abnormal.

When operating as above, it is easy to know whether the line breaker or single winding transformer is broken, whether the single winding transformer is located somewhere, or which section of the whole line is broken. In addition, by using the distance marking device of the distance relay itself, it is possible to reduce the facility cost of billions of dollars that need to be invested in installing the fault point expression device.

According to the present invention, in the case of a tramline accident, the opposite tramline without an accident can operate the train without a power failure, and in the case of a faulty transformer of a parallel feeder or a feeder division, a bidirectional operation of the tram can be performed without a power failure of the up and down tramway lines. By selectively blocking according to each position, it is possible to grasp the location of the fault even with the distance expression device of the distance relay itself without the trouble point expression device, and to reduce the installation cost by not having the trouble point expression device. By greatly reducing the number of openings and closings of breakers and operating mechanisms required to find a point, it is possible to reduce the cost and time required for breaker maintenance, and to easily improve the conventional Korean electric railway system vulnerable to line accidents and single winding transformer failure. To provide a parallel feed system protection system for And it has a.

Simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be seen to be included in the scope of the present invention.

Claims (6)

In an electric railway feed system protection system having at least one substation (SS), a parallel feed station (PP) and a feed section (SP), the parallel feed station is: Single winding transformer (AT3) connected between the up and down tram line of the electric railway; First and second breakers 52C and 52D for respectively disconnecting the connection between the single winding transformer and the up and down tram line; First and second air sections AS1 and AS2 respectively disconnecting up and down tram lines; A first gas insulated busbar or a first tank line directly connected to the front and rear tank lines before and after the first air section by equipping the first and second current transformers CT1 and CT2 between the front and rear tank lines of the first air section and the first breaker 52C. A second gas that directly connects the front and rear tank lines before and after the second air section by being equipped with third and fourth current transformers CT3 and CT4 respectively installed between the front and rear tram lines of the line GIB1 and the second air section and the second breaker 52D. An insulated bus bar or a second catenary direct connection line (GIB2); First and second distance relays c and d connected to the first and second current transformers, respectively, having protection directions opposite to each other, and operating the first breaker 52C when detecting a fault current; Third and fourth distance relays (e, f) respectively connected to the four current transformers and having protection directions opposite to each other and operating the second circuit breaker 52D when detecting a fault current; And An instrument transformer (PT) for supplying a voltage element to the first and second distance relays and the third and fourth distance relays; The protection direction of the first distance relay (c) to the fourth distance relay (f) is in parallel with the insulated bus or the direct-line lines (GIB1, GIB2) equipped with each of the distance relay on the tram line The first distance relay c and the third distance relay e facing the tram lines before and after the connected air sections AS1 and AS2, that is, the parallel feed station PP1 in which the distance relays are installed. ) And the second distance relay (d) and the fourth distance relay (f) in the direction toward the power supply substation (SS1) in the direction toward the parallel feed station (PP2), the next parallel feed station on the same tram line. A parallel feed system protection system for an electric railway, characterized in that the direction of protection of the distance relay and the opposite direction. The method of claim 1, wherein the first to fourth distance relay between the substations (SS), the parallel feed station (PP) or the feed section (SP) adjacent to each other in the protection direction and inside the parallel feed station (PP) belonging to Operate to transmit the interruption signal to the breaker within the first operating time when the fault current flows through the circuit, and to transmit the interruption signal to the breaker within the second operating time longer than the first operating time when the fault current flows outside the range. Parallel feed system protection system of an electric railway, characterized in that. 3. The feed section is symmetrically positioned with two sections connected by a central breaker 52Z for extended feeding to the left and right of the disconnected up and down tram line portion NS. Single winding transformer (AT7) connected between the up and down tram line of the electric railway; Third and fourth circuit breakers 52G and 52H respectively blocking the connection between the single winding transformer AT7 and the up-and-down tram line; A fifth current transformer CT9 connected to the ascending tramline and a sixth current transformer CT10 connected to the descending tramline; Fifth and sixth distances connected to the fifth and sixth current transformers, respectively, and having a protective direction facing outwards from the feeder division, and operating the extension circuit breaker and the third or fourth circuit breaker when a fault current is detected. Relay k, l; And An instrument transformer (PT) for supplying a voltage element to said fifth and sixth distance relays; Each consists of The substation is connected to each of the connecting lines connected to the up and down tram line, Substation breakers 52A and 52B for shutting off the supply of electricity to the tram line; Current transformers CT11; CT12; Single winding transformer (AT1; AT2); A substation distance relay (a; b) connected to the current transformer, having a protection direction from the substation to the outside, and operating the substation breaker when a fault current is detected; And An instrument transformer (PT) for supplying a voltage element to the substation distance relay; Parallel feed system protection system of an electric railway comprising a. 4. The fifth and sixth distance relays (k, l) provided in the feed section (SP) and the distance relays (a, b) provided in the substation are the same as the protection direction of each distance relay. Between a parallel feed station (PP) or a feed branch (SP) Inside fault substation (SS1) or feed branch (SP) When the fault current flows, within the first operating time, the distance relay a operates to deliver a blocking signal to the breaker 52A, and the distance relay k operates to deliver a blocking signal to the breaker 52G. When the fault current flows in the same tram line, the distance relays operate to transmit a cutoff signal to the circuit breaker within a second operation time, and the substation distance relay (a) is operated by the fault current to the opposite tank line. If the flow continues even after the elapse of time, it operates to transmit a cutoff signal to the circuit breaker 52A at a third operation time longer than the second operation time, and the substation distance relay b has a fault current in the opposite vehicle line. If it continues to flow even after the operation time has elapsed, it operates to transmit a cutoff signal to the circuit breaker 52B at a third operation time longer than the second operation time. Parallel feed system protection system of an electric railway, characterized in that to cut off the electric system. The system of claim 4, wherein the difference between the first and second operating time and the difference between the second and third operating time is greater than or equal to the breaker operating time. 6. The electric railway system according to any one of claims 1 to 5, wherein the parallel feeder is provided with a preliminary single winding transformer (AT4) which can be replaced in case of failure of the single winding transformer (AT3) of the parallel feeding station. Parallel feed system protection system.

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