JPS6325972B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a method for protecting the power supply system of a DC electric railway, and in particular, when the number of feeder lines is double-tracked, even if there is an accident in the feeder line, the intact feeder line will be protected. The present invention aims to provide a new power supply system protection method that allows predetermined operation operations to continue without any impact.

In DC electric railway power supply systems, thyristors are connected in anti-parallel (or thyristor diodes are connected in anti-parallel) to replace DC high-speed circuit breakers for reasons of maintenance and protection coordination. A static switch such as a thyristor circuit breaker or a stopper diode is applied,
Furthermore, thyristor rectifiers are increasingly being used as forward power converters in place of silicon rectifiers. In this way, in DC power supply systems, everything except the disconnector is now static.
The power supply system itself has become extremely reliable, and in this respect it can be said to be revolutionary. However, even if a DC high-speed circuit breaker with a mechanical operation mechanism is simply replaced with a static switch, accidents such as short circuits may occur at any substation in the power supply system or between substations. In such a case, if the accident occurs between substations, both substations that sandwich the accident point will immediately stop power supply and cut off the accident section as soon as the accident is detected, so it will not be possible to connect multiple circuits with uplinks and downlinks. Not only does the power supply to the faulty line stop, but also the power supply to the healthy line installed in parallel with the faulty line also stops. In this case, for example, if there is a power-running vehicle on the healthy line, the problem arises that the power-running vehicle is forced to stop. This kind of situation deviates from the main mission of ensuring smooth operations, and is by no means desirable.

The present invention was invented in view of this point, and the circuit configuration shown in the figure to which the present invention is applied will first be described in detail below. In the figure, A and B indicate two substations located next to each other in a group of substations installed in the power supply system, and in the example, substation A is a substation that only has the function of supplying power running power, and the other substation is Substation B is a substation that has the function of supplying power running power and at the same time allowing regenerative power from the regenerative vehicle. Now, in these two substations, ₁₁ and ₁₂ are three-phase commercial frequency power supply buses, ₂₁ to ₂₅ are AC circuit breakers, and ₃₁ to ₃₄ step down the input AC power to an appropriate voltage value. 3 ₅ indicates a regenerative transformer. 4 ₁ to 4 ₄ are forward power converters for converting AC power into DC power, and these forward power converters are constructed by connecting thyristor elements in a pure bridge connection. 4 ₅ is a reverse power converter that reversely converts DC power into AC power, and is constructed by connecting thyristor elements in a pure bridge like the forward power converter. 5 ₁ to 5 ₅ are disconnectors, and 6 ₁ is a negative electrode bus bar. 7 ₁ and 7 ₂ are DC positive electrode busbars (also called power running busbars), and below these DC positive electrode busbars are a first group of stopper diodes designated by symbols 9 ₁ to 9 ₈ , and a group of stopper diodes designated by symbols 11 ₁ to 11 ₈ . A series circuit with a group of disconnectors is connected, and desired DC power is supplied to each of the feeder lines 12 ₁ and 12 ₂ through these series circuits. The first group of stopper diodes 9 ₁ to 9 ₈ are for blocking the inflow of power from an unillustrated substation adjacent to the substation, and allow this inflow of power.
Furthermore, to allow regenerative power from the regenerative vehicle, in the case of A substation, a second stopper diode group 10 _{1 to 10} connected below the regenerative bus 8 ₁ is used.
If 10 ₄ is substation B, the second stopper diode group 10 ₅ is connected under the DC positive bus 7 ₂ .
~ ₁₀₈ each have the above functions. 14 is a DC switch that has the function of supplying regenerative power from the regenerative vehicle to the power running vehicle during normal operation, and in the event of an accident, disconnects the regenerative power from the regenerative vehicle and connects to the accident point of the A substation. It also has the ability to instantly disconnect the fault point from other intact power lines. 13 ₁ and 13 ₂ are the rails of vehicle D, and L ₁ and L ₂ are reactors inserted to limit overcurrent. These reactors can be removed from the main circuit without any problem in operation. . In addition, in the figure, the first stopper diode group 9 ₁ to 9 ₄ ,
Although we have described the case where ₉₅ to ₉₈ are applied, for example, even if a thyristor circuit breaker is used instead of these stopper diodes, the operation is exactly the same,
If a thyristor circuit breaker is applied in this way, the structure of the thyristor circuit breaker itself is a configuration in which a thyristor and a diode are connected in anti-parallel, as is well known in the art, so the stopper circuit breaker as seen in substation A and substation B can be used. The diode group becomes unnecessary.

Now, the operation of the power supply system configured as described above during steady state is as follows: At both substations A and B, the commercial frequency power supply bus ₁
The three-phase AC power input _{from 12} is first stepped down to _an appropriate voltage value by transformers _31-32 , _33-34 ,
This AC power is converted into forward power converters 4 ₁ -4 ₂ , 4 ₃ -
Step ₄ converts the DC power into DC power, and converts this DC power to the disconnector 5 ₁ -5 ₂ , 5 ₃ -5 ₄ → reactor L ₁ , L ₂ → DC positive electrode bus 7 ₁ , 7 ₂ → first stopper. Diode group 9 ₁ -9 ₄ , 9 ₅ -9 ₈ →Disconnector 11 ₁ -11 ₄ ,
11 ₅ -11 ₈ →Feeding wire 12 ₁ -12 ₂ →Negative bus bar 6
Power is supplied to the vehicle through each of the routes ₁ , 6, _{and 2} . Assuming that the vehicle D is in regenerative operation, the regenerative power from the regenerative vehicle D is transferred from the vehicle to the feeder line 12 ₂ to the disconnector 11 ₃ -11 at the A substation.
₄ → Second stopper diode 10 ₃ −10 ₄ →
DC switch 14 → DC positive bus 7 ₁ → first stopper diode 9 ₁ -9 ₂ → disconnector 11 ₁ -1
1 ₂ →Flows through the path of feeder line 12 ₁ , and feeder line 1
2 If there is a power running vehicle in ₁ , regenerative power will be supplied to this power running vehicle as power running power. Similarly, at substation B, the regenerative power from the regenerative vehicle D is fed to the feeder line 12 ₂ → disconnector 11 ₇ -11 ₈ → second stopper diode 10 ₇ -10 ₈ → disconnector 5 ₅ → reverse power The converter 4 ₅ → transformer 3 ₅ → circuit breaker 2 ₅ → commercial frequency power supply bus 1 ₂ is regenerated to the AC input power source side, and a part of the regenerated power is also transferred to the feeder line 1.
2 ₂ → Disconnector 11 ₇ -11 ₈ → Second stopper diode 10 ₇ -10 ₈ → DC positive electrode bus 7 ₂ → First
Stopper diode 9 ₅ -9 ₆ → Disconnector 11 ₅
-11 ₆ →Flows through the route of the feeder line 12 ₁ , and if there is a vehicle on the feeder line 12 ₁ during power running, a part of the regenerated power is supplied to this power running vehicle as power running power. In this way, in the power supply system shown in the figure, if there is a vehicle under each feeder line during regenerative operation, the regenerative power of this regenerative vehicle is regenerated to the AC input power supply side, and at the same time, when there is a vehicle under the other feeder line during powering operation. If there is a power running vehicle, the regenerated power is supplied to the power running vehicle as power running power, so the regenerated power is not consumed in the power supply system and is all used as energy, creating a power supply system that is in line with the trend of "energy saving". I can say that.

Now, suppose that the power supply system operates as described above during normal operation, and for some reason a short-circuit accident occurs at point ○A in the figure. In the case of this short-circuit accident, if the conventional protection method were used, the forward power converters 4 ₁ - 4 ₂ and 4 ₃ would be installed at substation A and substation B, which sandwich the fault point in ○A.
Disconnector 11 1 -11 2 , which tightens the gate of 4 ₄ to the minimum position, shifts the gate, stops power supply instantly, and then supplies power to feeder line _{12 1} at fault point ○ _A .
11 ₅ - 11 ₆ are opened respectively to isolate the fault point ○A from other healthy feeder wires, but with this type of protection method, the fault point ○A can be sandwiched between the fault points ○A and Since the power supply to both substations will be stopped,
For example, healthy feeder line 1 opposite to failed feeder line 12 ₁
2 In the case where a vehicle D is in power running as shown in the figure ₂ , the power supply to vehicle D is stopped and it is no longer possible to continue the specified operation. As is well known, this outage period is until the accident at point ○A is completely removed and power is restored to substations A and B.

As described above, the biggest drawback of the conventional protection method is that it has a great influence on the healthy feeder wire side, but according to the present invention, the conventional method can be improved by performing the following operations. This is an attempt to resolve the pending issues all at once. That is, in the protection method according to the present invention, first, the power supply is preferentially stopped to only one of the substations A and B, which are located between the accident point of ○A. In this case, assuming that the substation to which power supply is to be stopped is substation A, if a detector (not shown) detects a short circuit at fault point Disconnector 1 connected to “Command” and accident line 12 ₁ side
1 ₁ - 11 ₂ and the "opening command" at the same time, A
The gates of the forward power converters 4 ₁ - 4 ₂ of the substation are shifted to the minimum position, and the DC switch 14 is turned off to instantly stop the power supply to the A substation. In the above operation process, the forward power converter and the DC switch are each turned off in an extremely short period of several milliseconds, but due to its mechanical mechanism, the disconnector turns off several times after the opening command is input. 10m
The pole will be opened after s. After confirming that the power supply to the A substation is stopped and the designated disconnectors 11 ₁ - 11 ₂ are opened, first the forward power converters 4 ₁ - 4 ₂ and the DC switch 14 of the A substation are connected. each again
ON finger cooling is applied to restore power to substation A, and at the same time, to substation B on the other side, a forward power exchange device and a DC switch (not shown) are installed between the reverse power converter and the DC positive bus. (generally inserted) and gives an OFF command to the fault line 12 _1
An opening command is given to the disconnectors 11 _{5 -} 11 ₆ that are connected to
OFF and stop power supply to B substation. Disconnect switch 1 of the B substation specified when the power supply to the B substation is stopped.
As mentioned _above , _15-116 opens with a slight delay, and fault point ○A is completely cut off from other healthy lines. After confirming that the designated disconnector of the B substation is opened in this way, the forward power converter 4 ₃ - 4 ₄ of the B substation and the DC switch (not shown) are turned on.
Turned on again by command and turned on the accident line 1 at the accident point ○A.
2 ₁ remains cut off, and a healthy line 12 ₂ is installed in parallel with the failed line 12 ₁ from substation A and substation B.
By supplying the desired DC power to the line ₁₂₂ , the vehicle D on the healthy line 122 continues to operate.

As is clear from the above explanation of the operation, according to this protection method, when an accident occurs, the power supply is immediately stopped to only one of the substations A and B, which is located between the accident point, and then the power supply is stopped. At the same time, power is restored to the substations that have stopped supplying power, and at the same time, power is stopped to the substations that have been supplying power up until now, completely cutting off only the faulty line, and then power is restored to the substations that have recently stopped supplying power. As a result, the desired power is supplied to the healthy line through the fault line, so that the healthy line installed in parallel with the faulty line will remain in good condition for a period of time until power is restored to both substations A and B through predetermined protective operations at the same time as the accident occurs. Power is first supplied to the line from substation B, then from substation A, and finally from both substations A and B. Power is supplied to a healthy line in an instant. There is no stopping either. Therefore, according to the present invention, even if an accident occurs in the power system for some reason, it is a system that can continue power supply without any effect on healthy lines, so firstly, it has a very reliable power supply. Secondly, it is possible to provide a power supply system that can maintain smooth operation throughout the power supply system, and thirdly, the regenerative power can be supplied to the AC input power supply side or to the power running vehicle. Since it is a system that uses everything effectively without consuming it, it is possible to provide a power supply system that is in line with the trend of "energy saving".
With the protection method of the present invention, for example, in the case of a power supply system as shown in the figure, actual verification has shown that it takes about 120ms to completely shut off the faulty line, but this time is sufficient for a general power supply system. This is the time required to achieve the desired purpose, and for example, if a thyristor circuit breaker is used instead of a group of stopper diodes, there is an advantage that the circuit breaker can be shortened to about 40 ms to 70 ms.

[Brief explanation of the drawing]

The figure is a circuit configuration diagram showing a specific example of a power supply system to which the protection method of the present invention is applied. 1 ₁ - 1 ₂ is a commercial frequency power supply bus, 2 ₁ - 2 ₅ is an AC breaker, 3 ₁ - 3 ₅ is a transformer, 4 ₁ - 4 ₄ is a forward power converter, 4 ₅ is a reverse power converter, 5 ₁ -5 ₅ and 1
1 ₁ - 11 ₈ is a disconnector, 6 ₁ - 6 ₂ is a negative electrode bus, 7 ₁ -
7 ₂ is a DC positive electrode bus, 8 ₁ is a regenerative bus, 9 ₁ -9 ₈ and 10 ₁ -10 ₈ are stopper diodes, 12 ₁
-12 ₂ is the feeder line, 13 ₁ -13 ₂ is the rail.

Claims (1)

[Claims] 1. AC power input from a commercial frequency power supply bus is converted into DC power by a forward power converter, and this DC power is transferred between a group of static switches and a group of disconnectors connected under the DC positive bus. A power supply system that supplies power to each feeder line through each series circuit, and is designed to protect the power supply system from accidents that occur at any substation or between substations in a group of substations that are installed parallel to the feeder line. At the same time as the fault is detected, the power supply is stopped to only one of the two substations located between the fault point, and only the disconnector connected to the fault line is opened at that substation. At the same time, the substation that has been supplying power will be stopped, and only the disconnector connected to the faulty circuit will be opened at the substation. Under extreme conditions, the substation that had cut off power supply will be restored and the faulty line will be completely cut off, and the faulty line will be cut off without stopping the power supply to the healthy lines that are installed in parallel to the faulty line. A protection method for a DC power supply system characterized by: 2. The method for protecting a DC power supply system according to claim 1, in which a stopper diode or a thyristor circuit breaker in which a thyristor and a diode are connected in anti-parallel is applied as a static switch.