JP2002234365A - Dc electromotive system and operating method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a DC electromotive system having little cross current among substations, and suppressing a rated capacity of equipment to a required minimum capacity, and little power loss, and to provide an operating method thereof. SOLUTION: The DC electromotive system is provided with a plurality of substations connected to be parallel with each other on a feeder 40 of a DC electric railroad. The substations respectively have: a power converter 1a, 1b, 1c, 1d for converting an AC current to a DC current; a current detector 2b, 2c, 2d for detecting the output current of the substation flowing through the feeder; and a voltage controller 3a, 3b, 3c, 3d for controlling the output voltage of the power converter based on a current value detected by the current detector. The DC electromotive system is operated by a method comprising the steps of: under a state free from load and when a train is not in an electromotive interval of a predetermined reference substation, controlling the output voltage of the substations neighboring the reference substation so that the current flowing from the neighboring substations to the reference substation becomes zero or nearly equal to zero; and controlling the output voltage of the further neighboring substations of the neighboring substations based on the neighboring substations. Therefore, the output voltage is adjusted one after another as described above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC feeding system for converting AC power into DC power at a DC railway substation and supplying the DC power to an electric railway, and a method of operating the same.

[0002]

2. Description of the Related Art Silicon rectifiers have long been used as power converters for converting AC power into DC power at DC railway substations. Further, a thyristor rectifier using a thyristor has been introduced. In recent years, advances in power semiconductors have made it possible to apply self-excited converters.
The use of the self-excited converter has a number of advantages such as a constant DC voltage for both power running and regeneration, and a power factor of 1.0 for the AC input power.

FIG. 6 is a block diagram of a conventional DC railway substation using a self-excited converter. Reference numeral 21 denotes a transformer for converting an AC voltage to a predetermined voltage, 22 denotes a self-excited converter, 23 denotes a DC capacitor of the self-excited converter, 24 denotes a DC reactor that limits a short-circuit current when a feeder circuit is short-circuited, , 26 are DC breakers that cut off the short-circuit current when the electric wire is short-circuited. 31 to 36 are the same equipment in the adjacent substation. With such a configuration,
AC power from the commercial AC system 20 is converted to DC power.
Supply to 40.

In such a configuration, the self-excited converter 22 is controlled so that the voltage of the DC capacitor 23 becomes constant. When there is a power running vehicle in the feeder section, current flows from the DC capacitor 23 to the power running vehicle, and the voltage of the DC capacitor 23 decreases. It works to keep it constant.

Conversely, when there is a regenerative vehicle in the feeding section, a current flows from the vehicle into the DC capacitor 23, and the voltage of the DC capacitor 23 rises. Therefore, the self-excited converter 22 keeps the voltage of the DC capacitor 23 constant. To regenerate power from DC to AC. In this manner, the self-excited converter 22 is controlled so as to keep the voltage of the DC capacitor 23 constant, and is kept at the same constant voltage in both the feeding direction and the regenerative direction. The same applies to the operation of the adjacent substation including the converter transformer 31 to the DC breaker 36.

[0006]

In the conventional DC railway substation as described above, the difference between the DC voltage controlled by the self-excited converter 22 and the DC voltage controlled by the self-excited converter 32 of the adjacent substation is different. For example, if the DC voltage of the self-excited converter 22 is higher than the DC voltage of the self-excited converter 32, the self-excited converter 22 Electric current flows. This current is determined by the resistance of the electric wire 40 when the DC voltage between the self-excited converters 22 and 32 is different. Assuming that the difference in DC voltage is 45 V, which is 3% of the rated 1500 V, and the resistance value of the feeder line 40 is 150 mΩ, the self-excited converter 22 always supplies a current of 300 A, and the self-excited converter 32 always supplies a current of 300 A. It will regenerate.

For this reason, the capacity of the self-excited converters 22 and 32 needs to take into account the increase in the rated current for this current.
If the converter is kW, the rated current is 3000A, so 10%
This leads to an increase in capacity. In addition, the feeder line 40 also suffers loss due to the current and the resistance, so that the efficiency of the DC feeder system is reduced.

As described above, in the conventional DC railway substation, the rated capacity of the self-excited converter is increased to increase the size and cost, and the efficiency is reduced due to an increase in feeder line loss. There's a problem.

Accordingly, an object of the present invention is to provide a DC feeding system in which the cross current between substations is small, the rated capacity of equipment is kept to a necessary minimum, and the power loss is small, and an operation method thereof.

[0010]

To achieve the above object, the invention of claim 1 comprises a plurality of substations connected in parallel to a feeder of a DC electric railway, wherein the substation converts an alternating current into a direct current. A power converter that replaces the power supply, a current detector that detects an output current of the substation flowing through the feeder line, and a voltage control that controls an output voltage of the power converter based on a detected current value of the current detector. In a method of operating a DC feeder system including a transformer, in a no-load state where there is no train in the feeder section based on a predetermined substation, the substation adjacent to the reference substation and the reference The output voltage of the adjacent substation is adjusted so that the current flowing to the substation becomes zero or a value close to zero, and the output voltage of the substation adjacent to the adjacent substation is further adjusted to the adjacent substation. Adjust as a reference and output sequentially And operation method to adjust the pressure.

According to the present invention, the cross current between the substations can be reduced, and an unnecessary increase in the capacity of the power converter can be prevented, so that a power converter having a minimum necessary capacity can be applied. Further, it is possible to prevent power loss due to the resistance of the electric wire at the time of cross current, and it is possible to improve the efficiency of the DC feeding system.

According to a second aspect of the present invention, in the method for operating a DC feed system according to the first aspect, first, a predetermined substation is activated as a reference, and a substation adjacent to the reference substation is subsequently activated. Adjusting the output voltage of the adjacent substation so that the cross current flowing to the reference substation after starting is zero or a value close to zero, and further changing the substation next to the adjacent substation to the next substation. The operation method is to start up, adjust the output voltage based on the adjacent substation, and sequentially start the substations to adjust the output voltage. According to the present invention, it is possible to reduce the influence on other substations, adjust the output voltage of the substation, and reduce the cross current.

According to a third aspect of the present invention, in the operation method of the DC feeding system according to the first aspect, a first level near zero and a second level larger than the first level with respect to the output current of the substation. And an operation method for adjusting the output voltage of the substation when the output current stays for a predetermined time between the first level and the second level. According to the present invention, adjustment between substations can be performed during the operation period after each substation is started.

According to a fourth aspect of the present invention, there are provided a plurality of substations connected in parallel to a feeder of a DC electric railway, wherein the substation comprises:
A power converter for exchanging AC to DC, a current detector for detecting an output current of the substation flowing through the feeder line, and controlling an output voltage of the power converter based on a detected current value of the current detector. And a small current detector for detecting a cross current with an adjacent substation provided on the feeder line and outputting a signal related to the cross current to the voltage controller. And a short-circuit device for short-circuiting the device. ADVANTAGE OF THE INVENTION According to this invention, adjustment between substations can be performed more accurately and cross current can be reduced.

According to a fifth aspect of the present invention, in the method for operating a DC feeding system according to the first aspect, a small current which is provided on the feeder line and detects a cross current with an adjacent substation and outputs a signal related to the cross current to a voltage controller. A detector and a short circuit for short-circuiting the small current detector, and adjusting the output voltage of the substation based on the detected current value of the small current detector. The operation method will be short-circuited. ADVANTAGE OF THE INVENTION According to this invention, adjustment between substations can be performed more accurately and cross current can be reduced.

According to a sixth aspect of the present invention, there is provided a plurality of substations connected in parallel to a feeder of a DC electric railway, wherein the substation comprises:
A power converter for exchanging AC to DC, a current detector for detecting an output current of the substation flowing through the feeder line, and controlling an output voltage of the power converter based on a detected current value of the current detector. In a DC feeding system including a voltage controller, a connection line that connects the DC output terminals of the respective substations in parallel, and a current flowing through the connection line is detected, and a signal related to the current is sent to the voltage controller. And an output current detector. ADVANTAGE OF THE INVENTION According to this invention, a detection current value can be made small and adjustment between substations can be performed accurately by a small current detector.

According to a seventh aspect of the present invention, in the operation method of the DC feeding system of the first aspect, a connection line for connecting the DC output terminals of the respective substations in parallel, and a voltage controller which detects a current flowing through the connection line And a current detector that outputs a signal related to the current, and adjusts the output voltage of the substation so that the current flowing through the connection line becomes zero or a value close to zero. ADVANTAGE OF THE INVENTION According to this invention, a detection current value can be made small and adjustment between substations can be performed accurately by a small current detector.

According to an eighth aspect of the present invention, in the operation method of the DC feeding system according to the first aspect, the output current of the substation is compared with the output current of a substation adjacent to the substation, and when the currents are substantially equal to each other. The operation method is to adjust the output voltage of the substation so that the output current is zero or close to zero.
According to the present invention, it is possible to adjust the output voltage of the substation at all times, even when there is a train on the feeder line.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A DC feeding system according to a first embodiment of the present invention and a method for operating the same will be described with reference to FIG. In FIG. 1, reference numeral 1a denotes a power converter of a first substation, 1b denotes a power converter of a second substation adjacent to the first substation, and 1c denotes a power converter of a third substation adjacent to the second substation. The sub-station power converter, 1d detects the power converter of the fourth sub-station adjacent to the third sub-station, and 2b detects the current flowing to the first sub-station side of the second sub-station. Current detector 2c is a current detector that detects a current flowing on the second substation side of the third substation, and 2d is a current detector that detects a current flowing on the third substation side of the fourth substation. Current detectors 3a, 3b, 3c, and 3d detect power converters 1a, 1
b, 1c and 1d.

The operation of the DC feeding system having such a configuration is first based on the output voltage of the power converter 1a of the first substation. The output DC voltage of the power converter 1b of the second substation is such that when there is no train between the first substation and the second substation and there is no power running current or regenerative current, the current of the current detector 2b is Adjust so that it is close to zero. Specifically, when current is flowing from the second substation to the first substation, the second
Is adjusted by the voltage control circuit 3b so as to reduce the DC voltage of the power converter 1b of the substation, and conversely, if a current flows from the first substation to the second substation, the second substation Voltage control circuit 3b so as to increase the DC voltage of power converter 1b
Adjust with. In this way, the voltages of the first substation and the second substation are made equal, and adjustment is made so that no current flows between the first substation and the second substation.

Next, the output DC voltage of the power converter 1c of the third substation is similarly adjusted with reference to the output DC voltage of the power converter 1b of the second substation. In this case, adjustment is made in the same manner as described above by the current of the current detector 2c. Further, the power converter 1d of the fourth substation performs adjustment with the current of the current detector 2d based on the power converter 1c of the third substation. As described above, the difference voltage between the substations is eliminated, and the cross current between the substations is adjusted so as to be close to zero in order.

In this example, the power converter 1a of the first substation
However, the reference need not be the terminal substation, and may be, for example, the power converter 1c of the third substation. In that case, the power converter 1 of the third substation
The second and fourth power converters 1b and 1d are adjusted with reference to the output DC voltage of c. In this case, the power converter 1b of the second substation is adjusted by the current flowing from the second substation to the third substation.

As described above, according to the DC feeding system and the operation method of the first embodiment, the cross current between the substations can be reduced, and the unnecessary increase in the capacity of the power converter can be prevented. Inexpensive power converters can be applied. Further, it is possible to prevent power loss due to the resistance of the electric wire at the time of cross current, and it is possible to improve the efficiency of the DC feeding system.

The second embodiment of the present invention employs a different operation method depending on the DC feeding system (FIG. 1) having the same configuration as the first embodiment. That is, in the present embodiment, first, the power converter 1a of the first substation is started to establish a DC voltage. The power converter 1b of the second substation is activated after the establishment of the DC voltage or after a lapse of time sufficient for the establishment of the DC voltage. After the DC voltage of the power converter 1b is established, the DC voltage of the power converter 1b is adjusted by the voltage control circuit 3b so that the detection current of the current detector 2b approaches zero. This adjustment is performed by increasing or decreasing the DC voltage of the power converter 1b according to the direction of the current, as in the first embodiment. Next, the power converter 1c of the third substation is activated, and the DC voltage of the power converter 1c is similarly adjusted by the current flowing between the third substation and the second substation. Starting and adjusting the fourth substation and the fifth substation in this order. In this operation method as well, the cross current between the substations can be adjusted to be close to zero.

The effect of the second embodiment is basically the same as that of the first embodiment. However, in the second embodiment, the power converters 1a, 1b, 1c,
Since 1d is sequentially activated, the influence on the power converters of other substations is small. That is, in the first embodiment, when the adjustment is performed between the first and second power converters 1a and 1b, the fluctuation of the DC voltage of the second power converter 1b is applied to the third power converter 1c. Although it may have an effect, in the second embodiment, adjustment is performed after the DC voltage is established, and thereafter,
Since the power converter at the subsequent stage is started, the power converter at the subsequent stage is less affected.

Next, a third embodiment of the present invention will be described. This embodiment employs a different operation method depending on the DC feeding system having the same configuration (FIG. 1) as the first and second embodiments. FIG. 2 is an explanatory diagram of the operation in the operation method according to this embodiment. In this embodiment, the current of the feeder is detected by a current detector 2b, and a predetermined value is set between a first level whose absolute value is close to zero and a second level larger than the first level. When the current is flowing, the DC voltage of the power converter 1b of the substation is raised when the current flows in the substation, and the DC voltage of the power converter 1b is lowered when the current flows out of the substation. . The same is applied to the third and subsequent substations to reduce the cross current.

That is, when a load is applied as shown in FIG. 2, there is a large fluctuation in the DC current, so that the DC voltage is not adjusted during that period. The DC voltage is adjusted only when the no-load period starts and the DC current continues to be at a certain level for a predetermined period. The effect of the third embodiment is basically the same as that of the first embodiment, but has an effect that adjustment between substations can be performed even during operation after startup.

Next, a fourth embodiment of the present invention will be described with reference to FIG. The same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. Reference numerals 4b, 4c, and 4d denote current detectors for detecting small cross currents, and 5b, 5c, and 5d.
Is a short-circuit device for short-circuiting the current detectors 4b, 4c, 4d. If the current detectors 2b, 2c and 2d are current detectors generally used in the feeding system, the current detector 4
b, 4c and 4d are current detectors for smaller currents. This is possible because the cross current to be detected by the DC feeding system according to the present embodiment is a small current near zero.

In this embodiment, the current detectors 2b, 2
Using the current signals of the current detectors 4b, 4c, and 4d together with c and 2d, the voltage is adjusted by the voltage control circuits 3b, 3c, and 3d.
After the adjustment is completed, the current detectors 4b, 4c, 4d are short-circuited by the short-circuit devices 5b, 5c, 5d. The current detectors 4b, 4c,
4d is selected so that a current smaller than the current detectors 2b, 2c and 2d can be detected, and can be adjusted to a current closer to zero. Thus, the cross current between the substations is reduced.

The effects of the fourth embodiment are basically the same as those of the first embodiment. However, in this embodiment, since the current detectors 5b, 5c, and 5d for small current are provided, the adjustment can be performed with high accuracy.

Next, FIG. 4 is a configuration diagram of a DC feeding system according to a fifth embodiment of the present invention. The same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. Reference numeral 6 denotes a connection line for connecting the substations, which is provided separately from the feeder line for supplying power to the train. The resistance value of the connection line 6 is selected to be higher than that of the feeder wire. Reference numerals 7b, 7c and 7d are current detectors for detecting a current flowing through the connection line 6. With such a configuration, the current flowing through the connection line 6 is detected by the current detectors 7b, 7c, 7d, and the power converters 1b,
The DC voltages 1c and 1d are adjusted. Thus, the cross current between the substations is reduced.

In the fifth embodiment, the current hardly flows because the resistance value of the connection line between the substations is large. Therefore, the current value is reduced, and the cross current between the substations can be adjusted accurately.

Next, a DC feeding system according to a sixth embodiment of the present invention and an operation method thereof will be described with reference to FIG. In FIG. 5, reference numeral 8a denotes a current detector for detecting a feeder current flowing from the first substation to the second substation.
The current of the current detector 2b and the current of the current detector 8a are compared, and when they are substantially equal, the DC voltage of the power converter 1b of the second substation is adjusted according to the current direction. When the current flows in the substation, the power converter 1 of the substation is used.
The DC voltage of the power converter 1b is decreased in the case where the DC voltage of the power converter 1b is flowing out of the substation. The same is applied to the third and subsequent substations to reduce the cross current.

In the sixth embodiment, the current detector 2
b and the current detector 8a are provided near the first and second substations, respectively. When there is a train in the feeder section, power is received from the first and second substations. However, the length of the feeder line from the substation to the train, that is, the resistance changes depending on the position of the train, so the supply balance Changes. This change in balance is detected by comparing the current detectors 2b and 8a,
If there is a difference, it is determined that there is a train in the feeder section and no adjustment is performed.

[0035]

According to the present invention, the cross current between the substations can be reduced, the unnecessary increase of the capacity of the power converter can be prevented, and the power converter having the minimum necessary capacity can be applied. . Further, it is possible to prevent power loss due to the resistance of the electric wire at the time of cross current, and it is possible to improve the efficiency of the DC feeding system.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of a DC feeding system according to first, second, and third embodiments of the present invention.

FIG. 2 is a view for explaining an operation method of a DC feeding system according to a third embodiment of the present invention.

FIG. 3 is a circuit diagram showing a configuration of a DC feeding system according to a fourth embodiment of the present invention.

FIG. 4 is a circuit diagram showing a configuration of a DC feeding system according to a fifth embodiment of the present invention.

FIG. 5 is a circuit diagram showing a configuration of a DC feeding system according to a sixth embodiment of the present invention.

FIG. 6 is a circuit diagram showing a configuration of a conventional DC feeding system.

[Explanation of symbols]

1a: power converter of the first substation, 1b: power converter of the second substation, 1c: power converter of the third substation, 1d
... power converter of the fourth substation, 2b ... current detector of the second substation, 2c ... current detector of the third substation, 2d ... current detector of the fourth substation, 3a, 3b , 3c, 3d: voltage control circuit, 4b, 4c, 4d: current detector, 5b, 5
c, 5d: short circuit, 6: connection line, 7b, 7c, 7d: current detector, 8a, 8b, 8c: current detector, 20: commercial AC system, 21, 31: transformer for converter, 22, 32 ... Self-excited converter, 23,33 ... DC capacitor, 24,34 ... DC reactor, 25,26,35,36 ... DC circuit breaker, 40 ... Feed line.

Continuation of the front page (72) Inventor Kenji Ito 1-1-1, Shibaura, Minato-ku, Tokyo F-term in the head office of Toshiba Corporation (reference) 5G065 CA01 DA06 GA03 HA01 JA01 LA02 5H006 BB05 CA01 CC04 DA04 DC02 DC02

Claims (8)

[Claims] 1. A substation connected in parallel to a feeder of a DC electric railway, wherein the substation comprises a power converter for converting AC to DC, and an output current of the substation flowing through the feeder. In a method for operating a DC feeding system, comprising: a current detector that detects a current and a voltage controller that controls an output voltage of the power converter based on a detected current value of the current detector. In the no-load state where there is no train in the feeder section as a reference, the current flowing from the substation adjacent to the reference substation to the reference substation is set to zero or a value close to zero so that the current flowing to the reference substation becomes zero. Adjusting the output voltage of the substation to further adjust the output voltage of the substation next to the adjacent substation with reference to the adjacent substation,
A method for operating a DC feeding system, comprising sequentially adjusting an output voltage. 2. Start up based on a predetermined substation,
Next, start the substation adjacent to the reference substation, and adjust the output voltage of the adjacent substation so that the cross current flowing to the reference substation after starting is zero or a value close to zero. And further starting the substation next to the adjacent substation, adjusting the output voltage based on the adjacent substation, and sequentially starting the substations to adjust the output voltage. The operation method of the DC feeding system according to claim 1. 3. An output current of a substation having a first current near zero.
And a second level larger than the first level are provided, and the output voltage of the substation is adjusted when the output current stays for a predetermined time between the first level and the second level. The method for operating a DC feeding system according to claim 1, wherein: 4. A substation connected in parallel to a feeder of a DC electric railway, wherein the substation comprises a power converter for converting AC to DC, and an output current of the substation flowing through the feeder. And a voltage controller that controls the output voltage of the power converter based on the detected current value of the current detector. A direct current feeding system comprising: a small current detector that detects a cross current with a substation and outputs a signal related to the cross current to a voltage controller; and a short-circuit device that short-circuits the small current detector. 5. A small current detector provided on a feeder line for detecting a cross current with an adjacent substation and outputting a signal related to the cross current to a voltage controller, and a short-circuit device for short-circuiting the small current detector. 2. The operation of the DC feeding system according to claim 1, wherein the output voltage of the substation is adjusted based on the detected current value of the small current detector, and then the small current detector is short-circuited by the short-circuit device. Method. 6. A substation connected in parallel to a feeder of a DC electric railway, wherein the substation includes a power converter for converting AC to DC, and an output current of the substation flowing through the feeder. And a voltage controller for controlling the output voltage of the power converter based on the detected current value of the current detector, wherein the DC output terminal of each of the substations And a current detector that detects a current flowing through the connection line and outputs a signal related to the current to a voltage controller. 7. A connection line for connecting DC output terminals of each substation in parallel, and a current detector for detecting a current flowing through the connection line and outputting a signal related to the current to a voltage controller, The method according to claim 1, wherein the output voltage of the substation is adjusted so that the current flowing through the connection line becomes zero or a value close to zero. 8. An output current of the substation is compared with an output current of a substation adjacent to the substation and an output current of the substation is set such that when the currents are substantially equal, the output current becomes zero or close to zero. The method for operating a DC feeding system according to claim 1, wherein the voltage is adjusted.