JP2010264924A - Power extending device and its method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power extending device which can easily receive extended feed power from a power substation between adjacent power supply zones without the need for newly developing a facility for obtaining drive power corresponding ot AC power different in frequency, and its method. <P>SOLUTION: The power extending device is arranged between a first power substation supplying the AC power of a first frequency of the power extending device to an overhead wire of a first feeder and a second power substation supplying the AC power of a second frequency different from the first frequency to an overhead wire of a second feeder, and includes a frequency converter arranged between the overhead wires of the first feeder and second feeder, converting the frequency of AC power from either the first frequency and second frequency to the other, and performing extended feed from either the first feeder and the second feeder to the other. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention provides a power source for use in extending a power source from one substation to the other when one power substation fails at a matching location of different frequencies at a feeding section in an AC powered railway. The present invention relates to an extension device and a method thereof.

In an AC powered electric railway, a plurality of substations that supply electric power for traveling to a vehicle are provided.
As shown in FIG. 6, a feeding section is provided at the boundary of feeding of each substation to separate feeding sections. In the case of the AC feeding system, a switching section is provided in the feeding section (SP) so that alternating currents with different phases between adjacent substations are not short-circuited, and the overhead wire is insulated and separated in this switching section. (For example, refer to Patent Document 1).

This feeding section may be divided into feeding sections as places where AC power sources having different frequencies of 60 Hz and 50 Hz are abutted as in the case of a maintenance Shinkansen.
Here, when a 50 Hz power supply substation that outputs a 50 Hz AC power supply fails, as shown in FIG. 7, the 60 H AC power supply in the feeding section adjacent to the feeding section of the 50 Hz power supply substation is replaced with this failure. The power supply for driving the vehicle is secured by extending the power supply to the power supply section of the 50 Hz power substation (connecting adjacent power supply sections).

JP 2007-189863 A

However, in the case of performing the above-described extension feeding, the equipment for obtaining the driving power corresponding to the AC power sources having different frequencies of 50 Hz and 60 Hz in response to the abnormality such as the failure of the power supply substation, And it is necessary to provide for signal equipment.
Since the equipment corresponding to both 50 Hz and 60 Hz has no track record, a new equipment for obtaining driving power corresponding to the power sources of both frequencies must be developed.

  The present invention has been made in view of such circumstances, and it is not necessary to newly develop equipment for obtaining driving power corresponding to AC power sources having different frequencies. It is an object of the present invention to provide a power supply extension device and method for receiving power extension from a substation.

  A power supply extension device according to the present invention includes a first power substation that supplies an AC power source having a first frequency to an overhead line in a first feeding section, and an AC power source having a second frequency different from the first frequency. A power supply extension device provided between the second power supply substation that supplies the overhead line of the second feeder section, and between the overhead lines of the first feeder section and the second feeder section. Provided, converting the frequency of the AC power source from one of the first frequency and the second frequency to the other and extending from one of the first feeding section and the second feeding section to the other And a frequency converter that performs power feeding.

  In the power supply extension device of the present invention, the first feeding section and the second feeding section are provided alternately, and the power substations in the adjacent first feeding section and second feeding section are provided. When a fault occurs, power is extended in parallel from the frequency converters inserted respectively from both power feeding sections adjacent to the power feeding section of the power substation.

  The power supply extension device of the present invention further includes a vehicle detection unit that detects intrusion of a vehicle from one of the first feeding section and the second feeding section to the other and outputs a train detection signal. If any one of the power substations in one feeding section or the second feeding section fails and the extension feeding is performed from the other feeding section to the other feeding section, the train detection When a signal is input, the frequency converter reduces the voltage value of the AC power supply that is output to the subject of the extended power supply.

  The power supply extension device of the present invention further includes a vehicle detection unit that detects intrusion of a vehicle from one of the first feeding section and the second feeding section to the other and outputs a train detection signal. If any one of the power substations in one feeding section or the second feeding section fails and the extension feeding is performed from the other feeding section to the other feeding section, the train detection When a signal is input and the frequency value output from the frequency converter exceeds the set threshold value, the current value of the AC power source is set to a preset current value for a certain period. It is characterized by performing control to reduce.

  The power supply extension apparatus of the present invention is characterized in that the frequency converter has a function of performing reactive power compensation in an adjacent feeding section.

  The power supply extension method of the present invention includes a first power supply substation that supplies an AC power supply having a first frequency to an overhead line of a first feeding section, and an AC power supply having a second frequency different from the first frequency. A power supply extension method using a power supply extension device provided between the second power supply section and a second power supply substation to be supplied to the overhead line of the second power supply section, wherein the first power supply section and the second power supply section The frequency converter provided between the overhead lines converts the frequency of the AC power source from one of the first frequency and the second frequency to the other, and the first feeding section and the second feeding section It has a frequency conversion process of extending power from either one to the other.

  As described above, according to the present invention, in the case where extension power is supplied from one to the other between feeding sections having different AC frequencies, the AC frequency in the feeding section in which extension feeding is performed is extended. By converting the frequency converter to the side to be electrified, it is possible to install the equipment fixed to the AC frequency of the AC power source provided in each feeding section without providing equipment corresponding to two different frequencies in each feeding section. Thus, the feeding extension can be easily performed between feeding sections having different AC frequencies.

  Further, according to the present invention, when a power substation in a certain power supply section fails, the power supply substations on both sides adjacent to the power supply section of the failed power substation are respectively subjected to extended power, that is, adjacent power supplies. In order to receive the extension power in parallel from the power section, even if the frequency converter between one power section and the power converter cannot supply power, the power from the other power section It is possible to prevent the supply from being stopped and the vehicle from stopping.

  In addition, according to the present invention, when extended feeding is performed, intrusion of the vehicle from the feeding section on the side where the extension feeding is performed to the feeding section on the side that receives the extension feeding is detected. In order to reduce the voltage value of the AC voltage to be extended until the entire vehicle is invaded into the feeding section on the side that has been fully extended, the excitation inrush current can be reduced. It is possible to suppress the state where the frequency conversion unit stops due to the current.

It is a conceptual diagram which shows the structural example of the feeder circuit using the power supply extension apparatus by the 1st Embodiment of this invention. It is a block diagram which shows the structural example of the power supply extension apparatus by one Embodiment of this invention in FIG. It is a flowchart which shows the operation example of the power supply extension apparatus by one Embodiment of this invention. It is a conceptual diagram which shows the position of the overhead line 5, the overhead line 6, and the middle section 4 of a train corresponding to the flowchart of FIG. It is a conceptual diagram which shows the structural example of the feeder circuit using the power supply extension apparatus by the 2nd Embodiment of this invention. It is a conceptual diagram which shows the structural example of the conventional feeder circuit. It is a conceptual diagram explaining the extension feeding in the conventional feeding circuit.

<First Embodiment>
Hereinafter, a power extension device according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration example of an AC feeder circuit using the power extension device according to the embodiment.
In this figure, the power supply extension device 1 is connected between an overhead line 5 and an overhead line 6. The overhead line 5 is supplied with electric power for driving the train 9 from a power substation (for example, a substation facility) 110. The overhead line 6 is supplied with electric power for driving the train 9 from the power substation 111. In the present embodiment, the power substation 110 is a 60 Hz AC power source, and the power substation 111 is a 50 Hz AC power source.
The switching section includes a middle section 4, a switching switch 2, and a switching switch 3. When the train does not exist in the middle section 4, the switching switch 2 disposed on the front side in the middle section 4 with respect to the traveling direction with respect to the traveling direction of the train 9 by the vehicle detection unit 12 described later. In the middle section 4, the switching switch 3 arranged next to the switching switch 2 in the middle section 4 is opened.

The power supply extension device 1 converts the frequency of the AC power supply of the power supply substation 110 from 60 Hz to 50 Hz when the power supply substation 110 breaks down, extends power from the overhead line 5 to the overhead line 6, and When the station 111 breaks down, the frequency of the AC power source of the power substation 111 is converted from 50 Hz to 60 Hz, and extension power is controlled from the overhead line 6 to the overhead line 5. That is, when one of the power supplies of the power supply substation 110 and the power supply substation 111 fails, the power supply extension device 1 controls extension power supply from the other power supply that has not failed.
Between the overhead line 5 and the overhead line 6, a middle section 4 is provided as a switching section for different power sources of the power source substation 110 and the power source substation 111. The middle section 4 is separated from the overhead line 5 by providing an air section 100 between the overhead line 5 and separated from the overhead line 6 by providing an air section 101 between the overhead line 6.
The train 9 receives driving power between the overhead line 5, the overhead line 6, or the middle section 4 and the rail 7, and travels by rotating the motor.

The switching switch 2 is a switch that performs switching of connection and separation between the overhead wire 5 and the middle section 4, and the overhead wire 5 and the middle section 4 are connected in the turned-on state (on state), and the opened state (off state). The overhead line 5 and the middle section 4 are separated at.
The switching switch 3 is a switch that performs switching of connection and separation between the overhead wire 6 and the middle section 4. The overhead wire 6 and the middle section 4 are connected in the closing state, and the overhead wire 6 and the middle section 4 are opened in the opened state. Are separated.
The train position detection track circuit 8 is arranged in the middle section 4 at a position close to the overhead line 6 with respect to the overhead line 5, detects the train by a detection unit provided with a preset length, and train 9 Detects that the vehicle has completely entered the middle section 4, that is, continuously outputs a train detection signal while a train is present on its own detection unit.
In the present embodiment, a description will be given below in a state in which the train travels from one direction to the other direction (arrow direction in FIG. 4 described later) and enters the switching section.

Next, the configuration of the power extension device 1 of FIG. 1 will be described with reference to FIG. FIG. 2A is a block diagram illustrating a configuration example of the power extension device 1 of FIG.
The power extension device 1 includes a control unit 11, a vehicle detection unit 12, a voltage conversion unit 13, a frequency conversion unit 14, and a reactive power compensation unit 15.
When the control unit 11 receives notification of a failure of the power substation 110 or the power substation 111 from a control center (not shown), an extension control signal for performing an extension feeding process on the frequency conversion unit 4 and the voltage conversion unit 14. Is output.

The frequency conversion unit 14 is activated when the extension control signal is input, and performs an extension feeding process on the overhead line connected to the faulty power source from the overhead line connected to the faulty power source. On the other hand, when the extension control signal is not input, the operation is stopped.
This frequency conversion unit 14 is supplied with an AC voltage of an overhead line supplied with power from a non-failed power source as an extension power process, and is supplied from a normal power source of the overhead line to which the failed power source is connected. The power is converted into an AC frequency of the AC voltage, and the power is supplied to the faulty power source or the connected overhead line.
The reactive power compensator 15 stops when the extension control signal is input. On the other hand, when the extension control signal is not input, the reactive power compensation unit 15 generates reactive power between the overhead lines 5 and 6 due to voltage imbalance, voltage fluctuation, and the like. The operation state is the voltage control mode in which reactive power compensation is performed.

The vehicle detection unit 12 controls each of the switching switch 2 and the switching switch 3 to be in an on state or an open state by a train detection signal input from the train position detection track circuit 8.
In a state where the voltage conversion unit 13 performs extension feeding, that is, when the extension control signal is input, when the train detection signal is input, the voltage conversion unit 13 supplies the power supplied by the extension feeding of the frequency conversion unit 14. The frequency converter 14 is controlled so that the voltage value is supplied by being lowered compared to the voltage normally supplied by extension feeding.

  Next, the operation of the power extension device according to this embodiment will be described with reference to FIGS. 1, 2A, 3 and 4. FIG. FIG. 3 is a flowchart showing an operation example of the power extension device according to the present embodiment. FIG. 4 is a conceptual diagram showing the positions of the overhead line 5, the overhead line 6 and the middle section 4 of the train corresponding to the flowchart of FIG. In the following description, a case will be described in which the power supply substation 111 that supplies an AC voltage with an AC frequency of 50 Hz to the overhead line 6 fails and power is extended from the overhead line 5 to which the power supply substation 110 is connected.

In the case of normal power supply in which both the power substation 110 and the power substation 111 are operating normally, the internal reactive power compensator 15 operates in the voltage control mode in the power extension device 1, and the frequency converter 14 stops operating (step S1).
The train travels in the direction of the arrow in FIG. 4 (from the right to the left in the figure), but when the train has not entered the middle section 4 in the switching section, the vehicle detection unit 12 turns on the switching switch 2. The switching switch 3 is in an open state.
Further, the vehicle detection unit 12 keeps the switching switch 2 in the on state even when the train travels in the direction of the arrow and the train enters the intermediate section 4 from the overhead line 5 as shown in FIG. The switching switch 3 is kept open.

And as shown in FIG.4 (b), the electric vehicle position detection track circuit 8 will detect the approach of a train, if a train approachs on a detection part, and will output a train detection signal. When this train detection signal is input, the vehicle detection unit 12 brings the switching switch 2 into an open state and maintains the switching switch 3 in an open state.
Next, as shown in FIG.4 (c), the vehicle detection part 12 passed the preset switching no-voltage time (time determined by driving | running the distance which the train set by fixed speed). When this is detected, the switching switch 3 is turned on.
And as shown in FIG.4 (d), the electric vehicle position detection track circuit 8 will detect the advance with respect to the overhead line 6 of a train, and will stop the output of a train detection signal, when a train no longer exists on a detection part. .
When the train detection signal is not input, the vehicle detection unit 12 puts the switching switch 3 into an open state, and then puts the switching switch 2 into an on state. The above is a state in which normal feeding is performed in step S <b> 1 in which the overhead line 5 is supplied with power from the power supply substation 110 and the overhead line 6 is supplied with power from the power supply substation 111.

  Next, the control unit 1 determines whether or not a notification indicating a failure of the power substation 111 (or the power substation 110) has been input from the control center (step S2). If there is no notification, the process proceeds to step S1. On the other hand, if a notification is input, the process proceeds to step S3.

When a notification indicating a failure of the power substation 111 is input, the control unit 1 outputs an extension control signal to the frequency conversion unit 14, the reactive power compensation unit 15, and the voltage conversion unit 13.
As a result, the reactive power compensator 15 shifts from the operating state of the voltage control mode to the non-operating state. Then, the frequency conversion unit 14 converts the AC voltage of the overhead line 5 having a frequency of 60 Hz into an AC voltage having a frequency of 50 Hz, and shifts to the extension feeding mode to be supplied to the overhead line 6 (step S3). Thereby, the overhead line 6 is in a state where power is supplied from the power source substation 110 in the same manner as the extension power from the overhead line 4, that is, the overhead line 5.

Here, as shown in FIG. 4A, when the train 9 enters the middle section 4 from the overhead line 5, the vehicle detection unit 12 maintains the input state of the switching switch 2, and the switching switch 3 Maintain the release state.
At this time, the train 9 is in a state of receiving power supply from the power substation 110 via the middle section 4 and the overhead line 5.
In this state, the vehicle detection unit 12 detects whether or not the train detection signal is input from the electric vehicle position detection track circuit 8, that is, whether or not the train 9 exists on the detection unit of the electric vehicle position detection track circuit 8. When the train detection signal is input, the process proceeds to step S5. When the train detection signal is not input, the train 9 moves over the detection unit of the electric vehicle position detection track circuit 8. Assuming that the vehicle is not running, the process of step S4 is repeated.

Next, as shown in FIG. 4B, when the train 9 travels on the detection unit of the electric vehicle position detection track circuit 8, the electric vehicle position detection track circuit 8 has the train on the detection unit. Is detected and a train detection signal is output.
At this time, when a train detection signal is input, the vehicle detection unit 12 brings the switching switch 2 into an open state while maintaining the open state of the switching flattening unit 3. As a result, the middle section 4 is disconnected from the overhead line 5, and the train 9 is in a power failure state and continues running due to inertia.
The voltage conversion unit 13 receives the extension control signal, and when the train detection signal is input, the voltage value of the AC voltage output from the frequency conversion unit 14 is changed to the voltage value in the case of normal extension feeding. Control for lowering is performed (step S5).
At this time, the vehicle detection unit 12 starts counting time with an internal counter after opening the switching switch 2.

  Next, the frequency conversion section 14 turns on the switching switch 3 corresponding to whether or not the internally counted time exceeds the switching no-voltage time, that is, the overhead wire 6 on the side of the extended power supply. In step S6, when the time exceeds the switching no-voltage time, a count-up signal is output to the vehicle detection unit 12 and the voltage conversion unit 13, and the process is processed to step S7. On the other hand, if the time does not exceed the switching no-voltage time, the process of step S6 is repeated.

When the count-up signal is input from the frequency conversion unit 14, the vehicle detection unit 12 turns on the switching switch 3 while keeping the switching switch 2 open as shown in FIG. And
After the switching switch 3 is turned on, the voltage conversion unit 13 performs control to return the voltage value of the AC voltage output from the frequency conversion unit 14 to the voltage value in the case of normal extension feeding (step S7). ).
And as shown in FIG.4 (d), when the train 9 no longer exists on a detection part, ie, the train 9 advances from the middle section 4 to the overhead line 6, as shown in FIG.4 (d), train detection Stop signal output.
When the train detection signal is not input, the vehicle detection unit 12 sets the switching switch 2 to the on state after opening the switching switch 3.

Next, the control unit 11 detects the presence / absence of a notification indicating that the power substation 111 has recovered from the control center, that is, determines whether or not to shift from an extended feed to a normal feed (step S8). If the notification is not detected, the process returns to step S4 in order to continue the extended feeding.
On the other hand, when the notification is detected, the control unit 11 shifts to a process for returning to normal feeding and returns the process to step S1.

In the process of returning to normal feeding, the control unit 11 stops outputting the extension control signal that is output to perform the extension feeding process.
When the extension control signal is not input, the frequency conversion unit 14 converts the AC voltage of the overhead line 5 into the AC frequency of the power supply substation 111 connected to the overhead line 6, and the extension performed from the overhead line 5 to the overhead line 6. Stops feeding operation.
On the other hand, when the extension control signal is not input, the reactive power compensator 15 shifts to the operation state of the voltage control mode.

Further, in the configuration described above, the train 9 exists in the middle section 4, and the overhead line that supplies the AC voltage to the middle section 4 by opening and closing the switching switch is from the overhead line that supplies the power of the extended power supply. In order to prevent a large magnetizing inrush current from flowing when shifting to the side receiving the extended feeding power, the overhead wire receiving the extended feeding power and the middle section 4 are switched open and closed. When the voltage converter 13 is connected, the voltage value of the AC voltage output from the frequency converter 14 is lowered as compared with a case where normal extension feeding is performed.
As another configuration, instead of the voltage conversion unit 13 in FIG. 2A, as shown in FIG. 2B, when the extension power is supplied, the current value to the extension power supply destination is changed. A current converter 23 to be adjusted may be provided. FIG. 2B is a block diagram showing another configuration example of the power extension device 1 of FIG. Then, in the operation of step S5 in the flowchart of FIG. 3, a large excitation inrush current flows through the current value of the AC voltage output from the frequency conversion unit 14 by the current conversion unit 23 instead of reducing the voltage value of the AC voltage. In order to suppress this, control may be performed so as to decrease compared to the case of performing normal extension feeding.
In this case, after the train detection signal is input, the current conversion unit 23 measures the current value that the frequency conversion unit 14 supplies to the power supply destination of the extended power, and sets a preset threshold value (current value). It is determined whether or not the upper limit is exceeded. When the current value supplied to the supply destination exceeds the threshold value, the current conversion unit 23 sets the current value to the supply destination to a preset current value as compared with a case where normal extension feeding is performed. On the other hand, if the current value supplied to the supply destination is less than or equal to the threshold value, the current value for normal extension feeding is supplied as it is. Here, the set current value is set as the lowest current value at which the train 9 can be operated. Further, the period during which the current value is reduced to the set current value is set to a time during which the excitation inrush current obtained by experiment does not flow.

  Further, in the above-described embodiment, since the power substation 111 has failed, it has been described that power is extended from the overhead line 5 to which the power substation 110 is connected to the overhead line 6. If a failure occurs, power can be extended from the overhead line 6 to which the power substation 111 is connected to the overhead line 5. That is, the frequency conversion unit 14 converts an AC voltage with an AC frequency of 60 Hz into an AC voltage with an AC frequency of 50 Hz, or conversely converts an AC voltage with an AC frequency of 50 Hz into an AC voltage with an AC frequency of 60 Hz. It is also configured so that it can be done in both directions.

<Second Embodiment>
FIG. 5 is a conceptual diagram showing a configuration example of a feeder circuit using the power supply extension device according to the second embodiment of the present invention. The same code | symbol is attached | subjected with respect to the structure similar to 1st Embodiment.
Similarly to the first embodiment, the power substation 110 supplies an AC voltage with an AC frequency of 60 Hz to the overhead line 5, and the power source substation 111 supplies an AC voltage with an AC frequency of 50 Hz to the overhead line 6. In the second embodiment, the power substation 112 supplies an AC voltage with an AC frequency of 60 Hz to the overhead line 7.
Here, a switching section A exists between the overhead line 5 to which the power supply substation 110 is connected and the overhead line 6 to which the power supply substation 111 is connected. The same processing as in the first embodiment is performed.
Further, a switching section B exists between the overhead line 6 to which the power supply substation 111 is connected and the overhead line 7 to which the power supply substation 112 is connected. The same processing as in the first embodiment is performed. The case where the power supply substations which supply the alternating current power supplies of different alternating frequency are alternately and continuously arranged corresponds to this embodiment.

That is, the notification that the power substation 111 has failed is notified to both the power extension device 1 in the switching section A and the power extension device 1 in the switching section B from the control device in the control center.
As a result, since the overhead line that performs the extension power supply to the overhead line 6 becomes the two overhead lines 5 and 7 adjacent to the overhead line 6, it is possible to supply the extension power to the overhead line 6 in parallel. The amount of power to be supplied can be increased.
As a result, the power supply is stopped by the gate block due to the inrush current of the train, that is, the output voltage of the frequency conversion unit 14 is lower than the allowable voltage due to the inrush current, thereby protecting the AC voltage supply from being stopped. Therefore, it is possible to maintain the electric circuit with high reliability.

Also in the case of the second embodiment, similarly to the first embodiment, control of the voltage to the power supply destination in the extension power supply using the voltage conversion unit 13 in FIG. Any one of the control of the current value for the power supply destination in is performed individually by the power supply extension device 1 of each of the switching section A and the switching section B.
Here, the synchronization acquisition device arranged in any one of the management center, the switching section, and the like has the power supply extension device 1 that extends power in parallel to a certain overhead line, for example, the switching section A and the switching section B. Synchronous control between the power extension devices 1 is performed. That is, the voltage value and the phase of each of the switching section A and the switching section B are detected, and the phase is set to the phase of the AC waveform output from one of the frequency converters 14 within the phase range set in advance. The control is performed so that the phases of the AC waveforms are matched and synchronized. When the synchronization acquisition device detects that the phases are synchronized, the voltage conversion unit 13 controls the voltage so that both voltage values are the same, or the voltage conversion unit 23 controls the voltage value. The voltage value is controlled by controlling the current. Thereby, both phase and voltage value can be made the same, and the circulating current between the power supply extension apparatuses 1 which are carrying out the extension feeding in parallel with respect to a certain overhead wire can be suppressed.

DESCRIPTION OF SYMBOLS 1 ... Power supply extension device 2, 3 ... Switching switch 4 ... Middle section 5, 6 ... Overhead wire 7 ... Rail 8 ... Train position detection track circuit 9 ... Train 11 ... Control part 12 ... Vehicle detection part 13 ... Voltage conversion part 14 ... Frequency converter 15 ... Reactive power compensator 100, 101 ... Air section 110, 111, 112 ... Power substation

Claims (6)

A first power substation that supplies an AC power source having a first frequency to an overhead line in a first feeding section, and an AC power source having a second frequency that is different from the first frequency is an overhead line in a second feeding section. A power supply extension device provided between the second power supply substation supplied to
It is provided between the overhead lines of the first feeding section and the second feeding section, and converts the frequency of the AC power source from one of the first frequency and the second frequency to the other. A power supply extension device, comprising: a frequency conversion unit that extends power from one of the feeding section and the second feeding section to the other. The first feeding section and the second feeding section are provided alternately,
When the power substations in the first feeding section and the second feeding section that are adjacent to each other fail, they are inserted respectively from both feeding sections on both sides adjacent to the feeding section that has failed in the power substation. The power extension device according to claim 1, wherein power is extended in parallel from the frequency conversion unit. A vehicle detection unit that detects a vehicle intrusion from one of the first feeding section and the second feeding section to the other and outputs a train detection signal;
When one of the power supply substations of the first feeding section and the second feeding section fails and the extension feeding is performed from the other feeding section to the other feeding section,
3. The power extension according to claim 1, wherein when the train detection signal is input, the frequency converter reduces a voltage value of an AC power supply that is output to an extension power target. 4. apparatus. A vehicle detection unit that detects a vehicle intrusion from one of the first feeding section and the second feeding section to the other and outputs a train detection signal;
When one of the power supply substations of the first feeding section and the second feeding section fails and the extension feeding is performed from the other feeding section to the other feeding section,
When the train detection signal is input and the frequency conversion unit exceeds the set threshold value for the current value to be output to the extension power supply target, the current value of the AC power source is preset for a certain period of time. The power supply extension device according to claim 1, wherein control for reducing the current value is performed.   The power supply extension device according to any one of claims 1 to 4, wherein the frequency conversion unit has a function of performing reactive power compensation in an adjacent feeding section. A first power substation that supplies an AC power source having a first frequency to an overhead line in a first feeding section, and an AC power source having a second frequency that is different from the first frequency is an overhead line in a second feeding section. A power extension method using a power extension device provided between the second power substation supplied to
A frequency converter provided between the overhead lines of the first feeding section and the second feeding section converts the frequency of the AC power source from one of the first frequency and the second frequency to the other. A power supply extension method comprising: a frequency conversion process of extending power from one of the first feeding section and the second feeding section to the other.

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