Field
[0001] The present invention relates to a station-building power supply device that supplies power to electrical facilities (hereinafter, "station load") such as an air-conditioning system, a lighting system, and an elevator in a station yard using both AC power supplied from an AC system and the surplus regenerative power of trains.
Background
[0002] In recent years, regenerative power generated by regenerative brakes of trains is used as running power for other trains via a feeder in a DC feeding network. In such a DC feeding network, a feeding voltage increases when the regeneracrve power excsecis cue running power in me same transformation zone, and the feeding voltage decreases when the regenerative power falls below the running power. For examole a conventional technique has been disclosed in which the surplus regenerative power occurring when regenerative power exceeds running power is transformed into AC power to be supplied to a station load via an AC system, the power that exceeds the consumption power for the station load is stored in a secondary battery, and the secondary battery is discharged when a feeding voltage is decreased to supply DC power to a feeder, thereby stabilizing the feeding voltage and also effectively using the surplus regenerative power to an extent that prevents a reverse power from flowing to the AC system (for example, Patent Literature 1).

Patent Literature
[0003] Patent Literature 1: Japanese Patent No. 4432675
Summary
Technical Problem
[0004] However, in the conventional technique listed above, power is regenerated to send to the AC system connected to the station load when surplus regenerative power occurs. Therefore, there is a problem in that a power amount of the AC system fluctuates intermittently and is destabilized.
[0005] The present invention has been achieved in view of the above problem, and an objective of the present invention is to provide a station-building power supply device that can effectively use surplus regenerative power while suppressing fluctuations in the power amount of an AC system that supplies AC power to a station load.
Solution to Problem
[0006] In order to solve the problem and achieve the QK-iGQ^yo the ^resent invention relates to a station-building power supply device that supplies power to a station load using both AC power supplied from an AC system and surplus regenerative power generated by trains. The station-building power supply device includes a feeding-voltage detection unit that detects a feeding voltage; a capacitor unit that stores therein the surplus regenerative power; an SOC (State Of Charge) detection unit that detects an SOC of the capacitor unit; a first power conversion unit that performs DC/DC power conversion in both directions between a feeder and the capacitor unit; a second power conversion unit that converts DC power supplied from the capacitor unit to AC power and supplies the AC power to the

station load; and a control unit that controls the first power conversion unit and the second power conversion unit on the basis of the feeding voltage and the SOC. The control unit controls the first power conversion unit such that power is supplied from the feeder to the capacitor unit when the feeding voltage exceeds a predetermined first voltage threshold, and controls the second power conversion unit such that power is supplied from the capacitor unit to the station load when the SOC exceeds a predetermined first SOC threshold.
Advantageous Effects of Invention
[0007] According to the present invention, surplus regenerative power can be effectively used while suppressing fluctuations in the power amount of an AC system that supplies AC power to a station load.
Brief Description of Drawings
[0008J FIG. 1 is a diagram illustrating an example configuration of a station-building power supply device according to an embodiment.
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charts of the station-building power supply device according to the embodiment.
FIGS. 3 are diagrams illustrating an example of time charts of a conventional station-building power supply device not including a capacitor unit that stores therein surplus regenerative power.
Description of Embodiments
[0009] Exemplary embodiments of a station-building power supply device according to the present invention will be explained below in detail with reference to the accompanying drawings. The present invention is not

limited to the embodiments. [0 010] Embodiment
FIG. 1 is a diagram illustrating an example configuration of a station-building power supply device according to an embodiment of the present invention. In a station building 2, a transformer 3 that transforms high-voltage AC power supplied from an AC system 1 {an AC6600 V system in this example) into low-voltage AC power (an AC210 V system in this example) is provided in a station electrical room (not illustrated) or the like, and power is supplied to electrical facilities 4-1, 4-2, • ■ ■ and 4~n (hereinafter, "station loads 4") such as an air-conditioning system, a lighting system, and an elevator in the station yard. A station-building power supply device 100 according to the present embodiment is configured to transform surplus regenerative power that has not been consumed in an electrical transformation zone in which trains 5 run into low-voltage AC power and to supply the AC power to the station loaas 4. Tnat is, tne sracron roacis v'j.tiv-0 ijt_i_>-jiiv_j_ \ j,iiuxu-U u\->a y~J y L-* O ^ _i_ .■_>-< ±J.IIU ^ a. j. JL \_> « e- \ \-A J J
than that in a case where discharging to the capacitor unit 9 is not performed (indicated by a dashed line in FIG. 2(a) ) .
[0033] When the SOC of the capacitor unit 9 falls below the second SOC threshold at the time tlO (FIG. 2(c)), the control unit 13 stops the operation of the first power conversion unit 11 to turn OFF the discharging from the capacitor unit 9 to the feeder 6.
[0034] In the period from the time tlO to a time til, while the feeding voltage is below the first voltage threshold (FIG. 2(a)), discharging from the capacitor unit 9 to the feeder 6 is not performed because the SOC of the

capacitor unit 9 is below the second SOC threshold (FIG. 2(C)). That is, in the period from the time tlO to a time tl2r only the discharging from the capacitor unit 9 to the station loads 4 is performed similar to in the period from the time t4 to the time t7 and thus the SOC of the capacitor unit 9 gradually decreases {FIG. 2(c)). [0035] When the feeding voltage exceeds the first voltage threshold at the time tl2 (FIG. 2(a)), the control unit 13 operates the first power conversion unit 11 to turn ON charging from the feeder 6 to the capacitor unit 9. [0036] After the time t!2f charging from the feeder 6 to the capacitor unit 9 is performed similar to in the period from the time t3 to the time t4, so that the SOC of the capacitor unit 9 increases (FIG. 2(c)) and the feeding voltage becomes lower (indicated by a solid line in FIG. 2(a)) than that in a case where the charging to the capacitor unit 9 is not performed (indicated by a dashed line in FIG. 2(a)).
[0037] In this way, in the example illustrated in FIGS. 2, surplus regenerative power, which has been charge in the capacitor unit 9 in a period in which the feeding voltage
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station loads 4 at a substantially constant power amount, except for a period in which the SOC of the capacitor unit 9 is below the first SOC threshold.
[0038] A conventional configuration not including a capacitor unit that stores therein surplus regenerative power is described next. FIGS. 3 are diagrams illustrating an example of time charts of a conventional station-building power supply device not including a capacitor unit that stores therein surplus regenerative power. FIG. 3(a) illustrates transition of a feeding voltage and FIG. 3(b) illustrates power consumption of station loads. [0039] In the conventional configuration illustrated in

FIGS. 3, only when the feeding voltage exceeds a voltage threshold, that is, only when surplus regenerative power occurs, the power from a feeder is supplied to the station loads and thus the amount of power supplied from an AC system fluctuates intermittently. Accordingly, even when the power supplied from the feeder is equal to or below the power consumption amount of the station loads, the total power amount of the AC system fluctuates intermittently, which may cause fluctuations in the AC system voltage.
[0040] In the configuration according to the present embodiment, the surplus regenerative power occurring intermittently is stored in the capacitor unit 9 and power supplied continuously from the AC system 1 to the station loads 4 is supplemented with the surplus regenerative power stored in the capacitor unit 9, in a period in which the capacitor unit 9 maintains an SOC that enables discharging. Therefore, the surplus regenerative power can be effectively used while fluctuations in the total power amount or tne Ao' sysreitt ± are suppresseo.
[0041] As described above, the station—building power supply device according to the present embodiment includes the capacitor unit that stores therein surplus regenerative power in an electrical transformation zone; the first power conversion unit that performs DC/DC power conversion in both directions between the feeder and the capacitor unit; and the second power conversion unit that converts DC power supplied from the capacitor unit to AC power to be supplied to the station loads. A voltage threshold (a first voltage threshold) for the feeding voltage and an SOC threshold (a first SOC threshold) for the SOC of the capacitor unit are set; a value that indicates occurrence of surplus regenerative power in the electrical transformation zone is set as the first voltage threshold; and a value that indicates whether the capacitor unit can discharge is set

as the first SOC threshold. The first power conversion unit is controlled so as to supply power from the feeder to the capacitor unit to perform charging of the capacitor unit when the feeding voltage exceeds the first voltage threshold; and the second power conversion unit is controlled so as to supply power from the capacitor unit to the station loads when the SOC of the capacitor unit exceeds the first SOC threshold. Therefore, each time generation of surplus regenerative power in the electrical transformation zone occurs, the capacitor unit is charged with the surplus regenerative power, and power supplied continuously from the AC system to the station loads can be supplemented with the surplus regenerative power with which the capacitor unit has been charged in a period in which the capacitor unit maintains an SOC that enables discharging. Accordingly, the surplus regenerative power can be effectively used while fluctuations in the voltage of the feeder and fluctuations in the amount of power supplied from the AC system are suppressed.
[004 2] The second power conversion unit is controlled so as to cause the amount of power supplied from the capacitor unit to the station loads to be substantially constant. Accordingly, the amount of power supplied from the AC system can be more stable.
[0043] Furthermore, the second voltage threshold smaller than the first voltage threshold is provided for the feeding voltage, and the second SOC threshold larger than the first SOC threshold is provided for the SOC of the capacitor unit. A value that indicates a shortage of power in the electrical transformation zone is set as the second voltage threshold, and a value that indicates whether the capacitor unit can supplement a power shortage in the electrical transformation zone is set as the second SOC threshold. When the feeding voltage falls below the second

voltage threshold and the SOC of the capacitor unit exceeds the second SOC threshold, the first power conversion unit is controlled such that the power is supplied from the capacitor unit to the feeder. Therefore, in a period in which the capacitor unit maintains an SOC that enables supplementation of a power shortage in the electrical transformation zone, the power shortage in the electrical transformation zone can be supplemented with surplus regenerative power with which the capacitor unit has been charged. Accordingly, voltage fluctuations of the feeder can be more stable.
[0044] The configuration described in the above embodiment is only an example of the contents of the present invention. The configuration can be combined with other well-known techniques, and it is needless to mention that the present invention can be configured while modifying it without departing from the scope of the invention, such as omitting a part thereof.
Reference Signs List
[0045] 1 AC system, 2 station building, 3 transformer, 4, 4-1, 4-2, . .., 4-n station load, 5 train, 6 feeder, 7 rail, 8 feeding-voltage detection unit, 9 capacitor unit, 10 SOC detection unit, 11 first power conversion unit, 12 second power conversion unit, 13 control unit, 21 bidirectional DC/DC converter, 22 inverter, 23 transformer, 100 station-building power supply device.

1. A station-building power supply device that supplies power to a station load using
both AC power supplied from an AC system and surplus regenerative power from trains, the
station-building power supply device comprising:
a feeding-voltage detection unit (8) that detects a feeding voltage;
a first power conversion unit (11) that performs DC/DC power conversion in both directions between a feeder and a capacitor unit (9) that stores therein the surplus regenerative power;
a second power conversion unit (12) that converts DC power supplied from the capacitor unit (9) to AC power and supplies the AC power to the station load;
an SOC (State Of Charge) detection unit (10) that detects an SOC of the capacitor unit (9); and
a control unit (13) that controls the first power conversion unit (11) and the second power conversion unit (12) on the basis of the feeding voltage and the SOC, wherein
the control unit (13)
controls, when the feeding voltage exceeds a predetermined first voltage threshold, the first power conversion unit (11) such that power is supplied from the feeder to the capacitor unit (9),
controls, when the SOC exceeds a predetermined first SOC threshold, the second power conversion unit (12) such that power is supplied from the capacitor unit (9) to the station load, and
controls, when the SOC falls below the predetermined first SOC threshold, the second power conversion unit (12) such that power supplied from the capacitor unit (9) to the station load is decreased in a predetermined time period.
2. A station-building power supply device that supplies power to a station load using
both AC power supplied from an AC system and surplus regenerative power generated by
trains, the station-building power supply device comprising:
a feeding-voltage detection unit (8) that detects a feeding voltage;
an SOC (State Of Charge) detection unit (10) that detects an SOC of a capacitor unit (9) that stores therein the surplus regenerative power;
a first power conversion unit (11) that performs DC/DC power conversion in both directions between a feeder and the capacitor unit (9);
a second power conversion unit (12) that converts DC power supplied from the capacitor unit (9) to AC power and supplies the AC power to the station load; and
a control unit (13) that controls the first power conversion unit (11) and the second power conversion unit (12) on the basis of the feeding voltage and the SOC, wherein

the control unit (13)
controls, when the SOC exceeds a predetermined first SOC threshold, the second power conversion unit (12) such that power is supplied from the capacitor unit (9) to the station load, and
controls, when the SOC exceeds a second SOC threshold that is larger than the first SOC threshold, the first power conversion unit (11) such that power is supplied from the capacitor unit (9) to the feeder.