Station building energy supply

Abstract

Station building energy supply (6), which has: a power converter (8) for converting direct current energy into alternating current energy; a housing (14) that accommodates the power converter (8); an alternating current system circuit (15) for supplying the alternating current energy output by the power converter (8) to an electrical device (22) outside the housing (14); and a filter circuit (10) for applying a high-frequency current (33, 34) generated in the power converter (8) from the AC system circuit (15) to the housing (14), wherein the power converter (8) and the housing (14) are grounded, the power converter (8) is grounded via the housing (14).

Description

Area

[0001] The present invention relates to a station building power supply that converts surplus regenerative energy from DC power into AC power in a station building, which supplies power to an electric device in the station by using AC power supplied from an AC system and surplus regenerative energy of a DC feeder train. background

[0002] Renewable energy generated by a regenerative brake of a DC feeder train is now used as the traction power for another DC feeder train via an overhead line. In such a DC feeder system, the overhead line voltage increases when the regenerative energy exceeds the traction power in the same substation section, and the overhead line voltage decreases when the regenerative energy becomes less than the traction power in the same substation section. A station building power supply converts excess regenerative energy generated when the regenerative energy exceeds the traction power into AC power and supplies the AC power to an electrical device in the station building via an AC system.Thus, the station building power supply effectively utilizes excess renewable energy within a range that does not cause reverse current to the AC system while stabilizing the overhead line voltage. Such a method is disclosed in Patent Literature 1.

[0003] Patent Literature 2 shows that in a system for supplying power from an AC power supply to a three-phase motor via a converter and an inverter, a leakage current reducing device is connected to a connecting line between the AC power supply and the converter. A common-mode transformer detects, as a common-mode voltage, a common-mode current flowing from the AC power supply to the connecting line. The common-mode voltage is supplied to a voltage amplifier via a filter device. An output voltage obtained by voltage amplification passes through a capacitor and is then supplied as an AC component to a star point of capacitors connected in a star connection so as to have the same phase as that of the common-mode voltage. Consequently, current is generated.which has the same phase as that of the common-mode current, is fed to the converter via the capacitors through the connecting line, so that the common-mode current is reduced. Citation listPatent literature Patent literature 1: JP 2015 - 107 766 A Patent literature 2: DE 11 2011 102 817 T5 SummaryTechnical problem

[0004] In the station building where the station building power supply is installed, devices are grounded, such as a power converter that converts excess renewable energy from direct current to alternating current, and a transformer that converts the voltage of the alternating current power supplied by an alternating current system. However, in the station building, there are cases where each device cannot be individually grounded due to the installation environment, such as a subway station, or restrictions on the building's structure. In such a case, the ground terminal of each device and a grounding electrode provided in the station building are connected by a grounding wire, and the grounding electrode is divided so that each device can be grounded.In a case where a plurality of devices share a grounding electrode and are grounded, an AC system circuit, which represents the path of AC power from the station building power supply to the electrical device installed in the station building, and a double line including the grounding wire are formed. In this case, a high-frequency current generated in the power converter of the station building power supply circulates in the double line. In other words, this means that the high-frequency current generated in the power converter leaks from the station building power device. For this reason, outside the station building power supply, it is possible that the electrical device installed in the station building will malfunction due to the influence of the high-frequency current.

[0005] The present invention has been made in view of the above and aims to obtain a station building power supply capable of preventing a malfunction of an external electrical device due to a high frequency current. Solution to the problem

[0006] To solve the above-mentioned problems and achieve the object, a station building power supply of the present invention comprises: a power converter that converts direct current power into alternating current power; a casing that houses the power converter; an alternating current system circuit that supplies the alternating current power output from the power converter to an electrical device outside the casing; and a filter circuit that allows a high-frequency current generated in the power converter to flow from the alternating current system circuit to the casing. The station building power supply is characterized in that the power converter and the casing are grounded, and the power converter is grounded via the casing. Advantageous effects of the invention

[0007] According to the present invention, a station building power supply has the effect of preventing a malfunction of the external electrical device due to a high frequency current. Short description of the drawings Fig. 1 is a diagram illustrating an example configuration of a railway system including a station building power supply according to a first embodiment. Fig. 2 is a diagram illustrating an example of the flow of a high-frequency current in a railway system in a case where the filter circuit is omitted from the station building power supply according to the first embodiment. Fig. 3 is a diagram illustrating an example configuration of a station building power supply according to a second embodiment. Fig. 4 is a diagram illustrating an example configuration of a station building power supply according to a third embodiment. Fig. 5 is a diagram illustrating an example configuration of a station building power supply according to a fourth embodiment. Description of the embodiments

[0008] The following provides a detailed description of station building power supplies according to embodiments of the present invention with reference to the drawings. It should be noted that the present invention is not limited by the embodiments. First embodiment.

[0009] Fig. 1 is a diagram illustrating an example configuration of a railway system 100 including a station building power supply 6 according to a first embodiment of the present invention. The railway system 100 includes an electrical substation 1, an overhead line 2, rails 3, a DC feeder train 4, a station building 5, and a commercial power source 21.

[0010] The electrical substation 1 represents a direct current supply system and is an electrical substation in the same substation section as the station building 5, which includes the station building power supply 6. The electrical substation 1 supplies traction energy, which serves as a motive force, to the direct current supply train 4, which runs under its control in the substation section. It should be noted that although only one direct current supply train 4 is in Fig. 1, there are a plurality of DC feeder trains 4 in the substation section controlled by the electrical substation 1.

[0011] The overhead line 2 represents the path of the current flowing when electrical power is supplied from the electrical substation 1 to the DC feeder train 4. Furthermore, the overhead line 2 represents the path of the current flowing when regenerative energy generated by braking the DC feeder train 4 is supplied to another DC feeder train 4 (not illustrated) or the station building power supply 6.

[0012] The rails 3 form a track on which the DC supply train 4 runs. The rails 3 also form the path serving as a return path through which the power returns to the electrical substation 1 via the DC supply train 4 in a case where the electrical energy supplied by the electrical substation 1 is consumed as motive power by the DC supply train 4.

[0013] The DC feeder train 4 consumes the electrical power supplied from the electrical substation 1 as traction power. Furthermore, when the DC feeder train 4 is braked while stopping at a station or the like, regenerative energy is generated, which serves as the braking force for the DC feeder train 4. The DC feeder train 4 supplies the generated regenerative energy to another DC feeder train 4 (not illustrated) or to the station building power supply 6 via the overhead line 2.

[0014] The station building 5 includes the station building power supply 6, a station building electrical room 16, and an electrical device 22. The station building power supply 6 converts excess regenerative energy 31 of the DC feed train 4 from DC power into AC power and supplies excess regenerative energy 32, which is the AC power after conversion, to the electrical device 22. The station building electrical room 16 includes a transformer 17. The transformer 17 converts the voltage of the AC power supplied by the commercial power source 21 into a voltage that can be used by the electrical device 22 and supplies the converted AC power to the electrical device 22.The electrical device 22 uses both the AC power supplied by the commercial power source 21 and the surplus renewable energy 32 supplied by the station building power supply 6. It should be noted that although there is an electrical device 22 in the station building 5 in . Fig. 1, a plurality of electrical devices 22 are actually provided in the station building 5. The electrical devices 22 represent electrical devices such as an air conditioner, a lighting device, an elevator, or a railway signaling device for the DC feeder train 4 in the station where the station building power supply 6 is installed.

[0015] The commercial power source 21 is an alternating current system that supplies alternating current power to the electrical device 22.

[0016] Next, the configuration of the station building power supply 6 will be described. The station building power supply 6 includes: a high-speed circuit breaker 7; a power converter 8; an electromagnetic output contactor 9; a filter circuit 10; a voltage sensor 12; and a casing 14. The station building power supply 6 also includes part of an AC system circuit 15, which represents the path of the AC power at a time when AC power output from the power converter 8 is supplied to the electrical device 22 outside the station building power supply 6 or outside the casing 14. The AC system circuit 15 represents a three-wire power line, as shown in Fig. 1 is illustrated.

[0017] The high-speed breaker 7 is a breaker for blocking excessive random current and the like flowing from the overhead line 2 to the power converter 8. The high-speed breaker 7 outputs the excess regenerative energy 31 from the overhead line 2 to the power converter 8 during normal operation.

[0018] The power converter 8 is arranged between the high-speed breaker 7 and the electromagnetic output contactor 9 and converts the surplus regenerative energy 31, which is a direct current power generated by the direct current feeder train 4, into an alternating current power of the voltage used by the electrical device 22 of the station building 5, wherein the alternating current power represents the surplus regenerative energy 32.

[0019] The electromagnetic output contactor 9 is an electromagnetic contactor arranged closer to the power converter 8 than the contact point between the AC system circuit 15 and the filter circuit 10, and opens and closes the path of the AC system circuit 15. The electromagnetic output contactor 9 outputs the excess regenerative energy 32 from the power converter 8 to the electrical device 22 during normal operation.

[0020] The filter circuit 10 connects the AC system circuit 15 and the housing 14 in an AC-like manner and allows a high-frequency current 33 generated by the power converter 8 to flow from the AC system circuit 15 to the housing 14. The filter circuit 10 includes three high-frequency capacitors 11-1 to 11-3. In the filter circuit 10, the ends of the high-frequency capacitors 11-1 to 11-3 are connected on one side by a Y-connection, and the neutral point is connected to the housing 14. The Y-connected neutral point of the high-frequency capacitors 11-1 to 11-3 has a lower impedance than the AC system circuit 15, which is located closer to the electrical device 22 than the contact point between the AC system circuit 15 and the filter circuit 10.Further, in the filter circuit 10, the ends of the high-frequency capacitors 11-1 to 11-3 on the other side are connected to the AC system circuit 15 or to other wires of the three-wire power line.

[0021] The voltage sensor 12 detects a voltage value representing the voltage value between the housing 14 and the rails 3, which represents a charged state of the housing 14. The housing 14 houses the high-speed circuit breaker 7, the power converter 8, the electromagnetic output contactor 9, the filter circuit 10, and the like, which are electrical components of the station building power supply 6.

[0022] In the station building power supply 6, the casing 14 is grounded to a ground electrode 18 provided in the station building 5 through a ground terminal 13-2 via a ground wire 20. The power converter 8 is grounded to the ground electrode 18 through a ground terminal 13-1 via the casing 14 and the ground wire 20. The voltage sensor 12 is grounded to the ground electrode 18 through a ground terminal 13-3 via the casing 14 and the ground wire 20. Furthermore, in the station building electrical room 16, the transformer 17 is grounded to the ground electrode 18 through a ground terminal 17-1. Furthermore, the electrical device 22 is grounded to the ground electrode 18 through a ground terminal 23. In the station building 5, there are cases where each device cannot be individually grounded due to the installation environment, such as a subway station, or due to restrictions on the structure of the building.In the track system 100, the ground terminals of the respective devices are connected to the ground electrode 18, and the ground electrode 18 is divided so that the respective devices are grounded. In the embodiment shown in FIG. Fig. In the example illustrated in Figure 1, the grounding electrode 18, which is connected to the grounding terminal 17-1 of the transformer 17, is connected to the grounding terminal 13-2 of the housing 14 of the station building power supply 6 by the grounding wire 20. In this configuration, the transformer 17 and the power converter 8, which is connected to the housing 14, share the grounding electrode 18.

[0023] Next, an operation in which the power converter 8 supplies the surplus regenerative energy 32 to the electrical device 22 in the station building 5 will be described. In the station building power supply 6, the power converter 8 converts the surplus regenerative energy 31, which is direct current power input via the high-speed circuit breaker 7, into the surplus regenerative energy 32, which is alternating current power. The station building power supply 6 supplies the surplus regenerative energy 32, which is the alternating current power converted by the power converter 8, to the electrical device 22 via the electromagnetic output contactor 9 and the AC system circuit 15.Here, in the power converter 8, a high-frequency current is generated by the operation of converting the excess regenerative energy 31, which is direct current energy, into the excess regenerative energy 32, which is alternating current energy. As the excess regenerative energy 32 is released, the high-frequency current leaks out of the power converter 8 through a path formed by the electromagnetic output contactor 9 and the AC system circuit 15.

[0024] However, in the station building power supply 6, the filter circuit 10 is connected between the AC system circuit 15 and the housing 14 in an AC-like manner. The filter circuit 10 has the neutral point where the three high-frequency capacitors 11-1 to 11-3 are connected by a Y connection, and the neutral point is connected to the housing 14 with a low impedance. As shown in Fig. 1, the high-frequency current 33 output from the power converter 8 accordingly passes through the electromagnetic output contactor 9, the AC system circuit 15, the filter circuit 10, the casing 14, and the ground terminal 13-1, and then returns to the power converter 8. In this way, the high-frequency current 33 circulates in the station building power supply 6. Since the station building power supply 6 includes the filter circuit 10 connecting the AC system circuit 15 and the casing 14 in an AC-like manner as described above, the high-frequency current 33 can be prevented from leaking out of the station building power supply 6, namely, from leaking into the electrical device 22.

[0025] Furthermore, it may be difficult to add more grounding electrodes in the existing station building 5 due to architectural restrictions. In a case where the station building power supply 6 shares the grounding electrode 18 of the station building 5 for a new electrical device 22 with the grounding terminal 13-1 of the power converter 8, the grounding terminal 17-1 of the transformer 17, the grounding terminal 23 of an existing electrical device 22, and the like, the station building power supply 6 can also prevent the high-frequency current 33 from leaking from the station building power supply 6. By preventing the high-frequency current 33 from leaking into both the existing and new electrical devices 22, the station building power supply 6 can prevent malfunctions in both the existing and new electrical devices 22.

[0026] Here, the flow of a high-frequency current in a case where the filter circuit 10 is not provided will be described. Fig. 2 is a diagram illustrating an example of the flow of a high-frequency current 34 in a railway system 101 in a case where the filter circuit 10 is omitted from the station building power supply 6 according to the first embodiment. Fig. Figure 2 illustrates a comparative example regarding the flow of the high frequency current 33 in the Fig. 1 illustrated railway system 100. A station building 50 comprises a station building power supply 60 instead of the station building power supply 6 of the Fig. 1 illustrated station building 5. The station building power supply 60 is the same as that shown in Fig. 1, except that the filter circuit 10 is omitted. In the Fig. In the example illustrated in Figure 2, the high-frequency current 34 generated by the power converter 8 leaks into the station building electrical room 16 via the electromagnetic output contactor 9 and the AC system circuit 15. The high-frequency current 34 flowing into the station building electrical room 16 passes through the ground terminal 17-1, the ground wire 20, and the ground terminals 13-2 and 13-1, and returns to the power converter 8 of the station building power supply 60 via a floating capacitor 19 of the AC system circuit 15, a V-phase ground of the secondary side of the transformer 17, and the like. In other words, this means that the high-frequency current 34 flows into a double line including the station building electrical room 16 outside the station building power supply 60, as shown in Figure 2. Fig. 2. Here, if the high-frequency current 34 that has flowed into the station building electrical room 16 also flows into the electrical device 22, the electrical device 22 may be affected by the high-frequency current 34 and malfunction. Furthermore, if the high-frequency current 34 flows into the path through which the transformer 17 supplies AC power to the electrical device 22, there is a possibility that the transformer 17 will be affected by the high-frequency current 34, and the AC power output from the transformer 17 will also be affected.

[0027] In contrast to the Fig. 2, the station building power supply 6 of the first embodiment shown in Fig. 1, it can prevent the high-frequency current 33 from leaking from the station building power supply 6 even in a case where the ground terminals of a plurality of devices in the station building 5 share the ground electrode 18. By preventing the high-frequency current 33 from leaking into the electrical device 22, the station building power supply 6 can avoid a situation in which a malfunction occurs in the electrical device 22.

[0028] Although it is in the Fig. 1 and Fig. 2, some of the diodes or some of the switching elements constituting the power converter 8 may be formed with wide-gap semiconductors made of silicon carbide (SiC), gallium nitride (GaN), or diamond. Switching elements and diodes formed with such wide-gap semiconductors have high voltage resistance and high allowable current density. Accordingly, the elements can be downsized, and a semiconductor module integrated with these elements can also be downsized. Furthermore, these elements also have high thermal resistance. Accordingly, a heat sink can be downsized, and thus the semiconductor module can also be downsized. Furthermore, these elements have low power loss.Accordingly, the switching elements and diodes can be designed to be highly efficient, and the semiconductor module can also be designed to be highly efficient. Alternatively, the same effects as above can be achieved with a MOSFET (metal-oxide-semiconductor field-effect transistor) with a superjunction structure, which is known as a highly efficient switching element.

[0029] As described above, according to the first embodiment, in the station building power supply 6, the AC system circuit 15, which provides the path of the AC power from the power converter 8 to the electrical device 22, which is the surplus regenerative energy 32, and the casing 14 are connected in an AC-like manner through the filter circuit 10. The filter circuit 10 has the neutral point where the three high-frequency capacitors 11-1 to 11-3 are connected by a Y connection, and the neutral point is connected to the casing 14 with a low impedance. In the station building power supply 6, the high-frequency current 33 generated in the power converter 8 returns to the power converter 8 via the electromagnetic output contactor 9, the AC system circuit 15, the filter circuit 10, the casing 14, and the ground terminal 13-1, thus circulating in the station building power supply 6.In other words, even in a case where the grounding electrode 18 is shared between the power converter 8 in the station building power supply 6 and a device in the station building electrical room 16 or the electrical device 22, the station building power supply 6 can prevent the high-frequency current 33 generated in the power converter 8 from leaking out of the station building power supply 6 or the casing 14. Thus, the station building power supply 6 can prevent a malfunction of the electrical device 22 due to the high-frequency current 33 outside the station building power supply 6 or the casing 14. Second embodiment.

[0030] In a second embodiment, the output section from the AC system circuit 15 to the outside has a high impedance, thus further reducing leakage of the high-frequency current 33 from the station building power supply to the outside. The differences between the second embodiment and the first embodiment will be described below.

[0031] Fig. Fig. 3 is a diagram illustrating an example configuration of a station building power supply 6a according to the second embodiment. In a railway system of the second embodiment, the station building power supply 6 of the Fig. 1 is replaced by the station building power supply 6a. Although not illustrated in the drawing, for convenience of explanation, the railway system of the second embodiment is a railway system 100a, and the station building is a station building 5a. The railway system 100a is the same as the railway system 100 of the first embodiment shown in Fig. 1, with the exception of the station building power supply configuration 6a.

[0032] The station building power supply 6a is the same as the station building power supply 6 of the first embodiment shown in Fig. 1, except for a core 24 further included. The core 24 is designed to make the AC system circuit 15 a high-impedance circuit to prevent the high-frequency current 33 from leaking from the station building power supply 6a or the casing 14. The core 24 is, for example, a ferrite core. The core 24 normally has an annular shape. The AC system circuit 15 is made to extend through the annular hole of the core 24, so that the AC system circuit 15 and the core 24 form a coil, which is an inductor. The coil becomes larger in impedance as the frequency becomes higher. Accordingly, the core 24 functions as a low-pass filter that blocks the flow of the high-frequency current 33.In the station building power supply 6a, the core 24 in the AC system circuit 15 is arranged closer to the external electrical device 22 than the contact point between the AC system circuit 15 and the filter circuit 10. In the station building power supply 6a, the path to the outside of the AC system circuit 15, that is, to the electrical device 22, has a high impedance, so more of the high-frequency current 33 flows into the filter circuit 10 than in the first embodiment.

[0033] As described above, according to the second embodiment, in the station building power supply 6a, the core 24 in the AC system circuit 15 is arranged closer to the electrical device 22 than the contact point between the AC system circuit 15 and the filter circuit 10. Accordingly, the station building power supply 6a can more effectively prevent the high-frequency current 33 from leaking from the power converter 8 to the outside than in the first embodiment. As a result, the station building power supply 6a can more effectively prevent the malfunction of the external electrical device 22 due to the high-frequency current 33 than in the first embodiment. Third embodiment.

[0034] In a third embodiment, a circuit pattern different from that of the first embodiment will be described.

[0035] Fig. Fig. 4 is a diagram illustrating an example configuration of a station building power supply 6b according to the third embodiment. In a railway system of the third embodiment, the station building power supply 6 of the railway system 100 shown in Fig. 1 is replaced by the station building power supply 6b. Although not illustrated in the drawing, for convenience of explanation, the railway system of the third embodiment is a railway system 100b, and the station building is a station building 5b. The railway system 100b is the same as the railway system 100 of the first embodiment shown in Fig. 1, with the exception of the station building power supply configuration 6b.

[0036] In the third embodiment, as shown in Fig. As illustrated in FIG. 4, the positions of the electromagnetic output contactor 9 and the filter circuit 10 in the station building power supply 6b are reversed. The electromagnetic output contactor 9 in the AC system circuit 15 is arranged closer to the power converter 8 than the contact point between the AC system circuit 15 and the filter circuit 10 in the first embodiment. In the third embodiment, on the other hand, the electromagnetic output contactor 9 is arranged closer to the electrical device 22 than the contact point between the AC system circuit 15 and the filter circuit 10. In this way, the same effects as those of the first embodiment can also be achieved. Fourth embodiment.

[0037] In a fourth embodiment, a circuit pattern different from that of the second embodiment will be described.

[0038] Fig. Fig. 5 is a diagram illustrating an example configuration of a station building power supply 6c according to the fourth embodiment. In a railway system of the fourth embodiment, the station building power supply 6a of the railway system 100a shown in Fig. 3 is replaced by the station building power supply 6c. Although not illustrated in the drawing, for convenience of explanation, the railway system of the fourth embodiment is a railway system 100c, and the station building is a station building 5c. The railway system 100c is the same as the railway system 100a of the second embodiment shown in Fig. 3, with the exception of the station building power supply configuration 6c.

[0039] In the fourth embodiment, as shown in Fig.As illustrated in FIG. 5, the positions of the electromagnetic output contactor 9, the filter circuit 10, and the core 24 in the station building power supply 6c are reversed. The electromagnetic output contactor 9 in the AC system circuit 15 is arranged closer to the power converter 8 than the contact point between the AC system circuit 15 and the filter circuit 10 in the second embodiment. In the fourth embodiment, on the other hand, the electromagnetic output contactor 9 is arranged closer to the electrical device 22 than the contact point between the AC system circuit 15 and the filter circuit 10 and than the core 24. In this case, the same effects as those of the second embodiment can also be achieved.

[0040] The configurations described in the above-mentioned embodiments are examples of the subject matter of the present invention and may be combined with other known methods or may be partially omitted or modified without departing from the scope of the present invention. List of reference symbols

[0041] 1 electrical substation; 2 overhead line; 3 rails; 4 DC feeder train; 5 station building; 6 station building power supply; 7 high-speed breaker; 8 power converter; 9 electromagnetic output contactor; 10 filter circuit; 11-1 to 11-3 high-frequency capacitor; 12 voltage sensor; 13-1 to 13-3, 23 grounding terminal; 14 enclosure; 15 AC system circuit; 16 station building electrical room; 17 transformer; 18 grounding electrode; 19 ungrounded capacitor; 20 grounding wire; 21 commercial power source; 22 electrical device; 24 core; 31, 32 surplus regenerative energy; 33, 34 high-frequency power; 100, 101 railway system.

Claims

[1] Station building power supply (6), which has: a power converter (8) for converting direct current energy into alternating current energy; a housing (14) accommodating the power converter (8); an AC system circuit (15) for supplying the AC power output from the power converter (8) to an electrical device (22) outside the housing (14); and a filter circuit (10) for applying a high-frequency current (33, 34) generated in the power converter (8) from the AC system circuit (15) to the housing (14), wherein the power converter (8) and the housing (14) are earthed, wherein the power converter (8) is earthed via the housing (14). [2] Station building power supply (6) according to claim 1, wherein the AC system circuit (15) is a three-wire power line and in the filter circuit (10), ends of three high-frequency capacitors (11-1, 11-2, 11-3) are connected on one side by a Y-connection, a neutral point is connected to the housing (14), and ends of the three high-frequency capacitors (11-1, 11-2, 11-3) on the other side are connected to different wires of the three-core power line. [3] The station building power supply (6) according to claim 1 or 2, further comprising an electromagnetic contactor for opening and closing a path of the AC system circuit (15), the electromagnetic contactor being arranged closer to the power converter (8) than a contact point between the AC system circuit (15) and the filter circuit (10). [4] The station building power supply (6) according to claim 1 or 2, further comprising an electromagnetic contactor for opening and closing a path of the AC system circuit (15), the electromagnetic contactor being arranged closer to the electrical device (22) than a contact point between the AC system circuit (15) and the filter circuit (10). [5] A station building power supply (6) according to any one of claims 1 to 4, further comprising a core (24) arranged closer to the electrical device (22) than a contact point between the AC system circuit (15) and the filter circuit (10). [6] A station building power supply (6) according to any one of claims 1 to 5, wherein a ground terminal (13-1, 13-2, 13-3, 23) of a transformer (17) that converts a voltage of an alternating current power supplied from a commercial power source (21) into a voltage that can be used in the electrical device (22) and a ground terminal (13-1, 13-2, 13-3, 23) of the housing (14) are connected to a ground electrode (18) provided in a station building (5). [7] Station building power supply (6) according to claim 6, wherein the electrical device (22) is provided in the station building (5), and wherein a ground terminal (13-1, 13-2, 13-3, 23) of the electrical device (22) and the ground terminal (13-1, 13-2, 13-3, 23) of the housing (14) are connected to the ground electrode (18).

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