Power supply systems for railway vehicles

Abstract

A power supply system (2) for a railway car comprises a plurality of power supply devices (1) which are mounted on the cars of a train and which are capable of supplying, in parallel, AC power to a plurality of air conditioning devices (55) in the train via an output contactor (12) and a common bus (15). The air conditioning device (55) in each car generates step calorie information which is information regarding electric power required for an air conditioning target space. A collection device (56) collects the step calorie information generated by the air conditioning device (55) of each car and calculates step calorie information of all the cars, in which the step calorie information for all cars is totaled. On the basis of the step calorie information of all the cars transmitted from the collection device (56), the power supply devices (1) determine whether or not supply of power to the air conditioning devices (55) is to be suspended.

Description

[Technical Field]

[0001] The present disclosure relates to a power supply system for railway vehicles that is mounted on train cars and supplies power to loads within the car, such as air conditioning devices and lighting devices, via an output contactor and a common bus. [Background technology]

[0002] Patent Document 1 listed below discloses a power supply system for railway vehicles that aims to reduce power loss. Specifically, the power supply system described in Patent Document 1 describes that two power supply devices in a train mutually monitor the load power of the in-vehicle loads of the train and another train, and when both load powers fall below a specified value, the operation of one of the power supply devices supplying power to one of the in-vehicle loads is stopped. In other words, the technology described in Patent Document 1 discloses a pause control that uses information on the load power of the in-vehicle load to determine whether or not to pause the power supply to the in-vehicle load. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-166730 Summary of the Invention [Problem to be solved by the invention]

[0004] Among the loads within a vehicle, an air conditioner is one of the loads that requires a large amount of power. The output power of an air conditioner varies greatly depending on the temperature and the occupancy rate. Furthermore, in a power supply device for a railway vehicle that supplies power via an output contactor, the power supply to the load within the vehicle is stopped using the output contactor. Therefore, if the technology of Patent Document 1 is applied to a power supply device with this configuration, there is a risk that some power supply devices will frequently be stopped and started again as the load power fluctuates. In this case, there is a problem that the contacts of the output contactors connected to those power supply devices will wear out at a faster rate, shortening the lifespan of the output contactors.

[0005] The present disclosure has been made in consideration of the above, and aims to provide a power supply system for railway vehicles that can efficiently supply power to loads within the vehicle while suppressing a decrease in the lifespan of the output contactor. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the present disclosure provides a power supply system for railway vehicles that is mounted on a train car and includes a plurality of power supply devices configured to be able to supply AC power in parallel to a plurality of air conditioning devices on the train via output contactors and a common bus. Each air conditioning device generates first power information that is information about the power required for the air-conditioned space. A collection device collects the first power information generated by each air conditioning device and calculates second power information by adding up the multiple first power information. The power supply device determines whether to suspend power supply to the air conditioning device based on the second power information transmitted from the collection device. [Effects of the Invention]

[0007] The power supply system for a railway vehicle according to the present disclosure has the advantage of being able to efficiently supply power to loads within the vehicle while suppressing a decrease in the lifespan of the output contactor. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing the basic configuration of a power supply device for a railway vehicle according to a first embodiment and its relationship with other components. [Figure 2] FIG. 1 is a diagram showing a configuration of a power supply system for a railway vehicle according to a first embodiment; [Figure 3] FIG. 1 is a system configuration diagram illustrating the operation of pause operation control according to the first embodiment. [Figure 4] 1 is a flowchart illustrating the operation of pause operation control according to the first embodiment; [Figure 5] FIG. 10 is a diagram illustrating the effect of pause operation control according to the first embodiment. [Figure 6]FIG. 1 is a block diagram showing an example of a hardware configuration for realizing the functions of a control unit according to a first embodiment. [Figure 7] FIG. 10 is a block diagram showing another example of a hardware configuration for realizing the functions of the control unit according to the first embodiment. [Figure 8] 10 is a flowchart illustrating the operation of pause operation control according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, a power supply system for a railway vehicle according to an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings.

[0010] Embodiment 1 FIG. 1 is a diagram showing the basic configuration of a power supply device for a railway vehicle according to a first embodiment (hereinafter simply referred to as a "power supply device") and its relationship with other components. FIG. 1 shows the main components of power supply device 1 according to the first embodiment. Power supply device 1 is mounted on a train vehicle. As shown in FIG. 1, power supply device 1 includes a power conversion device 10, a current detector 11, and an output contactor 12. Power conversion device 10 receives DC power supplied from an overhead line 50 via a current collector 52, converts the received DC power to AC power, and supplies it to in-vehicle loads 54. In-vehicle loads 54 are loads mounted on train vehicles other than the traction motor. Examples of in-vehicle loads 54 include air conditioning systems, interior lighting systems, door opening and closing systems, safety equipment, and control power supplies.

[0011] A current detector 11 is disposed between the power conversion device 10 and the output contactor 12. The current detector 11 detects current flowing in and out of the power conversion device 10. Power is supplied to the in-vehicle load 54 via the output contactor 12. When power is to be supplied to the in-vehicle load 54, the contacts of the output contactor 12 are closed. When power supply to the in-vehicle load 54 is to be temporarily stopped, the contacts of the output contactor 12 are opened. The power conversion device 10 controls the opening and closing of the contacts of the output contactor 12.

[0012] 1 shows a case where the power supplied from the overhead line 50 is DC power, that is, a case where the overhead line 50 is a DC overhead line, but the overhead line 50 may also be an AC overhead line. When the overhead line 50 is an AC overhead line, a main transformer is inserted between the current collector 52 and the power converter 10. The power converter 10 converts the AC power supplied from the main transformer into DC power, and then converts the converted DC power into AC power for supply to the loads 54 inside the vehicle.

[0013] FIG. 2 is a diagram showing the configuration of a power supply system for a railway vehicle (hereinafter simply referred to as the "power supply system") according to the first embodiment. In FIG. 2, power supply system 2 is provided with two power supply devices 1A, 1B to ensure redundancy. The capacity of each of power supply devices 1A, 1B is set higher than the capacity actually required so that even if one of them fails, the remaining device can still supply power to all or major in-car loads 54. The number of power supply devices is determined according to the number of cars in the train, and if the train has a large number of cars, three or more power supply devices may be installed.

[0014] Power supply devices 1A and 1B are connected to a three-phase common bus 15 that is wired inside the cars and between the cars. A plurality of in-car loads 54 (not shown in Fig. 2) are connected to common bus 15. That is, in power supply system 2, power supply devices 1A and 1B are configured to be able to supply AC power in parallel to a plurality of in-car loads 54 inside the train via common bus 15.

[0015] Next, the configuration and functions of power supply units 1A and 1B will be described. Note that the configuration and functions of each unit are identical, and the following description will refer to power supply unit 1A. Furthermore, in the following description, when power supply units 1A and 1B are not to be distinguished from one another, they will be referred to as "power supply unit 1" without the subscript.

[0016] The power supply device 1 includes voltage detectors 13 and 14 in addition to the current detector 11 and output contactor 12 described above. The power conversion device 10 also includes an inverter 20 and a control unit 22. The inverter 20 is a power converter that converts DC or AC power supplied from an overhead line 50 into three-phase AC power for a vehicle load 54. The voltage detector 13 detects the voltage of the common bus 15, i.e., the three-phase AC voltage applied to the common bus 15. The voltage detector 14 detects the voltage between the inverter 20 and the output contactor 12, thereby detecting the three-phase AC voltage output by the inverter 20. The detected values ​​of the voltage detectors 13 and 14 are input to the control unit 22, along with the detected value of the current detector 11. The control unit 22 controls the operation of the inverter 20 based on the detected values ​​of the voltage detectors 13 and 14 and the detected value of the current detector 11. The control unit 22 also controls the opening and closing of the output contactor 12.

[0017] The multiple power supply units 1 perform synchronous parallel operation for the multiple in-car loads 54 in the train. Synchronous parallel operation is a method of operating the multiple power supply units 1 while matching the amplitude and phase of the output voltages between them when they output three-phase AC voltage to the common bus 15. To perform this synchronous parallel operation, each power supply unit 1 is provided with a voltage detector 13, 14. In the example of FIG. 2, when both power supply units 1A and 1B output three-phase AC voltage, power supply units 1A and 1B equally share the load power demand within the train. Therefore, in this case, power supply units 1A and 1B each share half of the total load current. The current detector 11 of each power supply unit 1A and 1B detects this half of the load current.

[0018] Next, we will use the example of an air conditioner as the in-vehicle load 54 to explain the issues that arise when multiple power supply units 1 operating in synchronous parallel supply power to the air conditioner. First, the capacity of the power supply unit 1 is set with the consideration that the air conditioner, which is the main in-vehicle load 54, can operate continuously at its maximum output point. However, in actual operation, the output of the air conditioner fluctuates depending on the temperature, weather, and occupancy rate, and on average, the air conditioner spends much of its time operating at a low output. The operating efficiency of the power supply unit 1 deteriorates as the load factor relative to the rated capacity of the power supply unit 1 decreases. This is because the iron loss of the reactor and transformer built into the power supply unit 1 accounts for an increasing proportion of the power consumption of the power supply unit 1.

[0019] Therefore, in the first embodiment, in order to increase the operating efficiency of the power supply units 1, when the load factor within the formation is low, the operation of one power supply unit 1 is paused and the output of the remaining power supply units 1 is increased so that the power supply units 1 operate at a load factor point where their efficiency is high. That is, in the first embodiment, operation control is performed in coordination with the air conditioning units, which are the main loads on the power supply units 1. Hereinafter, operation under this control is referred to as "pause operation". Furthermore, the control to perform pause operation is referred to as "pause operation control".

[0020] Next, the operation during pause operation control according to the first embodiment will be described with reference to Fig. 3 and Fig. 4. Fig. 3 is a system configuration diagram for explaining the operation of pause operation control according to the first embodiment. Fig. 4 is a flowchart for explaining the operation of pause operation control according to the first embodiment. The power supply system 2 according to the first embodiment includes a collection device 56 in addition to the components described above.

[0021] As shown in the system configuration diagram of FIG. 3, the power supply system 2 according to the first embodiment further includes a collection device 56 in addition to the components described above. The collection device 56 may be any device configured to receive information from the air conditioning device 55 and to transmit the information held by the air conditioning device 55 to the control unit 22 of the power supply device 1. Recent trains are equipped with train information management systems that manage train information. The central device of the train information management system has the function of grasping the operating status of the loads 54 inside the vehicle. Therefore, the central device of the train information management system can be used as the collection device 56.

[0022] In Figure 4, the air conditioner 55 of each vehicle generates step calorie information and transmits it to the collection device 56 (step S11). The step calorie information is information about the power required for the space to be air-conditioned by the air conditioner 55. The air conditioner 55 constantly predicts the power consumption for the air conditioning process for the space to be air-conditioned by calculation. The air conditioner 55 calculates the step calorie information based on the difference between the set temperature inside the vehicle and the temperature inside the vehicle, information about the occupancy rate of each vehicle, etc.

[0023] The collection device 56 generates step calorie information for all vehicles by adding up the step calorie information for each vehicle. The collection device 56 also transmits the generated step calorie information for all vehicles and the received step calorie information for each vehicle to the control unit 22 of the power supply device 1 (step S12).

[0024] The control unit 22 determines whether the current value detected by the current detector 11 is equal to or less than threshold A, which is a first threshold (step S13). If the current value detected by the current detector 11 is equal to or less than threshold A (step S13, Yes), the control unit 22 determines whether the step calorie information of all cars is equal to or less than threshold B, which is a second threshold (step S14). If the step calorie information of all cars is equal to or less than threshold B (step S14, Yes), the control unit 22 determines that the operating state of the air conditioners 55 in the train is a light load state, and transitions to paused operation (step S15). Thereafter, the processing from step S11 is repeated.

[0025] Returning to step S14, if the step calorie information of all vehicles exceeds threshold B (step S14, No), the control unit 22 determines that there has been no significant change in the load state of the air conditioners 55 and maintains the current state (step S16). That is, if pause operation control is being performed on the air conditioners 55, pause operation control is continued. Also, if pause operation control is not being performed on the air conditioners 55 and normal synchronous parallel operation is being performed, synchronous parallel operation is continued. Thereafter, the processing is repeated from step S11.

[0026] Returning to step S13, if the current value detected by the current detector 11 exceeds threshold A (step S13, No), the control unit 22 determines whether the step calorie information of all cars is equal to or less than threshold B (step S17). If the step calorie information of all cars exceeds threshold B (step S17, No), the control unit 22 determines that the operating state of the air conditioners 55 in the train is in a high-load state or will transition to a high-load state, and cancels pause operation (step S18). That is, if pause operation control is being performed on the air conditioners 55, pause operation is canceled and synchronous parallel operation is performed. Also, if synchronous parallel operation is being performed on the air conditioners 55, synchronous parallel operation is continued. Thereafter, the processing from step S11 is repeated.

[0027] Returning to step S17, if the step calorie information of all vehicles is equal to or less than threshold value B (step S17, Yes), the control unit 22 maintains the current state (step S16). That is, if pause operation control is being performed on the air conditioners 55, pause operation control is continued. Also, if pause operation control is not being performed on the air conditioners 55 and synchronous parallel operation is being performed, synchronous parallel operation is continued. Thereafter, the processing from step S11 is repeated.

[0028] The process flow in FIG. 4 is not performed by all power supply devices 1 in the train, but by a specific power supply device. The specific power supply device is one or more power supply devices selected from the power supply devices 1 in the train. The specific power supply device is changed daily or in a preset rotation. For example, in the configuration of FIG. 2, if power supply device 1A is the specific power supply device, only power supply device 1A executes the process flow in FIG. 4, and power supply device 1B does not execute the process flow in FIG. 4. When power supply device 1A performs a pause operation, power supply device 1B alone meets the power demand of the in-vehicle load 54. When the specific power supply device is changed daily, power supply device 1B becomes the specific power supply device on the next operating day. This allows the operation of the output contactors 12 to be equalized among multiple power supply devices 1, making it possible to prevent wear on the contacts of some or specific output contactors 12.

[0029] Furthermore, if there are three power supply devices 1 in a train, one or two of the power supply devices are set as specific power supply devices, and the remaining power supply devices 1 cover the power demand during low load times in the in-car loads 54. Note that if there are four or more power supply devices 1, the specific power supply devices can be determined using a similar approach.

[0030] Furthermore, although the above describes a case where the information output from each air conditioner 55 is step calorie information, this is not limiting. The information output from the air conditioner 55 does not have to be step calorie information, and any information may be used as long as it is information that can grasp the power requirements of the air-conditioned space for each air conditioner 55. For this reason, in the following description, information equivalent to the step calorie information output from each air conditioner 55 may be referred to as "first power information," and information equivalent to the step calorie information of all vehicles, which is the sum of the step calorie information of each vehicle, may be referred to as "second power information."

[0031] Figure 5 is a diagram illustrating the effect of pause operation control according to the first embodiment. In Figure 5, the horizontal axis represents the load factor within the formation, and the vertical axis represents the operating efficiency of one power supply unit 1. The load factor within the formation is expressed as a percentage of the power required by the air conditioning unit 55 relative to the power required by the load 54 within the car within the formation. The solid line curve connecting the diamond-shaped plots represents the operating efficiency when two units are operated synchronously in parallel, and the dash-dot line curve connecting the triangular plots represents the operating efficiency during pause operation control, i.e., when one of the two units is paused.

[0032] As shown in Figure 5, the steady-state load, which is a typical load factor within a train of air conditioning units 55, is in the range of just under 60% to just under 80% in summer and winter, but in the range of just under 10% to just under 30% in spring and autumn. For this reason, in the case of synchronous parallel operation, high operating efficiency can be maintained in summer and winter, but operating efficiency decreases in spring and autumn. In contrast, in the case of pause operation control, by pausing the operation of one power supply unit 1, it is possible to operate the remaining power supply unit 1 at a load factor point where its efficiency is high. This makes it possible to maintain high operating efficiency in summer and winter while suppressing decreases in operating efficiency in spring and autumn.

[0033] As described above, the power supply system according to the first embodiment includes a collection device that collects first power information generated by each air conditioning device in the train and calculates second power information by summing multiple pieces of first power information. The first power information is power requirement information for the air-conditioned space of each air conditioning device and is generated by each air conditioning device. The power supply device determines whether to suspend power supply to the air conditioning device, i.e., whether to implement suspend operation control, based on the second power information transmitted from the collection device. The second power information is power requirement information for the air conditioning devices of the entire train. Therefore, by performing suspend operation control using the second power information, it is possible to prevent some power supply devices from frequently switching between suspend and operation. This reduces the shortening of the lifespan of the output contactors connected to those power supply devices. Furthermore, suspend operation control that suspends operation of some power supply devices allows the power supply devices that are not suspending operation to operate at a load factor at which they are most efficient. This allows for efficient power supply to the loads within the train.

[0034] When the above-mentioned pause operation control is performed, it is desirable to set a specific power supply device and change the specific power supply device daily or in a preset rotation. Setting a specific power supply device can prevent the lifespan of some output contactors from being drastically reduced.

[0035] Furthermore, in the pause operation control according to the first embodiment, when the current value detected by the current detector of a specific one of the power supply devices is equal to or less than the first threshold value and the second power information is equal to or less than the second threshold value, the specific power supply device transitions to pause operation and suspends the supply of power to the air conditioner. By using two threshold values ​​for the determination process, the transition to pause operation can be easily and reliably performed.

[0036] Furthermore, in the pause operation control according to the first embodiment, a specific one of the power supply devices cancels pause operation when the current value detected by the current detector exceeds the first threshold and the second power information exceeds the second threshold. By using two thresholds for the determination process, pause operation can be canceled easily and reliably.

[0037] Next, a hardware configuration for realizing the functions of the control unit 22 described above will be described with reference to the drawings of Fig. 6 and Fig. 7. Fig. 6 is a block diagram showing an example of a hardware configuration for realizing the functions of the control unit 22 according to the first embodiment. Fig. 7 is a block diagram showing another example of a hardware configuration for realizing the functions of the control unit 22 according to the first embodiment.

[0038] When realizing some or all of the functions of the control unit 22 according to embodiment 1, the configuration can include a processor 300 that performs calculations, a memory 302 that stores programs read by the processor 300, and an interface 304 that inputs and outputs signals, as shown in FIG. 6.

[0039] Processor 300 is an example of a computing means. Processor 300 may be a computing means called a microprocessor, a microcomputer, a CPU (Central Processing Unit), or a DSP (Digital Signal Processor). Examples of memory 302 include non-volatile or volatile semiconductor memories such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable ROM), and EEPROM (registered trademark) (Electrically EPROM), as well as magnetic disks, flexible disks, optical disks, compact disks, minidisks, and DVDs (Digital Versatile Discs).

[0040] The memory 302 stores a program that executes the functions of the control unit 22 according to the first embodiment. The processor 300 exchanges necessary information via the interface 304, executes the program stored in the memory 302, and refers to the table stored in the memory 302, thereby performing the above-described processing. The calculation results by the processor 300 can be stored in the memory 302.

[0041] 7 can be used to implement part of the functions of the control unit 22 according to the first embodiment. The processing circuit 303 may be a single circuit, a composite circuit, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof. Information to be input to the processing circuit 303 and information to be output from the processing circuit 303 can be obtained via an interface 304.

[0042] It is also possible that some of the processing in the control unit 22 is performed by the processing circuit 303 , and the processing that is not performed by the processing circuit 303 is performed by the processor 300 and the memory 302 .

[0043] Embodiment 2 In the second embodiment, a modified process for canceling pause operation in the pause operation control according to the first embodiment will be described. FIG. 8 is a flowchart illustrating the operation of the pause operation control according to the second embodiment. In FIG. 8, parts that are the same as or equivalent to the processes shown in the flowchart of FIG. 4 are given the same reference numerals. The following description will focus on the processes added in FIG. 8. The configuration of the power supply system 2 that performs the processes of the second embodiment is the same as or equivalent to that of the first embodiment. Furthermore, the process flow of FIG. 8 is also performed by a specific power supply device, as in the first embodiment.

[0044] By the processing of step S11, the collection device 56 receives the step calorie information. Furthermore, by the processing of step S12, the generated step calorie information for all vehicles and the received step calorie information for each vehicle are transmitted to the control unit 22.

[0045] Furthermore, the collection device 56 determines the number of air conditioners 55 that exceed the third threshold value C among the step calorie information of each vehicle, and transmits information about the number to the control unit 22 of the power supply device 1 (step S21). The threshold value C is a value smaller than the second threshold value B.

[0046] In step S13, it is determined whether the current value detected by the current detector 11 is equal to or less than threshold value A. In step S14, it is determined whether the step calorie information of all vehicles is equal to or less than threshold value B.

[0047] If the step calorie information of all vehicles exceeds threshold B (step S14, No), the control unit 22 determines whether the number of air conditioners 55 for which the step calorie information of each vehicle exceeds threshold C exceeds threshold D, which is a fourth threshold (step S22). If the number of air conditioners 55 for which the step calorie information of each vehicle exceeds threshold C is equal to or less than threshold D (step S22, No), it determines that there has been no significant change in the load state of the air conditioners 55, and maintains the current state (step S16). Thereafter, the processing from step S11 is repeated.

[0048] Returning to step S22, if the number of air conditioners 55 whose step calorie information of each car exceeds threshold C exceeds threshold D (step S22, Yes), the control unit 22 determines that the operating state of the air conditioners 55 in the train is in a high load state or will transition to a high load state, and cancels the paused operation (step S18). Thereafter, the processing from step S11 is repeated.

[0049] As described above, in the pause operation control according to the second embodiment, the collection device determines whether the first power information exceeds a third threshold value that is smaller than the second threshold value, and determines the number of air conditioners whose first power information exceeds the third threshold value and transmits that number to the power supply devices. A specific power supply device among the power supply devices cancels pause operation if the current value detected by the current detector exceeds the first threshold value and the second power information exceeds the second threshold value, or if the current value detected by the current detector exceeds the first threshold value and the number of air conditioners whose first power information exceeds the third threshold value exceeds a fourth threshold value. This allows for a simple and reliable transition to pause operation, similar to the first embodiment. Furthermore, compared to the first embodiment, the determination process includes two additional threshold values, further improving the reliability of the pause operation cancellation process.

[0050] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, and parts of the configurations may be omitted or modified without departing from the spirit of the invention. [Explanation of symbols]

[0051] 1, 1A, 1B power supply unit, 2 power supply system, 10 power conversion unit, 11 current detector, 12 output contactor, 13, 14 voltage detector, 15 common bus, 20 inverter, 22 control unit, 50 overhead line, 52 current collector, 54 load inside vehicle, 55 air conditioning unit, 56 collector, 300 processor, 302 memory, 303 processing circuit, 304 interface.

Claims

1. A power supply system for a railway vehicle, the power supply system including a plurality of power supply devices mounted on a vehicle of a train and configured to supply AC power in parallel to a plurality of air conditioning devices in the train via output contactors and a common bus, each of the air conditioners generates first power information that is information about the power required for the space to be air-conditioned; a collection device that collects the first power information generated by each of the air conditioners and calculates second power information by adding up a plurality of the first power information; the output contactor is provided for each of the power supply devices; a current detector is provided between each of the power supplies and the corresponding output contactor; the power supply device determines whether to suspend power supply to the air conditioner based on the second power information transmitted from the collection device; When the current value detected by the current detector is equal to or less than a first threshold value and the second power information is equal to or less than a second threshold value, a specific power supply device among the power supply devices transitions to a pause operation and pauses the supply of power to the air conditioner. A power supply system for a railway vehicle.

2. A specific power supply device among each of the power supply devices cancels the pause operation when the current value detected by the current detector exceeds a first threshold value and the second power information exceeds a second threshold value.

2. The power supply system for a railway vehicle according to claim 1.

3. The collecting device determines whether the first power information exceeds a third threshold value that is smaller than the second threshold value, and determines the number of air conditioning devices whose first power information exceeds the third threshold value, and transmits this number to the power supply device; A specific power supply device among the power supply devices cancels the pause operation when the current value detected by the current detector exceeds a first threshold and the second power information exceeds a second threshold, or when the current value detected by the current detector exceeds the first threshold and the number of air conditioners whose first power information exceeds the third threshold exceeds a fourth threshold.

2. The power supply system for a railway vehicle according to claim 1.

4. The specific power supply is changed daily or on a pre-set rotation.

4. The power supply system for a railway vehicle according to claim 1.

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