DC power distribution system and DC switchboard

Abstract

The present invention provides a DC power distribution system and a DC switchboard which make it possible to flexibly establish a power distribution path in accordance with the configuration or state of equipment. In the present invention, DC wiring LNd forms DC loop wiring by making a round through at least two DC switchboards 1 among a plurality of DC switchboards 1. A first DC switchboard 1B, which is one of the plurality of DC switchboards 1, has a bidirectional DC / DC converter 11A and is configured to enable connection, via the bidirectional DC / DC converter 11A, of a DC power storage device 4 that stores DC power. A power distribution system control device 6 adjusts power flow in the DC wiring LNd by controlling the bidirectional DC / DC converter 11A.

Description

DC power distribution system and DC switchboard

[0001] The present invention relates to a DC power distribution system and a DC power distribution panel.

[0002] Patent Literature 1 (JP 2015-163032 A) discloses a power supply system that supplies power from a DC power supply device to a load device via a power supply path. A switch unit is inserted in the power supply path. Also disclosed are a dendritic power supply path, a bus power supply path, and a loop power supply path as connection configurations of the power supply path. In a dendritic power supply path, a load device is connected to the end of a path that branches out in a dendritic shape. In a bus power supply path, a distribution board is connected to the end of a branch from a branch point on the bus. In a loop power supply path, multiple load devices are connected to a loop wiring connected to a single distribution board.

[0003] JP 2015-163032 A

[0004] In recent years, renewable energy has become increasingly popular as a measure to combat global warming. Among these, solar power generation, which is easy to install, has attracted particular attention. As part of efforts to improve energy utilization efficiency in solar power generation, a DC power distribution system is being considered, which distributes DC power generated by solar power generation to loads without converting it to AC.

[0005] Furthermore, if a power storage device is installed in addition to solar power generation, surplus solar power can be stored. This will enable operations such as promoting private use, reducing energy costs by charging and discharging in accordance with fluctuations in retail electricity prices, and backing up important loads in the event of a disaster. As with solar power generation, power storage devices are also expected to improve utilization efficiency through DC power distribution.

[0006] For example, when a DC power distribution path is to be widely installed across an entire floor of a factory facility, it is possible to use a power distribution path such as a dendritic, bus-based, or loop-based path as shown in Patent Document 1. It is also possible to insert a switch into the power distribution path. With such a configuration, it is possible to limit the power distribution range by opening or closing the switch to stop power distribution to a specific range. However, it has been difficult to flexibly configure a power distribution path according to the configuration or situation of the facility when, for example, the configuration of the facility is changed, or when the operating status of the facility or the power generation status of solar power generation changes.

[0007] The present invention has been made in consideration of the above, and one of its objects is to provide a DC power distribution system or DC distribution panel that can flexibly construct a power distribution path according to the configuration or situation of the equipment.

[0008] The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[0009] A DC power distribution system according to one embodiment includes a plurality of DC distribution panels that distribute input DC power, DC wiring that transmits the DC power between the plurality of DC distribution panels, and a power distribution system control device that performs overall control of the plurality of DC distribution panels. The DC wiring forms a DC loop wiring by making a circuit through at least two or more of the plurality of DC distribution panels. A first DC distribution panel, which is one of the plurality of DC distribution panels, has a bidirectional DC / DC converter and is configured to be connectable to a DC storage device that stores DC power via the bidirectional DC / DC converter. The power distribution system control device adjusts the power flow on the DC wiring by controlling the bidirectional DC / DC converter.

[0010] According to the embodiment, it is possible to flexibly construct a power distribution path according to the configuration or situation of the facility.

[0011] 5A is a schematic diagram showing an example of the configuration of a DC power distribution system according to a first embodiment. FIG. 5B is a schematic diagram showing an example of the configuration of a DC power distribution system obtained by expanding the configuration shown in FIG. 1. FIG. 5C is a perspective view showing an example of the internal configuration of a DC distribution panel in FIG. 1. FIG. 5D is a block diagram showing an example of the configuration of a power distribution system control device in FIG. 1. FIG. 5E is a circuit diagram showing an example of the configuration of a bidirectional DC / DC converter, which is one form of a DC / DC converter, in FIG. 1. FIG. 5F is a block diagram showing an example of the configuration of a DC / DC converter controller in FIG. 5A. FIG. 5G is a schematic diagram showing an example of an electric circuit model constructed by the power flow simulation unit in FIG. 4. FIG. 6 is a schematic diagram showing an example of a power flow change when a parameter value is changed in the electric circuit model shown in FIG. 6. FIG. 6G is a schematic diagram explaining an example of a detection algorithm of a noise detection unit in FIG. 4. FIG. 6H is a schematic diagram explaining an example of a detection algorithm of a noise detection unit in FIG. 4. FIG. 6I is a schematic diagram explaining an example of a detection algorithm of a noise detection unit in FIG. 4. FIG. 6I is a schematic diagram explaining an example of a detection algorithm of a noise detection unit in FIG. 4. FIG. 6I is a schematic diagram explaining an example of a detection algorithm of a noise detection unit in FIG. 4. FIG. 6I is a perspective view showing an example of an arrangement configuration when a DC power distribution system according to a second embodiment is applied to equipment. Fig. 10A is a plan view showing a schematic arrangement example when the DC power distribution system shown in Fig. 9 is seen from above. Fig. 10B is a plan view showing an arrangement example obtained by modifying the arrangement shown in Fig. 10A.

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments are examples for explaining the present invention, and appropriate omissions and simplifications have been made for clarity of explanation. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be singular or plural. The position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc., in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.

[0013] Although various types of information may be described using expressions such as "table," "list," and "queue" as examples, the various types of information may also be expressed using data structures other than these. For example, various types of information such as "XX table," "XX list," and "XX queue" may also be expressed as "XX information." When describing identification information, expressions such as "identification information," "identifier," "name," "ID," and "number" are used, but these are interchangeable.

[0014] Furthermore, when there are multiple components having the same or similar functions, they may be described by adding different subscripts to the same reference numeral. For example, one component may be designated by the reference numeral "1," and multiple components may be distinguished by "1A," "1B," etc. When it is not necessary to distinguish between these multiple components, the subscripts may be omitted.

[0015] In the embodiments, there may be described processes performed by executing a program. As an example, a computer executes a program using a processor (e.g., a CPU or a GPU) and performs the processes defined in the program while using storage resources (e.g., memory) and interface devices (e.g., communication ports). Therefore, the entity performing the processes by executing the program may be the processor. Alternatively, the entity performing the processes by executing the program may be a controller, device, system, computer, or node having a processor.

[0016] Furthermore, the processing performed by executing the program may be performed by a computing unit, and may include a dedicated circuit for performing specific processing, such as a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), or a complex programmable logic device (CPLD).

[0017] A program may be installed on a computer from a program source. The program source may be, for example, a program distribution server or a computer-readable storage medium. When the program source is a program distribution server, the program distribution server may include a processor and storage resources for storing the program to be distributed, and the processor of the program distribution server may distribute the program to be distributed to other computers. In addition, in the embodiments, two or more programs may be realized as one program, or one program may be realized as two or more programs.

[0018] (First embodiment) <Configuration of DC power distribution system> Fig. 1 is a schematic diagram showing an example of the configuration of a DC power distribution system according to a first embodiment. The DC power distribution system shown in Fig. 1 is applied to various facilities, such as a production factory. The DC power distribution system includes a plurality of DC distribution boards 1A, 1B, and 1C (three in this example), a plurality of DC switches 5 (three in this example), a distribution system control device 6, and an energy management device 7. Each DC distribution board 1 distributes input DC power. That is, the plurality of DC distribution boards 1 are interconnected via DC wiring LNd and transmit DC power via the DC wiring LNd.

[0019] Here, the DC wiring LNd forms a DC loop wiring by making a circuit via at least two or more of the multiple DC distribution boards 1. In this example, the DC loop wiring is formed via three DC distribution boards 1A, 1B, and 1C, but it can also be formed as a minimum unit via two DC distribution boards 1. Each DC distribution board 1 mainly includes a DC branch unit 10, a DC / DC converter 11, a current sensor 12, a DC circuit breaker 13, and a distribution board controller 14.

[0020] The DC branch unit 10 is part of a power circuit that connects multiple DC wirings LNd drawn out to the outside and aggregates or branches the multiple DC wirings LNd, and is made of a conductive material such as a copper bar or a terminal block. The DC / DC converter 11 is connected to the DC branch unit 10 via power supply wiring LNp. The DC / DC converter 11 converts power between a DC terminal on the primary side and a DC terminal on the secondary side. In this specification, the terminal connected to the DC branch unit 10 is referred to as the secondary side.

[0021] The current sensor 12 measures the current of each wiring connected to the DC branch section 10. In this example, the current sensor 12 measures the current flowing in the power supply wiring LNp connected to the DC / DC converter 11, the load power line LNl connected to the external DC load 2 via the DC circuit breaker 13, and the multiple DC wirings LNd connected to the outside.

[0022] The DC circuit breaker 13 is a circuit breaker for connecting the DC load 2 provided outside the DC distribution panel 1 to the DC branch unit 10, and is inserted into the load power line LN1 that connects the DC load 2 and the DC branch unit 10. Specifically, when an abnormal current occurs in the load power line LN1 due to a ground fault, a short circuit, or the like, the DC circuit breaker 13 detects the abnormal current and cuts off the path of the load power line LN1. In this way, the DC circuit breaker 13 protects other DC systems connected to the DC branch unit 10.

[0023] In this example, a DC distributed power source 3 is connected to the primary side of a DC / DC converter 11A included in a DC distribution panel (second DC distribution panel) 1A. The DC distributed power source 3 may be, for example, a solar power generation panel or a current collection box connected to the panel. In this case, the DC / DC converter 11A only needs to have a one-way power conversion function from the primary side to the secondary side. When a solar power generation panel is used, it is desirable to have a function such as maximum power point tracking control, which searches for a maximum power point by manipulating the terminal voltage in response to the amount of solar radiation. This function may be installed in, for example, the DC / DC converter 11, the distribution panel controller 14, or the energy management device 7.

[0024] Meanwhile, a DC storage device 4 is connected to the primary side of a DC / DC converter 11B included in the DC distribution board (first DC distribution board) 1B. Examples of the DC storage device 4 that can be used include a lithium ion battery, a lead storage battery, an electric double layer capacitor, a lithium ion capacitor, and an electrolytic capacitor. The DC / DC converter 11B when connected to the DC storage device 4 is preferably a bidirectional DC / DC converter. The bidirectional DC / DC converter has a bidirectional power conversion function in a direction from the primary side to the secondary side and a direction from the secondary side to the primary side.

[0025] As in this example, by connecting a DC distributed power source 3 to the DC distribution panel 1A and a DC storage device 4 to the DC distribution panel 1B and configuring the DC distribution panels 1 at both ends to be able to distribute power through DC wiring LNd, it becomes possible to operate the system in a way that increases energy self-sufficiency using renewable energy, for example. That is, for example, if the DC generated power generated by the DC distribution panel 1A is surplus compared to the consumption by the DC load 2A, this surplus power can be charged to the DC storage device 4 of the DC distribution panel 1B. The power charged to the DC storage device 4 can then be used, for example, when there is a shortage of DC generated power or during a disaster.

[0026] When using the DC storage device 4, it is desirable to provide a function for managing the state of charge (SOC), for example, in order to prevent overcharging that may occur due to a finite storage energy capacity. This function may be provided in, for example, the switchboard controller 14 or the energy management device 7.

[0027] The DC switch 5 is inserted into the DC wiring LNd and is configured to be able to open and close two terminals. In this example, one DC switch 5 is inserted into each of the three DC wirings LNd that connect the multiple DC distribution boards 1A, 1B, and 1C to one another. The DC switch 5 is opened and closed for various purposes. For example, the DC switch 5 can be opened and closed for the purpose of reducing wiring loss depending on the status of the power generation in the system and the power consumption of the DC load 2. Alternatively, the DC switch 5 can be opened and closed for the purpose of locally isolating some DC distribution boards 1 for periodic maintenance.

[0028] The switchboard controller 14 can be realized, for example, by a wiring board equipped with a microcontroller including a processor, a memory, and an external communication interface. The switchboard controller 14 controls the entire DC switchboard 1. As one of its functions, the switchboard controller 14 acquires information from the current sensor 12 and the DC / DC converter 11 provided inside the DC switchboard 1, and further transmits and receives information to and from the externally provided power distribution system control device 6 or a switchboard controller 14 included in another DC switchboard 1. The switchboard controller 14 then controls the DC / DC converter 11 by providing a command value to the DC / DC converter 11 based on the acquired information.

[0029] The switchboard controller 14 may also include a DC switch operating circuit that drives the DC switch 5 to open or close. The DC switch operating circuit includes, for example, a driver circuit that outputs a drive signal for opening or closing the DC switch 5. In this case, the switchboard controller 14 drives the DC switch 5 installed nearby to open or close in response to an opening or closing command from an external device, for example, the power distribution system control device 6.

[0030] Each of the power distribution system control device 6 and the energy management device 7 can be realized by, for example, a computer system including a processor, a memory, and an external communication interface. The power distribution system control device 6 mainly controls the overall operation of the DC power distribution system. As one of its functions, the power distribution system control device 6 adjusts the power flow in the DC wiring LNd, i.e., the DC loop wiring, by controlling the DC / DC converter 11. On the other hand, the energy management device 7 mainly manages the power generated or consumed in the entire DC power distribution system.

[0031] In this example, the power distribution system control device 6 and the energy management device 7 are provided separately, but since both are devices that communicate and control the DC distribution board 1, it is also possible to provide a single management device that integrates both functions. Alternatively, a system configuration may be used in which some functions, such as the functions of the energy management device 7, are implemented on a cloud server, and the remaining functions are implemented on site equipment such as a production factory, and the two are operated in cooperation with each other.

[0032] Fig. 2 is a schematic diagram showing an example of the configuration of a DC power distribution system that is an extension of the configuration shown in Fig. 1. The DC power distribution system shown in Fig. 2 includes one DC distribution board 1D in addition to the three DC distribution boards 1A, 1B, and 1C shown in Fig. 1. For example, the DC distribution board 1A inputs or outputs power Pa to or from the outside based on the difference between the power generated by the DC distributed power source 3 and the power consumed by the DC load 2A as shown in Fig. 1. Similarly, the DC distribution boards 1B, 1C, and 1D input or output power Pb, Pc, and Pd to or from the outside, respectively, based on the power from the DC distributed power source 3 or the DC energy storage device 4 and the power from the DC load 2.

[0033] When such a configuration is used, a DC loop wiring LP1 is formed by three DC wirings LNd between three DC distribution boards 1A, 1B, and 1C, as in the case of Fig. 1. In addition to this, another DC loop wiring LP2 is formed by three DC wirings LNd between three other DC distribution boards 1B, 1C, and 1D. In this specification, a distribution path in which multiple DC loop wirings are arranged in a grid or mesh pattern like this is called a mesh-like distribution path.

[0034] In this example, two DC loop wirings LP1 and LP2 are formed, but for example, three or four DC loop wirings can be formed by adding another DC distribution board 1. In a mesh-shaped power distribution path, at least one of the multiple DC distribution boards 1, in the example shown in Fig. 2, each of the two DC distribution boards 1B and 1C, is commonly connected to the multiple DC loop wirings LP1 and LP2.

[0035] As described above, by forming a DC loop wiring via multiple DC distribution panels 1, it is possible to flexibly configure a power distribution path according to the status of the facility. As an example, in Fig. 1, even if there is a shortage of generated power from the DC distributed power source 3 connected to the DC distribution panel 1A, power can be supplied from the DC energy storage device 4 connected to the DC distribution panel 1B to the DC loop wiring and, in turn, to the DC loads 2A, 2B, and 2C connected to the DC loop wiring. Alternatively, for example, even if a fault occurs in the clockwise power distribution path for a specific DC load 2, a counterclockwise alternative path can be secured.

[0036] 1, for example, a wiring topology can be constructed in which the power flow in the DC wiring LNd between adjacent DC distribution boards 1, three DC wirings LNd in this example, can be individually adjusted by the input power or output power of the three DC distribution boards 1A, 1B, and 1C. Therefore, the power flow in each DC wiring LNd can be finely adjusted according to the configuration or situation of the facility, and as a result, a power distribution path can be flexibly constructed according to the configuration or situation of the facility.

[0037] Furthermore, by using a mesh-type power distribution path as shown in Fig. 2, a power distribution path can be flexibly constructed according to the configuration or situation of the facility. That is, for example, if a mesh-type power distribution path is formed in advance in a facility such as a production factory, even if the configuration or layout of devices within the facility changes, or if the operating status of the facility or the power generation status of solar power generation changes, a suitable power distribution path can be flexibly constructed according to the changes. Specifically, for example, in order to reduce power transmission loss, a power distribution path can be determined using a DC switchgear 5, and the power flow in the power distribution path, more specifically, in each DC wiring LNd, can be adjusted using a DC distribution panel 1.

[0038] In addition, for example, in a power distribution route based on a tree-like, bus-based, or loop-based system, as shown in Patent Document 1, changing the configuration of the equipment may require re-laying of power sources. Furthermore, in such a power distribution route, it is difficult to finely adjust the power flow. Furthermore, in a tree-like power distribution route, for example, batteries must be placed in the main system, and the branch circuits must be started up sequentially. On the other hand, in a mesh-like power distribution route, a stepwise start-up is possible, in which a section that can be supplied with power by arbitrarily placed batteries is first started up and stabilized, and then the section is gradually expanded. This allows for flexible backup start-up, especially in emergencies.

[0039] <Details of DC Distribution Panel> Fig. 3 is a perspective view showing an example of the internal configuration of the DC distribution panel 1 in Fig. 1. The DC distribution panel 1 shown in Fig. 3 is configured with a single housing 17 that houses a plurality of components. The plurality of components include DC power storage devices 4A, 4B, DC branch units 10P, 10N, a DC / DC converter 11, current sensors 12G, 12L, 12B, DC circuit breakers 13A, 13B, 13C, a distribution panel controller 14, and an overcurrent protection element 15. In this example, the DC / DC converter 11 is a bidirectional DC / DC converter.

[0040] A plurality of DC wirings LNd drawn out to the outside are connected to the positive and negative DC branch sections 10P, 10N. As described in FIG. 1 , the plurality of DC wirings LNd transmit power to and from other DC distribution boards 1. To form a DC loop wiring, at least two or more DC wirings LNd are connected to the DC branch section 10; in this example, three or three pairs of DC wirings LNd1, LNd2, and LNd3 are connected. Any one of the plurality of DC wirings LNd is connected to any other one of the plurality of DC wirings LNd via an external wiring path.

[0041] The first current sensor 12G measures the currents in the three DC wirings LNd1, LNd2, and LNd3. The second current sensor 12L measures the current in the load power line LNl connecting the DC branch unit 10 and the DC circuit breaker 13. The third current sensor 12B measures the current in the power supply wiring LNp connecting the DC branch unit 10 and the DC / DC converter 11.

[0042] The overcurrent protection element 15 is formed of, for example, a fuse or a thermistor, and is inserted into a portion of the wiring within the panel, in this example, the power wiring LNp. By providing the overcurrent protection element 15, a safety measure can be realized, such as preventing the spread of effects in the event of an overcurrent caused by a short circuit in the circuit before or after the element 15. In this example, the distribution panel controller 14 is equipped with a DC switch operating circuit as described in FIG. 1. As a result, the distribution panel controller 14 drives the DC switch 5 to open or close in response to an opening or closing command from, for example, the power distribution system control device 6.

[0043] 3, the DC power storage device 4 is housed inside the housing 17 that constitutes the DC switchboard 1. Two DC power storage devices 4A, 4B are connected to two power storage device terminals provided on the DC / DC converter 11. By configuring the DC / DC converter 11 in this way so that a plurality of DC power storage devices 4 can be connected, even if a failure occurs in the DC power storage device 4A, the system can continue to operate using the DC power storage device 4B.

[0044] When the DC storage device 4 is configured as a storage module in which a plurality of cells are connected in series or in parallel, it is desirable to provide a storage controller 4C that manages the voltage of the cells inside, as shown in Fig. 3. The storage controller 4C manages the voltage of such cells by, for example, communicating with a controller in the DC storage device 4 and the DC / DC converter 11.

[0045] 3, when the DC distribution board 1 is configured with a substantially rectangular parallelepiped housing 17, it is desirable that a first wiring hole 18a be provided in an upper portion of the housing 17 and a second wiring hole 18b be provided in a lower portion thereof. The first wiring hole 18a is a hole for drawing out the DC wiring LDd connected to the DC branch section 10 to the outside. The second wiring hole 18b is a hole for drawing out the load power line LNl connected to the DC branch section 10 to the outside. The load power line LNl is connected to an external DC load 2 via a primary DC circuit breaker 13A and secondary DC circuit breakers 13B and 13C.

[0046] By using such a DC distribution board 1, a mesh-shaped power distribution path such as that shown in FIG. 2 can be easily constructed. This internal layout configuration of the DC distribution board 1, details of which will be described in FIG. 9, makes it easier to incorporate the DC distribution board 1 into equipment in terms of equipment layout. Furthermore, power is transmitted in the order of the primary DC circuit breaker 13A and then the secondary DC circuit breakers 13B and 13C, which is excellent at preventing operational errors. In this specification, directions horizontal to the ground are referred to as the X-axis and Y-axis directions, and a direction perpendicular to the ground is referred to as the Z-axis direction. Up and down refer to the relative positional relationship in the Z-axis direction.

[0047] 3, the DC storage device 4 is provided below the DC / DC converter 11, and the DC branching section 10 is provided above the DC / DC converter 11. This allows, for example, when an insulated DC / DC converter 11 is used, to clearly insulate the DC storage device 4 from the DC branching section 10, thereby strengthening the prevention of contact between the DC / DC converter 11.

[0048] The space for accommodating the DC power storage device 4 is provided below the housing 17. This facilitates the replacement of the DC power storage device 4, which is generally heavy and has a short lifespan. Furthermore, since the DC power storage device 4 is generally a heat-generating component, taking in outside air at a relatively low position can effectively promote cooling.

[0049] <Details of the power distribution system control device> Figure 4 is a block diagram showing an example configuration of the power distribution system control device 6 in Figure 1. The configuration shown in Figure 4 is realized, for example, by a computer system including a processor and a memory, and can be realized mainly by program processing using the processor. The power distribution system control device 6 includes a wiring information storage unit 61, an operation policy information storage unit 62, a switching state acquisition unit 63, a power flow state acquisition unit 64, a noise detection unit 65, a power flow simulation unit 66, a switching operation unit 67, and a voltage adjustment unit 68.

[0050] The wiring information storage unit 61 stores in advance information on the connection relationships between multiple DC distribution boards 1 via the DC wiring LNd. Specifically, the wiring information storage unit 61 stores, for example, information on which DC distribution board 1 both ends of each DC wiring LNd are connected to and to which position in the DC branch unit 10 the wiring information storage unit 61 is connected to, as well as information on the type of DC wiring LNd, wiring resistance, and heat resistance index. The operation policy information storage unit 62 stores information on predetermined system operation policies, such as evaluation index items and target values. The wiring information storage unit 61 and the operation policy information storage unit 62 are realized by memories.

[0051] The switching state acquisition unit 63 acquires the switching state of the DC switch 5, for example, by communicating with the DC switch 5 or by communicating with the switchboard controller 14 that is responsible for driving the switching of the DC switch 5. The power flow state acquisition unit 64 acquires power flow information of the DC wiring LNd. In detail, the power flow state acquisition unit 64 acquires information detected by each current sensor 12, information on the current and voltage detected in the DC / DC converter 11, and the like, by communicating with each switchboard controller 14. This makes it possible to determine the state of the current flowing through each DC wiring LNd, the state of the voltage applied to each DC wiring LNd, and the like, throughout the DC power distribution system.

[0052] The noise detection unit 65, details of which will be described later, detects that a noise current has been superimposed on the DC loop wiring based on the information acquired by the open / close status acquisition unit 63 and the power flow status acquisition unit 64. It is generally known that when electromagnetic external noise occurs in a ring-shaped conductor, a return current is induced by electromagnetic induction. The return current caused by noise causes an error when determining the power flow of the entire system.

[0053] Therefore, by identifying the noise current, it becomes possible to perform a process to cancel out the error. Specifically, the power distribution system control device 6 can correct the data acquired by the power flow status acquisition unit 64, such as current data, so as to cancel out the current change due to noise. Alternatively, the power distribution system control device 6 can suppress the generation of noise current itself by switching to an open state some of the DC switches 5 on the DC loop wiring where noise is generated. In a mesh-type power distribution route, power distribution to the DC load 2 can be maintained even if some of the loops are opened in this way.

[0054] The power flow simulator 66 constructs an electric circuit model and parameters representing voltage, current, or power values ​​on the electric circuit model based on the information stored in the wiring information storage unit 61 and the information acquired by the switching state acquisition unit 63 and the power flow state acquisition unit 64. The power flow simulator 66 then predicts and calculates power flow changes when the values ​​of the predetermined parameters are changed. Alternatively, the power flow simulator 66 predicts and calculates power flow changes when the switching state of the DC switch 5 is changed.

[0055] As an example, the power flow simulation unit 66 predicts and calculates a power flow change when the DC voltage of any DC distribution board 1 is changed from the current operating state. Alternatively, the power flow simulation unit 66 predicts a power flow change and a terminal voltage change of multiple DC distribution boards 1 when the DC power of any bidirectional DC / DC converter is changed from the current operating state. Then, while performing such parameter scanning, the power flow simulation unit 66 identifies parameter conditions that cause the evaluation index defined in the operation policy information storage unit 62 to approach the target value. For example, the power flow simulation unit 66 identifies how much the DC voltage from each DC distribution board 1 should be adjusted.

[0056] The switching operation unit 67 outputs a switching command to a predetermined DC switch 5 or to the switchboard controller 14 that drives the switching, based on the prediction calculation result of the power flow simulation unit 66. That is, the switching operation unit 67 determines whether or not changing the open / close state of the predetermined DC switch 5 will bring the evaluation index closer to the target value, based on the prediction calculation result of the power flow simulation unit 66, and changes the open / close state so that the evaluation index approaches the target value.

[0057] Furthermore, the switching operation unit 67 outputs a switching command to a predetermined DC switch 5 or the switchboard controller 14 to open the loop based on the detection result of the noise detection unit 65. When such a switching operation unit 67 is provided, the switching state acquisition unit 63 may be configured to acquire the operation result of the switching operation unit 67.

[0058] Based on the prediction calculation result of the power flow simulation unit 66, the voltage adjustment unit 68 outputs a voltage adjustment command value ΔV ＊ That is, the voltage adjustment unit 68 notifies the DC distribution panel 1 identified by the power flow simulation unit 66 of the specified voltage adjustment amount. Also, as will be described in detail later, even when the switching operation unit 67 outputs an opening / closing command for any DC switch 5, the voltage adjustment unit 68 notifies the DC distribution panel 1 identified by the power flow simulation unit 66 of the specified voltage adjustment amount in order to reduce damage to the DC switch 5.

[0059] In this way, by providing the power distribution system control device 6 equipped with the power flow simulation unit 66, in other words, a circuit simulator, it becomes possible to sequentially optimize the operation of the DC power distribution system, specifically the power flow state, etc., based on the system operation policy. Also, by providing the noise detection unit 65, it becomes possible to detect noise currents that may be side effects of DC loop wiring, and to take measures to reduce the effects of the noise currents.

[0060] <Details of Bidirectional DC / DC Converter> Fig. 5A is a circuit diagram showing an example configuration of a bidirectional DC / DC converter, which is one form of DC / DC converter 11 in Fig. 1. Fig. 5B is a block diagram showing an example configuration of DC / DC converter controller 110 in Fig. 5A. The bidirectional DC / DC converter shown in Fig. 5A includes primary-side terminals PNp1 and PNn1, secondary-side terminals PNp2 and PNn2, a main circuit that converts power between the two terminals, and DC / DC converter controller 110 that controls the main circuit.

[0061] The main circuit includes an isolation transformer 112 that isolates the primary side from the secondary side, a group of semiconductor switches 111 in a bridge configuration that drives the primary side of the isolation transformer 112, a group of semiconductor switches 113 in a bridge configuration that drives the secondary side of the isolation transformer 112, and DC capacitors 114 and 115 connected to the secondary side. To promote energy transfer by switching, an inductance element or capacitance element (not shown) may be added to the primary or secondary side. This type of main circuit is called a dual active bridge (DAB) and can exchange power in both directions.

[0062] As an example, in a DAB, the magnitude and direction of power transmission can be controlled by controlling the phase difference between the switching phase of semiconductor switch group 111 and the switching phase of semiconductor switch group 113. Note that the main circuit of DC / DC converter 11 is not limited to DAB, and various configurations can be applied. That is, an appropriate main circuit can be selected by appropriately combining unidirectional / bidirectional and isolated / non-isolated types depending on the system configuration and application.

[0063] This example also shows a system in which a capacitor group consisting of a plurality of series-connected DC capacitors 114, 115 is connected between the secondary terminals PNp2, PNn2 of the DC / DC converter 11, and the neutral point of the capacitor group is grounded. By using such a system, the voltage difference between the ground voltage GND and the secondary voltage can be reduced, which makes it easier to select and test voltage-resistant components and reduces the cost of the system.

[0064] The DC / DC converter controller 110 receives detection information such as a primary voltage V1, a primary current I1, secondary voltages V2H and V2L, and secondary currents I2H and I2L detected using sensors. The DC / DC converter controller 110 then controls the conversion operation of the main circuit based on an operation command value obtained from an external communication terminal Com_M, internal information of the DC power storage device 4 collected from a power storage controller communication terminal Com_B, and the input detection information. In this example, the DC / DC converter controller 110 controls the switching operation of the semiconductor switch group 111 using control signals SW11-SW14, and controls the switching operation of the semiconductor switch group 113 using control signals SW21-SW24.

[0065] The external communication terminal Com_M is connected to the power distribution board controller 14 in Fig. 1 and Fig. 2. The power storage controller communication terminal Com_B is connected to the power storage controller 4C in Fig. 3. The DC / DC converter controller 110 can be realized, for example, by program processing using a processor in a microcontroller, or by an FPGA or the like.

[0066] 5B, the DC / DC converter controller 110 includes a charge / discharge power control unit 116, a voltage adjustment control unit 117, a storage-side charge / discharge control unit 118, and a maximum power point tracking control unit 119. The charge / discharge power control unit 116 receives a charge / discharge power command value P ＊ and the information detected by the sensors (V2H, V2L, I2H, I2L). ＊can be changed as appropriate, for example, taking into account reduction in energy costs.

[0067] The voltage adjustment control unit 117 receives the voltage adjustment command value ΔV from the power distribution system control device 6 shown in FIG. 4 via the power distribution board controller 14 and the external communication terminal Com_M. ＊ and the information (V2H, V2L) detected by the sensors, the storage-side charge / discharge control unit 118 generates a second command value. The storage-side charge / discharge control unit 118 controls the voltage or current of the DC power storage device 4 based on the first command value from the charge / discharge power control unit 116 and the second command value from the voltage adjustment control unit 117.

[0068] A storage battery, which is a typical example of the DC storage device 4, charges and discharges power through chemical reactions according to the amount of charge. For this reason, it is desirable to apply control based on the integrated current value of the storage battery. Therefore, in the example shown in FIG. 5B , the storage-side charge / discharge control unit 118, which is the final control stage, is configured with a primary-side current control system, and controls the DC storage device 4 side, i.e., the primary-side current command value I1, which is generated based on the first command value and the second command value. ＊ The storage side charge / discharge control unit 118 inputs the value of the primary side current I1 and the primary side current command value I1 ＊ The control signals SW11 to SW14 and SW21 to SW24 are generated so that the error between the two approaches zero.

[0069] 5B also shows a configuration example in which a solar power generation panel is connected instead of the DC storage device 4. When a solar power generation panel is connected, the DC / DC converter controller 110 may include a maximum power point tracking control unit 119 that executes maximum power point tracking control as described in FIG. 1. The maximum power point tracking control unit 119 is, for example, configured as a primary side voltage control system, and receives input of a primary side voltage V1 and a primary side current I1 to calculate a primary side voltage command value V1. ＊ The storage-side charge / discharge control unit 118 generates a value of the primary-side voltage V1 and a primary-side voltage command value V1 ＊ The error is controlled to approach zero.

[0070] <Operation of the Power Flow Simulation Unit> Fig. 6 is a schematic diagram showing an example of an electric circuit model constructed by the power flow simulation unit 66 in Fig. 4. Fig. 6 shows a circuit model in which all DC switches 5 are in the closed state in the meshed power distribution route shown in Fig. 2. The power flow simulation unit 66 uses this circuit model to predict and calculate, for example, the effect of the voltage of the DC distribution board 1 on the power flow in the DC wiring LNd.

[0071] 6, as in the case of FIG. 2, four DC distribution boards 1A, 1B, 1C, and 1D are provided, and these are connected to each other by five DC wirings LNd, thereby forming two triangular DC loop wirings LP1 and LP2 in a mesh pattern. The voltages of the DC branch sections 10 in the four DC distribution boards 1A, 1B, 1C, and 1D are given by Va, Vb, Vc, and Vd, respectively. The resistance values ​​of the five DC wirings LNd are given by Ra, Rb, Rc, Rd, and Re, respectively.

[0072] The power balance for the DC loop wiring in the four DC distribution boards 1A, 1B, 1C, and 1D is given by Pa, Pb, Pc, and Pd, respectively. The power balance is the power equivalent to the difference between the power inflow from the DC distributed power source 3 and the power consumption in the DC load 2, or the power equivalent to the difference between the charging / discharging power of the DC energy storage device 4 and the power consumption in the DC load 2.

[0073] Fig. 7 is a schematic diagram showing an example of power flow changes when parameter values ​​are changed in the electric circuit model shown in Fig. 6. In Fig. 7, the powers Pa, Pb, Pc, and Pd in ​​Fig. 6 are shown as bar graphs, and the voltages Va, Vb, Vc, and Vd are shown as line graphs. In Case A in Fig. 7, under the condition that the impedances (here, resistance values) of the DC wiring LNd are the same, for example, power Pa is generated in the DC distribution board 1A and power Pd is consumed in the DC distribution board 1D.

[0074] 7, with Case A as the reference, in DC distribution panel 1B, power Pb is discharged from the DC storage device 4, and in DC distribution panel 1C, power Pc is charged to the DC storage device 4. As can be seen from a comparison between Case A and Case B, while powers Pa and Pd and voltages Va and Vd are common, by manipulating power Pb and power Pc, it is possible to create a situation in which voltages Va and Vb are approximately the same, and voltages Vc and Vd are approximately the same.

[0075] In this way, by manipulating the DC power in the DC distribution boards 1 of the entire system, the voltage between the two terminals of the DC switchgear 5 inserted in any DC wiring LNd can be made closer to each other, thereby limiting the power flow in the DC wiring LNd. As a result, for example, when changing the DC switchgear 5 from a closed state to an open state, the current flowing through the DC switchgear 5 can be reduced, ideally to zero. This makes it possible to reduce damage caused by arc generation accompanying the opening operation of the DC switchgear 5 and extend the life of the DC switchgear 5.

[0076] As a specific example, in Case B, the DC switches 5 (not shown) provided between the DC distribution boards 1A and 1B and between the DC distribution boards 1C and 1D in Fig. 6 can be changed from a closed state to an open state. Even in this case, because a mesh-like power distribution path is used, the power distribution path to the DC loads 2 (not shown) connected to each DC distribution board 1 is maintained.

[0077] While the example described here is a change from a closed state to an open state, the same applies to a change from an open state to a closed state. That is, by changing from an open state to a closed state while the voltage between the two terminals of the DC switch 5 is brought closer to each other, damage caused by inrush currents and the like that accompany the closing operation of the DC switch 5 can be reduced. Furthermore, a state in which the current flowing through the DC switch 5 is zero is equivalent to the DC switch 5 being in an open state. Therefore, from another perspective, it is also possible to switch the distribution path of the meshed power distribution path without the opening and closing operation of the DC switch 5. In this case, the number of opening and closing operations of the DC switch 5 can be reduced, thereby extending the life of the DC switch 5.

[0078] As an example of an actual operation method, first, based on the results of the prediction calculation in the power flow simulation unit 66 in Fig. 4, it is determined that it is better to change the open / closed state of a predetermined DC switch 5. In this case, before outputting an opening / closing command to the predetermined DC switch 5, the switching operation unit 67 outputs information about the opening / closing command to the voltage adjustment unit 68. As a preliminary operation for the opening or closing operation of the predetermined DC switch 5, the voltage adjustment unit 68 uses the power flow simulation unit 66 to adjust the power flow so as to reduce the voltage difference between the two terminals of the predetermined DC switch 5.

[0079] At this time, the voltage adjusting unit 68 outputs a voltage adjustment command value ΔV , which indicates the amount of voltage adjustment, to the bidirectional DC / DC converter via the switchboard controller 14 so as to change the voltage Vb in case A to the voltage Vb in case B, for example. ＊ Similarly, the voltage adjusting unit 68 outputs a voltage adjustment command value ΔV to the bidirectional DC / DC converter via the power distribution board controller 14 so as to change the voltage Vc in case A to the voltage Vc in case B. ＊ Output.

[0080] 7 , unlike Case A, the impedances (here, resistance values) of the DC wiring LNd are non-uniform. In Case C, for example, in the DC distribution panel 1A, the DC distributed power source 3 generates power Pa, and in the DC distribution panel 1D, the DC load 2 consumes power Pd. Furthermore, in the DC distribution panel 1B, the DC storage device 4 is charged with power Pb, and in the DC distribution panel 1C, the DC storage device 4 is discharged with power Pc. Meanwhile, in Case D, unlike Case C, the DC distribution panel 1B discharges power Pb, and the DC distribution panel 1C charges power Pc.

[0081] As can be seen from a comparison between Case C and Case D, while the powers Pa and Pd and the voltages Va and Vd are substantially the same, varying the power Pb and power Pc can reduce the potential difference between the voltages Va and Vb and the potential difference between the voltages Vb and Vc. As a result, power loss throughout the system can be reduced. In this example, wiring loss can be reduced in the DC wiring LNd connecting the DC distribution board 1B and the DC distribution board 1C, and in particular in the DC wiring LNd with high resistance connecting the DC distribution board 1A and the DC distribution board 1B. In this way, the power distribution system control device 6 can adjust the power flow so as to reduce power loss along the power distribution path from the DC distributed power source 3 to the DC load 2 via the DC wiring LNd.

[0082] <Details of Noise Detection Unit> Figures 8A, 8B, 8C, 8D, and 8E are schematic diagrams illustrating an example of a detection algorithm of the noise detection unit 65 in Figure 4. In the example shown in Figure 8A, a DC loop wiring LP is formed by a DC wiring pair LNd-PN that connects four DC distribution boards 1. The DC wiring pair LNd-PN is composed of a positive DC wiring LNd-P and a negative DC wiring LNd-N.

[0083] When the magnetic field lines change direction to pass through the DC loop wiring LP, as shown in FIG. 8B, in-phase noise currents are generated in both the positive DC wiring LNd-P and the negative DC wiring LNd-N. For example, a noise current IA1P on the positive side and a noise current IA1N on the negative side, which are in-phase with the positive side, are generated. If the noise current on the positive side and the noise current on the negative side are added together, an in-phase noise current, for example, "1A1P+1A1N," can be extracted as shown in FIG. 8C.

[0084] 4 acquires the positive and negative currents from a DC distribution panel 1, and the noise detection unit 65 adds the positive and negative currents together. The AC-like current obtained by this addition, for example, "1A1P+1A1N," is an in-phase noise current. That is, unlike in-phase noise current, in a normal current, the sum of the positive and negative currents is zero in AC terms.

[0085] Furthermore, the noise detection unit 65 calculates common-mode noise currents for two or more DC wiring pairs LNd-PN that form the DC loop wiring LP and correlates the calculated two or more common-mode noise currents. As a result, if there is a correlation, the noise detection unit 65 can determine that the common-mode noise current is a return current generated by electromagnetic induction. In the example shown in Figures 8A and 8C, there is a correlation between the common-mode noise current "1A1P + 1A1N" in one DC distribution board 1 and the common-mode noise current "1B1P + 1B1N" in another DC distribution board 1, so the noise detection unit 65 determines that the common-mode noise current is a return current.

[0086] Furthermore, if frequencies that can be expected to be noise can be identified in advance, the noise detection unit 65 may perform filtering to extract the frequency components of one of the positive and negative currents, for example, "1A1P," as shown in Fig. 8D, instead of performing current addition as shown in Fig. 8C. This allows the noise detection unit 65 to extract the noise current "1A1P_fil" as shown in Fig. 8E. Then, similar to the case of Fig. 8C, the noise detection unit 65 may extract noise currents from two or more DC wirings LNd that form the DC loop wiring LP, and calculate correlations with two or more noise currents, for example, "1A1P_fil" and "1B1P_fil."

[0087] In this way, by detecting noise currents from two or more DC wirings LNd or DC wiring pairs LNd-PN and correlating the two or more detected noise currents, it is possible to more reliably determine whether the noise current is a return current. If the noise current is a return current, measures can be taken, such as changing some of the DC switches 5 in the DC loop wiring LP to an open state or correcting the data acquired from the DC switchboard 1 on the DC loop wiring LP.

[0088] When extracting the noise current, in order to exclude noise whose influence can be ignored, an amplitude threshold may be set in advance, and the noise detection unit 65 may be configured to ignore currents with amplitudes smaller than the threshold. Alternatively, a threshold may be set for the amount of change in current over time, and the noise detection unit 65 may be configured to ignore currents with an amount of change over time smaller than the threshold.

[0089] <Major Effects of the First Embodiment> As described above, in the system of the first embodiment, a DC loop wiring that loops around is formed via two or more DC distribution panels. Preferably, a mesh-like power distribution path is constructed by arranging multiple DC loop wirings in a grid or mesh pattern. Using such a configuration makes it possible to flexibly construct a power distribution path according to the configuration or situation of the facility. Furthermore, two or more DC distribution panels can adjust the power flow on the DC wiring connecting the DC distribution panels. This can reduce damage, for example, caused by the opening and closing operations of DC switches inserted in the DC wiring.

[0090] (Second embodiment) <Application example of DC power distribution system> Fig. 9 is a perspective view showing an example of the layout configuration when the DC power distribution system according to the second embodiment is applied to a facility. Fig. 9 shows an example of the layout configuration of each part when the DC power distribution system described in the first embodiment is installed on the floor of a facility such as a production factory. In Fig. 9, four DC distribution boards 1E, 1F, 1G, and 1H are arranged in each of the four corners of a quadrangular, e.g., rectangular, grid. In the entire facility, such grids are arranged sequentially in the X-axis and Y-axis directions.

[0091] The four DC distribution panels 1E, 1F, 1G, and 1H are connected via four DC wiring lines LNd, which correspond to the four sides of the grid. The DC wiring lines LNd are installed, for example, as a ceiling-suspended wiring rack. The DC wiring lines LNd may be cables or bus ducts. Meanwhile, DC loads 2E, 2F, 2G, and 2H, such as manufacturing equipment, are connected to the DC distribution panels 1E, 1F, 1G, and 1H via load power lines LN1 installed in a pit or the like on the floor. By using this exemplary layout configuration, a DC power distribution system suitable for a vertical layout within the DC distribution panel 1 shown in FIG. 3 can be constructed.

[0092] Four DC switches 5EF, 5FH, 5GH, and 5EG are inserted into each of the four DC wirings LNd. Each DC switch 5 is preferably located near the DC distribution board 1 so as to facilitate operation using the DC distribution board 1. Each DC distribution board 1, more specifically, the distribution board controller 14, is preferably configured to allow the addition of more DC switch operation circuits, such as driver circuits. Each DC distribution board 1 is also preferably configured to allow the addition of more first current sensors 12G (shown in FIG. 3 ) for measuring the current in the DC wiring LNd.

[0093] Generally, in production factories and the like, straight lines are frequently used as the flow lines of conveying machines, so it is desirable to arrange the DC distribution boards 1 in a grid pattern with a square as the standard, as shown in Fig. 9. Therefore, in the DC distribution board 1 that is an intersection of the grid, the maximum number of DC switchgear operation circuits that can be mounted can be four. Similarly, the maximum number of current sensors 12G that can be mounted in the DC distribution board 1 can also be four.

[0094] Fig. 10A is a plan view showing a schematic arrangement example of the DC power distribution system shown in Fig. 9 when viewed from above. In Fig. 10A, as described above, the grid is configured as a rectangle on the XY plane. In this case, it is not necessary for all DC distribution panels 1 to drive the DC switches 5, and it is sufficient that DC distribution panels 1 determined based on a certain standard drive the DC switches 5. Similarly, it is not necessary for all DC distribution panels 1 to measure the current flowing in the DC wiring LNd, and it is sufficient that DC distribution panels 1 determined based on a certain standard measure the current flowing in the DC wiring LNd.

[0095] Here, as a certain standard, in at least a part of the area, the DC distribution boards 1a of the first group, which are shown in black, and the DC distribution boards 1b of the second group, which are shown in white, are alternately arranged on the XY plane. The DC distribution boards 1a of the first group drive the DC switches 5 and measure the current flowing in the DC wiring LNd. On the other hand, the DC distribution boards 1b of the second group do not drive the DC switches 5 and do not measure the current flowing in the DC wiring LNd.

[0096] By providing such a fixed standard, for example, it is possible to simplify the switching management of the DC switchgear 5 and to avoid redundant measurement of the current flowing through the DC wiring LNd. Furthermore, the second group DC distribution panel 1b does not need to be equipped with a DC switchgear operating circuit or the first current sensor 12G. This reduces component costs. Regarding the DC wiring LNd between the DC distribution panel 1, as shown in area 102, the power transmission capacity between the DC distribution panel 1 may be expanded by connecting two systems of DC wiring in parallel to the DC branch section 10.

[0097] Fig. 10B is a plan view showing an example of an arrangement configuration that is a modification of the arrangement shown in Fig. 10A. In Fig. 10B, the grid is configured as a hexagon including at least one pair of parallel sides. In this case, the DC distribution board 1 drives up to three DC switches 5 and measures the current flowing through up to three DC wirings LNd. In Fig. 10B, as in Fig. 10A, the first group of DC distribution boards 1a and the second group of DC distribution boards 1b are alternately arranged on the XY plane in at least a portion of the area.

[0098] The invention made by the inventor has been specifically described above based on the embodiments, but the present invention is not limited to the above embodiments and can be modified in various ways without departing from the spirit of the invention. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0099] 1: DC distribution board, 2: DC load, 3: DC distributed power source, 4: DC storage device, 5: DC switch, 6: power distribution system control device, 10: DC branch section, 11: DC / DC converter, 12: current sensor, 13: DC circuit breaker, 14: distribution board controller, 17: housing, 18: wiring hole, 61: wiring information storage section, 63: open / close status acquisition section, 64: power flow status acquisition section, 65: noise detection section, 66: power flow simulation section, 68: voltage adjustment section, LNd: DC wiring, LNl: load power line, LNp: power supply wiring, LP: DC loop wiring

Claims

1. A DC distribution system comprising: a plurality of DC distribution boards that distribute input DC power; DC wiring that transmits the DC power between the plurality of DC distribution boards; and a distribution system control device that performs overall control of the plurality of DC distribution boards, wherein the DC wiring forms DC loop wiring by making a circuit through at least two or more DC distribution boards among the plurality of DC distribution boards, a first DC distribution board that is one of the plurality of DC distribution boards has a bidirectional DC / DC converter and is configured to be connectable to a DC storage device that stores the DC power via the bidirectional DC / DC converter, and the distribution system control device adjusts the power flow on the DC wiring by controlling the bidirectional DC / DC converter.

2. A DC distribution system as claimed in claim 1, further comprising a DC switch inserted in the DC wiring and configured to be capable of opening and closing between two terminals, and the distribution system control device adjusts the power flow so as to reduce the voltage difference between the two terminals as a preliminary operation for opening or closing the DC switch.

3. A DC distribution system as described in claim 1, wherein a second DC distribution board which is another of the plurality of DC distribution boards has a DC / DC converter and is configured to be connectable to a DC distributed power source which generates electricity via the DC / DC converter, at least one of the plurality of DC distribution boards is configured to be connectable to a DC load via a DC circuit breaker which cuts off the path when an abnormal current is detected, and the distribution system control device adjusts the power flow so as to reduce power loss on the distribution path from the DC distributed power source to the DC load via the DC wiring.

4. A DC distribution system as claimed in claim 2, wherein the distribution system control device comprises: a wiring information storage unit which retains information on the connection relationships between the multiple DC distribution boards via the DC wiring; a power flow state acquisition unit which acquires power flow information of the DC wiring; an opening and closing state acquisition unit which acquires the opening and closing state of the DC switchgear; a power flow simulation unit which constructs an electric circuit model and parameters which represent voltage values, current values ​​or power values ​​on the electric circuit model based on the information retained in the wiring information storage unit and the information acquired by the power flow state acquisition unit and the opening and closing state acquisition unit, and which predicts and calculates power flow changes when values ​​of the parameters are changed; and a voltage adjustment unit which outputs a voltage adjustment command value which represents the amount of voltage adjustment to one of the multiple DC distribution boards based on a result of the prediction calculation by the power flow simulation unit.

5. A DC power distribution system according to claim 4, wherein the power flow simulation unit predicts and calculates a change in power flow when the DC voltage of any one of the plurality of DC distribution boards is changed.

6. A DC power distribution system according to claim 4, wherein the power flow simulation unit predicts and calculates power flow changes and terminal voltage changes of the plurality of DC distribution boards when the DC power of the bidirectional DC / DC converter is changed.

7. A DC distribution system as claimed in claim 4, wherein the distribution system control device further comprises a noise detection unit which detects that a noise current has been superimposed on the DC loop wiring based on the information acquired by the opening / closing state acquisition unit and the power flow state acquisition unit.

8. A DC distribution system according to claim 7, wherein the distribution system control device changes the DC switch of a part of the DC loop wiring to an open state when the noise detection unit detects noise.

9. A DC power distribution system according to claim 7, wherein the power distribution system control device corrects the acquired data from the current state acquisition unit so as to cancel out current changes caused by the noise when the noise detection unit detects noise.

10. A DC power distribution system as described in claim 7, wherein the noise detection unit detects the noise current from two or more DC wirings that form the DC loop wiring, and if there is a correlation between the two or more detected noise currents, determines that the noise current is a return current associated with electromagnetic induction.

11. A DC power distribution system according to claim 1, wherein a plurality of the DC loop wirings are formed, and at least one of the plurality of DC distribution boards is commonly connected to the plurality of DC loop wirings.

12. A DC power distribution system as claimed in claim 11, further comprising a DC switch inserted into the DC wiring and configured to be capable of opening and closing between two terminals, wherein the plurality of DC distribution boards include a first group of DC distribution boards that drive the DC switch to open and close and measure the current flowing in the DC wiring, and a second group of DC distribution boards that do not drive the DC switch to open and close and do not measure the current flowing in the DC wiring, and the first group of DC distribution boards and the second group of DC distribution boards are arranged alternately.

13. A DC distribution board composed of a single case accommodating a plurality of components, the plurality of components including: a DC branch section connected to a plurality of DC wirings drawn out to the outside and made of a conductive material; a bidirectional DC / DC converter connected to the DC branch section via a power supply wiring; a DC storage device that accumulates DC power and is connected to the DC branch section via the bidirectional DC / DC converter; a DC circuit breaker inserted in a load power line connecting the DC branch section and a DC load provided externally and that cuts off the path of the load power line when an abnormal current is detected; a first current sensor that measures the currents of each of the plurality of DC wirings; a second current sensor that measures the current of the load power line; a third current sensor that measures the current of the power supply wiring; and a distribution board controller that controls the DC distribution board, including controlling the bidirectional DC / DC converter; and any one of the plurality of DC wirings is connected to any other one of the plurality of DC wirings via an external wiring path.

14. A DC distribution board as claimed in claim 13, wherein, on the assumption that a DC switch configured to be capable of opening and closing between two terminals is inserted into at least one of the plurality of DC wirings, the distribution board controller comprises a DC switch operating circuit for driving the DC switch to open and close.

15. A DC distribution board as described in claim 13, wherein, when the relative positional relationship in a direction perpendicular to the ground is upward and downward, the housing is provided with a first wiring hole at the upward side for drawing out the multiple DC wirings to the outside, and a second wiring hole at the downward side for drawing out the load power lines to the outside.

16. A DC distribution board according to claim 15, wherein the DC branch section, the bidirectional DC / DC converter, and the DC storage device are arranged in this order from the top toward the bottom.

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