Control device, control method, and program

Abstract

This control device is used for performing a control on a DC power feeding system in which a plurality of hubs are connected with feeders, said plurality of hubs having at least a first hub equipped with a first power feeding device and a second hub equipped with a second power feeding device and a load device. The control device comprises: an information acquiring unit that acquires information of the bus between the second power feeding device and the load device; a determination unit that determines, on the basis of the information and a threshold value, whether or not to perform a voltage control in the DC power feeding system; and a control unit that, when it is determined by the determination unit that the control is performed, performs the voltage control on at least either the first power feeding device or the second power feeding device.

Description

[Technical Field]

[0001] The present invention relates to a technique for ensuring the stability of power supply. [Background technology]

[0002] In telecommunications buildings, data centers, etc., high-voltage DC power supply systems are being introduced to reduce power loss throughout the system and to save energy. In DC power supply systems, power is supplied (distributed) at a high voltage of, for example, 380V.

[0003] Conventional DC power supply systems are generally used indoors. Indoor DC power supply systems use cables up to 60 meters long to supply power. Furthermore, power is supplied in one direction only, to loads such as ICT equipment. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] IEEJ2021 General Lecture 6-056 "Study on Short-Circuit Protection Methods for Outdoor DC Power Supply Systems" Hanaoka et al. Summary of the Invention [Problem to be solved by the invention]

[0005] It is expected that outdoor DC power supply systems that supply DC power via outdoor power lines will be introduced in the future (for example, Non-Patent Document 1). It is also expected that multiple bases each equipped with power supply converters will be connected in an n-to-n configuration, enabling bidirectional power supply between the bases.

[0006] Outdoor DC power supply systems may need to supply power to loads located several kilometers away (for example, up to 4 km). In such cases, the impedance (resistance and inductance components) becomes much larger than in conventional indoor DC power supply systems.

[0007] When multiple base stations with power supply converters are connected in an n-to-n ratio and power is shared between the base stations, there is a problem that current and voltage fluctuate, making it impossible to supply power stably.

[0008] The present invention has been made in view of the above points, and has an object to provide a technique for stably supplying power in a DC power supply system in which a plurality of base stations are connected by power supply lines. [Means for solving the problem]

[0009] According to the disclosed technology, there is provided a control device for executing control over a DC power supply system in which a plurality of bases, including at least a first base having a first power supply device and a second base having a second power supply device and a load device, are connected by a power supply line, the control device comprising: an information acquisition unit that acquires information about a bus between the second power supply device and the load device; a determination unit that determines whether to control the voltage in the DC power supply system based on the information and a threshold value; a control unit that controls a voltage of at least one of the first power supply device and the second power supply device when the determination unit determines that the control should be performed; the information is an actual measurement value of the current flowing through the bus; The determination unit calculates a predicted value of the current from a voltage of the first power supply device and a voltage of the second power supply device, and determines whether to execute the control based on the predicted value, the actual measured value, and the threshold value. A control device is provided. [Effects of the Invention]

[0010] According to the disclosed technology, stable power supply can be achieved in a DC power supply system in which a plurality of base stations are connected by power supply lines. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram illustrating an example of the overall configuration of a DC power supply system. [Figure 2] FIG. 1 is a diagram illustrating an example of a DC power supply system in one building. [Figure 3] FIG. 1 is a diagram illustrating an example of a DC power supply system that connects bases with outdoor power supply lines. [Figure 4] FIG. 2 is a diagram illustrating an example of the configuration of a control device. [Figure 5] 4 is a flowchart illustrating the operation of the control device. [Figure 6] FIG. 10 is a diagram showing the relationship between current and potential difference. [Figure 7] FIG. 10 is a diagram for explaining a specific example of determination. [Figure 8] FIG. 2 illustrates an example of a hardware configuration of the apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention (the present embodiment) will be described with reference to the drawings. The embodiment described below is merely an example, and the embodiment to which the present invention is applied is not limited to the following embodiment.

[0013] (Example of overall system configuration) An example of the overall configuration of a DC power supply system according to this embodiment is shown in Fig. 1. The DC power supply system shown in Fig. 1 supplies power at a high voltage (for example, 380 V) over a long distance (for example, about 4 km) using an outdoor power supply line.

[0014] In the example of FIG. 1, there are three bases, namely, Building A, Building B, and Building C, and each building is equipped with a power supply converter and is capable of supplying power to the other buildings. In other words, bidirectional power supply is possible between any two of the three bases. In the example of FIG. 1, Building A is a base building such as a communications building, and Buildings B and C are buildings such as evacuation shelters. The power supply converters may also be called power supply devices. However, the term "power supply device" is not limited to power supply converters.

[0015] As shown in Figure 1, each base is equipped with power generation facilities such as photovoltaic (PV) generators and wind power generators, as well as loads such as EVs and storage batteries, and converters enable bidirectional power interchange between bases.

[0016] (Issues and Solutions) The following describes in detail the problems that the technology according to the present invention aims to solve. First, for comparison, an example of a conventional indoor (inside a communication building) DC power supply system is shown in Fig. 2. As shown in Fig. 2, this DC power supply system includes AC 200V 1, a rectifier 2, a current distribution device 3, and a load 4 (device using DC 380V).

[0017] As shown in Figure 2, power is supplied one-way from the rectifier 2 to the load 4 via a cable up to about 60 m long. This allows stable transmission of power to the load 4, such as ICT equipment.

[0018] Figure 3 shows a DC power supply system corresponding to the area enclosed by the dotted line in Figure 1. As shown in Figure 3, Building A (a communications building) is equipped with an AC 200V power supply 1A, a bidirectional inverter 2A, a power supply converter A (10A), and an input / output panel 20A. Building B is equipped with an input / output panel 20B, a power supply converter 10B, and a load device 30B.

[0019] Building A and building B are connected by an outdoor power feeder that can supply power in both directions, and the length of this feeder is, for example, up to 4 km.

[0020] When power is fed over a long distance as in the configuration of FIG. 3, the impedance (resistance component and inductance component) is about two orders of magnitude larger than the impedance in the configuration shown in FIG.

[0021] The following describes the problems that arise in the long-distance power supply described above. Fig. 3 shows a control device 100 that performs control to solve the problems, but first, we will explain the problems that arise when the control device 100 is not present.

[0022] In this embodiment, the control method for the power supply converters for power interchange between bases is a method (droop control system) in which the amount of power that can be interchanged is determined by the difference in input / output voltage between the power supply converters at the two bases that are interchanged.

[0023] In the configuration shown in Figure 3, when the load power, which is the power supplied to the load device 30B in building B, decreases, the voltage of the internal bus (the voltage of the internal bus between the power supply converter 10B and the load device 30B) increases. Therefore, the power supply converter B controls the voltage to return (decrease) the voltage. When this operation is repeated, the voltage and current of the internal bus oscillate, which poses a problem of making it impossible to supply power stably.

[0024] In this embodiment, in order to solve the above problem, a control device 100 is provided. Also, it is assumed that an internal bus in building B is provided with a sensor capable of measuring current, voltage, or both. Note that the control device 100 may be provided anywhere. For example, it may be provided outside building B.

[0025] The control device 100 acquires the current value (actual measured value) of the internal bus in building B from a sensor, and adjusts at least one of the voltage V1 of the power supply converter 10A and the voltage V2 of the power supply converter 10B based on the acquired current value and the predicted current value. This suppresses an increase in the internal bus voltage and stabilizes the power supply. V1 is the target voltage on the private line side of the power supply converter 10A, and V2 is the target voltage on the private line side of the power supply converter 10B. For example, if the target value V1 is 380 V and the target value V2 is 360 V, the voltage of the outdoor power supply line will be 370 V, which is the average of V1 and V2. The private line side refers to the outdoor power supply line side.

[0026] In the above example, control is performed based on the current value (actual measurement value) of the internal bus, but control may also be performed based on the voltage value (actual measurement value) of the internal bus.

[0027] (Configuration of control device 100) Fig. 4 shows an example of the configuration of the control device 100 in this embodiment. As shown in Fig. 4, the control device 100 includes an information acquisition unit 110, a determination unit 120, a control unit 130, and a data storage unit 140. The operation of each unit is outlined below.

[0028] The information acquisition unit 110 acquires a current value or a voltage value of an internal bus at a base where a load device is installed. The determination unit 120 determines whether or not to control the voltage of the power supply converter based on the information acquired by the information acquisition unit 110 and information (such as a threshold value) stored in the data storage unit 140.

[0029] The control unit 130 controls the voltage to the power supply converter when the determination unit 120 determines that voltage control to the power supply converter should be performed. Note that the control may be for either the power supply converter of the power supply source or the power supply converter of the power supply destination.

[0030] The data storage unit 140 stores the current voltage setting values ​​and threshold values ​​of the power supply converter of the power supply source and the power supply converter of the power supply destination.

[0031] (Example of operation of the control device 100) Next, an example of the operation of the control device 100 will be described in accordance with the procedure of the flowchart in Fig. 5. Here, an example of the control operation for the DC power supply system shown in Fig. 3 will be described. In the configuration shown in Fig. 3, power is supplied from the power supply converter 10A in building A to the power supply converter 10B in building B via an outdoor power feeder line, and power is supplied from the power supply converter 10B to the load device 30B via an internal bus. Basically (theoretically), the magnitude of the current supplied from the power supply converter B to the load device 30B is determined by the difference between the voltage of the power supply converter 10A and the voltage of the power supply converter B.

[0032] In S101, the information acquisition unit 110 acquires the actual current value (actual measurement value) flowing through the internal bus of building B from a sensor attached to the internal bus.

[0033] In S102, the determination unit 120 determines whether or not to control the voltage of the power supply converters 10A / 10B using the current value acquired in S101. Note that the voltage of the power supply converters 10A / 10B means "the voltage of the power supply converter 10A," "the voltage of the power supply converter 10B," or "both the voltage of the power supply converter 10A and the voltage of the power supply converter 10B." The detailed contents of the determination process are as follows:

[0034] The determination unit 120 reads the current set value (V1) of the voltage of the power supply converter 10A and the current set value (V2) of the voltage of the power supply converter 10B from the data storage unit 140. The determination unit 120 calculates V1-V2 and predicts the value of the current flowing through the internal bus from V1-V2.

[0035] For example, for an internal bus, a relationship between a potential difference ("V1-VV") and a current value is prepared in advance, as shown in Fig. 6, and its slope α is stored in the data storage unit 140. The determination unit 120 reads α from the data storage unit 140 and can calculate a predicted value of the current flowing through the internal bus by (V1-V2) × (1 / α).

[0036] The determination unit 120 compares the predicted value with the actual measured value, and determines to control (adjust) the voltage of the power supply converters 10A / 10B when, for example, |predicted value-actual measured value| is greater than a threshold value.

[0037] A specific example will be described with reference to FIG. 7. In the example of FIG. 7, α=5 (V / A). Furthermore, the predicted value of the current is Ip and the actual measured value is Ie. In the case of normal 1, V1=380V and V2=360V, so Ip=20×(1 / 5)=4A. Since Ie=4A, which is equal to Ip, the judgment unit 120 judges that control will not be performed. In the case of normal 2, V1=380V and V2=350V, so Ip=30×(1 / 5)=6A. Since Ie=6A, which is equal to Ip, the judgment unit 120 judges that control will not be performed.

[0038] In the case of an abnormality (vibration), V1 = 380 V and V2 = 350 V, so Ip = 30 × (1 / 5) = 6 A. On the other hand, Ie = 5 A, so Ip is larger by 1 A. Here, for example, assume that the threshold value used to compare |Predicted value−Actual measurement value| is 0.5 A. In this case, |Predicted value−Actual measurement value|>0.5 A, so the determination unit 140 determines to control the voltage of the power supply converters 10A / 10B.

[0039] As described above, when it is determined that the voltage of power supply converters 10A / 10B is to be controlled, control unit 130 executes the control in S103 of FIG.

[0040] Specifically, the control unit 130 controls the voltage of the power supply converters 10A / 10B so that |predicted value−actual measurement value| is equal to or less than a threshold value. For example, if the threshold value is 0.5, the control unit 130 adjusts the voltage of the power supply converters 10A / 10B so that (Ip−Ie)≦0.5A.

[0041] In the abnormal case shown in Fig. 7, (Ip - Ie) = 6A - 5A, so control is performed to reduce Ip by 1 A. From the relationship in Fig. 6, it can be calculated that (Ip - Ie) × α = (6A - 5A) × 5 = 5V, so here control is performed so that V1 - V2 decreases by 5V, for example, V2 is increased by 5V. Specifically, control unit 130 instructs (sets) power supply converter 10A to set a voltage value of 380V, and instructs (sets) power supply converter 10B to set a voltage value of 355V.

[0042] If the actual measured value is 5 A and there is no change, the predicted value will be 5 A through the above control, which will match the actual measured value, and therefore the normal state will be achieved.

[0043] As shown in the flow of FIG. 5, by repeating the above-described control at regular time intervals, for example, it is possible to maintain a stable power supply state.

[0044] In the above example, the control device 100 acquires a current value from a sensor on the internal bus to perform judgment and control, but this is just an example. The control device 100 may acquire a voltage value from a sensor on the internal bus to perform judgment and control.

[0045] 5, the information acquisition unit 110 acquires a voltage value (the voltage between the positive and negative lines of the internal bus) from a sensor on the internal bus. In S102, the determination unit 120 compares the voltage value acquired in S101 with a predetermined threshold, and determines to perform control if the voltage value is higher than the threshold (e.g., 390 V).

[0046] In S103, when control is performed, the control unit 130 performs control so that V1-V2 becomes smaller, for example, by increasing the voltage V2. The amount by which the voltage is increased (the amount by which V1-V2 is reduced) may be determined in advance. By repeating this type of control, for example, at regular time intervals, a stable power supply state can be maintained.

[0047] (Example of device hardware configuration) The control device 100 can be realized, for example, by causing a computer to execute a program. This computer may be a physical computer or a virtual machine on the cloud.

[0048] That is, the control device 100 can be realized by using hardware resources such as a CPU and memory built into a computer to execute a program corresponding to the processing performed by the control device 100. The program can be recorded on a computer-readable recording medium (such as a portable memory) and can be saved or distributed. The program can also be provided via a network such as the Internet or email.

[0049] Fig. 8 is a diagram showing an example of the hardware configuration of the computer. The computer in Fig. 8 includes a drive device 1000, an auxiliary storage device 1002, a memory device 1003, a CPU 1004, an interface device 1005, a display device 1006, an input device 1007, an output device 1008, and the like, all of which are interconnected by a bus BS.

[0050] A program for realizing processing on the computer is provided by a recording medium 1001 such as a CD-ROM or a memory card. When the recording medium 1001 storing the program is set in the drive device 1000, the program is installed from the recording medium 1001 to the auxiliary storage device 1002 via the drive device 1000. However, the program does not necessarily have to be installed from the recording medium 1001, but may be downloaded from another computer via a network. The auxiliary storage device 1002 stores the installed program as well as necessary files, data, etc.

[0051] The memory device 1003 reads and stores the program from the auxiliary storage device 1002 when an instruction to start the program is received. The CPU 1004 realizes functions related to the control device 100 in accordance with the program stored in the memory device 1003. The interface device 1005 is used as an interface for connecting to a network, various measuring devices, etc. The display device 1006 displays a GUI (Graphical User Interface) etc. according to the program. The input device 1007 is composed of a keyboard, mouse, buttons, touch panel, etc., and is used to input various operation instructions. The output device 1008 outputs the calculation results.

[0052] (Effects of the embodiment) The technology according to the present embodiment enables stable power supply in a DC power supply system in which multiple base stations are connected by power supply lines. That is, it is possible to prevent a voltage rise on the internal bus and stabilize the power supply so that the voltage and current on the internal bus do not oscillate.

[0053] (Addendum) This specification discloses at least the control device, control method, and program described in the following items. (Additional note 1) A control device for executing control over a DC power supply system in which a plurality of bases, including at least a first base having a first power supply device and a second base having a second power supply device and a load device, are connected by a power supply line, Memory and at least one processor coupled to said memory; Including, The processor: acquiring information about a bus between the second power supply device and the load device; determining whether to control the voltage in the DC power supply system based on the information and a threshold value; When it is determined that the control is to be performed, voltage control is performed on at least one of the first power supply device and the second power supply device. Control device. (Additional note 2) the information is an actual measurement value of the current flowing through the bus; The processor calculates a predicted value of the current from a voltage of the first power supply device and a voltage of the second power supply device, and determines whether to execute the control by comparing a difference between the predicted value and the actual measured value with the threshold. Item 1. The control device according to item 1. (Additional note 3) The processor controls a voltage of at least one of the first power supply device and the second power supply device so that a difference between the predicted value and the actual measured value is equal to or less than the threshold value. The control device according to claim 2. (Additional note 4) the information is an actual measurement value of the voltage of the bus; The processor compares the actual measurement value with the threshold value to determine whether or not to execute the control. Item 1. The control device according to item 1. (Additional note 5) A control method in a computer for executing control of a DC power supply system in which a plurality of bases, including at least a first base having a first power supply device and a second base having a second power supply device and a load device, are connected by a power supply line, the method comprising: an information acquisition step of acquiring information about a bus between the second power supply device and the load device; a determination step of determining whether to control the voltage in the DC power supply system based on the information and a threshold value; a control step of controlling a voltage of at least one of the first power supply device and the second power supply device when it is determined in the determination step that the control is to be performed; A control method comprising: (Additional note 6) A non-transitory storage medium storing a program for causing a computer to function as each unit in the control device according to any one of appended claims 1 to 4.

[0054] Although the present embodiment has been described above, the present invention is not limited to such a specific embodiment, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims. [Explanation of symbols]

[0055] 100 control device 110 Information Acquisition Department 120 Judgment section 130 Control Unit 140 Data storage unit 1000 Drive Device 1001 Recording media 1002 Auxiliary storage device 1003 Memory device 1004 CPU 1005 Interface device 1006 Display device 1007 Input Device 1008 Output Device

Claims

1. A control device for executing control over a DC power supply system in which a plurality of bases, including at least a first base having a first power supply device and a second base having a second power supply device and a load device, are connected by a power supply line, an information acquisition unit that acquires information about a bus between the second power supply device and the load device; a determination unit that determines whether to control the voltage in the DC power supply system based on the information and a threshold value; a control unit that controls a voltage of at least one of the first power supply device and the second power supply device when the determination unit determines that the control should be performed; the information is an actual measurement value of the current flowing through the bus; The determination unit calculates a predicted value of the current from a voltage of the first power supply device and a voltage of the second power supply device, and determines whether to execute the control based on the predicted value, the actual measured value, and the threshold value. Control device.

2. The control unit controls a voltage of at least one of the first power supply device and the second power supply device so that a difference between the predicted value and the actual measured value becomes equal to or less than the threshold value. The control device according to claim 1 .

3. A control method in a control device for executing control of a DC power supply system in which a plurality of bases, including at least a first base having a first power supply device and a second base having a second power supply device and a load device, are connected by a power supply line, comprising: an information acquisition step of acquiring information about a bus between the second power supply device and the load device; a determination step of determining whether to control the voltage in the DC power supply system based on the information and a threshold value; a control step of controlling a voltage of at least one of the first power supply device and the second power supply device when it is determined in the determination step that the control is to be performed; the information is an actual measurement value of the current flowing through the bus; In the determining step, the control device calculates a predicted value of the current from a voltage of the first power supply device and a voltage of the second power supply device, and determines whether or not to execute the control based on the predicted value, the actual measured value, and the threshold value. Control method.

4. A program for causing a computer to function as each unit in the control device according to claim 1 or 2.

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