Device, processing method, and program

Abstract

This device executes control which is in accordance with sum of current values measured for each of a plurality of circuit-breaking units.

Description

Apparatus, processing method, and program

[0001] The present invention relates to power line protection systems.

[0002] A conventional technique for protecting a DC grid through which a DC current flows is disclosed in Non-Patent Document 1. In this conventional technique, a capacitor is installed in a circuit breaker, and a discharge current from the capacitor is supplied to the fault point. This allows the circuit breaker closest to the fault point to operate at high speed, enabling protective coordination with other circuit breakers.

[0003] Study on short-circuit protection methods for loop-wired outdoor DC power supply systems (IEEJ National Convention 2024)

[0004] However, the above-mentioned conventional technology has a problem in that when the load current is several amperes (A) lower than the interruption threshold, an abnormal current may cause a circuit breaker other than the one closest to the fault point to malfunction (falsely open).

[0005] The present invention has been made in view of the above points, and has an object to provide a technique for suppressing malfunction of a circuit breaker in a power line protection system.

[0006] According to the disclosed technology, a device is provided that executes control according to the sum of current values ​​measured for each of a plurality of interrupter units.

[0007] The disclosed technology provides a technology for suppressing malfunction of a circuit breaker in a power line protection system.

[0008] FIG. 1 is a diagram for explaining the problem. FIG. 1 is a diagram for explaining the problem. FIG. 2 is a diagram for explaining a specific example of state determination. FIG. 3 is a diagram for explaining a specific example of state determination. FIG. 4 is a diagram for explaining an abnormal current extraction method. FIG. 5 is a diagram for explaining an abnormal current extraction method. FIG. 6 is a diagram for explaining a method of changing a tripping threshold. FIG. 7 is a diagram for explaining an example of the device configuration of a three-way circuit breaker 100. FIG. 8 is a diagram for explaining other example configurations. FIG. 9 is a flowchart for explaining the operation of the three-way circuit breaker 100. FIG. 10 is a diagram for explaining an example of the hardware configuration of the device.

[0009] Hereinafter, an embodiment of the present invention 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.

[0010] In the following, a protection system for a DC power line will be described as an example of a protection system using the technology of the present invention. The power line may be a bus-type wiring, a loop-type wiring, or any other wiring method.

[0011] In the following, the problem will be explained in more detail first, and then the technology according to the present embodiment will be explained. Note that the technology disclosed in Non-Patent Document 1 is publicly known, but the explanation of the problem below is not publicly known. Also, in the following explanation, for the sake of convenience, "current" may be used to mean "current value."

[0012] (Regarding the Issues) As mentioned above, a conventional technique for protecting power lines is disclosed in Non-Patent Document 1. In this conventional technique, a capacitor is installed in a circuit breaker, and a discharge current from the capacitor is supplied to the fault point. This allows the circuit breaker closest to the fault point to operate at high speed, enabling protection coordination with other circuit breakers.

[0013] However, the above-mentioned conventional technology has a problem in that when the load current is several amperes lower than the interruption threshold, an abnormal current may cause a malfunction (false opening) of a circuit breaker other than that located immediately adjacent to the fault point. This problem will be explained with reference to Figs. 1 and 2.

[0014] 1 shows a configuration in which a three-way circuit breaker 10 and a three-way circuit breaker 20 are provided on a power line. The three-way circuit breaker 10 has a circuit breaker A11, a circuit breaker B12, a circuit breaker C13, and a capacitor 14. The three-way circuit breaker 20 has a circuit breaker A21, a circuit breaker B22, a circuit breaker C23, and a capacitor 24. A load current flows to the left in FIG. 1.

[0015] As an example, circuit breakers A11, C13, A21, and C23 are provided on the power line of the loop wiring, and circuit breakers B12 and B22 are provided on each branch line extending from the loop wiring to the consumer.

[0016] In the configuration of Figure 1, suppose an accident (e.g., a short circuit) occurs in the power line on the left side of the three-way circuit breaker 10. At this time, a large current (fault current) flows from the capacitor 14 toward the circuit breaker A11, causing the circuit breaker A11 to open (interrupt the current).

[0017] Furthermore, due to the above-mentioned fault, an abnormal current flows in addition to a load current in circuit breakers B12, A21, and B22. At this time, as shown in Fig. 2, if the load current is several amperes lower than the circuit breaker's tripping threshold, the load current and the abnormal current may cause malfunctions in circuit breakers other than those closest to the fault point (circuit breakers C13, A21, and C23 in Fig. 1).

[0018] 1 shows a situation in which a malfunction (false opening) occurs in the circuit breaker C13, the circuit breaker A21, and the circuit breaker C23. Such a malfunction should be suppressed.

[0019] In this embodiment, in order to solve the above problem, a control device (configured to have a storage unit, a determination unit, and a control unit) described below determines whether the current state is a normal state or an abnormal state based on the sum of the currents flowing through each breaker of a three-way breaker, and distinguishes between a normal load current and an abnormal current in an abnormal state. This allows the control unit of the control device to execute control depending on whether the current state is a normal state or an abnormal state.

[0020] In this embodiment, an overcurrent is determined based on a change in current during an abnormality, so that malfunction (false opening) of the circuit breaker can be suppressed.

[0021] (Details of the Determination Method) Here, a determination method implemented by the control device to distinguish between a load current during normal operation and an abnormal current during an abnormal operation will be described. The configuration of the control device will be described later. The control device may be located inside the three-way circuit breaker or outside the three-way circuit breaker.

[0022] The control device determines whether a normal load current is flowing in the power line or whether an abnormal current such as a short-circuit current or an inrush current is flowing in addition to the load current, based on the sum of the currents flowing from the three breakers in the three-way breaker to the connection point between the three breakers. A specific example of this determination will be described with reference to Figures 3 and 4.

[0023] 3 is a diagram showing an example of currents that normally flow in the three-way circuit breaker 10. As shown in FIG. 3, the sum of the currents in the three circuit breakers normally is 5+3-8=0A.

[0024] 4 is a diagram showing an example of the current that flows during an abnormality in the three-way circuit breaker 10. As shown in Fig. 4, during an abnormality, there is a discharge current from the capacitor 14, so the sum of the currents in the three circuit breakers of the three-way circuit breaker does not become 0 A, but becomes 5 + 3 - 38 = -30 A. The reason for this sum is that the discharge current from the capacitor 14 is not measured.

[0025] If the sum of the currents is 0 A, the control device determines that a normal load current is flowing through the power line, and if the sum of the currents is not 0 A, the control device determines that an abnormal current such as a short-circuit current or an inrush current is flowing in addition to the load current. Note that "the sum of the currents is 0 A" may mean "the magnitude of the sum of the currents is equal to or less than S," using a certain threshold value S (e.g., 0.5 A). Furthermore, "the sum of the currents is not 0 A" may mean "the magnitude of the sum of the currents is greater than S."

[0026] (Method for extracting abnormal current during abnormality) When the control device determines that the current state is abnormal as a result of determining whether the current state is normal or abnormal using the above method, it extracts the current change during abnormality by subtracting the immediately preceding normal current. The method for extracting the current change will be described with reference to FIGS. 5 and 6.

[0027] 5 shows a state in which a load current several amperes smaller than the tripping threshold flows through a circuit breaker. Note that the "load current several amperes smaller than the tripping threshold" may be expressed as "(tripping threshold - load current) < Q" using a certain threshold Q (e.g., 3 A).

[0028] As shown in Fig. 5, it is assumed that an abnormal current flows during the period indicated by T. At this time, as shown in Fig. 5(a), during the period T, the load current plus the abnormal current exceeds the trip threshold.

[0029] At this time, when the control device determines that an abnormality has occurred at T using the method described above, it extracts the current change during the abnormality by subtracting the current (load current) during normal operation immediately before from the current (abnormal current + load current). In other words, it extracts the abnormal current. The control device compares this abnormal current with the tripping threshold to determine whether or not to perform tripping. In the case of Figure 5(b), this abnormal current does not exceed the tripping threshold. In other words, it is possible to prevent the tripping threshold from being exceeded.

[0030] Note that the period T in Figure 5 (the period when the current is offset as in (b)) is the time during which charge flows from the capacitor, so it is short, at just a few tens of milliseconds, and the power line (cable) will not be damaged even if a current (load current + abnormal current) flows during the period T.

[0031] FIG. 6 shows a state in which a load current flows in a direction opposite to the direction of the current assumed at the interruption threshold.

[0032] As shown in Fig. 6, an abnormal current (current flowing in the opposite direction to the load current) flows during the period indicated by T. At this time, as shown in Fig. 6(b), the sum of the load current and the abnormal current does not exceed the tripping threshold.

[0033] In this embodiment, as shown in Figure 6(b), the control device removes the load current from the "load current + abnormal current" and extracts only the abnormal current, and compares this abnormal current with the tripping threshold. In the case of Figure 6(b), the abnormal current exceeds the tripping threshold. In other words, in this case, the circuit breaker is opened.

[0034] As described above, when a load current several amperes smaller than the tripping threshold flows (FIG. 5), it is possible to prevent the circuit breaker from opening erroneously when an abnormal current occurs. Also, when a load current flows in the reverse direction (FIG. 6), it is possible to open the circuit breaker in proportion to the abnormal current value.

[0035] (Method of Changing the Cutoff Threshold) Instead of extracting a current change during an abnormality by subtracting the current during normal operation immediately before the abnormality as in the examples shown in Figures 5 and 6, the current during normal operation immediately before the abnormality may be added to the cutoff threshold to set a changed cutoff threshold. An example of this case will be described with reference to Figure 7.

[0036] Figure 7 shows the state when a load current several amperes smaller than the tripping threshold flows through a circuit breaker. As shown in Figure 7, an abnormal current flows during the period indicated by T. At this time, as shown in Figure 7(a), the load current plus the abnormal current exceeds the tripping threshold during the period T.

[0037] At this time, when the control device determines that an abnormality has occurred at T, it adds the current during normal operation immediately before to the tripping threshold, and compares the changed tripping threshold with "load current + abnormal current." In the case of Figure 7(b), this "load current + abnormal current" does not exceed the changed tripping threshold. In other words, it is possible to prevent the tripping threshold from being exceeded.

[0038] (Device Configuration Example) Fig. 8 shows a device configuration example of a three-way circuit breaker 100 that performs the above-described operation. As shown in Fig. 8, the three-way circuit breaker 100 has a current interruption unit A110, a current measurement unit A111, a current interruption unit B120, a current measurement unit B121, a current interruption unit C130, a current measurement unit C131, a capacitor 140, a memory unit 150, a determination unit 160, and a control unit 170. The configuration that has the "memory unit 150, the determination unit 160, and the control unit 170" may be referred to as a "control device." Furthermore, the determination unit 160 and the control unit 170 may be referred to as a determination device and a control device, respectively.

[0039] Each current measurement unit measures the current flowing through the adjacent current interruption unit. The storage unit 150 stores the current value measured by each current measurement unit and the overcurrent threshold (interruption threshold) of each current interruption unit.

[0040] The determination unit 160 adds up the measurement values ​​of the three current measurement units and determines whether the current state is normal or abnormal. If the current state is normal, the determination unit 160 determines whether the measured current for each current measurement unit exceeds the overcurrent threshold. If the current state is abnormal, the determination unit 160 offsets the load current from the measured current for each current measurement unit and then determines whether the measured current exceeds the overcurrent threshold. As described above, the overcurrent threshold may be changed. The control unit 170 issues an open signal to a current interruption unit that has exceeded the overcurrent threshold.

[0041] (Other Configuration Examples) The "storage unit 150, determination unit 160, and control unit 170" may be provided outside the three-way circuit breaker 100. An example configuration of a control device 200 having the "storage unit 150, determination unit 160, and control unit 170" provided outside the three-way circuit breaker 100 is shown in FIG.

[0042] 9 includes a communication unit 210 in addition to a storage unit 150, a determination unit 160, and a control unit 170. The communication unit 210 communicates with the three-way circuit breaker 100 via a communication network, allowing the "storage unit 150, determination unit 160, and control unit 170" to perform the same operations as when they are located inside the three-way circuit breaker 100.

[0043] (Processing Flow) Next, an example of the operation of the three-way circuit breaker 100 shown in Fig. 8 will be described with reference to the flowchart of Fig. 10. In the following description, X is used as a symbol to identify the current interrupting unit / current measuring unit. X represents any one, more than one, or all of A, B, and C.

[0044] In S1, each current measuring unit X measures a current value I ｘ In S2, the determination unit 160 measures the sum of the current values ​​of the current measuring units (I Ａ +I Ｂ +I Ｃ ) is calculated.

[0045] In S3, the determination unit 160 determines whether the total current value is 0 A. As described above, "the total current value is 0 A" may mean "the magnitude of the total current value is equal to or less than a threshold value (e.g., 0.5 A)." If the determination in S3 is Yes, proceed to S4, and if the determination is No, proceed to S7.

[0046] In S4, the determination unit 160 determines the current value I Ｘ is the overcurrent threshold OCP Ｘ That is, the determining unit 160 determines whether the current value exceeds the overcurrent threshold OCP. Ｘ If the determination in S4 is Yes, the process proceeds to S5, and if the determination is No, the process proceeds to S6.

[0047] In S5, the control unit 170 opens the current interruption unit X. In S6, the determination unit 160 determines whether the current value I Ｘ I Ｘ－１ The result is stored in the storage unit 150. After S6, the process returns to S1.

[0048] In S7, which is reached when the "total current value is not 0 A", the determination unit 160 determines the current current value I Ｘ to the previous current value I Ｘ－１ Subtract I Ｘ´ is stored in the storage unit 150 as I Ｘ´ = (I Ｘ -I Ｘ－１ )

[0049] In S8, the determination unit 160 determines whether the current I Ｘ´ is the overcurrent threshold OCP Ｘ If the determination in S8 is Yes, the process proceeds to S9, and if the determination is No, the process returns to S1. In S9, the control unit 170 opens the current interruption unit X.

[0050] (Hardware Configuration Example) Any of the devices (control device, determination device) described in this embodiment 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 a cloud.

[0051] That is, the device can be realized by executing a program corresponding to the processing performed by the device using hardware resources such as a CPU and memory built into a computer. The program can be recorded on a computer-readable recording medium (such as a portable memory) and stored or distributed. The program can also be provided via a network such as the Internet or email.

[0052] Fig. 11 is a diagram showing an example of the hardware configuration of the computer. The computer in Fig. 11 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 via a bus B. The computer may further include a GPU.

[0053] The program that realizes the 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.

[0054] The memory device 1003 reads and stores a program from the auxiliary storage device 1002 when an instruction to start the program is received. The CPU 1004 realizes functions related to the device 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, etc. The display device 1006 displays a GUI (Graphical User Interface) or the like according to the program. The input device 1007 is composed of a keyboard, mouse, buttons, a touch panel, etc., and is used to input various operation instructions. The output device 1008 outputs the results of calculations.

[0055] (Summary, Effects, etc. of the Embodiments) As described above, the techniques described in the present embodiments make it possible to suppress malfunction of circuit breakers in a power line protection system.

[0056] The following additional notes are provided regarding the above-described embodiments.

[0057] <Additional Notes> (Additional Item 1) A device that executes control according to the sum of current values ​​measured for each of a plurality of circuit breakers. (Additional Item 2) The device according to Additional Item 1 that executes control according to whether the magnitude of the sum is smaller than a threshold or greater than a threshold. (Additional Item 3) The device according to Additional Item 1 that, when the magnitude of the sum is greater than the threshold, determines whether to open the circuit breaker according to a value obtained by subtracting the immediately preceding current value from the measured current value and the circuit breaker threshold. (Additional Item 4) The device according to Additional Item 1 that, when the magnitude of the sum is greater than the threshold, determines whether to open the circuit breaker according to a value obtained by adding the immediately preceding current value to the circuit breaker threshold and the measured current value. (Additional Item 5) A device comprising: a determination unit that calculates the sum of current values ​​measured for each of a plurality of circuit breakers and determines a state based on the sum; and a control unit that executes control according to whether the state is a normal state or an abnormal state. (Supplementary Item 6) A processing method executed by a device, comprising: a determining step of calculating a sum of current values ​​measured for each of a plurality of breaker units and determining a state based on said sum; and a control step of executing control according to whether said state is a normal state or an abnormal state. (Supplementary Item 7) A non-transitory storage medium storing a program for causing a computer to function as the device according to any one of Supplementary Items 1 to 5.

[0058] 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.

[0059] 10, 20, 100 Three-way circuit breaker 11, 21 Circuit breaker A 12, 22 Circuit breaker B 13, 23 Circuit breaker C 14, 24 Capacitor 150 Storage unit 160 Determination unit 170 Control unit 200 Control device 210 Communication unit 1000 Drive device 1001 Recording medium 1002 Auxiliary storage device 1003 Memory device 1004 CPU 1005 Interface device 1006 Display device 1007 Input device 1008 Output device

Claims

1. A device that performs control based on the sum of the current values ​​measured for each of multiple circuit breakers.

2. The apparatus of claim 1, wherein the control is performed depending on whether the magnitude of the sum is less than a threshold or whether the magnitude of the sum is greater than a threshold.

3. The device according to claim 1, wherein if the magnitude of the sum is greater than a threshold value, it determines whether or not to open the circuit breaker based on the value obtained by subtracting the immediately preceding current value from the measured current value and the circuit breaker threshold value.

4. The device according to claim 1, wherein if the magnitude of the sum is greater than a threshold value, it determines whether or not to open the circuit breaker according to the value obtained by adding the immediately preceding current value to the circuit breaker threshold value and the measured current value.

5. A device comprising: a determining unit that calculates the sum of the current values ​​measured for each of a plurality of breaker units and determines the state based on said sum; and a control unit that executes control depending on whether said state is a normal state or an abnormal state.

6. A processing method executed by a device, comprising: a determination step of calculating the sum of current values ​​measured for each of a plurality of breakers and determining the state based on said sum; and a control step of executing control depending on whether said state is a normal state or an abnormal state.

7. A program for causing a computer to function as the device according to any one of claims 1 to 5.

Images