Cutoff system, detection device, cutoff device, cutoff method, and program

Abstract

This cutoff system includes a detection device and a cutoff device used on a power line. The detection device transmits an optical signal to the cutoff device via an optical communication line when an abnormality of a current or a voltage in the power line is detected. Upon receiving the optical signal, the cutoff device performs opening of the power line.

Description

Shutdown system, detection device, shutdown device, shutdown method, and program

[0001] The present invention relates to a technique for protecting a power system when an accident such as a short circuit occurs on a power line.

[0002] When an accident such as a short circuit occurs on a power line, a reclosing method is known as a technique for minimizing the impact of the accident (see, for example, Non-Patent Document 1). In the reclosing method, the fault section is isolated by opening a circuit breaker, and then the circuit breaker in the safe section is closed to restore power to the load.

[0003] Reclosing of overhead power transmission lines, https: / / jeea.or.jp / course / contents / 04108 / , retrieved on June 23, 2020

[0004] However, the reclosing method has the problem that power supply to the entire grid is temporarily stopped when power is restored.

[0005] The present invention has been made in consideration of the above points, and aims to provide a technology for protecting a system in the event of an accident in the system without causing a power outage to the entire system.

[0006] According to the disclosed technology, there is provided a shutdown system having a detection device and a shutdown device used on a power line, wherein the detection device transmits an optical signal to the shutdown device via an optical communication line when it detects an abnormality in the current or voltage on the power line, and the shutdown device opens the power line when it receives the optical signal.

[0007] According to the disclosed technology, a technology is provided for protecting a grid when an accident occurs in the grid without causing a power outage to the entire grid.

[0008] FIG. 1 is a diagram for explaining a reclosing method. FIG. 2 is a diagram for explaining a reclosing method. FIG. 3 is a diagram for explaining a configuration example of an interruption system. FIG. 4 is a diagram for explaining the operation of the interruption system. FIG. 5 is a diagram for explaining a configuration example of an interruption device 10 and a detection device 20. FIG. 6 is a flowchart for explaining a configuration example of an interruption device 10 and a detection device 20. FIG. 7 is a diagram for explaining Example 1. FIG. 8 is a diagram for explaining Example 2. FIG. 9 is a diagram for explaining Example 3. FIG. 10 is a diagram for explaining an example of a hardware configuration of a processing unit.

[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] Below, we will first explain in detail an example of the operation of the reclosing method in the prior art and the problems involved, and then we will explain in detail the technology according to this embodiment. Note that while Figures 1 and 2 show the configuration of the prior art, neither the operation nor the problems involved are publicly known.

[0011] (Example of operation of reclosing method) The reclosing method is a technology for protecting fault points in a power grid (which may also be called a system) and minimizing the impact of a fault. The mechanism for system protection and fault point detection using the reclosing method will be described with reference to Figures 1 and 2.

[0012] Consider the case where loads 1 to 4 are connected to the power lines extending from the power supply facility and circuit breakers A to D are installed on the power lines, as shown in Figure 1 (1) etc. Operation after a short circuit occurs will be explained with reference to Figures 1 and 2 (1) to (4).

[0013] (1) Protective operation in the event of an accident When a short circuit occurs between circuit breakers A and B, circuit breakers A to D on the power line detect the current fluctuation caused by the short circuit and open the circuit to protect the system.

[0014] (2) Fault point detection Next, the circuit breakers are closed in order starting from the one closest to the power supply equipment, up to circuit breaker B.

[0015] (3) Fault point detection As described above, when circuit breaker B, which is the circuit breaker on the power supply equipment side closest to the fault point, is closed, a short-circuit current occurs again, and all circuit breakers are opened again. This action shows that the fault point is farther from the power supply equipment than circuit breaker B. In other words, it is clear that the short-circuit point is between circuit breakers A and B.

[0016] (4) Restoring power to the safe section Finally, the circuit is closed again starting from the circuit breaker closest to the power supply equipment, and by closing the circuit up to circuit breaker C, which is just before circuit breaker B adjacent to the accident point, it becomes possible to supply power to loads 3 and 4, and the impact of the accident point can be minimized.

[0017] (Problems) As mentioned above, in the case of a fault, the reclosing method temporarily stops the power supply to the entire grid. Furthermore, the reclosing method cannot be used in a power system that uses distributed power sources and performs bidirectional power supply.

[0018] The configuration and operation of the shutdown system for solving the above problems will be described in detail below.

[0019] (Configuration and operation overview of shutdown system) Fig. 3 shows an example of the configuration of the shutdown system in this embodiment. As shown in Fig. 3, this shutdown system includes a shutdown device 10 and a detection device 20 on a power line. The shutdown device 10 and the detection device 20 are separated by a certain distance or more. The shutdown device 10 and the detection device 20 are also connected by a high-speed optical communication line. In the following drawings, a rectangle represents the shutdown device 10, and a circle represents the detection device 20.

[0020] In this tripping system, if an accident (here, a short circuit) occurs on the right side of the detection device 20 (the opposite side of the circuit breaking device 10), the detection device 20 detects an abnormality in the current / voltage (current or voltage) and notifies the abnormality to the circuit breaking device 10 by an optical signal. Upon receiving the optical signal, the circuit breaking device 10 opens the circuit.

[0021] As described above, by using optical communication to notify of an abnormality, it is possible for the circuit breaking device 10 to open the circuit before the current / voltage abnormality is propagated from the detection device 20 to the circuit breaking device 10. This technology is called a proactive breaking technology using optical communication.

[0022] The current / voltage and propagation speed v of optical communication are v = c / √ε, where c is the speed of light in a vacuum, and c ≈ 0.3 m ns －１ ε is the relative dielectric constant of the material through which the light propagates. The propagation speed in a typical power line is determined by the relative dielectric constant of the coating, and ε is around 3 to 5. On the other hand, in the case of optical communications, for example, optical fiber, ε is around 2.25. For this reason, the propagation time in an optical communication line is shorter than the propagation time of current / voltage, making it possible to cut off the light early.

[0023] (Example of operation of the interruption system) Figures 4(a) and 4(b) show a more specific example of the configuration of the interruption system. As shown in Figure 4(a) etc., this interruption system is provided with an interruption device 10-1, a detection device 20-1, an interruption device 10-2 and a detection device 20-2 on the power line.

[0024] An example of the operation of the circuit breaker system will be described with reference to Figures 4(a) and (b). As shown in Figure 4(a), when a short circuit occurs in the power line portion on the right side, a current fluctuation occurs. The current fluctuation caused by the short circuit is transmitted to the detection device 20-2, and when the detection device 20-2 detects a current abnormality, it sends an optical signal to the circuit breaker 10-2 to instruct it to close the circuit.

[0025] 4B, the optical signal instructing the closing of the power line reaches the circuit breaker 20-2 via the optical communication line before the current fluctuation reaches the circuit breaker 20-2, so that the circuit breaker 20-2 can close the power line before the current fluctuation reaches the circuit breaker 20-2.

[0026] (Device Configuration Example) FIG. 5 shows a configuration example of the interrupter device 10 and the detector device 20. As shown in FIG.

[0027] 5, the detection device 20 has a measurement unit 21, a processing unit 22, and a light-emitting unit 23. The measurement unit 21 monitors and measures the current / voltage in the power line. The processing unit 22 determines whether an abnormal current / voltage is occurring from the output of the measurement unit 21, and if it determines that an abnormal current / voltage is occurring, it transmits an optical signal transmission instruction to the issuing unit 23. The light-emitting unit 23 transmits an optical signal instructing to open the circuit in response to the determination by the processing unit 22. In other words, when the light-emitting unit 23 receives an optical signal transmission instruction from the processing unit 22, it transmits an optical signal instructing to open the circuit.

[0028] <Shutoff device 10> The shutdown device 10 has a light receiving unit 11 and a switching unit 12. The light receiving unit 11 generates an electrical signal when it receives an optical signal emitted from the detection device 20. The switching unit 12 opens the power line in response to the electrical signal from the light receiving unit 11. The electrical signal corresponds to an opening instruction.

[0029] In addition, the circuit breaking device 10 may also be equipped with a measuring unit and a processing unit to determine whether or not abnormal current / voltage is occurring, and if the processing unit detects an abnormality, the circuit may be opened by the opening / closing unit 12.

[0030] (Operation Flow) An example of the operation of the interruption system shown in Fig. 5 will be described with reference to the flowchart of Fig. 6. In S1, the measurement unit 21 of the detection device 20 measures the current / voltage at the point of the detection device 20. In S2, if the processing unit 22 detects an abnormality in the current / voltage (Yes in S2), the process proceeds to S3.

[0031] In S3, the light emitting unit 23 transmits an opening command to the adjacent circuit breaking device 10 by an optical signal.

[0032] In S4, the light receiving unit 11 of the circuit breaker 10 receives the optical signal. In S5, the switching unit 12 opens the power line. In S6, the switching unit 12 maintains the open state.

[0033] (Regarding transmission of optical signals) The time required for transmitting an optical signal (more specifically, the time from abnormality detection to opening the circuit) is the propagation time of the optical communication line plus the response and processing time within the detection device 20 and the response and processing time within the interruption device 10.

[0034] Therefore, the distance between the detection device 20 and the interruption device 10 needs to be longer than a certain value (details will be described later) so that the optical signal from the detection device 20 to the interruption device 10 can overtake the current / voltage fluctuations. For example, if a typical power line coating (ε=5) is used, a typical optical communication line material (ε=2.25) is used, and the response and processing speed (time required) within the device is 1 microsecond, the distance between the detection device 20 and the interruption device 10 may be approximately 400 m.

[0035] <How to determine the distance between the detection device 20 and the circuit breaker 10> The propagation speed of electricity is v ｅｌｅ = c / √ε ｅｌｅ (ε ｅｌｅ is the relative permittivity of the power line), and the propagation speed of the optical signal is v ｐｈｔ = c / √ε ｐｈｔ (ε ｐｈｔ is the relative dielectric constant of the optical communication line). The response and processing time within the detection device 20 and the cutoff device 10 is expressed as t ｐｒｏｃ Let's say.

[0036] The distance L between the detection device 20 and the cutoff device 10 needs to be determined so that the sum of the propagation time of the optical signal and the processing time within the device is shorter than the propagation time of the electricity. Therefore, L can be expressed as follows:

[0037] c ≈ 0.3 m ns －１ By calculating using the following, the following results can be obtained:

[0038] From the above formula, F ε ≒ 1.35 (ε ｅｌｅ = 5, ε ｐｈｔ = 2.25), t ｐｒｏｃ When the time tf is 1 μs, the distance L between the devices is 400 m or more.

[0039] In order to shorten the distance between the devices, the processing time t ｐｒｏｃ It is necessary to reduce the relative dielectric constant or to use an optical fiber with a smaller relative dielectric constant or a power cable with a larger relative dielectric constant. ｐｈｔHollow optical fibers are known in which t≒1. ｐｒｏｃ In order to reduce this, for example, it is conceivable to use an LED, which is a light-emitting element with a response speed of about 10 ns, as the light-emitting unit 23, and an MPPC (multipixel photon counter) or PMT (photomultiplier tubes), which is a light-receiving element, as the light-receiving unit 11.

[0040] Hereinafter, examples 1 to 3 will be described as examples of a proactive blocking technique using optical communication.

[0041] (First embodiment) The first embodiment is an example of protecting a DC grid using a preemptive interruption technique. Fig. 7 shows a loop-type DC grid in the first embodiment.

[0042] As shown in FIG. 7, by installing a breaker 10 and a detector 20 in the vicinity of the contact point between the loop (power line) and the load / power supply in the order of proximity to the contact point, the impact of an accident occurring on the loop can be minimized.

[0043] 7, a pair of circuit breaker 10-1 and detector 20-1 and a pair of circuit breaker 10-2 and detector 20-2 are installed on both sides of the junction between load 31 and the loop. Similarly, two pairs of circuit breaker 10 and detector 20 are installed near each of the junction between load 32 and the loop, the junction between power source 41 and the loop, and the junction between power source 42 and the loop.

[0044] The power sources 41 and 42 are, for example, consumers having "renewable energy, input from an AC system, a storage battery, an EV, etc." The loads 31 and 32 are, for example, consumers, a storage battery, an EV, etc.

[0045] 7, when a short circuit occurs on the loop between the power supply 41 and the load 32, only the breaker devices 10-4 and 10-5, which are closest to the short circuit point, open the circuit. This makes it possible to minimize the impact of an accident occurring on the loop, as described above.

[0046] Second Embodiment A second embodiment is another example of a DC grid protection using a proactive interruption technique. Fig. 8 shows a loop-type DC grid in the second embodiment.

[0047] As shown in FIG. 8, by alternately arranging the detection devices 20 and the interruption devices 10 on the loop, the loop can be divided into areas and protected without considering the connection points of the power source and the load.

[0048] 8, the circuit breaker 10-1 and the detection device 20-1 form one pair, the circuit breaker 10-1 and the detection device 20-8 form one pair, and the circuit breaker 10-8 and the detection device 20-8 form one pair. Similarly, the detection devices 20 and the circuit breakers 10 are installed alternately at other points on the loop.

[0049] Adjacent detection devices 20 and interruption devices 10 operate as a pair. The distance between adjacent interruption devices 10 and detection devices 20 is determined based on the above-mentioned calculation.

[0050] The power sources 41 and 42 are, for example, consumers having "renewable energy, input from an AC system, a storage battery, an EV, etc." The loads 31 and 32 are, for example, consumers, a storage battery, an EV, etc.

[0051] As shown in Figure 8, if a short circuit occurs on the loop between the power supply 41 and the load 32, protection is provided by detection devices 20-4 and 20-5 located close to the short circuit point, and by circuit breakers 10-4 and 10-5 located further back (farther from the short circuit point).

[0052] Third Embodiment A third embodiment is an example in which a DC bus wiring is protected using a proactive interruption technique. Fig. 9 shows a bus-type DC wiring in the third embodiment.

[0053] 9, by installing a breaker 10 and a detection device 20 for each power supply and load connected to the bus wiring, accidents at the power supply end or the load end can be prevented from affecting the bus. The distance between adjacent breakers 10 and detection devices 20 is determined based on the calculations described above.

[0054] 9, the detection device 20-1 and the interruption device 10-1 are arranged adjacent to the power source 41. The same applies to the other power sources / loads.

[0055] The power sources 41 and 42 are, for example, consumers having "renewable energy, input from an AC system, a storage battery, an EV, etc." The loads 31 to 35 are, for example, consumers, storage batteries, EVs, etc.

[0056] For example, if a short circuit occurs between the load 31 and the detection device 20-2, only the breaker device 10-2 closest to the short circuit point opens the circuit, thereby preventing an accident occurring in the load 31 from affecting the bus.

[0057] (Hardware Configuration Example) The processing unit 22 in the detection device 20 can be realized by, for example, causing a computer to execute a program. The detection device 20 may be an apparatus provided with the computer, the measurement unit 21, and the light-emitting unit 23.

[0058] That is, the processing unit 22 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 processing unit 22. 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.

[0059] Fig. 10 is a diagram showing an example of the hardware configuration of the computer. The computer in Fig. 10 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. The computer may further include a GPU.

[0060] 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.

[0061] 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 processing unit 22 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.

[0062] (Effects of the embodiment) As described above, with the technology described in the present embodiment, when an accident occurs on a power line, the circuit breaker 10 opens the circuit before the current / voltage abnormality propagates from the detection device 20 to the circuit breaker 10, so that the temporary interruption of power supply to the entire system, which occurs with conventional technology, does not occur.

[0063] The reclosing method, which is a conventional technique, cannot be used in a power system that uses a distributed power source and performs bidirectional power supply. In contrast, the technique according to this embodiment opens the circuit for system protection using only the adjacent detection device 20 and breaker device 10. Therefore, the technique according to this embodiment is not dependent on the shape and structure of the entire system and can be used in a power network that uses a distributed power source.

[0064] The following additional notes are provided regarding the above-described embodiments.

[0065] <Additional Notes> (Additional Item 1) An interruption system having a detection device and a breaking device used on a power line, wherein the detection device transmits an optical signal to the breaking device via an optical communication line when it detects an abnormality in the current or voltage on the power line, and the breaking device opens the power line when it receives the optical signal. (Additional Item 2) The interruption system according to Additional Item 1, wherein the interruption device and the detection device are provided on one side and the other side of a contact point between the power line and a load or a power source in a loop-type DC grid. (Additional Item 3) The interruption system according to Additional Item 1, wherein the detection device and the breaking device are provided alternately in a loop-type DC grid. (Additional Item 4) The interruption system according to Additional Item 1, wherein the detection device and the breaking device are provided for a load or a power source connected to an end point of a bus-type DC wiring. (Supplementary Item 5) The detection device in an interruption system having a detection device and an interruption device used on a power line, the detection device comprising: a processing unit that determines whether an abnormality in current or voltage has occurred on the power line, and that sends an optical signal transmission instruction when it determines that an abnormality has occurred, and a light emitting unit that sends an optical signal to the interruption device via an optical communication line in response to the optical signal transmission instruction from the processing unit. (Supplementary Item 6) The interruption system having a detection device and an interruption device used on a power line, the detection device transmits an optical signal to the interruption device via an optical communication line when it detects an abnormality in current or voltage on the power line, a light receiving unit that receives the optical signal, and a switching unit that opens the power line in response to an instruction from the light receiving unit that has received the optical signal. (Supplementary Item 7) A shutoff method in a shutoff system having a detection device and a shutoff device used on a power line, wherein the detection device transmits an optical signal to the shutoff device via an optical communication line when it detects an abnormality in current or voltage on the power line, and the shutoff device opens the power line when it receives the optical signal. (Supplementary Item 8) A non-transitory storage medium storing a program for causing a computer to function as the processing unit in the detection device described in Supplementary Item 5.

[0066] 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.

[0067] REFERENCE SIGNS LIST 10 Shut-off device 11 Light receiving unit 12 Opening / closing unit 20 Detecting device 21 Measuring unit 22 Processing unit 23 Light emitting unit 31 to 35 Load 41 to 43 Power supply 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 power line interruption system having a detection device and an interruption device for use on a power line, wherein the detection device transmits an optical signal to the interruption device via an optical communication line when it detects an abnormality in current or voltage on the power line, and the interruption device opens the power line when it receives the optical signal.

2. The interruption system according to claim 1, wherein the interruption device and the detection device are provided on one side and the other side of a contact point between a power line and a load or a power source in a loop-type DC grid.

3. The interruption system according to claim 1, wherein the detection device and the interruption device are alternately provided in a loop-type DC grid.

4. The interruption system according to claim 1, wherein the detection device and the interruption device are provided for a load or a power source connected to an end point of a bus wiring in a bus-type DC wiring.

5. A detection device in a shutdown system having a detection device and a shutdown device used on a power line, the detection device comprising: a processing unit that determines whether an abnormality in current or voltage has occurred on the power line, and sends an optical signal transmission instruction when it is determined that an abnormality has occurred; and a light emitting unit that transmits an optical signal to the shutdown device via an optical communication line in response to the optical signal transmission instruction from the processing unit.

6. A circuit breaker in a circuit breaking system having a detection device and a circuit breaker used on a power line, wherein the detection device transmits an optical signal to the circuit breaker via an optical communication line when it detects an abnormality in the current or voltage on the power line, and the circuit breaker comprises: a light receiving unit that receives the optical signal; and an opening / closing unit that opens the power line in response to an instruction from the light receiving unit that has received the optical signal.

7. A method for interrupting a power line in a power line interruption system having a detection device and an interruption device, wherein the detection device transmits an optical signal to the interruption device via an optical communication line when it detects an abnormality in the current or voltage on the power line, and the interruption device opens the power line when it receives the optical signal.

8. A program for causing a computer to function as the processing unit in the detection device according to claim 5.

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