Abnormality detection device for power transmission system of photovoltaic power generation system, remote security system, and abnormality detection method
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- SUNNY THANK YOU CO LTD
- Filing Date
- 2025-12-18
- Publication Date
- 2026-08-06
Smart Images
Figure JP2025044381_06082026_PF_FP_ABST
Abstract
Description
Anomaly detection device for power transmission systems of solar power generation systems, remote safety system, and anomaly detection method.
[0001] This disclosure relates to an anomaly detection device, remote safety system, and anomaly detection method for the power transmission system of a solar power generation system. More specifically, this disclosure relates to an anomaly detection device, remote safety system, and anomaly detection method for the DC power transmission section and AC power transmission section of a solar power generation system.
[0002] A solar power system typically comprises a solar panel containing at least one photovoltaic cell, a junction box, a power conditioner, and grid-connected AC equipment. In many solar power systems, one or more junction boxes correspond to one power conditioner, and each junction box corresponds to one or more solar panels. A junction box may also be provided between the junction box and the power conditioner as needed. In a typical solar power system, DC power from the solar panels is collected via the junction box and junction box before being sent to the power conditioner, where the DC power is converted to AC power and finally connected to the grid power network via the grid-connected AC equipment. For this power transmission, the solar power system is equipped with AC cables for connecting to the grid-connected AC equipment, as well as DC cables and safety equipment such as fuses to transmit high-current DC power.
[0003] Figure 1 is a diagram illustrating a configuration of a conventional solar power generation system using a centralized power conditioner (hereinafter referred to as the "centralized solar power generation system"). The centralized solar power generation system 90 includes solar panels (solar cells) 1 and 2, a power grid 600, junction boxes 100 and 200, and a centralized power conditioner 300. Solar panel 1 outputs the generated DC power to the centralized power conditioner 300 via fuses 101 and 102 and a switch 103 in the junction box 100. Similarly, solar panel 2 also outputs DC power to the centralized power conditioner 300 via fuses 201 and 202 and a switch 203 in the junction box 200. Thus, the configuration of the combination of junction boxes and solar panels is typically such that multiple identical units are installed in parallel. The centralized power conditioner 300 generally converts the DC power received from multiple junction boxes into AC power and outputs the AC power to the existing power grid 600. A typical centralized power conditioner 300 includes terminals 301 and 302, cable assemblies 35 and 36, a P-side main cable 1000, an N-side main cable 1100, a DC electromagnetic contactor 320, an inverter unit 330, and an AC electromagnetic contactor 340. Cable assemblies 35 and 36 consist of cables 150 from the junction box, fuses 310 and 311. The DC electromagnetic contactor 320 is opened and closed by electromagnetic means and incorporates a thermal relay, functioning as a DC-side switchgear. Fuses 310 and 311 are installed on the DC side for overcurrent protection. The inverter unit 330 converts the input DC power into AC power by altering its polarity through appropriate switching operations and outputs it. A step-up transformer 500 is installed between the inverter unit 330 and the power grid 600, transmitting power while insulating the inverter unit 330 from the power grid 600. The step-up transformer 500 is responsible for boosting the voltage, for example, the inverter output voltage (~500V) to transmit power to the grid (transmission lines, 6.6kV to 150kV). The AC contactor 340 is turned on when the inverter unit 330 is connected to the grid 600. The DC contactor 320 is turned on when the solar panel 1 is connected to the power conditioner 300 and functions as a switch.The P terminal 301 and the N terminal 302 are connected to the P - pole (+) side wiring and the N - pole (−) side wiring aggregated in the connection boxes 100 and 200. That is, the DC power passing through the connection boxes 100 and 200 is transmitted to the DC electromagnetic contactor 320 via the P - side DC cables 150 and 250 connected to the P terminal 301, the cable assembly 35 which may include an aggregate of fuses 310 installed in each cable, the N - side main cable 1100, and the N - side DC cables 160 and 260 connected to the N terminal 302, and the cable assembly 36 which may include an aggregate of fuses of each line.
[0004] FIG. 2 is a configuration diagram illustrating a solar power generation system 91 (hereinafter referred to as a “distributed solar power generation system”) using a conventional distributed power conditioner. In the distributed solar power generation system 91, solar panels 1, 2, etc. are divided into groups of a certain number, and small - sized power conditioners 2101, 2102,... are installed near each group of panels. The DC power generated by the solar panel 1 is converted into AC power by the power conditioner 2101 or the like, and then transmitted by the AC collector boxes 2201 or the like, three - phase AC cables 2301 - 2303, 2311 - 2313, and transmitted to the AC power receiving equipment 2000. This AC power is boosted by a step - up transformer 500 to, for example, an AC voltage (∼500V) in order to be transmitted to the grid power network (transmission line, 6.6 kV - 150 kV) via the circuit breaker 2001, main cables 2501, 2502, 2503, and is transmitted to the grid power network 600.
[0005] Abnormalities may occur in the members for transmitting the DC power and AC power illustrated in FIGS. 1 and 2. Typical abnormalities include cable theft and fuse blowing. In the centralized solar power generation system 90 of FIG. 1, two connection boxes are shown, and in the distributed solar power generation system 91 of FIG. 2, four power conditioners are shown. However, in an actual solar power generation system, the number of connection boxes and the number of solar panels are not particularly limited. For example, about 10 connection boxes and 10, 20, etc. solar panels corresponding thereto can be equipped.
[0006] In practical solar power generation systems, theft of some or all of the DC cables is a frequent occurrence. DC cables 150, 160, 250, and 260 installed between the junction box and the power conditioner, and AC cables 2301 to 2313 from the AC junction box to the power receiving equipment, have a large mass of copper wire per unit length and are expensive, so theft often involves cutting and removing these cables. In addition to this theft, fuses 310 and 311 that protect the system often blow when excessive current flows through the power cables due to lightning strikes, etc. Furthermore, irregular electrical conduction with the ground, also known as a ground fault, can occur. To address these abnormalities, there has been a need for highly reliable and practical methods for detecting abnormalities in the DC and AC power transmission systems in solar power generation systems.
[0007] Non-patent document 1 describes a system that uses infrared beams to detect intruders as a measure to prevent the theft of copper cables from solar power generation facilities. Non-patent document 2 describes a system that combines security cameras with AI.
[0008] Patent Document 1 (Japanese Patent Application Publication No. 2017-33219) discloses a conventional technology for detecting the theft of power transmission cables in a solar power generation system, which involves installing an LC oscillation circuit near the cable and utilizing the fact that the oscillation frequency changes when the relative position of the cable and the oscillation circuit changes, thereby detecting the change and monitoring for theft. Specifically, paragraph 0014 of Patent Document 1 discloses "The first aspect of the present invention is a cable theft monitoring system characterized by comprising: a power supply circuit unit; an LC oscillation circuit unit to which power supply current is supplied by the power supply circuit unit; a detection circuit unit for detecting the oscillation frequency of the LC oscillation circuit unit; and a determination circuit unit for determining the change in the oscillation frequency based on the detection result of the oscillation frequency by the detection circuit unit."
[0009] Furthermore, in the cable theft monitoring device disclosed in Patent Document 1, multiple wires are arranged as a wired communication medium for the purpose of theft monitoring in the LC oscillation circuit section and the alarm signal generation section. As another means of signal transmission, Non-Patent Document 3 ("Mapping Major LPWA Standards - Three Classifications of LPWA", Sonas Corporation website) introduces wireless communication, which has become widespread as a means of communication, in particular a narrowband wireless communication technology called LPWA (Low Power Wide Area). Non-Patent Document 3 explains the technical background of LPWA and discloses that the communication speed of LPWA is slower than that of mobile phone systems, that it can be operated for several years to several decades with a typical battery, and that it has a wide area capability that allows communication over several kilometers to tens of kilometers.
[0010] Japanese Patent Publication No. 2017-33219
[0011] Sosuke Kudo, "Solar Power Theft Prevention: Intrusion Notification Using 'Mesh Sensors'," Mega Solar Business Plus, Nikkei BP, September 24, 2023, URL: https: / / project.nikkeibp.co.jp / ms / atcl / 19 / news / 00001 / 03654 / (Last accessed December 13, 2025) Takuya Ogushi, "New Weapon for Solar Power Theft Prevention: AI Detects and Reports Intruders," Mega Solar Business Plus, Nikkei BP, October 30, 2023, URL: https: / / project.nikkeibp.co.jp / ms / atcl / 19 / feature / 00006 / 00046 / (Last accessed December 13, 2025) "Mapping Major LPWA Standards - Three Classifications of LPWA," SONAS Corporation Homepage (URL: https: / / www.sonas.co.jp), Top > Explanation Content > Blog: SONAS IoT / DX Lab > Sonas Corporation, April 1, 2021, URL: https: / / www.sonas.co.jp / media / iotdx-lab / lpwa001 (Last accessed January 27, 2025) "The Information and Communication Industry Becoming IoT-enabled," 2017 Information and Communications White Paper, Part 1, Chapter 3, Section 3, pp. 128-130, Ministry of Internal Affairs and Communications, Japan, July 28, 2017, URL: https: / / www.soumu.go.jp / johotsusintokei / whitepaper / ja / h29 / pdf / n3300000.pdf (Last accessed January 27, 2025)
[0012] Non-patent documents 1 and 2 disclose a system that uses infrared beam sensors and surveillance cameras to detect and alarm thieves who break into solar power plants with the aim of stealing copper cables. However, infrared beam sensors placed around all four sides of the solar power plant site are easily noticeable, and thieves can cut through wire mesh without beams to gain entry, or cut the main power supply to disable the sensors before entering, making this a relatively weak defense against theft rings. Furthermore, the installation costs are high. In addition, the infrared beams are blocked by animals such as deer, bears, and wild boars, as well as by overgrown weeds, resulting in frequent false alarms. Cable theft alarm systems often operate in conjunction with the alarm systems of security companies, and when an anomaly is detected, security guards are dispatched to provide protection. As mentioned above, infrared beam sensors have a high rate of false alarms, and the increased costs due to false dispatches are a major problem. Surveillance cameras also face similar problems.
[0013] Patent Document 1 discloses a configuration for monitoring theft by installing an LC oscillation circuit near the power transmission cable of a centralized solar power generation system. When the relative position of the cable and the oscillation circuit changes, the permeability of the coil L changes, which in turn changes the inductance and thus the oscillation frequency, and this change is detected. However, the relative position of the LC oscillation circuit and the coil differs for each solar power plant. Furthermore, even after being fixed with a fixing device, it changes due to aging, temperature changes, and vibrations caused by earthquakes, etc. For this reason, it is necessary to set the oscillation frequency for each power plant at the time of installation. Also, even after the initial setting, the oscillation frequency changes when the relative position changes over time. For this reason, in order to accurately detect abnormalities with the technology disclosed in Patent Document 1, it is necessary to deal with fluctuating physical quantities.
[0014] Thus, the conventional devices and methods disclosed in Non-Patent Documents 1 and 2, and Patent Document 1, cannot necessarily be expected to operate stably, and improvements in practicality are desired. There is a continuing need for practical methods that can reliably detect abnormalities in the transmission cables of centralized solar power generation systems, such as theft of transmission cables, blown fuses connected to transmission cables, and ground faults. Furthermore, in Patent Document 1, it is necessary to specially arrange multiple wires that do not contribute to solar power generation at all for signal transmission between the LC oscillation circuit section and the alarm signal generation section of the theft monitoring device, but such wiring incurs significant costs. Moreover, to the best of the inventor's knowledge, there are no prior art disclosures disclosing countermeasures for abnormalities in the transmission cables that constitute the AC power transmission section of distributed solar power generation systems, such as theft of transmission cables or blown fuses connected to transmission cables.
[0015] This disclosure aims to reliably and accurately detect abnormalities in the power transmission cables of a solar power generation system, such as theft of the power transmission cables, blown fuses connected to the power transmission cables, and ground faults. The inventors have created a method for detecting abnormalities in the DC power transmission section and AC power transmission section of a solar power generation system without adding complex circuit components, thereby completing the invention.
[0016] In other words, in one embodiment of the present disclosure, an abnormality detection device is provided for a power transmission unit that transmits power output from a solar panel as DC power or AC power, comprising: a sensing circuit having a terminal that is electromagnetically connected to at least one of the conductors for power transmission provided in the power transmission unit and sensing an AC voltage appearing in the conductor of the power transmission unit; a wireless transmitter connected to the sensing circuit and transmitting a wireless signal indicating a sensing signal which is the output of the sensing circuit; and an abnormality detection processing unit that receives the wireless signal from the wireless transmitter and outputs an abnormality detection signal indicating an abnormality in the power transmission unit based on the sensing signal indicated by the wireless signal. Furthermore, in one embodiment of the present disclosure, an abnormality detection method is also provided for a power transmission unit that transmits power output from a solar panel as DC power or AC power, the method comprising the steps of: being electromagnetically connected to at least one of the conductors for power transmission provided in the power transmission unit, sensing the AC voltage appearing in the conductor of the power transmission unit and emitting a sensing signal which is an output corresponding to the AC voltage; transmitting a wireless signal indicating the sensing signal; and receiving the wireless signal and outputting an abnormality detection signal indicating an abnormality in the power transmission unit based on the sensing signal indicated by the wireless signal.
[0017] Furthermore, in one embodiment of the present disclosure, a remote safety system is also provided for a power transmission unit that transmits power output from a solar panel as DC power or AC power, comprising: a sensing circuit that is electromagnetically connected to at least one of the conductors for power transmission provided in the power transmission unit and senses an AC voltage appearing in the conductor of the power transmission unit; a wireless transmitter connected to the sensing circuit and transmitting a wireless signal indicating a sensing signal which is the output of the sensing circuit; an abnormality detection processing unit that receives the wireless signal from the wireless transmitter and outputs an abnormality detection signal indicating an abnormality in the power transmission unit based on the sensing signal indicated by the wireless signal; and a remote alarm signal transmitting unit that receives the abnormality detection signal from the abnormality detection processing unit and transmits a remote alarm signal indicating an abnormality in the power transmission unit based on the abnormality detection signal.
[0018] In this disclosure, a wireless transmitter may include a wireless transceiver that utilizes a transmission function, and a wireless receiver may include a wireless transceiver that utilizes a reception function. A sensing circuit may include a circuit element and a circuit that includes the circuit element and electrical connection lines.
[0019] According to this disclosure, abnormalities in the DC power transmission section or AC power transmission section of a solar power generation system can be detected with high reliability.
[0020] Figure 1 is a block diagram illustrating an example configuration of a conventional centralized solar power generation system. Figure 2 is a block diagram illustrating an example configuration of a conventional distributed solar power generation system. Figure 3 is a block diagram illustrating an example of a centralized solar power generation system to which Example 1 is applied in an embodiment of this disclosure. Figure 4 is a circuit diagram showing an example of a sensing circuit and wireless transmitter configuration that may be adopted in Example 1 in an embodiment of this disclosure. Figure 5 is a block diagram illustrating an example of a centralized solar power generation system to which Example 2 is applied in an embodiment of this disclosure. Figure 6 is a circuit diagram showing an example of a sensing circuit and wireless transmitter configuration that may be adopted in Example 2 in an embodiment of this disclosure. Figure 7 is a block diagram illustrating an example of a distributed solar power generation system to which Example 3 is applied in an embodiment of this disclosure. Figure 8 is a block diagram illustrating an example of a distributed solar power generation system to which Example 4 is applied in an embodiment of this disclosure. Figure 9 is a circuit diagram showing an example of a sensing circuit and wireless transmitter configuration that may be adopted in Example 4 in an embodiment of this disclosure. Figure 10 is a block diagram illustrating an example of a distributed solar power generation system to which Example 5 is applied in an embodiment of this disclosure.
[0021] Embodiments of this disclosure are described below. Unless otherwise specified in the following description, common parts or elements are denoted by the same reference numerals throughout the figures. Also, in the figures, the elements of each embodiment are not necessarily shown in proportion to each other. Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.
[0022] 1. Overview The anomaly detection device and anomaly detection method of the embodiments of this disclosure will be described in comparison with conventional configurations (centralized photovoltaic power generation system 90 and distributed photovoltaic power generation system 91, Figures 1 and 2).
[0023] In short, the abnormality detection device of this embodiment has a configuration in which a circuit device for sensing abnormalities (hereinafter referred to as a sensing circuit) is added to a conventional centralized solar power generation system 90 illustrated in Figure 1 and a distributed solar power generation system 91 illustrated in Figure 2, and an abnormality detection processing unit is also added. This embodiment includes an abnormality detection device that employs wireless communication for signal transmission between the sensing circuit and the abnormality detection processing unit, and the abnormality detection method of this embodiment can be implemented as the operation of a centralized solar power generation system or a distributed solar power generation system equipped with such an abnormality detection device. As will be described later, in a centralized solar power generation system, the sensing circuit is typically electromagnetically connected between the DC input terminal and the ground terminal for the DC cable connecting the junction box and the power conditioner, or between the P-side DC cable and the N-side DC cable. In solar power generation systems, DC cables are generally connected to DC input terminals. Accordingly, the sensing circuit for the abnormality detection device of this embodiment can also respond to abnormalities in DC cables, blown fuses connected to them, and ground faults. Furthermore, in this embodiment, in a distributed solar power generation system, the sensing circuit is typically connected to an AC cable. In this case as well, it can respond to fuse blowouts and ground faults. For these operations, the sensing circuit in this embodiment can be an AC voltage detection device in a centralized solar power generation system, and a phase loss relay in a distributed solar power generation system. The sensing circuit in this embodiment can also be a circuit that detects the presence or absence of the DC output of an AC-DC converter that converts AC voltage to DC voltage. In this embodiment, by using wireless communication for signal transmission between the sensing circuit and the abnormality detection processing unit, it is not necessary to install new wiring solely for signal transmission.
[0024] The specific configuration and operation of the abnormality detection device and abnormality detection method of this embodiment will be described below with reference to the examples. The contents described in each embodiment can be applied to any of the abnormality detection devices and abnormality detection methods of this embodiment, insofar as they do not contradict each other. In the following embodiments, the solar power generation system is described in which one junction box is provided for one solar panel or group of solar panels (hereinafter referred to as "solar panels"), and two junction boxes are used for each solar power generation system. However, the number of solar panels per junction box and the number of junction boxes per solar power generation system are not particularly limited. Furthermore, in the description of each solar power generation system, the description of solar panel 1 and the junction box 100 connected thereto, and the AC current collector box 100 or 3301 also applies similarly to the part of solar panel 2 connected in parallel and the junction box 200 connected thereto.
[0025] 2. Example 1 2-1. Overall Configuration This embodiment can also be applied to a centralized solar power generation system. Figure 3 is a block diagram showing the configuration of a centralized solar power generation system 12 to which Example 1 of the abnormality detection device and abnormality detection method is applied in this embodiment. In this disclosure, the DC power transmission unit 30 of the solar power generation system 12 refers to the part that transmits the DC power obtained by power generation between the solar panels 1 and 2 and the power conditioner 300. This DC power transmission unit 30 is one of the targets for abnormality detection in the abnormality detection device and abnormality detection method of this disclosure. To explain using the centralized solar power generation system 12 shown in Figure 3 as an example, the DC power transmission unit 30 mainly consists of P-side DC cables 150 and 250, N-side DC cables 160 and 260, and fuses 310 and 311. Typical abnormalities in the DC power transmission unit 30 include the cutting of P-side DC cables 150, 250 and N-side DC cables 160, 260 (including those caused by theft or other human error), the blowing of fuses 310, 311, and ground faults. The centralized solar power generation system 12 (Figure 3) of Embodiment 1 of this embodiment is equipped with sensing circuits 4001, 4002, 4011, and 4012 between an appropriate location of the DC power transmission unit 30 and the ground in order to detect such abnormalities in the DC power transmission unit 30 with high reliability. Furthermore, DC interruption coupling capacitors 4101, 4102, 4111, and 4112 are attached in series to each sensing circuit. Thus, the sensing circuits of this disclosure may have coupling capacitors attached to one terminal or both terminals. The appropriate locations for the sensing circuits 4001, 4002, 4011, and 4012 are locations where abnormalities in the DC power transmission unit 30 or a part thereof can be detected through electromagnetic connections, and the physical location is not particularly limited. Appropriate locations typically include inside or near the junction boxes 100 and 200. For example, the DC power transmission unit 30 includes cable assemblies 35 and 36 that transmit DC power on the P and N pole sides. Corresponding to the junction boxes 100 and 200, cable assembly 35 includes the P-side DC cable 150 and the P-side DC cable 250, and cable assembly 36 includes the N-side DC cable 160 and the N-side DC cable 260, respectively.Cable assemblies 35 and 36 may be a single integrated cable, or they may refer to a collection of cables that are electrically connected directly or via a fuse during use. In this configuration, sensing circuits 4001 and 4002 are added between the P-side DC cable 150 and the N-side DC cable 160 and the ground, respectively. Similarly, sensing circuits 4011 and 4012 are added between the P-side DC cable 250 and the N-side DC cable 260 and the ground, respectively. In Figure 3, the connection point where sensing circuits 4001 and 4002 are connected to the P-side and N-side DC cables 150 and 160 is between the switch 103 and the power conditioner 300. However, in this embodiment of the abnormality detection device and abnormality detection method, there are no limitations on the connection point, and sensing circuits 4001 and 4002 can be provided at any location within the junction box 100 or near the solar panel 1. In the abnormality detection device and method of this embodiment, an abnormality detection range is defined, starting from the power conditioner 300 and ending at any position up to the solar panel 1, and sensing circuits 4001 and 4002 are installed at any position within this range from the starting point to the ending point. However, it is not necessary for all power cables to be connected to a sensing circuit. In this embodiment, the sensing circuit consists of an AC signal rectifier circuit, a reference value comparison circuit, and a contact output circuit.
[0026] On the other hand, the power conditioner 300 is equipped with a monitoring and processing unit 3000, which is an additional component compared to the centralized solar power generation system 90. The monitoring and processing unit 3000 is branched and connected from the P-side main cable 1000 and the N-side main cable 1100 via coupling capacitors 4021 and 4022 for blocking DC voltage. The monitoring and processing unit 3000 consists of an AC signal generator (detection signal generation unit) 3100, a wireless receiver 3200, an alarm signal processing unit 3001, and an alarm output device 3002 for abnormalities such as cable theft or ground faults. In the centralized solar power generation system 12, the monitoring and processing unit 3000 functions as an abnormality detection processing unit in this disclosure.
[0027] 2-2. Sensing Circuit and Wireless Transmitter The configuration of the sensing circuit of the centralized solar power generation system 12 in Embodiment 1 will be described in detail. Figure 4 is a circuit diagram showing the configuration of an example of a sensing circuit 4001 and a wireless transmitter 3201 that may be adopted in Embodiment 1. The AC signal (detection AC signal) generated by the AC signal generator (detection signal generation unit) 3100 in the monitoring processing unit 3000 is transmitted to the sensing circuit 4001 via the coupling capacitor 4021, using each DC cable as a communication path, and via the coupling capacitor 4101. The received AC signal is rectified by the rectifier circuit 4001R and smoothing circuit 4001S in the sensing circuit 4001 and converted to a DC voltage, and compared with a reference voltage Vref by the reference value comparison circuit 4001C. Typically, in a normal state where the DC power transmission cable is not cut, the output of the AC signal generator 3100 is set so that the DC voltage obtained by rectification by the rectifier circuit 4001R and the smoothing circuit 4001S is greater than the reference voltage Vref. If the DC power transmission cable 150, etc. is cut after this setting, the AC signal is interrupted, so the DC voltage obtained by rectification becomes less than the reference voltage, and the reference value comparison circuit 4001C emits a negative contact signal (sensing signal) to the wireless transmitter 3201. The signal ground of the reference value comparison circuit 4001C floats from the earth. The power supply for the reference value 4001C can be generated by down-converting the DC voltage of the solar panel during the day when the solar panel is generating power, and at night it can be obtained from the storage battery charged during the day. The power supply potential may be between the positive potential and the signal ground, or it may be a positive and negative DC power supply with the signal ground in between. Next, the wireless transmitter 3201 transmits a wireless signal indicating the received contact signal to the wireless receiver 3200 (Figure 3) in the monitoring processing unit 3000. The signal is then forwarded to the alarm signal processing unit 3001, and finally, the wireless alarm output device 3002 issues an alarm (abnormality detection signal) through the alarm output terminal 3003. In Embodiment 1, the signal generated by the AC signal generator 3100 in the monitoring processing unit 3000 is exemplified as an analog AC signal, but a digital signal may be generated and transmitted, and the presence or absence of the digital signal may be determined by the sensing circuit to issue a contact signal.
[0028] 3. Example 2 3-1. Overall Configuration Diagram 5 is a block diagram showing the configuration of a centralized solar power generation system 13 to which Example 2 of the abnormality detection device and abnormality detection method is applied in this embodiment. In the centralized solar power generation system 13, sensing circuits 4001 and 4002 are configured to be connected to the P-side DC cable 150 and N-side DC cable 160 and the P-side DC cable 250 and N-side DC cable 260, respectively, via DC blocking coupling capacitors 4101 and 4102 and 4111 and 4112. The operating principle of Example 2 is similar to that of Example 1, so the differences will be described in detail in the following section 3-2.
[0029] 3-2. Sensing Circuit and Wireless Transmitter The configuration of the sensing circuit of the centralized solar power generation system 13 in Embodiment 2 will be described in detail. Figure 6 is a circuit diagram showing the configuration of an example sensing circuit 4001 and wireless transmitter 3201 that may be adopted in Embodiment 2. The configuration and operation of Embodiment 2 are similar to those of Embodiment 1, and the differences from Embodiment 1 are as follows. In Embodiment 2, the AC signal (detection AC signal) generated by the AC signal generator (detection signal generation unit) 3100 in the monitoring processing device 3000 (Figure 5) is transmitted to the sensing circuit 4001 via the coupling capacitor 4021, each P-side DC cable 150, and coupling capacitor 4101, as shown in Figure 6, and is returned to the AC signal generator 3100 via the coupling capacitor 4102, each N-side DC cable 160, and coupling capacitor 4022. In Embodiment 1, the return path of the AC signal is the earth (or grounding wire), but in Embodiment 2, it is the N-side DC cable 160. The detection principle and alarm processing method for the disconnection of a DC cable via the wireless transmitter 3201 in Example 2 are the same as in Example 1. The signal ground of the reference value comparison circuit 4001C may be floated from the earth or grounded. The power supply for the reference value 4001C can be generated by down-converting the DC voltage of the solar panels during the day when the solar panels are generating power, and at night it can be obtained from the battery charged during the day. The power supply potential may be between the positive potential and the signal ground, or it may be a positive and negative DC power supply with the signal ground in between. The monitoring processing unit 3000 in the centralized solar power generation system 13 functions as an abnormality detection processing unit in this disclosure.
[0030] For the wireless transmitters 3201, 3202, and wireless receiver 3200 used in Examples 1 and 2, it is desirable to apply LPWA wireless communication technology (hereinafter referred to as "LPWA communication"). The advantage of LPWA communication is that it can communicate over a wide range of several kilometers to tens of kilometers with low power, and furthermore, no license is required for the user. Here, LPWA communication includes various communication methods, and in particular, LoRaWAN, SIGFOX, Eltres, and ZETA (which may be registered trademarks of their respective companies), also classified as narrowband LPWA, are suitable for this embodiment. LPWA is outlined, for example, in Non-Patent Document 4. For example, the junction boxes 100 and 200 used in the solar power generation system 12 of Example 1 in Figure 3 are distributed within the power plant site, for example, with distances of several hundred meters between them. However, by adopting LPWA wireless transmitters and receivers, it becomes possible to transmit and receive abnormal signals of the DC cables included in the DC power transmission unit 30. However, the wireless transmitter and receiver are not limited to LPWA communication; other types of wireless transmitters and receivers can be used as long as they meet the required specifications. For power supply to the sensing circuit and wireless transmitter, DC power can be branched from the DC cable during the daytime when the solar panels are generating power. On the other hand, at night when the solar panels are not generating power, the battery charged during the day can be used. The same applies to the solar power generation system 13 of Embodiment 2 shown in Figure 5.
[0031] 4. Example 3 4-1. Overall Configuration This embodiment can also be applied to a distributed photovoltaic power generation system. Figure 7 is a block diagram showing the configuration of a distributed photovoltaic power generation system 14 to which the abnormality detection device and abnormality detection method (Example 3) are applied in this embodiment. In the distributed photovoltaic power generation system 14, DC power is converted to AC power by small power conditioners 2101 to 2104 located near the solar panels 1 to 4, and then the AC power is transmitted to the AC power receiving equipment 2000 by three-phase AC cables 2301 to 2303 and 2311 to 2313. In this disclosure, the AC power transmission unit 50 of the distributed photovoltaic power generation system 14 refers to the part that transmits AC power from the distributed power conditioners 2101 to 2104 to the AC power receiving equipment 2000. This AC power transmission unit 50 is the target of abnormality detection in the abnormality detection device and abnormality detection method of this disclosure. Using the distributed solar power generation system 14 shown in Figure 7 as an example, the AC power transmission section 50 is mainly composed of three-phase AC cables 2301-2303 and 2311-2313.
[0032] Typical abnormalities in the AC power transmission unit 50 include the cutting of three-phase AC cables 2301-2303 and 2311-2313 (including those caused by theft or other human error) or ground faults. The distributed solar power generation system 14 (Figure 7) of Embodiment 2 of this embodiment is equipped with sensing circuits 5001 and 5011 between an appropriate location of the AC power transmission unit 50 and the ground in order to detect such abnormalities in the AC power transmission unit 50 with high reliability. An appropriate location here means a location from which an abnormality in the AC power transmission unit 50 or a part thereof can be detected through an electromagnetic connection, and the physical location is not particularly limited. An appropriate location is typically inside or near the current collection boxes 2201 and 2202. In 7, the sensing circuits 5001 and 5011 are installed in the current collection boxes 2201 and 2202 among the AC cables 2301 to 2303 and 2311 to 2313, between each distributed power conditioner 2101 to 2104 and the AC power receiving equipment 2000. However, the abnormality detection device and abnormality detection method of this embodiment are not limited to the wiring location and can be installed in any location within the current collection boxes 2201 and 2202, or near the solar panels 1 to 4.
[0033] On the other hand, as an additional configuration in Embodiment 3 compared to the distributed solar power generation system 91, for example, the AC power receiving equipment 2000 may be equipped with a monitoring and processing unit 3000. The monitoring and processing unit 3000 consists of a wireless receiver 3200, an alarm signal processing unit 3001, and an alarm output device 3002 for abnormalities such as cable theft or ground faults. In the distributed solar power generation system 14, the monitoring and processing unit 3000 functions as an abnormality detection processing unit in this disclosure.
[0034] 4-2. Sensing Circuits, Wireless Transceivers In the distributed solar power generation system 14 of Embodiment 3, for example, phase loss relays can be used as sensing circuits 5001 and 5011. A phase loss relay is a relay that has the function of detecting when one of the three-phase AC cables is broken and issuing a contact. Phase loss relays have mainly been used in motor control systems and are commonly used to prevent motor burnout when the motor is operated in a broken state. In the distributed solar power generation system 14, in addition to the daytime when the solar panels 1 to 4 are generating power, AC voltage is also applied to the three-phase AC cables 2301 to 2303 and 2311 to 2313 from the grid power network 600 via the step-up transformer 500 even at night when power is not being generated. If any one phase of the three-phase AC cable 2301-2303, 2311-2313, etc. is cut, the AC voltage for the corresponding phase is not applied. Therefore, the sensing circuits 5001 and 5011, which are equipped with phase loss relays, sense the phase loss and send a contact signal (sensing signal) to the wireless transmitters 3201 and 3202. Next, the wireless transmitters 3201 and 3202 transmit a wireless signal indicating the received contact signal to the wireless receiver 3200 in the monitoring and processing unit 3000. Then the signal is forwarded to the alarm signal processing unit 3001, and finally, an alarm (abnormality detection signal) is issued from the wireless alarm output device 3002 through the alarm output terminal 3003. Regarding the power supply to the sensing circuits 5001, 5011 and the wireless transmitters 3201, 3202, it is helpful that the three-phase AC cables 2301-2303, 2311-2313, etc. of the distributed solar power generation system are constantly charged with AC voltage from the power conditioner during daytime solar power generation and from the grid at night. In other words, it is preferable to install an AC / DC converter that can extract DC output from the three-phase AC cables 2301-2303, 2311-2313, etc. for the above power supply. Furthermore, in order to detect cable breakage in this disclosure, it is preferable to attach a dry cell battery or a constantly charged storage battery in preparation for cable breakage that results in the loss of AC power supply.
[0035] 5. Example 4 5-1. Overall Configuration This embodiment can also be applied to a distributed photovoltaic power generation system with a different configuration. Figure 8 is a block diagram showing the configuration of a distributed photovoltaic power generation system 15 to which the abnormality detection device and abnormality detection method (Example 4) are applied in this embodiment. The configuration differs from that of Example 3 only in the wiring of the sensing circuit, which is connected to any two phases of the three-phase AC cables 2301-2303 and 2311-2313.
[0036] 5-2. The sensing circuit diagram 9 is a circuit diagram showing the configuration of an example sensing circuit and wireless transmitter that may be used in Embodiment 4 in this embodiment. The sensing circuits 6001 and 6011 consist of an AC-DC power supply 6001P, a relay 6001R, a dry cell (or storage battery) 6001B, and reverse current prevention diodes 6001D1 and 6001D2. The AC-DC power supply 6001P is connected to any two phases of the three-phase AC cable 2301 to 2303, converts AC power to DC power and outputs it, supplying power to the wireless transmitter 3201. The relay 6001R is connected to the AC-DC power supply 6001P. When one of the two three-phase AC cables connected to the AC-DC power supply 6001P is cut, its DC output is lost and the contacts are opened. The monitoring and processing unit 3000 in the distributed photovoltaic power generation system 15 is the same as that in the distributed photovoltaic power generation system 14 and functions as an anomaly detection processing unit in this disclosure.
[0037] This enables the sensing circuit to function by providing disconnection information to the wireless transmitter 3201. Battery 6001B has the function of a backup power supply that supplies power to the wireless transmitter 3201 when the DC output of the AC-DC power supply 6001P is lost. Reverse current prevention diode 6001D1 prevents current from flowing back into battery 6001B when DC power is supplied by the AC-DC power supply 6001P under normal circumstances. Reverse current prevention diode 6001D2 prevents current from flowing back from battery 6001B when the DC voltage of the AC-DC power supply 6001P is lost. In reality, in cable theft, all three-phase AC cables 2301 to 2303 are cut, so even if the AC-DC power supply 6001P is not connected to the first cut cable, the relay 6001R will operate when the second cable is cut, so there is no practical problem.
[0038] The wireless transmitters 3201, 3202, and wireless receiver 3200 of Examples 3 and 4 can also be used for LPWA communication, particularly narrowband LPWA, as in Examples 1 and 2. However, the wireless transceivers are not limited to LPWA communication; other types of wireless transceivers can also be used as long as they meet the required specifications.
[0039] 6. Example 5 6-1. Overall Configuration Diagram 10 is a block diagram showing an example of a distributed solar power generation system 16 to which the remote security system (Example 5) is applied in this embodiment. The remote security system of the embodiment of this disclosure includes a cable break detection system detailed in Examples 1 to 4 with the addition of a remote alarm signal transmission unit, and functions, for example, as a cable theft monitoring and alarm system.
[0040] A remote alarm signal transmission unit 70 is connected to the distributed solar power generation system 16. The remote alarm signal transmission unit 70 typically includes an alarm signal processing unit 7001, a wide-area transmission device 7002, and a deterrent warning device 7003. The alarm signal processing unit 7001 is connected to an alarm output terminal 3003 from which an abnormality detection signal is output from the monitoring processing device 3000, which is the abnormality detection processing unit in this disclosure. In a distributed solar power generation system 16 with such a configuration, an abnormality in the AC power transmission unit 50 is detected, similar to that of the distributed solar power generation system 14. The functions and operations of the sensing circuits 5001, 5011, wireless transmitters 3201, 3202, and monitoring processing device 3000 are the same as those of the distributed solar power generation system 14 in the above-described embodiment 3. The configuration of adding the remote alarm signal transmission unit 70 to the wireless transmitters 3201, 3202, and monitoring processing device 3000 constitutes the remote security system in this disclosure.
[0041] 6-2. When an alarm (anomaly detection signal) is issued from the wireless alarm output device 3002 of the remote alarm signal transmission unit via the alarm output terminal 3003, the alarm signal processing unit 7001 receives the anomaly detection signal from the alarm output device 3002 in the remote alarm signal transmission unit 70, and the alarm signal processing unit 7001 transmits an alarm signal to the wide-area transmission device 7002 accordingly. The wide-area transmission device 7002 can communicate with a security system of a security company located in a remote location, for example, by wireless communication means, and transmits a wireless alarm signal corresponding to the above alarm signal. As a result, for example, the security company that receives the wireless alarm signal can immediately dispatch security guards to the site or have them handle the situation. The alarm signal processing unit 7001 may also be connected to a deterrent warning device 7003, such as a Patlite (registered trademark). The deterrent warning device 7003 functions to deter thieves from continuing potentially criminal acts by emitting threatening and warning sounds, including horn sounds and warning voices in various languages, and by flashing a rotating light. The wide-area transmitter 7002 may be a wireless communication device as shown in Figure 10, or it may be a wired communication device. For wireless communication, wireless communication technologies that enable communication with remote locations, such as LTE (Long Term Evolution), can be used. For wired communication, wired communication technologies that enable communication with remote locations, such as optical fibers, can be used. The alarm signal transmitted by the alarm signal processing unit 7001 and the wireless alarm signal transmitted by the wide-area transmitter 7002 constitute the remote alarm signal. However, the specific communication technologies used for wireless and wired communication are not particularly limited, and it can be a public network or a closed network.
[0042] In this embodiment, the remote security system was described using a distributed solar power generation system 16, which is a distributed solar power generation system 14 (Figure 7) to which a remote alarm signal transmission unit 70 has been added. However, this disclosure also includes other embodiments of solar power generation systems to which a remote alarm signal transmission unit has been added. For example, the remote security system of this disclosure can be implemented by adding the remote alarm signal transmission unit 70 to a distributed solar power generation system 15 (Figure 8), which is distributed similarly to the distributed solar power generation system 14, or by adding the remote alarm signal transmission unit 70 to a centralized solar power generation system 12, 13 (Figures 3 and 5), which are centralized. In that case, the abnormality will be detected in the DC power transmission unit 30, not the AC power transmission unit 50. The remote security system of this disclosure, which is added to any of the solar power generation systems, functions, for example, as a cable theft monitoring and alarm system.
[0043] 7. Conclusion This disclosure is not limited to the embodiments described above and includes various modifications. For example, the embodiments described above are described in detail for the purpose of illustrating this disclosure and are not necessarily limited to having all the configurations described. It is possible to replace some of the configurations of one embodiment with those of another embodiment, and it is also possible to add configurations of other embodiments to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace some of the configurations of each embodiment with those of other embodiments. In other words, a person skilled in the art may make various changes, combinations, subcombinations, and substitutions with respect to the components of the embodiments described above, within the technical scope of this disclosure or its equivalents.
[0044] 12, 13 Centralized solar power generation system 14, 15, 16 Distributed solar power generation system 1-4 Solar panels 100, 200 Junction boxes 101, 102, 201, 202, 310, 311 Fuses 103, 203 Switches 150, 250 P-side DC cables 160, 260 N-side DC cables 1000 P-side main cables 1100 N-side main cables 2000 AC power receiving equipment 2001 Circuit breakers 2101, 2102, 2103, 2104 Distributed power conditioners 2201, 2202 AC junction boxes 2301, 2302, 2303, 2311, 2312, 2313 Three-phase AC cables 2501, 2502, 2503 Main cables 30 DC power transmission unit 35 Cable assembly (P side) 36 Cable assembly (N side) 300 Centralized power conditioner 301 P terminal 302 N terminal 320 DC electromagnetic contactor 330 Inverter unit 340 AC electromagnetic contactor 310, 311 Fuses 3000 Monitoring and processing unit 3001 Alarm signal processing unit 3002 Alarm output device 3003 Alarm output terminal 3100 AC signal generator (detection signal generation unit) 3200 Wireless receiver 3201, 3202 Wireless transmitter 4001, 4011, 4002, 4012 Sensing circuit 4021, 4022, 4101, 4102, 4111, 4112 DC blocking coupling capacitor 50 AC power transmission unit 500 Step-up transformer 5001, 5011, 6001, 6002 Sensing circuits 600 Power grid 70 Remote alarm signal transmission unit 7001 Alarm signal processing unit 7002 Wide-area transmission device 7003 Intimidation warning device 92 Centralized solar power generation system (conventional) 94 Distributed solar power generation system (conventional)
Claims
1. An anomaly detection device for a power transmission unit that transmits power output from a solar panel as DC power or AC power, comprising: a sensing circuit that is electromagnetically connected to at least one of the conductors for power transmission provided in the power transmission unit and senses the AC voltage appearing in the conductor of the power transmission unit; a wireless transmitter connected to the sensing circuit and transmitting a wireless signal indicating a sensing signal which is the output of the sensing circuit; and an anomaly detection processing unit that receives the wireless signal from the wireless transmitter and outputs an anomaly detection signal indicating an anomaly in the power transmission unit based on the sensing signal indicated by the wireless signal.
2. The abnormality detection device according to claim 1, wherein the power transmission unit transmits the power output from the solar panel as DC power, is electromagnetically connected to the conductor, and further comprises a detection signal generation unit that generates a detection AC signal applied to the power transmission unit, and the AC voltage sensed by the sensing circuit is the detection AC signal generated by the detection signal generation unit.
3. The abnormality detection device according to claim 1, wherein the power transmission unit transmits the power output from the solar panel as AC power, and the AC voltage sensed by the sensing circuit is the AC voltage that appears in the power transmission unit.
4. The abnormality detection device according to claim 3, wherein the sensing circuit is a phase loss relay.
5. The abnormality detection device according to claim 3, wherein the power transmission unit is equipped with a three-phase AC cable for transmitting power by three-phase AC, and the sensing circuit is connected to at least two of the three-phase AC cables and senses the AC voltage that appears between the at least two cables.
6. An anomaly detection method for a power transmission unit that transmits power output from a solar panel as DC power or AC power, comprising the steps of: being electromagnetically connected to at least one of the conductors for power transmission provided in the power transmission unit, sensing an AC voltage appearing in the conductor of the power transmission unit and emitting a sensing signal which is an output corresponding to the AC voltage; transmitting a wireless signal indicating the sensing signal; and receiving the wireless signal and outputting an anomaly detection signal indicating an anomaly in the power transmission unit based on the sensing signal indicated by the wireless signal.
7. A remote safety system for a power transmission unit that transmits power output from a solar panel as DC power or AC power, comprising: a sensing circuit that is electromagnetically connected to at least one of the conductors for power transmission provided in the power transmission unit and senses the AC voltage appearing in the conductor of the power transmission unit; a wireless transmitter connected to the sensing circuit and transmitting a wireless signal indicating a sensing signal which is the output of the sensing circuit; an abnormality detection processing unit that receives the wireless signal from the wireless transmitter and outputs an abnormality detection signal indicating an abnormality in the power transmission unit based on the sensing signal indicated by the wireless signal; and a remote alarm signal transmitting unit that receives the abnormality detection signal from the abnormality detection processing unit and transmits a remote alarm signal indicating an abnormality in the power transmission unit based on the abnormality detection signal.
8. The remote security system according to claim 7, wherein the remote alarm signal transmitting unit is equipped with a wireless communication device capable of communicating with a remote location, and the remote alarm signal is transmitted wirelessly.