Anomaly detection device and method for power transmission systems of solar power generation systems.

Abstract

This device detects abnormalities in the DC or AC power transmission section of a solar power generation system. [Solution] The abnormality detection device of this disclosure is for a power transmission unit 30 that transmits DC or AC power output from a solar panel 1, and comprises sensing circuits 4001, 4002, an RFID reader / writer 3001, and an abnormality detection processing unit 3002. The sensing circuit is a two-terminal sensing circuit including an RFID tag, and one terminal is electromagnetically connected to at least one of the power transmission conductors provided in the power transmission unit 30. The RFID reader / writer determines the presence or absence of the RFID tag. The abnormality detection processing unit detects an abnormality in the power transmission unit when the RFID reader / writer determines the presence or absence of each RFID tag and determines that at least one of the RFID tags is absent.

Description

Technical Field

[0001] The present disclosure relates to an abnormality detection device and an abnormality detection method for a power transmission system of a photovoltaic power generation system. More specifically, the present disclosure relates to an abnormality detection device and an abnormality detection method for a direct current power transmission unit and an alternating current power transmission unit in a photovoltaic power generation system.

Background Art

[0002] A photovoltaic power generation system typically includes a solar panel including at least one photovoltaic cell, a junction box, a power conditioner, and grid-connected AC equipment. In many photovoltaic power generation systems, one or more junction boxes correspond to one power conditioner, and one or more solar panels correspond to each junction box. A collector box may be provided between the junction box and the power conditioner as needed. In a typical photovoltaic power generation system, DC power from the solar panel is aggregated through the junction box or the collector box and then sent to the power conditioner, where the DC power is converted into AC power and finally connected to the grid power network through the grid-connected AC equipment. For this power transmission, in addition to an AC power cable for connecting to the grid-connected AC equipment, the above photovoltaic power generation system is equipped with safety equipment such as DC power cables and fuses for transmitting 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 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 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~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 N terminal 302 are connected to the P-pole (+) side wiring and the N-pole (-) side wiring, which are consolidated in the junction boxes 100 and 200. In other words, the DC power passing through the junction 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 is a collection of fuses 310 installed on each cable, the N-side main cable 1100, and the N-side DC cables 160 and 260 connected to the N terminal 302, the cable assembly 36 which is a collection of fuses for each line, and the N-side main cable 1100.

[0004] Figure 2 is a diagram illustrating a configuration of a conventional distributed solar power generation system 91 (hereinafter referred to as the "distributed solar power generation system") using a distributed power conditioner. In the distributed solar power generation system 91, solar panels 1, 2, etc. are divided into groups of a certain number of panels, and small power conditioners 2101, 2102, ... are installed near each group of panels. The DC power generated by solar panel 1 is converted to AC power by power conditioner 2101, and then transmitted by AC junction box 2201, etc., and three-phase AC power cables 2301~2303, 2311~2313 to AC power receiving equipment 2000. Therefore, the power is then stepped up by the step-up transformer 500, via the circuit breaker 2001 and main cables 2501, 2502, and 2503, to be transmitted to the power grid (transmission lines, 6.6kV to 150kV), for example, an AC voltage (~500V), and then transmitted to the power grid 600.

[0005] The components that transmit DC and AC power, as illustrated in Figures 1 and 2, can experience malfunctions. Typical malfunctions include cable theft and blown fuses. Note that the centralized solar power generation system 90 in Figure 1 shows two junction boxes, and the distributed solar power generation system 91 in Figure 2 shows four power conditioners. However, in actual solar power generation systems, the number of junction boxes and solar panels are not particularly limited; for example, there may be around 10 junction boxes and correspondingly 10 or 20 solar panels.

[0006] In practical solar power generation systems, theft of some or all of the DC power cables is a frequent occurrence. DC power cables 150, 160, 250, and 260 installed between the junction box and the power conditioner, and AC power cables 2301, 2302, and 2303 from the AC junction box to the power receiving equipment, are expensive due to their high copper wire mass per unit length, and theft often involves cutting and removing these cables. In addition to this theft, fuses 310 and 311, which protect the system when excessive current flows through the power cables due to lightning strikes, etc., often blow. Furthermore, irregular electrical conduction with the ground, also known as a ground fault, can occur. To address these anomalies, there has been a need for highly reliable and practical methods for detecting anomalies in the DC power transmission system in solar power generation systems.

[0007] Patent Document 1 (Japanese Patent 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."

[0008] Patent Document 2 (Japanese Patent Publication No. 2007-5140115) discloses a configuration in which a radio frequency identification (RFID) tag is attached to an object to be protected from theft (in the case of the present invention, a power cable), and when the object to be protected from theft is taken away, the RFID tag, which moves simultaneously, is detected by an antenna installed at the exit of the security facility. Specifically, the abstract of Patent Document 2 states: "The present invention discloses a technology for detecting radio frequency identification (RFID) tags. For example, it describes an exit control system for detecting the unauthorized removal of articles from a protected facility. A series of antennas are installed to create a checkpoint near the exit of the protected area. RFID tags are attached to the protected articles. Each of the tags contains information that uniquely identifies the attached article and status information regarding whether or not the removal of the article from the facility is permitted. An RF reader outputs an RF signal via an antenna to generate an electromagnetic field within the checkpoint. The RF reader outputs RF radio waves from a single port to multiple antennas via a distributor / coupler. In this way, a single RF reader with only one transceiver port interrogates multiple antennas simultaneously. The invention then describes various technologies that enable the RF reader to detect the unauthorized removal of articles." [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2017-33219 [Patent Document 2] Special Publication No. 2007-5140115 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] Patent Document 1 describes a configuration for monitoring theft by installing an LC oscillation circuit near the power transmission cable of a 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. 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 if the relative position changes over time. It is necessary to deal with fluctuating physical quantities. 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.

[0011] Furthermore, the RFID tags described in Patent Document 2 are standardized to operate in the range of 135kHz to 2.45GHz. The maximum communication range for active tags equipped with batteries in the 433MHz band is at most 100m. While passive tags that do not require batteries are practical for applications such as preventing cable theft at solar power plants, passive tags have a short communication range of only about 5m. Even if power cables or other electrical components of a solar power system are stolen, and the stolen items are taken away from the solar power plant premises with RFID tags attached, it becomes impossible to detect them once they are far from the RF reader antenna.

[0012] Thus, the conventional devices and methods disclosed in Patent Documents 1 and 2 cannot necessarily be expected to operate reliably, and improvements in practicality are desired. There is a continuing need for practical methods that can reliably detect abnormalities in the transmission cables of solar power generation systems, such as theft of transmission cables, blown fuses connected to transmission cables, and ground faults. [Means for solving the problem]

[0013] 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, and have completed the invention.

[0014] In other words, in one embodiment of the present disclosure, an anomaly detection device is provided for a power transmission unit that transmits DC power or AC power output from at least one solar panel, comprising: at least one sensing circuit with two terminals including a radio frequency identification (RFID) tag, wherein one of the two terminals is electromagnetically connected to at least one conductor for power transmission provided in the power transmission unit; an RFID reader / writer electromagnetically connected to the conductor for determining the presence or absence of the RFID tag of the sensing circuit; and an anomaly detection processing unit that detects an anomaly in the power transmission unit when the RFID reader / writer determines that the RFID tag is not present.

[0015] Furthermore, in one embodiment of the present disclosure, there is a method for detecting an anomaly for a power transmission unit that transmits DC power or AC power output from at least one solar panel, wherein the power transmission unit is provided with at least one two-terminal sensing circuit including a radio frequency identification (RFID) tag, such that one of the two terminals is electromagnetically connected to at least one of the DC transmission conductors provided in the power transmission unit, and the method includes the steps of determining the presence or absence of the RFID tag using an RFID reader / writer electromagnetically connected to the conductor, and generating and outputting an anomaly detection signal indicating an anomaly in the DC power transmission unit in the absence of the RFID tag.

[0016] In the present disclosure, as will be described later, the electric wire of the DC power cable provided in the DC power transmission unit or the AC power cable provided in the AC transmission unit is used as part of the communication path of the electrical signal between the RFID tag and the RFID reader / writer. The term "electromagnetically connected" in the present disclosure means any connection that may include a wireless connection or a proximity communication connection that is a connection through an electric field or a magnetic field.

Advantages of the Invention

[0017] According to the present disclosure, an abnormality in the DC power transmission unit or the AC power transmission unit of the photovoltaic power generation system can be detected with high reliability.

Brief Description of the Drawings

[0018] [Figure 1] FIG. 1 is a block diagram showing an exemplary configuration of a conventional centralized photovoltaic power generation system. [Figure 2] FIG. 2 is a block diagram showing an exemplary configuration of a conventional decentralized photovoltaic power generation system. [Figure 3] FIG. 3 is a block diagram showing a basic configuration of an RFID that can be adopted in an embodiment of the present disclosure. [Figure 4] FIG. 4 is a block diagram showing the configuration of a centralized photovoltaic power generation system to which Example 1 of the abnormality detection device and the abnormality detection method in the embodiment of the present disclosure is applied. [Figure 5] FIG. 5 is a circuit diagram of a sensing circuit including an RFID tag that can be adopted in an embodiment of the present disclosure. [Figure 6] FIG. 6 is a circuit diagram of an RFID signal processing unit including an RFID reader / writer that can be adopted in an embodiment of the present disclosure. [Figure 7] FIG. 7 is a circuit diagram of a sensing circuit that adopts a signal transmission transformer in an embodiment of the present disclosure. [Figure 8] FIG. 8 is a circuit diagram of an RFID signal processing unit that adopts a signal transmission transformer in an embodiment of the present disclosure. [Figure 9]FIG. 9 is a block diagram showing a centralized solar power generation system to which Example 2 is applied in an embodiment of the present disclosure. [Figure 10] FIG. 10 is a block diagram showing a centralized solar power generation system to which Example 3 is applied in an embodiment of the present disclosure. [Figure 11] FIG. 11 is a circuit diagram showing the configuration of a sensing circuit that can be adopted in an embodiment of the present disclosure. [Figure 12] FIG. 12 is a circuit diagram showing the configuration of an RFID signal processing unit that can be adopted in an embodiment of the present disclosure [Figure 13] FIG. 13 is a circuit diagram showing the configuration of a sensing circuit that can be adopted in an embodiment of the present disclosure. [Figure 14] FIG. 14 is a circuit diagram showing the configuration of an RFID signal processing unit that can be adopted in an embodiment of the present disclosure. [Figure 15] FIG. 15 is a block diagram showing the configuration of a distributed solar power generation system to which Example 4 is applied in an embodiment of the present disclosure. [Figure 16] FIG. 16 is a circuit diagram showing the configuration of a sensing circuit that can be adopted in an embodiment of the present disclosure. [Figure 17] FIG. 17 is a circuit diagram showing the configuration of an RFID signal processing unit that can be adopted in an embodiment of the present disclosure. [Figure 18] FIG. 18 is a circuit diagram showing the configuration of a sensing circuit that can be adopted in an embodiment of the present disclosure. [Figure 19] FIG. 19 is a circuit diagram showing the configuration of an RFID signal processing unit that can be adopted in an embodiment of the present disclosure. [Figure 20] FIG. 20 is an example of a BPF that can be adopted in an embodiment of the present disclosure, and is a circuit diagram of a series resonance circuit composed of a resistor R, an inductor L, and a capacitor C. [Figure 21] FIG. 21 is the frequency characteristic of the impedance of a BPF that can be adopted in an embodiment of the present disclosure. [Figure 22]Figure 22 is a circuit diagram of an anti-resonant circuit consisting of a resistor R, an inductor L, and a capacitor C, which is an example of a BRF that may be used in the embodiments of this disclosure. [Figure 23] Figure 23 shows the frequency characteristics of the impedance of a BRF that may be used in embodiments of this disclosure. [Figure 24] Figure 24 is a block diagram showing an example of a distributed photovoltaic power generation system to which Example 5 is applied in an embodiment of this disclosure. [Figure 25] Figure 25 is a block diagram showing an example of a distributed photovoltaic power generation system to which Example 6 is applied in an embodiment of this disclosure. [Figure 26] Figure 26 is a circuit diagram showing the configuration of the sensing circuit section of a distributed photovoltaic power generation system in Embodiment 6 of this disclosure. [Figure 27] Figure 27 is a circuit diagram showing the configuration of the BPF and RFID signal processing unit of a distributed photovoltaic power generation system in Embodiment 6 of this disclosure. [Figure 28] Figure 28 is a circuit diagram showing the configuration of the sensing circuit section of a distributed photovoltaic power generation system in Embodiment 6 of this disclosure. [Figure 29] Figure 29 is a circuit diagram showing the configuration of the BPF and RFID signal processing unit of a distributed photovoltaic power generation system in Embodiment 6 of this disclosure. [Modes for carrying out the invention]

[0019] 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.

[0020] 1. RFID First, let's describe the RFID that may be applied to this disclosure. Figure 3 is a block diagram showing the basic configuration of an RFID that may be adopted in the embodiments of this disclosure. An RFID tag consists of an antenna for transmitting and receiving signals, signal decoding, encoding, communication control, memory, a retaining battery, and a power supply. An RFID reader / writer transmits and receives communication electrical signals (AC signals obtained by modulating an AC current of a certain carrier frequency with a digital signal) to and from an RFID tag via an antenna using electromagnetic induction or radio waves, reads the number (ID number) information individually assigned to each RFID tag, and determines whether or not the RFID tag exists based on the presence or absence of that number.

[0021] One typical example of an RFID tag to which this disclosure applies is the passive tag, although active tags are also applicable to this disclosure. A passive tag is an RFID tag that operates using radio waves from an RFID reader / writer as its energy source and does not require a built-in battery. The antenna of the RFID tag reflects a portion of the radio waves from the RFID reader / writer, and the ID information is returned on these reflected waves. Because the intensity of the reflected waves is very low, the reception range of passive tags is relatively short compared to active tags, but they have the advantages of being inexpensive and operating almost permanently. The RFID reader / writer needs to supply relatively strong radio waves so that it can receive and decode the very weak reflected waves from the tag.

[0022] Communication signals are electrical signals obtained by modulating alternating current at a predetermined carrier frequency with a digital signal. The carrier frequency is standardized within the range of 135 kHz to 2.45 GHz.

[0023] In passive tag communication, an RFID tag has a built-in rectifier circuit that rectifies the radio waves from the RFID reader / writer, converts them to DC, and uses this as power to operate the integrated circuit. Typically, the radio waves from the RFID reader / writer are modulated with a command bit sequence following a preamble. This is followed by an unmodulated carrier. The preamble stores enough energy for the initial operation of the integrated circuit. The command bit sequence is then demodulated and interpreted, and the unmodulated carrier portion is used to transmit a response on the reflected wave, returning the information.

[0024] In this disclosure, communication signals are transmitted through DC or AC power cables of a solar power generation system. Therefore, typically, systems employing low frequencies, such as medium wave (135 kHz) or short wave (13.56 MHz), which allow for relatively low transmission loss, are used as carrier frequencies. However, the RFID communication method in this disclosure is not limited to these. Between the RFID reader / writer or RFID tag and the transmission path, such as a DC or AC power cable, communication signals are not directly coupled but transmitted and received via an antenna or transformer capable of communicating through space. The principle of signal transmission via antennas is electromagnetic induction for medium wave and short wave frequencies (135 kHz, 13.56 MHz), and radio wave transmission for UHF band and microwave frequencies (422 MHz, 900 MHz, 2.45 GHz).

[0025] The ID number, which is a uniquely assigned number to each RFID tag, is digital information. Therefore, it is possible to accurately determine the presence or absence of a very large number of RFID tags, and to identify any RFID tags that are not present. By taking advantage of these benefits and attaching RFID tags individually to the objects whose presence or absence you want to determine, it is possible to identify the presence or absence and quantity of each object.

[0026] 2. 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).

[0027] In essence, the abnormality detection device of this embodiment has a configuration in which a circuit for sensing abnormalities (hereinafter referred to as the sensing circuit) is added to the conventional centralized solar power generation system 90 and distributed solar power generation system 91 illustrated in Figures 1 and 2, and an abnormality detection processing unit is also added. The abnormality detection method of this embodiment can be implemented as an operation of such a centralized solar power generation system or distributed solar power generation system. 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. Since the DC cable is connected to the DC input terminal, the sensing circuit can also respond to the blown fuse and ground fault of the DC cable and the fuse connected to it. In a distributed solar power generation system, the sensing circuit is typically connected to the AC power cable. In this case as well, it can also respond to the blown fuse and ground fault. For these operations, the sensing circuit is a circuit block consisting of an RFID tag, an antenna (or transformer) as a signal transmission means, and a circuit for blocking DC or AC voltage from the RFID tag. A preferred sensing circuit may also include a transformer as a signal transmission means. By using DC or AC power cables as the communication path, the distance between the RFID tag and the RFID reader / writer can be greater than the distance over which the RFID tag and RFID reader / writer can communicate directly.

[0028] 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 example 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 examples, a photovoltaic power generation system is described using a configuration 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 photovoltaic power generation system. However, the number of solar panels per junction box and the number of junction boxes per photovoltaic power generation system are not particularly limited. Furthermore, in the description of each photovoltaic 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.

[0029] 3. Example 1 3-1. Overall Structure Figure 4 is a block diagram showing the configuration of a centralized photovoltaic power generation system 12 to which Embodiment 1 of the abnormality detection device and abnormality detection method is applied in this embodiment. In this disclosure, the DC power transmission section of the photovoltaic power generation system 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 section is the target of abnormality detection in the abnormality detection device and abnormality detection method of this disclosure. To explain using the centralized photovoltaic power generation system 12 shown in Figure 4 as an example, the DC power transmission section 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 section 30 include cutting of the P-side DC cables 150 and 250 and N-side DC cables 160 and 260 (including human error such as theft), blowing of fuses 310 and 311, and ground faults. The centralized solar power generation system 12 (Figure 4) of Embodiment 1 of this embodiment is equipped with sensing circuits 4001, 4002, 4011, and 4012 between an appropriate location on the DC power transmission unit 30 and the ground in order to reliably detect abnormalities in the DC power transmission unit 30. Furthermore, DC blocking coupling capacitors 4101, 4109, 4111, and 4112 are attached in pairs with each sensing circuit. The sensing circuits of this disclosure have coupling capacitors attached to one terminal or both terminals, as clearly shown in the figure, but the description of coupling capacitors will be omitted in the following explanation. It is not necessarily required to use an electronic component capacitor as this coupling capacitor. For example, if a coupling capacitor is formed between the cable copper wire and the antenna or transformer of the RFID tag by installing an RFID tag near or in contact with the cable sheathing material, and the required capacitance is achieved there, then the installation of an electronic component capacitor becomes unnecessary.

[0030] 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 poles, respectively. 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. Cable assemblies 35 and 36 may be a single cable, or they may refer to a collection of cables that are electrically connected directly or via a fuse or the like 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 4, 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, the abnormality detection device and abnormality detection method of this embodiment are not limited to the connection point, and sensing circuits 4001 and 4002 can be installed at any location within the junction box 100 or near the solar panel 1. In the anomaly detection device and anomaly detection method of this embodiment, the sensing circuits 4001 and 4002 are installed at any position within the range from the starting point to the ending point, defining a target range for anomaly detection that starts from the power conditioner 300 and ends at any position up to the solar panel 1. However, it is not necessary for all power cables to be connected to the sensing circuit. In this embodiment, the sensing circuit consists of an RFID tag and an antenna (or transformer) as a signal transmission means.

[0031] On the other hand, the power conditioner 300 is equipped with a monitoring and processing unit 3000 as 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. The monitoring and processing unit 3000 consists of coupling capacitors 4021 and 4022 for blocking DC voltage, an antenna (or transformer) which is an RFID tag and signal transmission means, a signal processing unit (hereinafter referred to as the RFID signal processing unit) 3001 which includes an RFID reader / writer, and an alarm output device 3002 for abnormalities such as cable theft or ground fault.

[0032] The RFID reader / writer in the signal processing unit transmits an alternating current (carrier wave) modulated with a command bit sequence to the RFID tags in the sensing circuits attached to each DC cable, using each DC cable as a communication path. Each RFID tag receives the carrier wave from the RFID reader / writer via electromagnetic induction (or radio waves) from an antenna (or transformer) in the sensing circuit, returns a reflected wave modulated with its own ID signal, and the RFID reader / writer receives and demodulates this reflected wave. The presence or absence of the RFID tag is determined by whether or not a signal corresponding to that RFID tag is obtained, and this allows detection of whether or not there is an abnormality in the corresponding DC cable. If the signal of one of the installed RFID tags is lost, an alarm is issued from the alarm output device 3002 via the alarm output terminal 3003.

[0033] 3-2. Sensing circuit and RFID signal processing unit The configuration of the sensing circuit of the centralized solar power generation system 12 in Example 1 is described in detail. Figures 5 and 6 are circuit diagrams of sensing circuits 4001, 4002, 4011, and 4012, which include RFID tags and may be used in embodiments of this disclosure, and a circuit diagram of the RFID signal processing unit 3001, which includes an RFID reader / writer. The carrier frequency of the communication electrical signal is a frequency with low transmission loss. In this disclosure, the DC power cable or AC power cable itself is used as part of the electromagnetic connection path, i.e., the transmission path, of the RFID tag, so losses occur depending on the carrier frequency due to their impedance. For this reason, when selecting the carrier frequency for RFID, the frequency is selected considering the amount of loss and the optimal antenna shape. In embodiments of this disclosure, a loop antenna is exemplified to correspond to the case where medium wave / short wave (135 kHz, 13.56 MHz) is used. However, it is not necessarily limited to these frequencies; UHF microwaves (433MHz, 2.45GHz) may also be used, in which case a dipole antenna should be used for the RFID tag antenna.

[0034] Figure 5 shows a specific configuration of a sensing circuit comprising an RFID tag using a DC cable and a loop antenna as a communication path, as disclosed in this invention. The communication electrical signal emitted from the RFID signal processing unit 3001 (Figure 4) is transmitted to the RFID tag, which includes an in-tag loop antenna 4104 and a signal processing circuit 4105, via the DC cable 150, a DC blocking coupling capacitor 4101, a signal transmission / reception loop antenna 4102, and a resonant capacitor 4103. The DC blocking coupling capacitor 4101 has the function of blocking the DC potential charged in the DC cable 150 from being applied to the signal transmission loop antenna 4102. It should be noted that it is not necessarily required to use an electronic component capacitor as this coupling capacitor. For example, by installing the RFID tag near or in contact with the cable sheathing, a coupling capacitor is formed between the cable copper wire and the antenna or transformer of the RFID tag, with the cable sheathing material as the dielectric, and if the required capacitance is achieved as a result, then the installation of an electronic component capacitor becomes unnecessary.

[0035] The signal transmission loop antenna 4102, together with the resonant capacitor 4103, forms a resonant circuit whose resonant frequency is the carrier signal frequency. Signals are transmitted and received between the signal transmission loop antenna 4102 and the tag's internal loop antenna 4104 by electromagnetic induction (induced electromotive force due to changes in the magnetic field generated by the loop antenna). If a portion of the multiple DC cables is cut due to an abnormal accident such as theft, or if it becomes connected to the ground due to a ground fault, the RFID tag cannot transmit or receive communication signals. As a result, the RFID signal processing unit 3001 will no longer be able to detect the RFID tag attached to the DC cable that has been cut or is experiencing a ground fault. In this case, the RFID signal processing unit 3001 determines that the RFID tag (such as 4001) no longer exists and transmits a signal corresponding to its absence to the alarm output device 3002 for abnormalities such as cable theft or ground faults, which then issues an alarm signal.

[0036] Figure 6 shows the specific configuration of the DC blocking coupling capacitor and the RFID signal processing unit 3001 (Figure 4). It consists of a signal transmission / reception loop antenna 4023, a resonant capacitor 4024, a loop antenna 4025 within the RFID reader / writer, and a signal processing circuit 4026, connected via a DC blocking coupling capacitor 4021 branched from the P-side main cable 1000 and a DC blocking coupling capacitor 4022 branched from the N-side main cable 1100.

[0037] The RFID tags in Figure 5 and the RFID reader / writer in Figure 6 can be replaced with commercially available devices. Commercially available RFID tags and RFID reader / writers each have a built-in loop antenna or dipole antenna. When using medium wave / short wave (135kHz, 13.56MHz), the loop antenna is a flat shape with sides of several millimeters. On the other hand, when using UHF / microwave (433MHz, 2.45GHz), if a half-wavelength antenna is used for the dipole antenna, the rod length becomes half the wavelength of the carrier wave, and at 1000MHz it becomes a large 150 millimeters. Thus, when using loop antennas or dipole antennas, the coupling efficiency of the antennas changes when the relative position of the antennas changes, so care must be taken when installing them.

[0038] Figure 7 is a circuit diagram of a sensing circuit that employs a signal transmission transformer with a primary coil 4106 and a secondary coil 4108 instead of the antenna pair 4102 and 4104 to eliminate the problems of the antenna described above. The transmission path of the communication electrical signal is the same as the configuration in Figure 5. A resonant circuit is formed between the primary coil 4106 and capacitor 4107 of the signal transmission transformer, with the carrier signal frequency as its resonant frequency. The signal is transmitted by electromagnetic induction to the signal processing circuit 4105 of the RFID tag, which is directly connected to the secondary coil 4108 of the same transformer. Signal processing in the event of a fault in the DC cable is the same as in Figure 5.

[0039] Figure 8 is a circuit diagram of the RFID signal processing unit 3001, which, like Figure 7, employs a signal transmission transformer with primary coil 4027 and secondary coil 4029 instead of the antenna pair 4023 and 4025 (Figure 6). Compared to the antenna pair 4023 and 4025 (Figure 6), the primary coil 4027 and secondary coil 4029 in the transformer are manufactured as a single unit, and the coupling efficiency does not change, thus achieving a stable electromagnetic connection and enabling stable operation.

[0040] Furthermore, the combination of using loop antennas or other antenna pairs, or transformers, for each RFID tag and RFID reader / writer is arbitrary and can be decided independently.

[0041] 4. Example 2 4-1. Overall Structure Figure 9 is a block diagram showing an example of a centralized solar power generation system 22 to which Embodiment 2 of this embodiment is applied. Comparing the centralized solar power generation system 22 to the centralized solar power generation system 12 in Figure 4, an additional circuit configuration is added: one end of coupling capacitor 4021 is connected to cable assembly 35, one end of coupling capacitor 4022 is connected to cable assembly 36, the other ends of coupling capacitors 4021 and 4022 are connected to each other, and an RFID signal processing unit 3001 is connected to the neutral point which serves as the interconnection point (connection node). Meanwhile, sensing circuits 4001 and 4002 each have one terminal connected to the P-side and N-side DC cables 150 and 160, respectively, and the other ends of sensing circuits 4001 and 4002 are connected in series at the interconnection point. This interconnection point serves as the neutral point and is not grounded. The neutral points of the sensing circuits 4001 and 4002 are connected to the RFID signal processing unit 3001 via a dedicated neutral wire 2008. The same applies to the sensing circuits 4011 and 4012, and their neutral points are also connected to the RFID signal processing unit 3001.

[0042] 4-2. Sensing circuit and RFID signal processing unit The configuration of the sensing circuits 4001, 4002, 4011, 4012, etc. is the same as that of Example 1 (Figure 5 or Figure 7). The configuration of the RFID signal processing unit 3001, which determines the presence or absence of each RFID tag, is also the same as that of Example 1. However, the other ends of the sensing circuits 4001 and 4002 in Example 1 are not grounded but connected to the neutral wire 2008 which is connected to the neutral point. One terminal of the RFID reader / writer included in the RFID signal processing unit 3001 is also connected to the neutral wire 2008, rather than being grounded. With this connection, abnormality detection of the cable assemblies 35 and 36 becomes possible without requiring AC or DC grounding for any of the sensing circuits 4001, 4002, 4011, and 4012.

[0043] 5. Example 3 5-1. Overall Structure In Example 1, sensing circuits 4001, 4002, 4011, and 4012 were connected between the P-side cable assembly 35 or the N-side cable assembly 36 and the ground. In this case, sensing circuits 4001, 4002, 4011, and 4012 are required to distinguish between the P-side and N-side DC cables 150, 250, 160, and 260 in each of the junction boxes 100 and 200 and detect abnormalities, resulting in a number of sensing circuits that is twice the number of junction boxes installed. However, there are cases where it is not always necessary to distinguish between the P-side and N-side. Example 3 is a configuration in which the required number of sensing circuits is the same as the number of junction boxes.

[0044] Figure 10 is a block diagram showing an example of a centralized solar power generation system 32 to which Embodiment 3 of this embodiment is applied. Compared to the centralized solar power generation system 12 in Figure 4, in Embodiment 3, the coupling capacitor 4021 is connected to the P-side main cable 1000 and one input of the RFID signal processing unit 3001, and the coupling capacitor 4031 is connected to the N-side main cable 1100 and the other input of the RFID signal processing unit 3001. Also, one end of the sensing circuit 4001 is connected to the P-side DC cable 150 and the other end to the N-side DC cable 160. Similarly, one end of the sensing circuit 4011 is connected to the P-side DC cable 250 and the other end to the N-side DC cable 260. In this configuration, the following series circuit is formed. Specifically, a series circuit is formed starting from one terminal of the RFID signal processing unit 3001, and ending with the coupling capacitor 4021, the P-side main cable 1000, the P-side DC cable 150, the coupling capacitor 4101, the sensing circuit 4001, the coupling capacitor 4109, the N-side DC cable 160, the N-side main cable 1100, and the other terminal of the RFID signal processing unit 3001. A similar series circuit, including the sensing circuit 4011, is also formed for the solar panel 2. Each series circuit is connected in parallel to form a series-parallel circuit.

[0045] The RFID signal processing unit 3001 determines the presence or absence of each RFID tag in each sensing circuit of this series-parallel circuit. If an abnormality such as a break occurs in either the P-side DC cable 150, 250 or the N-side DC cable 160, 260, the broken series circuit in the parallel series circuit becomes open, and the RFID tag in the corresponding sensing circuit 4001 or 4011 can no longer be detected. This change allows for the detection of an abnormality.

[0046] In Examples 1 and 2, as shown in Figures 4 and 9, one sensing circuit was installed on each of the P-side and N-side DC cables. In contrast, in Example 3, one sensing circuit is installed for each pair of P-side and N-side DC cables, thus halving the number of sensing circuits.

[0047] The centralized solar power generation system 32 of Example 3 can exhibit the following unique effects. Firstly, the cost is reduced because only one sensing circuit is needed for each pair of P-side and N-side DC cables. Secondly, the circuit that determines the presence or absence of an RFID tag does not include a ground wire (Example 1) or a neutral wire (Example 2), thus eliminating the need for these wires.

[0048] 5-2. Sensing circuit and RFID signal processing unit The sensing circuit of Example 3 can have the same configuration as the sensing circuits 4001 and 4011 of Examples 1 and 2. Specifically, the sensing circuit 4001 shown in Figure 5 or Figure 7 is configured to connect the ground electrode of the sensing circuit 4001 to the N-side DC cable 160 via a DC voltage blocking coupling capacitor 4109 (Figure 10). Note that the connection between the sensing circuit 4001 and the P-side DC cable 150 or the N-side DC cable 160 can also be reversed.

[0049] Similarly, the configuration of the RFID signal processing unit 3001 can be the same as in Figure 6 or Figure 8, where the ground electrode is connected to the N-side DC cable. The connection between the RFID signal processing unit 3001 and the P-side main cable 1000 or the N-side main cable 1100 can also be reversed.

[0050] However, in a configuration where one end of the sensing circuit or RFID signal processing unit 3001 is connected to the P-side or N-side DC cable without a DC voltage blocking coupling capacitor, there is a concern that the possibility of a short circuit due to electrical contact between the P-side cable and the N-side cable will increase. In such a case, a DC voltage blocking coupling capacitor can be installed at both ends of the sensing circuit and RFID signal processing unit. This configuration is shown in Figures 11 to 14.

[0051] Figure 11 is a circuit diagram showing the configuration of the sensing circuit 4001 in Example 3, which consists of a coupling capacitor, a resonant capacitor, an antenna, and an RFID tag. Figure 12 is a circuit diagram showing the configuration of the RFID signal processing unit 3001 in Example 3, which consists of a coupling capacitor, a resonant capacitor, an antenna, and an RFID reader / writer.

[0052] The sensing circuits 4001 (Figure 11) and 4002 (Figure 13) are connected to the P-side DC cable 150 and the N-side DC cable 160 via DC voltage blocking coupling capacitors 4101 and 4109. Additionally, the RFID signal processing units 3001 (Figure 12) and 3002 (Figure 14) are connected to the P-side main cable 1000 and the N-side main cable 1100 via DC voltage blocking coupling capacitors 4021 and 4031.

[0053] 6. Example 4 This embodiment can also be applied to configurations in which AC power is transmitted by a power transmission unit (distributed solar power generation system).

[0054] 6-1. Overall Structure Figure 15 is a block diagram showing the configuration of a distributed photovoltaic power generation system 42 to which the abnormality detection device and abnormality detection method (Example 4) are applied in this embodiment. In the distributed photovoltaic power generation system 42, DC power is converted to AC power by small power conditioners 2101 to 2104 located near the solar panels 1 to 4, and then transmitted to the AC power receiving equipment 2000 by three-phase AC power cables 2301 to 2303 and 2311 to 2313. In this disclosure, the AC power transmission unit 50 of the distributed photovoltaic power generation system 42 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 42 shown in Figure 15 as an example, the AC power transmission section 50 is mainly composed of three-phase AC power cables 2301-2303 and 2311-2313.

[0055] Typical abnormalities in the AC power transmission unit 50 include the cutting of AC power cables 2301-2303 and 2311-2313 (including those caused by theft or other human error) or ground faults. The distributed photovoltaic power generation system 42 (Figure 15) of Embodiment 4 of this embodiment is equipped with sensing circuits 5001-5003 and 5011-5013 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 is a location where an abnormality in the AC power transmission unit 50 or a part thereof can be sensed 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 Figure 15, the sensing circuits 5001-5003 and 5011-5013 are installed within the current collection boxes 2201 and 2202 of the AC power cables 2301-2303 and 2311-2313, between each distributed power conditioner 2101-2104 and the AC power receiving equipment 2000. However, the abnormality detection device and method of this embodiment are not limited to the wiring location and can be installed at any location within the current collection boxes 2201 and 2202, or near the solar panels 1-4.

[0056] In the abnormality detection device and method of this embodiment, AC voltage blocking BPFs (bandpass filters) or BRFs (band rejection filters) 5111-5113, 5121-5123 sensing circuits 5001-5003, 5011-5013 are installed at any position within the range from the AC power receiving equipment 2000 to any position on the solar panels 1-4, where the range to be detected for abnormalities is defined. However, it is not necessary for all power cables to be connected to sensing circuits. In this embodiment, the presence or absence of RFID tags on sensing circuits attached to each AC power cable, which are gathered in an AC power transmission section equipped with sensing circuits consisting of RFID tags, an antenna (or transformer) as a signal transmission means, and a circuit for blocking AC voltage from the RFID tags, is determined. This determination is performed by a monitoring and processing device 3000 which is installed branching off from the main cables 2501, 2502, and 2503. An abnormality in the AC power transmission unit is detected by determining the presence or absence of each RFID tag.

[0057] In contrast to the distributed photovoltaic power generation system 91, the distributed photovoltaic power generation system 42 of this embodiment employs a configuration in which, within the current collection boxes 2201-2202, one of the two terminals of the sensing circuits 5001-5003 and 5011-5013 is attached to the three-phase AC power cables 2301-2303 and 2311-2313, and the other terminal is interconnected in a star connection, with the connection point being grounded. The sensing circuits 5001-5003 and 5011-5013 have a configuration for realizing the function of sensing abnormalities in the AC power transmission unit 50. Specifically, they consist of an RFID tag, an antenna as a signal transmission means, and a circuit for blocking AC voltage from the RFID tag. In a preferred configuration, the sensing circuits 5001-5003 and 5011-5013 may include a transformer.

[0058] In contrast to the distributed solar power generation system 91, the AC power receiving equipment 2000 used in the distributed solar power generation system 42 of this embodiment includes a monitoring and processing unit 3000. The monitoring and processing unit 3000 consists of an AC voltage interruption BPF (bandpass filter) or BRF (band rejection filter) 5101 to 5103 in its front stage, an RFID signal processing unit 3001 including an antenna (or transformer) and a signal processing circuit, and an alarm output device 3002 for abnormalities such as cable theft or ground faults.

[0059] 6-2. Sensing circuit and RFID signal processing unit The configuration of the sensing circuit of the distributed photovoltaic power generation system 42 in Example 4 is described in detail. Figure 16 is a configuration diagram of the sensing circuit 5001 in Example 4, including the RFID tag. In Example 4, a loop antenna 4102 is exemplified as the antenna, corresponding to the case where medium wave / short wave (135 kHz, 13.56 MHz) is used. However, it is not necessarily limited to these frequencies, and UHF / microwave (433 MHz, 2.45 GHz) may also be used, in which case a dipole antenna is used as the antenna in Figure 16, as in the other examples.

[0060] Figure 17 is a diagram of the RFID signal processing unit 3001, which consists of an RFID reader / writer, etc. The communication electrical signal (an AC signal with a constant carrier frequency modulated by a digital signal) emitted from the signal processing circuit 4026 of the RFID reader / writer is electromagnetically transmitted from the signal transmission / reception loop antenna 4025 to the signal transmission / reception loop antenna 4023, and then transmitted via a resonant capacitor 4024, an AC voltage blocking BPF (bandpass filter) or BRF (band rejection filter) 5101, a main cable AC power cable 2501, an AC voltage blocking BPF (bandpass filter) or BRF (band rejection filter) 5111, a sensing circuit 5001, and a loop antenna 4102, to the signal processing circuit 4105 that forms the RFID tag via an electromagnetically connected loop antenna 4104.

[0061] Figure 18 shows a configuration similar to Figure 5, where the antenna pairs 4102 and 4104 are replaced with the primary coil 4106 and secondary coil 4108 of a transformer, in order to eliminate the problems of the antenna described above. Its operation and function are the same as in Figures 5 and 6.

[0062] The configuration of the RFID signal processing unit 3001 in Figure 19 is the same as in Figure 6. The AC voltage blocking BPF (bandpass filter) or BRF (band rejection filter) 5101 has the function of blocking the AC voltage (frequency 50Hz or 60Hz) charged in the AC power cable from being applied to the signal transmission loop antennas 4102 and 4023.

[0063] Figure 20 shows an example of the BPF5101, which is a circuit diagram of a series resonant circuit consisting of a resistor R, an inductor L, and a capacitor C. The resonant frequency of the BPF5101 is set to match the carrier frequency of the RFID. For example, to match the resonant frequency to 135 kHz, which is the medium wave carrier frequency of the RFID, R=1Ω, L=0.1mH, and C=13.9nF are set.

[0064] Figure 21 shows the frequency characteristics of the impedance of this BPF. At a frequency of 50Hz or 60Hz when the AC power cable is charged, the impedance is approximately 200kΩ. Therefore, if the AC voltage is 400V, the leakage current can be blocked to a sufficiently small value of approximately 2mA.

[0065] Figure 22 is an example of the BRF5101, and is a circuit diagram of an anti-resonant circuit consisting of a resistor R, an inductor L, and a capacitor C. Figure 23 shows the frequency characteristics of the impedance of the BRF with a resonant frequency of 50Hz, R1=0.001Ω, L=600mH, and C=16.9μF. At a frequency of 50Hz, when the AC power cable is charged, the impedance is approximately 400kΩ, so if the AC voltage is 400V, the leakage current can be blocked down to a sufficiently small value of approximately 1mA. For example, if the AC voltage frequency is 60Hz, the anti-resonant frequency is 60Hz, R1=0.001Ω, L=600mH, and C=11.7μF.

[0066] 7. Example 5 7-1. Overall Structure Figure 24 is a block diagram showing an example of a distributed solar power generation system 52 to which Embodiment 5 of this embodiment is applied. The distributed solar power generation system 52 will be explained in comparison to the distributed solar power generation system 42 in Figure 15. Inside the current collection boxes 2201-2202, one of the two terminals of the sensing circuits 5001-5003 and 5011-5013 is attached to the three-phase AC power cables 2301-2303 and 2311-2313, and the other terminals are interconnected in a star connection. This interconnection is connected to the neutral wire 2008. This neutral wire 2008 is connected to the RFID signal processing unit 3001. The other configurations are the same as in Embodiment 4 (Figure 15).

[0067] 7-2. Sensing circuit and RFID signal processing unit The configuration of the sensing circuits 5001-5003, 5011-5013 and the RFID signal processing unit 3001 is the same as in Example 4, and is shown in Figures 16 or 18 and 17 or 19, respectively. In Example 5, the grounding point in Figures 16-18 is replaced with a neutral point. Its operation and function are also the same as in Example 4.

[0068] 8. Example 6 8-1. Overall Structure Figure 25 is a block diagram showing an example of a distributed photovoltaic power generation system 62 to which Embodiment 6 of this embodiment is applied. Comparing the distributed photovoltaic power generation system 62 with the distributed photovoltaic power generation system 42 in Figure 15, the sensing circuits 5001-5003 and 5011-5013 are interconnected in a delta connection within the current collection boxes 2201 and 2202. Three-phase AC power cables 2301-2303 and 2311-2313 are connected to the sensing circuits 5001-5003 and 5011-5013 via BPF (or BRF) 5111-5113 and 5121-5123. Because a delta connection is used, the grounding wire in Embodiment 4 and the neutral wire in Embodiment 5 are unnecessary. Therefore, Embodiment 6 is particularly useful for power plants that do not have grounding or neutral wires.

[0069] In the distributed solar power generation system 62, within the AC power receiving equipment 3000, BPFs or BRFs are installed by branching from each of the main cables 2501, 2502, and 2503, and the terminals of any two of these BPFs (or BRFs) are interconnected and connected to one end of the RFID signal processing unit 3001. The terminals of the remaining BPF (or BRF) are connected to another terminal of the RFID signal processing unit 3001.

[0070] 8-2. Sensing circuit and RFID signal processing unit The configuration of the sensing circuit section of the distributed photovoltaic power generation system 62 in Example 6 is described in detail. Figure 26 is a circuit diagram showing the configuration. One terminal of the BPF (or BRF, hereafter omitted) is connected to a branch from the three-phase AC power cable. The other terminals are connected to the connection points of the delta-connected sensing circuits 5001-5003 and 5011-5013, respectively. The configuration and function of the RFID tag, resonant capacitor, and loop antenna are the same as in Examples 4 and 5.

[0071] Figure 27 is a circuit diagram showing the configuration of the BPF and the RFID signal processing unit 3001. In Examples 1 to 5, the path of the communication electrical signal for determining the presence or absence of each RFID tag is single, corresponding to each RFID. However, in Example 6, it is not single. Taking the sensing circuit 5001 in Figure 26 as an example, the communication electrical signal emitted from the RFID reader / writer signal processing circuit 4026 passes through the signal transmission / reception loop antennas 4025 and 4023, the resonant capacitor 4024, the BPF 5102, the main cable AC power cable 2502, the AC power cable 2302, and the BPF 5112 to the sensing circuit 5001, and from there it further passes through the BPF 5111, the AC power cable 2301, the main cable 2501, the BPF 5101, and the loop antenna 4023 to the antenna 4025 and signal processing circuit 4026 for the RFID reader / writer, forming a closed circuit. Alternatively, there is a route that goes through BPF5103, main cable 2503, AC power cable 2303, BPF5113, and sensing circuit 5002, and from there to sensing circuit 5001. In this way, there are always multiple routes for determining the presence or absence of each sensing circuit. If the presence or absence of RFID tags is determined by digital processing, even if there are multiple routes, they do not interfere with each other and do not negatively affect the presence or absence determination.

[0072] Figures 28 and 29, like Figures 16, 17, 18, and 19, show configurations in which a transformer is used instead of the loop antennas in Figures 26 and 27.

[0073] 9. 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 illustrative purposes 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. [Explanation of Symbols]

[0074] 90, 12, 22, 32 Centralized Solar Power Generation System 91, 42, 52, 62 Distributed Solar Power Generation Systems 1-4 Solar panels 100, 200 junction boxes 101, 102, 201, 202, 310, 311 fuses 103, 203 Switches 150, 250 P-side DC cable 160, 260 N-side DC cable 1000 P-side main cable 1100 N-side main cable 2000 AC power receiving equipment 2001 Circuit breaker 2008 Neutral Line 2101, 2102, 2103, 2104 Distributed Power Conditioner 2201, 2202 AC current collection box 2301, 2302, 2303, 2311, 2312, 2313 Three-phase AC power cables 2501, 2502, 2503 Main Cables 30 DC Power Transmission Section 35 Cable Assembly (P side) 36 Cable Assembly (N side) 300 Centralized Power Conditioner 301 P terminal 302 N terminal 320 DC Magnetic Contactor 330 Inverter section 340 AC Magnetic Contactor 310, 311 fuses 3000 monitoring and processing units 3001 RFID Signal Processing Unit 3002 Alarm output device 3003 Alarm output terminal 4001, 4011, 4002, 4012 Sensing circuit 4021, 4022, 4031, 4101, 4109, 4111, 4112 DC blocking coupling capacitors 4024, 4103 Capacitors for loop antenna resonance 4102, 4104, 4023, 4025 Loop Antennas 4105, 4026 Signal Processing Circuits 4106, 4027 Primary coil of the transmission transformer for the sensing circuit 4107, 4028 Capacitors for transformer resonance 4108, 4029 Secondary coil of the transmission transformer for RFID signal processing unit 50 AC Power Transmission Section 500 Step-up transformer 5001, 5002, 5003, 5011, 5012, 5013 Sensing circuit 5101~5103, 5111~5113, 5121~5123 AC voltage interruption BPF or BRF 600 grid power grid

Claims

1. An anomaly detection device for a power transmission unit that transmits DC or AC power output from at least one solar panel, A two-terminal sensing circuit including a radio frequency identification (RFID) tag, wherein one of the two terminals is electromagnetically connected to at least one of the power transmission conductors provided in the power transmission unit, An RFID reader / writer, which is electromagnetically connected to the conductor, for determining the presence or absence of an RFID tag in the sensing circuit, An abnormality detection processing unit detects an abnormality in the power transmission unit when the RFID reader / writer determines that the RIFD tag is not present. An anomaly detection device equipped with the following features.

2. The aforementioned at least one solar panel constitutes a plurality of sets, each set containing one solar panel. The power transmission unit includes a cable assembly in which the conductors are electrically connected in parallel to aggregate the power transmission outputs from each set of solar panels. The sensing circuit is provided in correspondence to each set of solar panels, and one terminal of each sensing circuit is electromagnetically connected to a position in the conductor of the cable assembly that is connected to the set of solar panels to which the sensing circuit belongs. The abnormality detection processing unit detects an abnormality in the power transmission unit when at least one of the RFID tags in the power transmission unit and the sensing circuit is missing. An anomaly detection device according to claim 1.

3. The RFID tag of the sensing circuit and the RFID reader / writer are electromagnetically connected to each other through the conductor. The RFID tag of the sensing circuit and the RFID reader / writer are positioned at a distance greater than the maximum distance at which the RFID tag of the sensing circuit and the RFID reader / writer can be directly electromagnetically connected without the conductor. An anomaly detection device according to claim 1 or 2.

4. An anomaly detection method for a power transmission unit that transmits DC power or AC power output from at least one solar panel, The power transmission unit is provided with at least one two-terminal sensing circuit including a radio frequency identification (RFID) tag, such that one of the two terminals is electromagnetically connected to at least one of the DC transmission conductors provided in the power transmission unit. The steps include determining the presence or absence of the RFID tag using an RFID reader / writer that is electromagnetically connected to the conductor, The steps include: generating and outputting an abnormality detection signal indicating an abnormality in the DC power transmission unit based on the absence of the RFID tag; and generating an abnormality detection signal using the abnormality detection processing unit in response to the absence of the RFID tag. An anomaly detection method including

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