CN113167829A - Communication device - Google Patents

Abstract

A communication device is used for a power system provided with an underground cable, and the communication device is provided with: a communication unit that outputs a communication signal including communication information; an inductive coupling unit that outputs the communication signal from the communication unit to a shield layer of the underground cable as a communication induced current by inductive coupling, and acquires a change in current flowing through the shield layer or a change in potential of the shield layer as a detection induced signal by inductive coupling and outputs the detection induced signal; and a discharge detection unit that detects a partial discharge in the underground cable based on the detection induction signal received from the inductive coupling unit.

Description

Communication device

Technical Field

The present invention relates to a communication apparatus.

The present application claims priority based on japanese application No. 2019-18141 filed on 2/4 of 2019, the entire disclosure of which is incorporated herein by reference.

Background

Patent document 1 (japanese patent application laid-open No. 9-101342) discloses the following insulation deterioration diagnosis system. That is, the insulation deterioration diagnosis system includes: a partial discharge detector mounted on an insulation connection portion of a power cable line in which optical fibers are laid in parallel; a partial discharge measurement device provided in the vicinity of an insulation connection portion to which the partial discharge detector is attached, and having a function of determining insulation degradation of the power cable line based on an output of the partial discharge detector; means for increasing a local transmission loss of the optical fiber based on a determination result of the partial discharge measurement device; and a measuring unit for detecting the increase amount of transmission loss generated in the optical fiber and the generation position of the transmission loss by an optical pulse reflection method, and diagnosing the insulation degradation of the power cable line.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 9-101342

Disclosure of Invention

(1) The communication device of the present disclosure is used for a power system having an underground cable, and includes: a communication unit that outputs a communication signal including communication information; an inductive coupling unit that outputs the communication signal from the communication unit to a shield layer of the underground cable as a communication induced current by inductive coupling, and acquires a change in current flowing through the shield layer or a change in potential of the shield layer as a detection induced signal by inductive coupling and outputs the detection induced signal; and a discharge detection unit that detects a partial discharge in the underground cable based on the detection induction signal received from the inductive coupling unit.

One aspect of the present disclosure can be realized not only as a communication apparatus provided with such a unique processing section, but also as a communication system provided with a communication apparatus. Further, an aspect of the present disclosure can be implemented as a semiconductor integrated circuit that realizes part or all of a communication device.

Drawings

Fig. 1 is a diagram showing a configuration of a power transmission system according to a first embodiment of the present invention.

Fig. 2 is a diagram showing an example of the configuration of an underground cable used in the power transmission system according to the first embodiment of the present invention.

Fig. 3 is a diagram showing an example of a method of connecting underground cables used in a normal connection section of a power transmission system according to a first embodiment of the present invention.

Fig. 4 is a diagram showing an example of a connection method of underground cables used in an insulated connection portion of a power transmission system according to a first embodiment of the present invention.

Fig. 5 is a diagram showing another example of a connection method of underground cables used in an insulated connection portion of a power transmission system according to the first embodiment of the present invention.

Fig. 6 is a diagram showing a configuration of a communication system according to a first embodiment of the present invention.

Fig. 7 is a diagram showing an example of the configuration of a communication device in the communication system according to the first embodiment of the present invention.

Fig. 8 is a diagram showing a configuration of a CT in the communication apparatus according to the first embodiment of the present invention.

Fig. 9 is a diagram showing another example of the configuration of the communication device in the communication system according to the first embodiment of the present invention.

Fig. 10 is a diagram showing a configuration of a metal foil electrode in a communication device according to a first embodiment of the present invention.

Fig. 11 is a diagram showing a configuration of a communication unit in the communication device according to the first embodiment of the present invention.

Fig. 12 is a diagram showing a configuration of a discharge detection unit in the communication device according to the first embodiment of the present invention.

Fig. 13 is a diagram showing an example of an impulse response waveform of the BPF in the discharge detection unit according to the first embodiment of the present invention.

Fig. 14 is a diagram showing the calculation result obtained by the discharge detection unit in the communication device according to the first embodiment of the present invention.

Fig. 15 is a diagram showing a communication band and a detection band in the communication device according to the first embodiment of the present invention.

Fig. 16 is a diagram showing a configuration of a discharge detection unit in modification 1 of the communication device according to the first embodiment of the present invention.

Fig. 17 is a diagram showing a configuration of a discharge detection unit in a communication device according to a second embodiment of the present invention.

Fig. 18 is a diagram showing operation timings of a receiving unit and a discharge detection unit in a communication device according to a second embodiment of the present invention.

Detailed Description

Conventionally, a technique for diagnosing deterioration of an insulating layer in an underground cable has been proposed.

[ problem to be solved by the present disclosure ]

In the insulation deterioration diagnosis system described in patent document 1, it is necessary to lay a transmission optical fiber underground in order to transmit the detection result of the partial discharge.

The present disclosure has been made to solve the above-described problems, and an object thereof is to provide a communication device capable of transmitting a detection result of partial discharge in an underground cable with a simple configuration.

[ Effect of the present disclosure ]

According to the present disclosure, the detection result of partial discharge in the underground cable can be transmitted with a simple configuration.

[ description of embodiments of the invention of the present application ]

First, the contents of the embodiments of the present invention are listed for explanation.

(1) A communication device according to an embodiment of the present invention is used for a power system including an underground cable, and includes: a communication unit that outputs a communication signal including communication information; an inductive coupling unit that outputs the communication signal from the communication unit to a shield layer of the underground cable as a communication induced current by inductive coupling, and acquires a change in current flowing through the shield layer or a change in potential of the shield layer as a detection induced signal by inductive coupling and outputs the detection induced signal; and a discharge detection unit that detects a partial discharge in the underground cable based on the detection induction signal received from the inductive coupling unit.

In this way, by outputting the communication signal as the communication induced current to the shield layer by the inductive coupling, acquiring a change in the current flowing through the shield layer or a change in the potential of the shield layer as the detection induced signal by the inductive coupling, and detecting the partial discharge in the underground cable based on the acquired detection induced signal, it is possible to transmit the detection result of the partial discharge as the communication information via the shield layer of the underground cable, for example. This makes it possible to favorably transmit information of the detection result of the partial discharge in the underground where transmission and reception of communication information by radio are difficult, for example. Therefore, the detection result of the partial discharge in the underground cable can be transmitted with a simple configuration.

(2) Preferably, a frequency band of the communication induced current is different from a frequency band of the detection induced signal.

With this configuration, the transmission of the communication information by the communication unit and the detection of the partial discharge by the discharge detection unit can be performed in parallel, and the relationship between the timing at which the communication process is performed and the timing at which the detection process is performed does not need to be adjusted.

(3) Preferably, the communication unit and the discharge detection unit perform transmission of the communication information and detection of the partial discharge in real time.

With this configuration, it is not necessary to divide the frequency band of the communication induced current used by the communication unit for transmitting the communication information and the frequency band of the detection induced signal used by the discharge detection unit for detecting the partial discharge, and therefore the filter circuit, the analog/digital conversion circuit, and the like in the communication unit and the discharge detection unit can be shared.

(4) Preferably, in the power system, a plurality of the underground cables are connected, and the inductive coupling portion is inductively coupled to the shielding layer at the connection portion of the underground cables.

In this way, by detecting the detection induced signal at the connection portion of the underground cable and detecting the partial discharge based on the detection induced signal, the partial discharge of the underground cable can be detected more accurately in the power system in which the underground cable has the connection portion.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding portions are denoted by the same reference numerals, and description thereof will not be repeated. At least some of the embodiments described below may be arbitrarily combined.

< first embodiment >

[ constitution and basic operation ]

Fig. 1 is a diagram showing a configuration of a power transmission system according to a first embodiment of the present invention.

Referring to fig. 1, power transmission system 502 includes underground cables 10A, 10B, and 10C, normal connection units 41A and 41B, insulation connection units 42A and 42B, and ground connection units 43A and 43B. Hereinafter, each of the underground cables 10A, 10B, and 10C is also referred to as an underground cable 10, each of the normal connection portions 41A and 41B is also referred to as a normal connection portion 41, and each of the insulating connection portions 42A and 42B is also referred to as an insulating connection portion 42. The power transmission system 502 includes, for example, an underground portion of a power system. In other words, a part of the power transmission system 502 is provided in, for example, an underground part in the power system.

The ground connection portion 43 includes cable terminations 11A, 11B, 11C. The underground cable 10 is connected to the cable terminals 11A, 11B, 11C at the above-ground connection portion 43. More specifically, the underground cable 10A is connected to the cable terminal 11A, the underground cable 10B is connected to the cable terminal 11B, and the underground cable 10C is connected to the cable terminal 11C.

The above-ground connection 43 is provided in a portion of the substation where the underground cable 10 is present on the ground, for example. The normal connection portion 41 and the insulation connection portion 42 are provided inside the service opening (manhole) 31.

Fig. 2 is a diagram showing an example of the configuration of an underground cable used in the power transmission system according to the first embodiment of the present invention.

Referring to fig. 2, the underground cable 10 is composed of a conductor 71, an inner semiconductive layer 72 made of a semiconductive Ethylene-Propylene (EP) rubber, an insulator 73 made of EP rubber, an outer semiconductive layer 74 as a semiconductive tape, a conductive shield layer 75, and a jacket 76 made of a vinyl resin (vinyl) in this order from the center.

The conductor 71 in the underground cable 10 is used for power transmission, and a high voltage is applied thereto. The shield layer 75 is conductive, and the shield layer 75 is grounded in the middle of the underground cable 10. Therefore, the shield layer 75 has a lower voltage than the conductor 71.

In the power transmission system 502, a three-phase three-wire system is used as a power distribution system, for example. In power transmission system 502, underground cables 10A, 10B, and 10C are provided as three-phase underground cables 10.

Referring again to fig. 1, the shield 75 of each of the underground cables 10A, 10B, 10C is exposed at the cable terminations 11A, 11B, 11C. Terminals are provided at exposed portions of the shield layers 75, respectively.

Underground cables 10A, 10B, 10C are connected to ground node 15 at cable terminations 11A, 11B, 11C, respectively. More specifically, the terminals provided in the underground cables 10A, 10B, and 10C are connected to the ground node 15 via a cable or the like, whereby the shield layer 75 of each underground cable 10 is grounded.

For example, the underground cable 10 is constituted by a plurality of cables whose ends are connected to each other at the ordinary connection portion 41 and the insulating connection portion 42.

Fig. 3 is a diagram showing an example of a method of connecting underground cables used in a normal connection section of a power transmission system according to a first embodiment of the present invention. In fig. 3, for convenience of explanation, the conductor 71 and the shield layer 75 in the underground cable 10A are mainly shown. The following description is also applicable to the underground cable 10B and the underground cable 10C.

Referring to fig. 3, underground cables 10a1, 10a2 are connected in a common connection portion 41. In the ordinary connection portion 41, for example, the shield layers 75 of the underground cables 10a1, 10a2 are exposed at the connection portion of the conductors 71 of the underground cables 10a1, 10a 2.

In the ordinary connection portion 41, for example, the shield layer 75 of the underground cable 10a1 and the shield layer 75 of the underground cable 10a2 are connected by using a conductive wire (wire) 12.

When the shield layer 75 of the underground cable 10a1 and the shield layer 75 of the underground cable 10a2 are connected, for example, a terminal 81 is provided in an exposed portion of the shield layer 75 of the underground cable 10a 2. The terminal 81 may be provided at an exposed portion of the shield layer 75 of the underground cable 10a 1.

The terminal 81 is connected to the ground node 13 via a cable or the like, whereby the shield layer 75 of the underground cable 10A is grounded.

Fig. 4 is a diagram showing an example of a connection method of underground cables used in an insulated connection portion of a power transmission system according to a first embodiment of the present invention. In fig. 4, for convenience of explanation, the conductor 71 and the shield layer 75 in the constitution of the underground cable 10A are mainly shown. The following description is also applicable to the underground cable 10B and the underground cable 10C.

Referring to fig. 4, underground cables 10a1, 10a2 are connected in an insulation connection 42. In the insulating connection unit 42, for example, the shield layers 75 of the underground cables 10a1 and 10a2 are exposed at the connection portions between the conductors 71 of the underground cables 10a1 and 10a2, and terminals 81 and the like are provided at the exposed portions, respectively.

In the insulating connection portion 42, in the case where the conductor 71 of the underground cable 10a1 and the conductor 71 of the underground cable 10a2 are connected, for example, the terminal 81 in the underground cable 10a1 and the terminal 81 in the underground cable 10a2 are wired using the wire rod 12, whereby the shield layer 75 of the underground cable 10a1 and the shield layer 75 of the underground cable 10a2 are connected.

Fig. 5 is a diagram showing another example of a connection method of underground cables used in an insulated connection portion of a power transmission system according to the first embodiment of the present invention.

Referring to fig. 5, in the insulating connection portion 42, the underground cables 10a1, 10a2 are connected, the underground cables 10B1, 10B2 are connected, and the underground cables 10C1, 10C2 are connected. In the insulating connection portion 42, for example, the shield layers 75 of the underground cables 10a1, 10a2 are exposed at the connection portions between the conductors 71 of the underground cables 10a1, 10a2, the shield layers 75 of the underground cables 10B1, 10B2 are exposed at the connection portions between the conductors 71 of the underground cables 10B1, 10B2, the shield layers 75 of the underground cables 10C1, 10C2 are exposed at the connection portions between the conductors 71 of the underground cables 10C1, 10C2, and terminals 81 and the like are provided at the exposed portions.

In the insulating connection portion 42, for example, the terminal 81 of the underground cable 10a1 and the terminal 81 of the underground cable 10B2 are connected by the wire 12, the shield layer 75 of the underground cable 10a1 and the shield layer 75 of the underground cable 10B2 are connected, the terminal 81 of the underground cable 10B1 and the terminal 81 of the underground cable 10C2 are connected by the wire 12, the shield layer 75 of the underground cable 10B1 and the shield layer 75 of the underground cable 10C2 are connected, and the terminal 81 of the underground cable 10C1 and the terminal 81 of the underground cable 10a2 are connected by the wire 12, and the shield layer 75 of the underground cable 10C1 and the shield layer 75 of the underground cable 10a2 are connected.

In this manner, in the power transmission system 502, the underground cables 10 may also be connected in the form of cross-connections (cross-bonds) at the insulation connection portions 42.

[ problem ]

For example, as in the insulation deterioration diagnosis system described in patent document 1, in order to detect deterioration of the insulator 73 of the underground cable 10 (hereinafter, also referred to as insulation deterioration), a method of detecting partial discharge in the insulation connection portion 42 and detecting insulation deterioration based on the detected partial discharge is conceivable.

However, the communication path for transmitting the detection result of the partial discharge to the ground is not easy to secure. For example, since the cover of the access opening is made of metal, it is difficult to wirelessly transmit information to a concentrator (concentrator) or the like on the ground. Therefore, for example, a maintenance person is required to enter the inspection hole to check the detection result of the partial discharge. Further, in the case where a communication cable for transmitting the detection result of the partial discharge is laid underground, the cost may increase. A technique capable of transmitting a detection result of partial discharge in an underground cable with a simple configuration is desired.

In contrast, the communication device according to the embodiment of the present invention solves the above-described problems with the following configuration and operation.

[ communication device ]

Fig. 6 is a diagram showing a configuration of a communication system according to a first embodiment of the present invention. In fig. 6, the underground cable 10A among the underground cables 10 is mainly shown for convenience of explanation. The following description is also applicable to the underground cable 10B and the underground cable 10C.

Referring to fig. 6, a communication system 501 includes communication devices 500A, 500B, and 500C. The communication devices 500A, 500B, and 500C are used in a power system including the underground cable 10. Hereinafter, each of the communication devices 500A, 500B, and 500C is also referred to as a communication device 500.

The communication device 500 is provided corresponding to the insulating connection portion 42 or the ground connection portion 43, for example. In the example shown in fig. 6, communication device 500A is provided corresponding to insulated connection unit 42A, communication device 500B is provided corresponding to insulated connection unit 42B, and communication device 500C is provided corresponding to ground connection unit 43.

The communication devices 500 exchange communication information with each other via the underground cable 10 by inductive coupling with the shielding layer 75 in the underground cable 10A.

For example, the communication devices 500A, 500B detect partial discharge of the underground cable 10. The communication devices 500A and 500B generate a communication signal including the detection result of the partial discharge of the underground cable 10 as communication information, and transmit the generated communication signal to another communication device 500 such as the communication device 500C. The communication devices 500A and 500B generate a communication signal including various measurement results obtained by one or more sensors 14 as communication information, for example, and transmit the generated communication signal to another communication device 500 such as the communication device 500C.

The Communication device 500 can perform Communication over a distance of several km at a variable transmission speed of 20kbps to 130kbps using, for example, a low-frequency PLC (Power Line Communication) used for Communication of smart meters and the like. Communication apparatus 500 may perform communication over a shorter distance at a transmission speed of 200Mbps at maximum using a high-frequency PLC.

For example, the underground cable 10A is equipped with a power coil. Induced current generated by the current flowing through the conductor 71 of the underground cable 10 flows to the power coil. Thus, the power coil can take out the current. The communication device 500 operates using power obtained from a power coil, for example.

[ constitution of communication apparatus ]

Fig. 7 is a diagram showing an example of the configuration of a communication device in the communication system according to the first embodiment of the present invention.

Referring to fig. 7, communication device 500 includes electromagnetic coupling unit 120, communication unit 200, and discharge detection unit 300.

The electromagnetic coupling portion 120 is inductively coupled with the shield layer 75 of the underground cable 10. Specifically, the electromagnetic coupling portion 120 is electromagnetically coupled to the shield layer 75 of the underground cable 10. The electromagnetic coupling portion 120 is an example of an inductive coupling portion.

The communication section 200 transmits communication information via the shield layer 75. The discharge detection section 300 detects a partial discharge in the underground cable 10.

[ electromagnetic coupling part ]

The electromagnetic coupling unit 120 includes a Current Transformer (CT) 100 and a signal distributor 110A. The electromagnetic coupling portion 120 is electromagnetically coupled to the shield layer 75 at, for example, the insulating connection portion 42 which is a connection portion of the underground cable 10.

Fig. 8 is a diagram showing a configuration of a CT in the communication apparatus according to the first embodiment of the present invention.

Referring to fig. 8, the CT100 includes a toroidal core 101 and a winding 102. A winding 102 is wound around the toroidal core 101. Winding 102 is connected to signal splitter 110A.

The CT100 is mounted, for example, such that the conductive cable 53 penetrates the toroidal core 101. The conductive cable 53 is, for example, a wire 12.

More specifically, referring again to fig. 4 and 6, the CTs 100 of the communication devices 500A, 500B in the insulated connection 42 are mounted such that the wire rods 12 connecting the shield layer 75 of the underground cable 10A1 and the shield layer 75 of the underground cable 10A2 penetrate the toroidal core 101. Further, the CT100 of the communication device 500C in the ground connection portion 43 is fitted so that a cable connecting between the cable terminal 11A and the ground node 15 penetrates the toroidal core 101.

In the signal distributor 110A, a current corresponding to a communication signal transmitted from the communication section 200 flows through the winding 102. When current flows through the winding 102, induced current flows through the conductive cable 53 and the shielding layer 75 by inductive coupling. Hereinafter, the above-described induced current flowing through the shield layer 75 is also referred to as a communication induced current.

The electromagnetic coupling portion 120 also functions as a current detection portion that detects a current flowing through the shield layer 75. In more detail, when a current flows through the shielding layer 75 and the conductive cable 53, a current is induced to flow through the winding 102 by the inductive coupling. The electromagnetic coupling portion 120 detects an induced current flowing through the winding 102. The communication unit 200 and the discharge detection unit 300 receive a detection induction signal as a signal according to a change in an induction current flowing through the winding 102 via the signal distributor 110A.

That is, electromagnetic coupling unit 120 receives a communication signal from communication unit 200, and outputs the received communication signal to shield layer 75 of underground cable 10 as a communication induced current by electromagnetic coupling. The electromagnetic coupling unit 120 acquires a change in the current flowing through the shield layer 75 as a detection induction signal by electromagnetic coupling, and outputs an analog signal corresponding to the acquired detection induction signal to the discharge detection unit 300.

Fig. 9 is a diagram showing another example of the configuration of the communication device in the communication system according to the first embodiment of the present invention.

Referring to fig. 9, the communication device 500 includes an electrostatic coupling unit 121, a communication unit 200, and a discharge detection unit 300.

The electrostatic coupling part 121 is inductively coupled with the shield layer 75 of the underground cable 10. Specifically, the electrostatic coupling portion 121 is electrostatically coupled to the shield layer 75 of the underground cable 10. The electrostatic coupling portion 121 is an example of an inductive coupling portion.

[ Electrostatic coupling part ]

The electrostatic coupling section 121 includes metal foil electrodes 105A and 105B and a signal distributor 110B. The electrostatic coupling portion 121 is electrostatically coupled to the shield layer 75 at, for example, an insulating connection portion 42 which is a connection portion of the underground cable 10.

Fig. 10 is a diagram showing a configuration of a metal foil electrode in a communication device according to a first embodiment of the present invention.

Referring to fig. 9 and 10, the metal foil electrodes 105A, 105B are connected to a signal distributor 110B.

The metal foil electrodes 105A, 105B are attached to the surface of the sheath 76 of the underground cable 10 on the opposite sides to each other, for example, via the insulating tube 77 in the insulating connection portion 42. More specifically, for example, in the insulating connection portion 42 in which the underground cables 10a1 and 10a2 are connected, the metal foil electrode 105A is attached to the surface of the sheath 76 of the underground cable 10a1, and the metal foil electrode 105B is attached to the surface of the sheath 76 of the underground cable 10a 2.

It should be noted that the metal foil electrodes 105A, 105B may also be attached to cover the outer circumference of the sheath 76 of the underground cable 10a 2. The positions and the number of the metal foil electrodes 105A and 105B to be attached are not limited, and three or more metal foil electrodes may be attached.

In the signal distributor 110B, a current corresponding to the communication signal transmitted from the communication unit 200 flows to the metal foil electrodes 105A and 105B. When current flows to the metal foil electrodes 105A, 105B, a communication induced current flows through the conductive cable 53 and the shielding layer 75 by electrostatic coupling.

The electrostatic coupling portion 121 also functions as a current detection portion that detects a current flowing through the shield layer 75. In more detail, when a current flows through the shielding layer 75 and the conductive cable 53, an induced current flows to the metal foil electrodes 105A, 105B by inductive coupling. The electrostatic coupling portion 121 detects an induced current flowing to the metal foil electrodes 105A and 105B. The communication unit 200 and the discharge detection unit 300 receive a detection induction signal as a signal corresponding to a change in the potential of the shield layer 75 via the signal distributor 110B.

That is, electrostatic coupling unit 121 receives a communication signal from communication unit 200, and outputs the received communication signal to shield layer 75 of underground cable 10 as a communication induced current by electrostatic coupling. The electrostatic coupling unit 121 acquires a change in the potential of the shield layer 75 as a detection induced signal by electrostatic coupling, and outputs an analog signal corresponding to the acquired detection induced signal to the discharge detection unit 300.

Hereinafter, the signal splitter 110A in the electromagnetic coupling portion 120 and the signal splitter 110B in the electrostatic coupling portion 121 are also referred to as only the signal splitters 110.

The communication unit 200 acquires communication information from an analog signal received via the signal distributor 110, that is, a communication signal from another communication device 500.

The communication unit 200 of the communication device 500C in the ground connection unit 43 transmits the acquired communication information to the central monitoring device 103 by wireless communication such as a mobile phone.

The discharge detection section 300 detects a partial discharge in the underground cable 10 based on the analog signal received via the signal distributor 110. The discharge detection unit 300 outputs detection information indicating the detection result of the partial discharge to the communication unit 200.

[ communication section ]

The communication section 200 transmits communication information using a communication induction current which is an induction current flowing through the shielding layer 75 by the inductive coupling of the inductive coupling section. More specifically, the communication unit 200 communicates with the communication unit 200 in the other communication device 500 using the communication induced current.

Fig. 11 is a diagram showing a configuration of a communication unit in the communication device according to the first embodiment of the present invention.

Referring to fig. 11, the communication unit 200 includes a data processing unit 210, a transmission unit 220, and a reception unit 260.

The reception unit 260 converts the communication signal received via the signal distributor 110 into a digital signal, generates demodulation data by performing demodulation processing and decoding processing on the converted digital signal, and outputs the generated demodulation data to the data processing unit 210.

Upon receiving the demodulated data from the reception unit 260, the data processing unit 210 acquires communication information from the received demodulated data.

Upon receiving the detection information from discharge detection unit 300, data processing unit 210 generates communication data including the received detection information as communication information, and outputs the generated communication data to transmission unit 220. When receiving measurement information indicating a measurement result from the sensor 14, the data processing unit 210 generates communication data including the received measurement information as communication information, and outputs the generated communication data to the transmission unit 220.

The communication unit 200 outputs a communication signal including communication information. More specifically, the transmission unit 220 in the communication unit 200 generates a communication signal by performing encoding processing and modulation processing on communication data received from the data processing unit 210, and outputs the generated communication signal to the signal distributor 110.

More specifically, each communication device 500 is given a unique ID. The data processing unit 210 generates communication data including information indicating the ID of the communication device 500 (hereinafter also referred to as ID information) as a part of the communication information. The data processing unit 210 outputs the generated communication data to the transmission unit 220.

Further, the data processing unit 210 checks ID information included in the demodulated data received from the receiving unit 260, and acquires communication information from the demodulated data when the checked ID information indicates the ID of the own communication device 500.

[ transmitting part ]

The transmission unit 220 includes: a FEC (Forward Error Correction) encoder 230 for performing encoding processing for Forward Error Correction, a modulation unit 240 for performing modulation processing, a DAC (Digital Analog Converter) 251, a Band-Pass Filter (BPF) 252, and a transmission amplifier 253. The FEC encoder 230 has a scrambler (scrambler)231, an encoder 232, and an interleaver (interleaver) 233. The modulation section 240 has a mapper (mapper)241 and an IFFT (Inverse Fast Fourier Transform) processing section 242.

The scrambler 231 scrambles the communication data received from the data processing unit 210, and outputs the processed communication data to the RS encoder 232.

The encoder 232 performs encoding processing on the communication data received from the scrambler 231, and outputs the processed communication data to the interleaver 233.

Interleaver 233 performs repetition coding and interleaving on the communication data received from encoder 232, and outputs the processed communication data to mapper 241.

The mapper 241 generates modulated data obtained by modulating the communication data received from the interleaver 233 by, for example, the DBPSK method (Differential Binary Phase Shift Keying), and outputs the generated modulated data to the IFFT processing unit 242.

The mapper 241 may generate modulated data obtained by modulating the communication data received from the interleaver 233 by the DQPSK (Differential quadrature Phase Shift Keying) method, or may generate modulated data obtained by modulating the communication data received from the interleaver 233 by the D8PSK (Differential Octal Phase Shift Keying) method.

The IFFT processing section 242 outputs the modulated data received from the mapper 241 after signal processing such as IFFT in an Orthogonal Frequency Division Multiplexing (OFDM) scheme to the DAC 251. In OFDM, signals can be transmitted well even in a state where the signal-to-noise ratio is close to zero dB.

The DAC251 converts the modulation data received from the IFFT processing unit 242 into an analog signal and outputs the analog signal to the BPF 252.

The BPF252 outputs an analog signal in which components outside a predetermined frequency band among the frequency components of the analog signal received from the DAC251 are attenuated, to the transmission amplifier 253.

The transmission amplifier 253 amplifies the analog signal received from the BPF252 with a predetermined gain, and outputs the amplified analog signal to the signal distributor 110 as a communication signal.

[ receiving part ]

The reception unit 260 includes a High-Pass Filter (HPF) 271, a reception amplifier 272, an ADC (Analog Digital Converter) 273, a demodulation unit 280 for performing demodulation processing, and an FEC decoder 290 for performing decoding processing in forward error correction. The demodulation unit 280 includes an FFT (Fast Fourier Transform) processing unit 281 and a demodulator 282. The FEC decoder 290 has a deinterleaver 291, a decoder 292, and a descrambler 293.

The HPF271 outputs a communication signal, in which a component equal to or lower than a predetermined frequency among frequency components of the communication signal received via the signal distributor 110 is attenuated, to the reception amplifier 272.

The reception amplifier 272 amplifies the communication signal received from the HPF271 by a predetermined gain, and outputs the amplified communication signal to the ADC 273.

The ADC273 converts the communication signal received as an analog signal from the reception amplifier 272 into a digital signal and outputs the digital signal to the FFT processor 281.

The FFT processor 281 performs signal processing such as FFT in the OFDM scheme on the digital signal received from the ADC273, and outputs the processed digital signal to the demodulator 282.

The demodulator 282 generates demodulated data obtained by demodulating the digital signal received from the FFT processor 281 in accordance with, for example, the DBPSK method, and outputs the generated demodulated data to the deinterleaver 291.

Deinterleaver 291 performs a repetitive decoding process and a deinterleaving process on the demodulated data received from demodulator 282, and outputs the processed demodulated data to decoder 292.

The decoder 292 performs decoding processing on the demodulated data received from the deinterleaver 291, and outputs the processed demodulated data to the descrambler 293.

Descrambler 293 descrambles the demodulated data received from decoder 292, and outputs the processed demodulated data to data processing unit 210.

[ discharge detection part ]

The discharge detection unit 300 detects the partial discharge in the underground cable 10 based on the detection induction signal received from the electromagnetic coupling unit 120 or the electrostatic coupling unit 121.

Fig. 12 is a diagram showing a configuration of a discharge detection unit in the communication device according to the first embodiment of the present invention. In fig. 12, a receiving section 260 in the communication section 200 is shown in addition to the discharge detection section 300.

Referring to fig. 12, the discharge detection unit 300 includes an HPF301, an LNA (Low Noise Amplifier) 302, an ADC303, an FFT processing unit 304, a filter processing unit 310, an AGC (Automatic Gain Control) Amplifier 305, an ADC306, a detection unit 320, a switch Control unit 330, and a storage unit 340.

The filter processing unit 310 includes an analog switch 311 and BPFs 312A, 312B, and 312C. Hereinafter, each of the BPFs 312A, 312B, 312C is also referred to as a BPF 312.

The HPF301 outputs a signal obtained by attenuating a component of the analog signal received via the signal splitter 110, the component being equal to or lower than a predetermined frequency, to the LNA 302. The analog signal received via the signal distributor 110 contains much noise in a frequency band of, for example, less than 1.6MHz superimposed on the transmission path of the underground cable 10 or the like. The HPF301 attenuates frequency components smaller than 1.6MHz, for example, thereby removing noise included in the analog signal received via the signal splitter 110.

The LNA302 amplifies the analog signal received from the HPF301 with a predetermined gain, and outputs the amplified analog signal to the ADC303 and the filter processing unit 310.

The ADC303 converts the analog signal received from the LNA302 into a digital signal and outputs the digital signal to the FFT processing unit 304.

The FFT processing unit 304 performs signal processing such as FFT on the digital signal received from the ADC303, and outputs the processed digital signal to the detection unit 320.

The detection unit 320 generates a spectrum of an analog signal output from the HPF301 based on the digital signal received from the FFT processing unit 304, and outputs the generated spectrum to the switch control unit 330.

The switch control unit 330 generates a switch control signal based on the frequency spectrum received from the detection unit 320, and outputs the generated switch control signal to the analog switch 311, thereby switching the analog switch 311.

The analog switch 311 switches the BPF312 of the output destination of the analog signal received from the LNA302 in accordance with the switch control signal received from the switch control unit 330.

The passbands of the three BPFs 312 are different, respectively. For example, the passband of the BPF312A is 5MHz or more and less than 10MHz, the passband of the BPF312B is 10MHz or more and less than 15MHz, and the passband of the BPF312C is 15MHz or more and less than 20 MHz.

The switch control unit 330 selects one BPF312 to be an output destination of the analog signal switched by the analog switch 311 from the three BPFs 312. More specifically, the switch control unit 330 determines the passband with the least noise component among the analog signals output from the LNA302 among the passbands of the three BPFs 312, and selects the BPF312 corresponding to the passband.

For example, the switch control unit 330 selects any one of the BPFs 312 from the plurality of BPFs 312 based on the current detected by the electromagnetic coupling unit 120 or the electrostatic coupling unit 121. More specifically, the switch control unit 330 selects, based on the spectrum received from the detection unit 320, the BPF312 corresponding to the passband in which the signal level of the analog signal output from the LNA302 is lowest among the passbands of the three BPFs 312.

Here, the current waveform generated by the partial discharge is a surge waveform. The components of the impulse waveform in the above frequency spectrum are equally distributed in the pass band of each BPF312, and therefore, the difference in the spectral level (spectral level) in each pass band due to the components of the impulse waveform is negligibly small. Therefore, based on the above frequency spectrum, the pass band in which the signal level of the analog signal output from the LNA302 is the lowest among the pass bands of the respective three BPFs 312 can be regarded as the pass band in which the noise component is the lowest.

The switch control unit 330 outputs the switch control signal to the analog switch 311, thereby switching the output destination of the analog signal switched by the analog switch 311 to the selected BPF 312.

For example, the switch control unit 330 selects the BPF312 periodically or aperiodically based on the spectrum received from the detection unit 320, and switches the analog switch 311 according to the selection result.

The switch control unit 330 is not limited to the configuration of switching the analog switch 311 based on the frequency spectrum received from the detection unit 320, and may be configured as follows: the digital signal received by the detection unit 320 from the ADC306 is monitored periodically or aperiodically, and the analog switch 311 is switched based on the value of the digital signal, that is, the change in the amount of the noise component included in the digital signal.

The BPF312 receives an analog signal corresponding to an induced current flowing through the winding 102, which is an example of a signal based on a current detected by the electromagnetic coupling portion 120 or the electrostatic coupling portion 121. In more detail, the BPF312 receives the analog signal via the HPF301, the LNA302, and the analog switch 311. BPF312 outputs an analog signal in which a component outside its own passband, out of the frequency components of the analog signal received from analog switch 311, is attenuated, to AGC amplifier 305.

The AGC amplifier 305 amplifies the signal received from the BPF312 so that the output level of the analog signal to the ADC306 becomes constant, and outputs the amplified signal to the ADC 306.

ADC306 converts the analog signal received from AGC amplifier 305 into a digital signal and outputs the digital signal to detection unit 320.

The detection unit 320 detects a partial discharge in the underground cable 10 based on the output of at least one BPF312 of the three BPFs 312 and the corresponding characteristic data relating to the physical properties of the BPF 312. More specifically, the detection unit 320 detects the partial discharge in the underground cable 10 based on the output of the BPF312 selected by the switch control unit 330 and the characteristic data relating to the physical properties of the BPF 312.

For example, the detection unit 320 receives the digital signal S obtained by amplifying and digitally converting the analog signal output from the selected BPF312 from the ADC306, and performs an operation using the received digital signal S and the characteristic data of the BPF312, thereby detecting the partial discharge in the underground cable 10.

The storage unit 340 stores characteristic data relating to the characteristics of the three BPFs 312. More specifically, the storage unit 340 stores, as the characteristic data, pulse (pulse) response characteristics of the three BPFs 312, for example, an impulse (impulse) response waveform Imp. The switch control unit 330 outputs selection information indicating the selected BPF312 to the detection unit 320.

The detection unit 320 acquires the impulse response waveform Imp of the BPF312 indicated by the selection information received from the switch control unit 330 from the storage unit 340, and performs an operation using the acquired impulse response waveform Imp and the digital signal S received from the ADC306, thereby detecting the partial discharge in the underground cable 10.

Some or all of the FFT Processing Unit 304, the detection Unit 320, and the switch control Unit 330 are realized by operating a Processor such as a CPU (Central Processing Unit) or a DSP (Digital Signal Processor) with software, for example. A part or all of the functions of the FFT processing unit 304, the detection unit 320, and the switch control unit 330 are realized by operating a processor such as a CPU or a DSP with software, for example.

Fig. 13 is a diagram showing an example of an impulse response waveform of the BPF in the discharge detection unit according to the first embodiment of the present invention.

Referring to fig. 13, the impulse response waveform Imp of the BPF312 is stored in the storage section 340 as a digital signal having the number of samples K in a period T1 from time T0 to time ta. For example, the impulse response waveform Imp is a waveform having one or more maximum values and one or more minimum values.

The detector 320 calculates the calculation value y (T) by multiplying the X-th value of the impulse response waveform Imp by the X-th value of the K sample values included in the digital signal S in the period T1 from the time T to the time T + T1 according to the following expression (1) and adding the K values obtained by the multiplication for each sample value.

[ numerical formula 1]

In equation (1), S (t) is the value of the digital signal S at time t.

Fig. 14 is a diagram showing the calculation result obtained by the discharge detection unit in the communication device according to the first embodiment of the present invention. In fig. 14, the vertical axis represents voltage, and the horizontal axis represents time.

Referring to fig. 14, the detection unit 320 calculates the calculated value y (T) corresponding to each start time by shifting the start time of the period T1 by one sample of the digital signal S. The detection unit 320 may calculate the calculation value y (t) by multiplying the digital signal S by the impulse response waveform Imp every time the digital signal S of one sample is received from the ADC306, and the detection unit 320 may calculate the calculation value y (t) by accumulating a predetermined number, for example, K sample values of the digital signal S received from the ADC306 and multiplying each of the accumulated sample values by the impulse response waveform Imp.

For example, when the digital signal S does not include the impulse waveform in the period T1 from the time tk to the time tk + T1, the calculated value y (tk) is a value close to zero. On the other hand, when the digital signal S in the period T1 from the time tm to the time tm + T1 includes the impulse waveform, the calculated value y (tm) becomes a somewhat large value.

The detection unit 320 detects the partial discharge based on the calculated operation value y (t). For example, the storage unit 340 stores a threshold ThA of the calculated value y (t) for detecting partial discharge. The detector 320 compares the calculated value y (t) with the threshold ThA, and determines that partial discharge has occurred when the calculated value y (t) is equal to or greater than the threshold ThA.

For example, when the partial discharge is detected, the detection unit 320 generates detection information indicating a detection result of the partial discharge, and outputs the generated detection information to the data processing unit 210.

The detection unit 320 calculates the level of the impact signal generated by the partial discharge. More specifically, for example, the storage unit 340 stores the gain of the LNA302 and the input/output ratio of the impulse response characteristic of the BPF 312. When the gain of AGC amplifier 305 can be monitored, detection unit 320 acquires the gain of LNA302 and the input/output ratio of the selected impulse response characteristic of BPF312 from storage unit 340, and calculates the level of the impulse signal generated by the partial discharge based on the gain of LNA302, the gain of AGC amplifier 305, the input/output ratio of the selected impulse response characteristic of BPF312, and calculated value y (t).

The detection unit 320 calculates the phase of the surge signal generated by the partial discharge in the high-voltage applied to the conductor 71 of the underground cable 10 (hereinafter, also referred to as a surge phase). More specifically, the data processing section 210 detects a 50Hz or 60Hz waveform of an induced current generated by a current flowing through the conductor 71, for example, via the power coil as described above attached to the underground cable 10. The data processing section 210 detects a zero-cross point (zero-cross point) of the waveform of the high voltage applied to the conductor 71 based on the detected waveform.

The data processing unit 210 generates zero-crossing information indicating the timing of the detected zero-crossing point and outputs the zero-crossing information to the detection unit 320. The detection unit 320 calculates the impulse phase based on the received zero-crossing information and the occurrence timing of the impulse signal due to the partial discharge. The data processing unit 210 in the communication device 500 may be configured to receive information related to the high voltage applied to the conductor 71, for example, the zero cross information from the central monitoring device 103 via the communication device 500C in the ground connection unit 43.

The detection unit 320 generates partial discharge information including the level, the impact phase, and the like of the impact signal generated by the detected partial discharge, and stores the generated partial discharge information in the storage unit 340. The detection unit 320 updates the threshold ThA, for example, by using a machine learning method, based on the partial discharge information stored in the storage unit 340.

Fig. 15 is a diagram showing a communication band and a detection band in the communication device according to the first embodiment of the present invention.

Referring to fig. 15, for example, the frequency band of the communication induced current used by the communication unit 200 for transmission of the communication information is different from the frequency band of the detection induced signal used by the discharge detection unit 300 for detection of the partial discharge.

More specifically, for example, the frequency band of the communication induced current used by the communication unit 200 for transmission of the communication information (hereinafter also referred to as the communication frequency band) is, for example, 10kHz to 450kHz, and the frequency band of the detection induced signal used by the discharge detection unit 300 for detection of the partial discharge (hereinafter also referred to as the detection frequency band) is, for example, 1.6MHz to 50 MHz.

Specifically, the BPF252 in the transmission unit 220 and the HPF271 in the reception unit 260 have a passband of 10kHz or more and attenuate components of frequencies less than 10kHz, while the HPF301 in the discharge detection unit 300 has a passband of 1.6MHz or more and attenuate components of frequencies less than 1.6 MHz.

For example, the communication unit 200 and the discharge detection unit 300 perform transmission of communication information and detection of partial discharge in parallel.

[ modification 1]

Fig. 16 is a diagram showing a configuration of a discharge detection unit in modification 1 of the communication device according to the first embodiment of the present invention. In fig. 16, in addition to discharge detection unit 300A, reception unit 260 in communication unit 200 is shown.

Referring to fig. 16, discharge detector 300A according to modification 1 does not include ADC303 and filter processor 310 includes LPF313, as compared to discharge detector 300 shown in fig. 12. More specifically, discharge detection unit 300A includes HPF301, LNA302, FFT processing unit 304, filter processing unit 310, AGC amplifier 305, ADC306, detection unit 320, switch control unit 330, and storage unit 340. Discharge detector 300A is the same as discharge detector 300 shown in fig. 12, except for the following description.

The Filter processing unit 310 includes an analog switch 311, BPFs 312A, 312B, and 312C, and a Low Pass Filter (LPF: Low-Pass Filter) 313. The cutoff frequency of the LPF313 is, for example, a frequency below 1/2 of the sampling frequency of the ADC 306.

The switch control unit 330 selects the LPF313 periodically or aperiodically as a filter to be an output destination of the analog signal switched by the analog switch 311, and switches the output destination of the analog signal switched by the analog switch 311 to the LPF 313.

LPF313 outputs to AGC amplifier 305 an analog signal obtained by attenuating a component of the analog signal received from analog switch 311, the component being equal to or higher than a predetermined frequency.

The AGC amplifier 305 amplifies the signal received from the LPF313 and outputs the amplified signal to the ADC306 so that the output level of the analog signal to the ADC306 becomes constant.

ADC306 converts the analog signal received from AGC amplifier 305 into a digital signal and outputs the digital signal to FFT processing unit 304.

The FFT processing unit 304 performs signal processing such as FFT on the digital signal received from the ADC306, and outputs the processed digital signal to the detection unit 320.

The detection unit 320 generates a spectrum of an analog signal output from the LPF313 based on the digital signal received from the FFT processing unit 304, and outputs the generated spectrum to the switch control unit 330.

The switch control unit 330 selects one BPF312 to be used as an output destination of the analog signal switched by the analog switch 311 from the three BPFs 312 based on the spectrum received from the detection unit 320. The switch control unit 330 outputs the switch control signal to the analog switch 311, thereby switching the output destination of the analog signal switched by the analog switch 311 to the selected BPF 312. The switch control unit 330 outputs selection information indicating that the LPF313 is selected to the detection unit 320.

[ modification 2]

Communication device 500 may be configured to operate using the power obtained by CT 100.

For example, the communication device 500 operates using an induced current of a current flowing through the shield layer 75 of the underground cable 10, and a frequency band of the induced current is different from a frequency band of a communication signal transmitted and received by the communication device 500.

More specifically, in addition to the current generated by the signal transmitted by the communication device 500, a sheath current, which is an induced current generated by the influence of the current for power transmission flowing through the conductor 71 of the underground cable 10, flows through the shield layer 75 of the underground cable 10.

In the communication system 501, the sheath current flowing through the shield layer 75 of the underground cable 10 can be extracted by providing the CT100 to the underground cable 10.

The communication device 500 includes a filter for passing a current having a frequency of 60Hz or less, for example. The communication device 500 uses a filter to extract low frequency current of 50Hz or 60Hz from each extracted sheath current.

Then, communication apparatus 500 rectifies and synthesizes the extracted low-frequency currents, thereby generating a power supply current sufficient to operate communication apparatus 500. The communication device 500 operates by the generated power supply current.

In the communication device according to the first embodiment of the present invention, the detection unit 320 in the discharge detection unit 300 is configured to detect the partial discharge in the underground cable based on the output of the BPF312 and the characteristic data relating to the physical properties of the BPF312, but the present invention is not limited to this configuration. The discharge detection unit 300 may detect partial discharge by another method.

For example, referring to fig. 12, the discharge detector 300 may have the following configuration. That is, the HPF301 outputs an analog signal in which a component equal to or lower than a predetermined frequency among the frequency components of the analog signal received via the signal splitter 110 is attenuated, to the LNA 302. The LNA302 amplifies an analog signal received from the HPF301 by a predetermined gain and outputs the amplified signal to the ADC 303.

The ADC303 converts the analog signal received from the LNA302 into a digital signal and outputs the digital signal to the FFT processing unit 304. The FFT processing unit 304 performs signal processing such as FFT on the digital signal received from the ADC303, and outputs the processed digital signal to the detection unit 320. The detection unit 320 generates a spectrum of an analog signal output from the HPF301 based on the digital signal received from the FFT processing unit 304, and detects a partial discharge based on the generated spectrum.

In the communication device according to the first embodiment of the present invention, the filter processing unit 310 in the discharge detection unit 300 has a configuration including three BPFs 312, but is not limited to this configuration. The filter processing unit 310 may have a configuration including two or less BPFs 312, or may have a configuration including four or more BPFs 312.

The communication device according to the first embodiment of the present invention is provided in the insulating connection portion 42 and the ground connection portion 43, but is not limited thereto. The communication device 500 may be provided in the normal connection unit 41. In this case, referring again to fig. 3, the CT100 of the communication device 500 in the normal connection portion 41 is mounted so that a cable connecting between the terminal 81 provided in the shield layer 75 and the ground node 13 penetrates the toroidal core 101.

In addition, the communication device according to the first embodiment of the present invention is configured to: in the discharge detection unit 300, the storage unit 340 stores the impulse response waveform Imp as the characteristic data of the BPF312, and the detection unit 320 calculates the calculation value y (t) by multiplying the digital signal S by the impulse response waveform Imp in the storage unit 340. That is, the storage unit 340 stores a waveform of a sine wave of a frequency included in the pass band of the BPF 312. The detection unit 320 calculates the calculation value y (t) by multiplying the digital signal S by the waveform of the sine wave in the storage unit 340.

Further, the following configuration is also possible. That is, in the discharge detection unit 300, the storage unit 340 stores characteristic data other than the impulse response characteristic as characteristic data of the BPF 312. The detection section 320 detects the partial discharge based on the digital signal S and the characteristic data in the storage section 340.

In the communication device according to the first embodiment of the present invention, the communication information is transmitted and the partial discharge is detected in parallel, but the present invention is not limited to this. The communication unit 200 and the discharge detection unit 300 may be configured to transmit communication information and detect partial discharge in a time-sharing manner. More specifically, the communication device 500 temporally alternates between transmission of communication information by the communication unit 200 and detection of partial discharge by the discharge detection unit 300.

In this case, for example, the data processing unit 210 controls the transmission timing of the communication signal by each communication device 500 and the detection timing of the partial discharge by the detection unit 320. More specifically, for example, the data processing unit 210 in any one of the communication devices 500 in the communication system 501 generates communication data including synchronization information indicating the transmission timing of the communication signal by each communication device 500 as communication information, and transmits the communication data to the other communication device 500 via the transmission unit 220 and the signal distributor 110. Each communication device 500 transmits a communication signal at the timing indicated by the synchronization information.

The data processing unit 210 generates a synchronization signal indicating the detection timing of the partial discharge, and outputs the generated synchronization signal to the detection unit 320. The detection unit 320 detects the partial discharge at the timing indicated by the synchronization signal. In this manner, the data processing unit 210 controls the transmission timing of the communication signal and the detection timing of the partial discharge to be different from each other, thereby performing the transmission of the communication information by the communication unit 200 and the detection of the partial discharge by the discharge detection unit 300 in time division.

In the communication device according to the first embodiment of the present invention, the communication band of the communication unit 200 is set to be 10kHz to 450kHz, and the detection band of the discharge detection unit 300 is set to be 1.6MHz to 50MHz, but the present invention is not limited thereto. The communication band of the communication unit 200 and the detection band of the discharge detection unit 300 may partially or entirely overlap. In this case, for example, as described above, the communication device 500 temporally alternates between transmission of communication information by the communication section 200 and detection of partial discharge by the discharge detection section 300.

In the communication device according to the first embodiment of the present invention, the communication device 500C in the ground connection unit 43 includes the communication unit 200 and the discharge detection unit 300, but is not limited thereto. Communication device 500C in ground connection unit 43 may be configured to include communication unit 200 without discharge detection unit 300.

In the communication device according to the first embodiment of the present invention, the electromagnetic coupling portion 120 is configured to electromagnetically couple the shield layer 75 to the connection portion of the underground cable 10, such as the ground connection portion 43 and the insulating connection portion 42. The electromagnetic coupling portion 120 may be configured to electromagnetically couple with the shield layer 75 at a portion other than the connection portion in the underground cable 10.

In the communication device according to the first embodiment of the present invention, the data processing unit 210 is configured to generate communication data including the measurement information received from the sensor 14 as communication information, but the present invention is not limited to this configuration. The data processing unit 210 may be configured to generate communication data including the detection information received from the discharge detection unit 300 as communication information, and not generate communication data including the measurement information received from the sensor 14.

In the communication device according to the first embodiment of the present invention, the data processing unit 210 is configured to generate communication data including ID information of the communication device 500 itself as a part of the communication information, but the present invention is not limited to this. The data processing unit 210 may generate communication data not including ID information.

In the communication device according to the first embodiment of the present invention, discharge detector 300 includes AGC amplifier 305, but is not limited to this. Discharge detector 300 may be configured to include a normal amplifier having no automatic gain control function instead of AGC amplifier 305.

Discharge detector 300 may include an amplifier whose gain can be adjusted from the outside, instead of AGC amplifier 305. In this case, for example, the detection unit 320 generates a gain control signal from the maximum value of the digital signal S in a predetermined period, for example, a period corresponding to several cycles of the high voltage applied to the conductor 71, and outputs the generated gain control signal to the amplifier, thereby adjusting the gain of the amplifier.

In addition, the communication device according to the first embodiment of the present invention is configured to: in the discharge detection unit 300, the switch control unit 330 selects one BPF312 to be an output destination of the analog signal switched by the analog switch 311 from among the three BPFs 312, and the detection unit 320 detects the partial discharge by an operation using the output of the selected BPF312, that is, the digital signal S received via the ADC306 and the corresponding impulse response waveform Imp. That is, the switch control unit 330 selects two or more BPFs 312 to be output destinations of the analog signals switched by the analog switch 311. The detection unit 320 performs an operation using the digital signal S and the corresponding impulse response waveform Imp for each selected BPF312, and detects a partial discharge based on the respective operation results.

Further, a technique capable of transmitting a detection result of partial discharge in an underground cable with a simple configuration is desired.

In contrast, the communication device according to the first embodiment of the present invention is used in a power system including the underground cable 10. The communication unit 200 outputs a communication signal including communication information. The inductive coupling unit outputs a communication signal from the communication unit 200 to the shield layer 75 of the underground cable 10 as a communication induced current by inductive coupling, and acquires a change in current flowing through the shield layer 75 or a change in potential of the shield layer 75 as a detection induced signal by inductive coupling and outputs the detection induced signal to the discharge detection unit 300. The discharge detection unit 300 detects a partial discharge in the underground cable 10 based on the detection induction signal received from the inductive coupling unit.

In this way, by outputting the communication signal as the communication induced current to the shield layer 75 by the inductive coupling, acquiring the change in the current flowing through the shield layer 75 or the change in the potential of the shield layer 75 as the detection induced signal by the inductive coupling, and detecting the partial discharge in the underground cable 10 based on the acquired detection induced signal, it is possible to transmit the detection result of the partial discharge as the communication information via the shield layer 75 of the underground cable 10, for example. This makes it possible to favorably transmit information of the detection result of the partial discharge in the underground where transmission and reception of communication information by radio are difficult, for example.

Therefore, in the communication device according to the first embodiment of the present invention, the detection result of the partial discharge in the underground cable 10 can be transmitted with a simple configuration.

In the communication device according to the first embodiment of the present invention, the frequency band of the communication induced current is different from the frequency band of the detection induced signal.

With this configuration, the transmission of the communication information by the communication unit 200 and the detection of the partial discharge by the discharge detection unit 300 can be performed in parallel, and the relationship between the timing of performing the communication process and the timing of performing the detection process does not need to be adjusted.

In the communication device according to the first embodiment of the present invention, a plurality of underground cables 10 are connected in the power system, and the inductive coupling portion is inductively coupled to the shield layer 75 at the connection portion of the underground cables 10.

In this way, by detecting the detection induced signal at the connection portion of the underground cable and detecting the partial discharge based on the detection induced signal, the partial discharge of the underground cable 10 can be detected more accurately in the power system in which the underground cable 10 has the connection portion.

The partial discharge detection device according to the first embodiment of the present invention is used in an electric power system including the underground cable 10. The inductive coupling detects the current flowing through the shield 75 of the underground cable 10. The discharge detection section 300 detects a partial discharge in the underground cable 10 based on a detection current that is a current detected by the inductive coupling section. The discharge detection unit 300 includes: a BPF312 receiving an analog signal based on the detection current; and a storage unit 340 for storing the characteristic data of the BPF 312. The discharge detection section 300 detects a partial discharge based on the output of the BPF312 and the characteristic data in the storage section 340.

In this way, by detecting the partial discharge based on the output of the BPF312 receiving the analog signal based on the current flowing through the shield layer 75 and the characteristic data of the BPF312, it is possible to sense whether or not the waveform corresponding to the characteristic data exists in the analog signal. This can reduce the influence of a noise component contained in the current flowing through the shield layer 75, for example, and can sense the current waveform generated by the partial discharge.

Therefore, in the partial discharge detection apparatus of the first embodiment of the present invention, the partial discharge in the underground cable 10 can be detected more accurately. In general, an ADC capable of performing high-speed sampling at a sampling frequency of several GHz, for example, is required to detect an impulse signal generated by a partial discharge by digital signal processing. In contrast, by the configuration in which the analog signal is analyzed through the BPF312, a relatively low-speed ADC corresponding to the passband of the BPF312 can be used, and the manufacturing cost can be reduced.

In the partial discharge detection device according to the first embodiment of the present invention, the storage unit 340 stores the impulse response characteristic of the BPF312 as characteristic data.

With this configuration, a detection device capable of satisfactorily sensing a pulse-like current waveform generated in large quantities due to partial discharge can be realized.

In the partial discharge detection device according to the first embodiment of the present invention, the discharge detection unit 300 includes a plurality of BPFs 312 having different pass bands. The storage unit 340 stores characteristic data of each of the plurality of BPFs 312. The discharge detection unit 300 detects a partial discharge based on the output of at least one of the BPFs 312 and the corresponding characteristic data.

With such a configuration, for example, an appropriate BPF312 corresponding to the installation environment of the underground cable 10 can be selected to detect the partial discharge. Thus, partial discharge can be detected more accurately under various environments.

In the partial discharge detection device according to the first embodiment of the present invention, the discharge detection unit 300 selects any one BPF312 from the plurality of BPFs 312 based on the detection current detected by the current detection unit 120, and detects a partial discharge based on the output of the selected BPF312 and the corresponding characteristic data.

With such a configuration, for example, the BPF312 having the pass band with the smallest noise component among the currents flowing through the shield layer 75 among the pass bands of the plurality of BPFs 312 can be selected to detect the partial discharge more accurately.

Next, another embodiment of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding portions are denoted by the same reference numerals, and description thereof will not be repeated.

< second embodiment >

The present embodiment relates to a communication device having a configuration in which the receiving unit 260 and the discharge detection unit 400 of the communication unit 200 share a part in comparison with the communication device of the first embodiment. The communication device of the present embodiment is the same as the communication device of the first embodiment except for the following description.

Fig. 17 is a diagram showing a configuration of a discharge detection unit in a communication device according to a second embodiment of the present invention. In fig. 17, receiving unit 260 in communication unit 200 is shown in addition to discharge detection unit 400. For example, the communication section 200 and the discharge detection section 400 are included in one semiconductor integrated circuit.

Referring to fig. 17, the reception unit 260 in the communication unit 200 includes an HPF271, a reception amplifier 272, an ADC273, a demodulation unit 280, and an FEC decoder 290. The demodulation unit 280 includes an FFT processing unit 281 and a demodulator 282.

Discharge detection unit 400 includes filter processing unit 410, detection unit 320, switch control unit 330, and storage unit 340.

The filter processing unit 410 includes a switch 411 and BPFs 412A, 412B, and 412C as digital filters. Hereinafter, each of the BPFs 412A, 412B, 412C is also referred to as a BPF 412.

Some or all of the FFT processing unit 281, the detection unit 320, the switch control unit 330, and the filter processing unit 410 are realized by operating a processor such as a CPU or a DSP with software, for example. A part or all of the functions of the FFT processing unit 281, the detection unit 320, the switch control unit 330, and the filter processing unit 410 are realized by operating a processor such as a CPU or a DSP with software, for example.

The HPF271 outputs a communication signal, in which a component equal to or lower than a predetermined frequency among frequency components of the communication signal received via the signal distributor 110 is attenuated, to the reception amplifier 272.

The reception amplifier 272 amplifies the communication signal received from the HPF271 by a predetermined gain, and outputs the amplified communication signal to the ADC 273.

The ADC273 converts the communication signal received as an analog signal from the reception amplifier 272 into a digital signal and outputs the digital signal to the FFT processing unit 281 and the BPF412 in the discharge detection unit 400.

The FFT processor 281 performs signal processing such as FFT in the OFDM scheme on the digital signal received from the ADC273, and outputs the processed digital signal to the demodulator 282 and the detector 320 in the discharge detector 400.

The detection unit 320 in the discharge detection unit 400 generates a spectrum of the communication signal output from the HPF271 based on the digital signal received from the FFT processing unit 281, and outputs the generated spectrum to the switch control unit 330.

The passbands of the three BPFs 412 are different, respectively. For example, the passband of the BPF412A is 5MHz or more and less than 10MHz, the passband of the BPF412B is 10MHz or more and less than 15MHz, and the passband of the BPF412C is 15MHz or more and less than 20 MHz.

The BPF412 outputs a digital signal in which a component outside its own passband, out of the frequency components of the digital signal received from the ADC273, is attenuated, to the switch 411.

The switch control unit 330 generates a switch control signal based on the frequency spectrum received from the detection unit 320, and outputs the generated switch control signal to the switch 411, thereby switching the switch 411.

The switch 411 selectively outputs the digital signal received from the BPF412 to the detection unit 320. More specifically, the switch 411 is switched among the following three according to the switch control signal received from the switch control unit 330: outputs the digital signal received from the BPF412A to the detection unit 320; outputs the digital signal received from the BPF412B to the detection unit 320; alternatively, the digital signal received from the BPF412C is output to the detection unit 320.

The switch control unit 330 selects one BPF412 among the three BPFs 412, which outputs a digital signal to the detection unit 320 via the switch 411. More specifically, the switch control unit 330 determines the passband with the least noise component among the digital signals output from the ADC273 among the passbands of the three BPFs 412, and selects the BPF412 corresponding to the passband.

For example, the switch control unit 330 selects, based on the spectrum received from the detection unit 320, the BPF412 corresponding to the passband in which the value of the digital signal output from the ADC273 is the smallest among the passbands of the three BPFs 412.

Here, the current waveform generated by the partial discharge is a surge waveform. The components of the impulse waveform in the above frequency spectrum are equally distributed in the pass band of each BPF412, and therefore, the difference in the spectral level in each pass band due to the components of the impulse waveform is negligibly small. Therefore, based on the above frequency spectrum, the pass band in which the value of the digital signal output from the ADC273 is the smallest among the pass bands of the respective three BPFs 412 can be regarded as the pass band in which the noise component is the smallest.

The switch control unit 330 outputs the switch control signal to the switch 411, thereby switching the BPF412 that outputs the digital signal to the detection unit 320 via the switch 411 to the selected BPF 412.

For example, the switch control unit 330 selects the BPF412 periodically or aperiodically based on the spectrum received from the detection unit 320, and switches the switch 411 according to the selection result.

The switch control unit 330 is not limited to the configuration of switching the switch 411 based on the spectrum received from the detection unit 320, and may be configured as follows: the digital signal received by the detection unit 320 from the switch 411 is monitored periodically or aperiodically, and the switch 411 is switched based on the value of the digital signal, that is, the change in the amount of noise component included in the digital signal.

The detection unit 320 detects the partial discharge in the underground cable 10 based on the output of the switch 411 and the characteristic data relating to the physical properties of the BPF412 selected by the switch control unit 330. The details of the method of detecting partial discharge by the detection unit 320 are the same as those described in the first embodiment.

In addition, a BPF control unit that controls the output of the BPF412 to the detection unit 320 may be used instead of the switch control unit 330 and the switch 411. That is, the BPF control unit selects the BPF412 corresponding to the passband in which the value of the digital signal output from the ADC273 is the smallest, based on the spectrum received from the detection unit 320. The BPF control unit outputs a control signal to each BPF412, thereby causing the selected BPF412 to start outputting a digital signal to the detection unit 320 and causing the other BPFs 412 to stop outputting a digital signal to the detection unit 320.

The detection unit 320 is configured to detect the partial discharge in the underground cable 10 based on the output of the switch 411 and the characteristic data relating to the physical properties of the BPF412, but is not limited to this. The detection unit 320 may be configured as follows: a portion of the spectrum made is extracted, and a partial discharge in the underground cable 10 is detected based on the extracted spectrum and characteristic data relating to the physical properties of the frequency band of the spectrum.

For example, at least a part of the communication band of the communication unit 200 overlaps with the detection band of the discharge detection unit 400.

Fig. 18 is a diagram showing operation timings of a receiving unit and a discharge detection unit in a communication device according to a second embodiment of the present invention.

Referring to fig. 18, for example, the communication unit 200 and the discharge detection unit 400 perform transmission of communication information and detection of partial discharge at different times.

More specifically, the communication device 500 temporally alternates between transmission of communication information by the communication unit 200 and detection of partial discharge by the discharge detection unit 400.

As described above, in the communication device according to the second embodiment of the present invention, the communication unit 200 and the discharge detection unit 400 perform transmission of communication information and detection of partial discharge in a time-sharing manner.

With this configuration, it is not necessary to divide the frequency band of the communication induced current used by the communication unit 200 for transmission of the communication information and the frequency band of the detection induced signal used by the discharge detection unit 400 for detection of the partial discharge, and therefore the filter circuit, the analog/digital conversion circuit, and the like in the reception unit 260 of the communication unit 200 and the discharge detection unit 400 can be shared.

Further, since the processor used for software processing of part or all of the units can be shared, the cost can be reduced.

Other configurations and operations are the same as those of the communication device according to the first embodiment, and therefore detailed description thereof will not be repeated here.

The above-described embodiments should be considered in all respects as illustrative and not restrictive. The scope of the present invention is indicated by the claims, rather than the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.

The above description includes the features hereinafter appended.

[ additional notes 1]

A communication device for use in a power system having an underground cable, the communication device comprising: an electromagnetic coupling section electromagnetically coupled to a shield layer of the underground cable; a communication section that transmits communication information via the shielding layer; and a discharge detection portion that detects a partial discharge in the underground cable, the communication portion transmitting communication information using a communication induction current that is an induction current flowing through the shielding layer by electromagnetic coupling of the electromagnetic coupling portion, the discharge detection portion detecting the partial discharge based on a detection induction current received from the electromagnetic coupling portion as an induction current of a current flowing through the shielding layer, the discharge detection portion including: a band-pass filter receiving a signal based on the detected induced current; and a storage unit that stores characteristic data relating to characteristics of the band-pass filter, wherein the discharge detection unit detects the partial discharge based on an output of the band-pass filter and the characteristic data in the storage unit.

[ appendix 2]

A communication device for use in a power system having an underground cable, the communication device comprising: an electromagnetic coupling section electromagnetically coupled to a shield layer of the underground cable; a communication section that transmits communication information via the shielding layer; and a discharge detection unit that detects a partial discharge in the underground cable, the communication unit transmitting the communication information using a communication induction current that is an induction current flowing through the shield layer by electromagnetic coupling of the electromagnetic coupling unit, the discharge detection unit detecting the partial discharge based on a detection induction current received from the electromagnetic coupling unit that is an induction current flowing through the shield layer.

Description of the reference numerals

10: underground cable

11: cable terminal

12: wire rod

13: ground node

14: sensor with a sensor element

15: ground node

31: access hole

41: common connection part

42: insulating connection

43: ground connection part

53: conductive cable

71: conductor

72: inner semi-conducting layer

73: insulator

74: outer semi-conducting layer

75: shielding layer

76: protective sleeve

77: insulating cylinder

81: terminal with a terminal body

100：CT

101: ring-shaped iron core

102: winding wire

103: central monitoring device

105A, 105B: metal foil electrode

110. 110A, 110B: signal distributor

120: electromagnetic coupling part

121: electrostatic coupling part

200: communication unit

210: data processing unit

220: transmitting part

230: FEC encoder

231: code scrambler

232: encoder for encoding a video signal

233: interleaving device

240: modulation part

241: mapping device

242: IFFT processing unit

251：DAC

252：BPF

253: transmission amplifier

260: receiving part

271：HPF

272: receiving amplifier

273：ADC

280: demodulation unit

281: FFT processing unit

282: demodulator

290: FEC decoder

291: de-interleaver

292: decoder

293: descrambling device

300: discharge detection unit

301：HPF

302：LNA

303：ADC

304: FFT processing unit

305: AGC amplifier

306：ADC

310: filter processing unit

311: analog switch

312：BPF

313：LPF

320: detection part

330: switch control unit

340: storage unit

400: discharge detection unit

410: filter processing unit

411: switch with a switch body

412：BPF

500: communication device

501: communication system

502: a power transmission system.

Claims (4)

1. A communication device for use in a power system having an underground cable, the communication device comprising:

a communication unit that outputs a communication signal including communication information;

an inductive coupling unit that outputs the communication signal from the communication unit to a shield layer of the underground cable as a communication induced current by inductive coupling, and acquires a change in current flowing through the shield layer or a change in potential of the shield layer as a detection induced signal by inductive coupling and outputs the detection induced signal; and

and a discharge detection unit that detects a partial discharge in the underground cable based on the detection induction signal received from the inductive coupling unit.

2. The communication device of claim 1,

the frequency band of the communication induced current is different from the frequency band of the detection induced signal.

3. The communication device of claim 1 or 2,

the communication unit and the discharge detection unit perform transmission of the communication information and detection of the partial discharge in real time.

4. The communication device of any one of claims 1 to 3,

in the power system, a plurality of the underground cables are connected,

the inductive coupling part is inductively coupled with the shielding layer at the connecting part of the underground cable.

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