CN113167829B

CN113167829B - Communication device

Info

Publication number: CN113167829B
Application number: CN201980082313.7A
Authority: CN
Inventors: 下口刚史
Original assignee: Sumitomo Electric Industries Ltd
Current assignee: Sumitomo Electric Industries Ltd
Priority date: 2019-02-04
Filing date: 2019-10-25
Publication date: 2024-05-17
Anticipated expiration: 2039-10-25
Also published as: JP7352199B2; JPWO2020161966A1; WO2020161966A1; CN113167829A

Abstract

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 section that outputs the communication signal from the communication section to a shield layer of the underground cable as a communication induction current by inductive coupling, and acquires a change in current flowing in the shield layer or a change in potential of the shield layer as a detection induction signal by inductive coupling and outputs the detection induction signal; and a discharge detection unit that detects 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 device.

The present application claims priority based on japanese patent application publication 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 an insulation degradation diagnosis system as described below. That is, the insulation degradation diagnosis system includes: a partial discharge detector mounted on an insulated connection portion of a power cable line in which optical fibers are laid in parallel; a partial discharge detector provided near an insulation connection portion to which the partial discharge detector is attached, the partial discharge detector having a function of determining insulation deterioration of the power cable line based on an output of the partial discharge detector; means for increasing the local transmission loss of the optical fiber based on the determination result of the partial discharge detector; and a measuring unit for detecting an increase in transmission loss and a position where the transmission loss occurs in the optical fiber by an optical pulse reflection method, and diagnosing insulation deterioration of the power cable line.

Prior art literature

Patent literature

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

Disclosure of Invention

(1) The communication device of the present disclosure is used for a power system provided with an underground cable, and comprises: a communication unit that outputs a communication signal including communication information; an inductive coupling section that outputs the communication signal from the communication section to a shield layer of the underground cable as a communication induction current by inductive coupling, and acquires a change in current flowing in the shield layer or a change in potential of the shield layer as a detection induction signal by inductive coupling and outputs the detection induction signal; and a discharge detection unit that detects 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 device provided with such a unique processing section but also as a communication system provided with the communication device. Further, one aspect of the present disclosure can be implemented as a semiconductor integrated circuit implementing a 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 structure 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 connection method of an underground cable used in a normal connection portion of the power transmission system according to the first embodiment of the present invention.

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

Fig. 5 is a diagram showing another example of a connection method of an underground cable 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 device according to the first embodiment of the present invention.

Fig. 9 is a diagram showing another example of the configuration of a 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 the communication device according to the 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 a BPF in the discharge detection section 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 communication bands and detection bands 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 the receiving unit and the discharge detecting unit in the communication device according to the 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 degradation 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 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 an underground cable can be transmitted with a simple configuration.

Description of embodiments of the application

First, the contents of the embodiments of the present invention are described.

(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 section that outputs the communication signal from the communication section to a shield layer of the underground cable as a communication induction current by inductive coupling, and acquires a change in current flowing in the shield layer or a change in potential of the shield layer as a detection induction signal by inductive coupling and outputs the detection induction signal; and a discharge detection unit that detects partial discharge in the underground cable based on the detection induction signal received from the inductive coupling unit.

In this way, the communication signal is outputted to the shield layer as a communication induced current by inductive coupling, and a change in the current flowing through the shield layer or a change in the potential of the shield layer is acquired as a detection induced signal by inductive coupling, and partial discharge in the underground cable is detected based on the acquired detection induced signal. Thus, for example, information of the detection result of partial discharge can be transmitted well in the underground where transmission and reception of communication information by radio is difficult. Therefore, the detection result of the partial discharge in the underground cable can be transmitted with a simple configuration.

(2) Preferably, 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 and the detection of the partial discharge by the discharge detection unit can be performed in parallel, and there is no need to adjust the relationship between the timing of performing the communication process and the timing of performing the detection process, so that the communication process and the detection process can be simplified.

(3) Preferably, the communication unit and the discharge detection unit transmit the communication information and detect the partial discharge at the same time.

With this configuration, it is not necessary to separate 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 with the shielding layer at the connection portion of the underground cables.

In this way, the detection sensing signal is detected at the connection portion of the underground cable, and the partial discharge is detected based on the detection sensing signal, so that the partial discharge of the underground cable can be detected more accurately in the electric power system having the connection portion of the underground cable.

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

< First embodiment >, first embodiment

[ Constitution and basic action ]

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

The ground connection portion 43 includes cable terminals 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 ground connection portion 43 is provided in a portion of the underground cable 10 that appears on the ground, for example, in a power substation. The common connection portion 41 and the insulating connection portion 42 are provided inside the access opening (manhole) 31.

Referring to fig. 2, the underground cable 10 is composed of, in order from a central portion, a conductor 71, an inner semiconductive layer 72 made of semiconductive ethylene propylene (EP: ethylene Propylene) rubber, an insulator 73 made of EP rubber, an outer semiconductive layer 74 as a semiconductive tape, a conductive shielding layer 75, and a sheath 76 made of vinyl resin (vinyl).

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

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

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

The underground cables 10A, 10B, 10C are connected to the ground node 15 at cable terminals 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 cables or the like, whereby the shield layers 75 of the underground cables 10 are grounded.

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

Fig. 3 is a diagram showing an example of a connection method of an underground cable used in a normal connection portion of the power transmission system according to the first embodiment of the present invention. In fig. 3, the conductors 71 and the shielding 75 in the underground cable 10A are mainly shown for ease of illustration. The same applies to the underground cable 10B and the underground cable 10C.

Referring to fig. 3, in the normal connection portion 41, underground cables 10A1, 10A2 are connected. In the normal connection portion 41, for example, the shielding layers 75 of the underground cables 10A1, 10A2 are exposed at the connection portion of the conductors 71 of the underground cables 10A1, 10A2 to each other.

In the normal 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 wired using conductive wires (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, the terminal 81 is provided at an exposed portion of the shield layer 75 of the underground cable 10 A2. The terminal 81 may be provided at an exposed portion of the shield layer 75 of the underground cable 10 A1.

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 an underground cable used in an insulated connection portion of a power transmission system according to the first embodiment of the present invention. In fig. 4, for convenience of explanation, the conductor 71 and the shield 75 in the constitution of the underground cable 10A are mainly shown. The same applies to the underground cable 10B and the underground cable 10C.

Referring to fig. 4, in the insulating connecting portion 42, the underground cables 10A1, 10A2 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 of the conductors 71 of the underground cables 10A1, 10A2, and terminals 81 and the like are provided at the exposed portions, respectively.

In the insulating connection portion 42, in a 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 12, whereby the shielding layer 75 of the underground cable 10A1 and the shielding layer 75 of the underground cable 10A2 are connected.

Referring to fig. 5, in the insulating connecting 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 portion 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 portion 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 portion between the conductors 71 of the underground cables 10C1, 10C2, and the terminals 81 and the like are provided at the exposed portions, respectively.

In the insulating connection portion 42, for example, the terminal 81 in the underground cable 10A1 and the terminal 81 in the underground cable 10B2 are wired using the wire 12, whereby the shield layer 75 of the underground cable 10A1 and the shield layer 75 of the underground cable 10B2 are connected, the terminal 81 in the underground cable 10B1 and the terminal 81 in the underground cable 10C2 are wired using the wire 12, whereby 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 in the underground cable 10C1 and the terminal 81 in the underground cable 10A2 are wired using the wire 12, whereby 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 cable 10 may be connected in the form of a cross-over interconnect (cross bond) at the insulated connection portion 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 (hereinafter, also referred to as insulation deterioration) of the underground cable 10, for example, 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, it is not easy to ensure a communication path for transmitting the detection result of the partial discharge to the ground. For example, the cover of the access opening is made of metal, and thus 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 access port to confirm the detection result of the partial discharge. Further, in the case of laying a communication cable for transmitting the detection result of partial discharge underground, the cost increases. A technique capable of transmitting the detection result of partial discharge in an underground cable with a simple configuration is desired.

In contrast, in the communication device according to the embodiment of the present invention, the above-described problems are solved by 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, for convenience of explanation, the underground cable 10A among the underground cables 10 is mainly shown. The same applies to the underground cable 10B and the underground cable 10C.

Referring to fig. 6, a communication system 501 includes communication apparatuses 500A, 500B, and 500C. The communication devices 500A, 500B, 500C are used in a power system including the underground cable 10. Hereinafter, each of the communication apparatuses 500A, 500B, 500C is also referred to as a communication apparatus 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, the communication device 500A is provided corresponding to the insulating connection portion 42A, the communication device 500B is provided corresponding to the insulating connection portion 42B, and the communication device 500C is provided corresponding to the ground connection portion 43.

The communication device 500 exchanges 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 communication signals including various measurement results obtained by the one or more sensors 14 as communication information, and transmit the generated communication signals to the other communication devices 500 such as the communication device 500C.

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

For example, a power coil is provided in the underground cable 10A. An induced current generated by a current flowing through the conductor 71 of the underground cable 10 flows to the power coil. Thus, the power coil can draw out current. The communication device 500 operates, for example, by electric power obtained from a power supply coil.

[ Constitution of communication device ]

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 shielding layer 75 of the underground cable 10. Specifically, the electromagnetic coupling portion 120 is electromagnetically coupled to the shielding 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 shielding layer 75. The discharge detection unit 300 detects partial discharge in the underground cable 10.

[ Electromagnetic coupling portion ]

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

Referring to fig. 8, the ct100 includes a toroidal core 101 and windings 102. A winding 102 is wound around the toroidal core 101. Winding 102 is connected to signal splitter 110A.

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

In more detail, referring again to fig. 4 and 6, the CT100 of the communication devices 500A, 500B in the insulating connection portion 42 is assembled so as to penetrate the annular core 101 with the wires 12 connecting the shield layer 75 of the underground cable 10A1 and the shield layer 75 of the underground cable 10A 2. The CT100 of the communication device 500C in the ground connection portion 43 is mounted so as to penetrate the annular core 101 through the cable connected between the cable terminal 11A and the ground node 15.

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

The electromagnetic coupling portion 120 functions as a current detecting portion that detects a current flowing through the shielding layer 75. In more detail, when a current flows through the shielding layer 75 and the conductive cable 53, the induced current flows through the winding 102 by 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 sensing signal as a signal corresponding to a change in the sensing current flowing through the winding 102 via the signal distributor 110A.

That is, the electromagnetic coupling portion 120 receives the communication signal from the communication portion 200, and outputs the received communication signal to the shield layer 75 of the underground cable 10 as 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.

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

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

[ Electrostatic coupling portion ]

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

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 opposite sides of 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 where 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 10 A2.

The metal foil electrodes 105A and 105B may be attached to cover the outer periphery of the sheath 76 of the underground cable 10 A2. 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 functions as a current detecting 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, the 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 sensing signal as a signal corresponding to a change in the potential of the shielding layer 75 via the signal distributor 110B.

That is, the electrostatic coupling portion 121 receives the communication signal from the communication portion 200, and outputs the received communication signal to the shield layer 75 of the underground cable 10 as communication induced current by electrostatic coupling. The electrostatic coupling unit 121 acquires a change in the potential of the shielding layer 75 as a detection sensing signal by electrostatic coupling, and outputs an analog signal corresponding to the acquired detection sensing 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 signal splitters 110 only.

The communication unit 200 acquires communication information from the analog signal received via the signal distributor 110, that is, the communication signal from the other 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 cellular phone.

The discharge detection unit 300 detects 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 communication induced current which is induced current flowing through the shielding layer 75 by inductive coupling of the inductive coupling section. More specifically, the communication unit 200 uses the communication induced current to communicate with the communication unit 200 in the other communication device 500.

Referring to fig. 11, the communication section 200 includes a data processing section 210, a transmitting section 220, and a receiving section 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.

When receiving the demodulated data from the receiving section 260, the data processing section 210 acquires communication information from the received demodulated data.

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

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

More specifically, each communication apparatus 500 is given a unique ID. The data processing unit 210 generates communication data including information indicating the ID of the own 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 transmitting unit 220.

The data processing unit 210 confirms ID information included in the demodulated data received from the receiving unit 260, and acquires communication information from the demodulated data when the confirmed ID information indicates the ID of the communication device 500 itself.

[ Transmitting section ]

The transmitting unit 220 includes: an FEC (Forward Error Correction: forward error correction) encoder 230 that performs encoding processing in Forward error correction, a modulation section 240 that performs modulation processing, a DAC (Digital Analog Converter: digital-to-analog converter) 251, a Band-pass filter (BPF: band-PASS FILTER) 252, and a transmission amplifier 253.FEC encoder 230 has a scrambler (scrambler) 231, an encoder 232, and an interleaver (interleaver) 233. The modulation unit 240 includes a mapper 241 and an IFFT (INVERSE FAST Fourier Transform: inverse fast fourier transform) processing unit 242.

The scrambler 231 performs scrambling processing on 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.

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

The mapper 241 generates modulated data obtained by modulating the communication data received from the interleaver 233 by, for example, a DBPSK method (DIFFERENTIAL BINARY PHASE SHIFT KEYING: differential binary phase shift keying), and outputs the generated modulated data to the IFFT processing section 242.

The mapper 241 may be configured to generate modulated data obtained by modulating the communication data received from the interleaver 233 according to the DQPSK method (DIFFERENTIAL QUATERNARY PHASE SHIFT KEYING: differential quaternary phase shift keying), or may be configured to generate modulated data obtained by modulating the communication data received from the interleaver 233 according to the D8PSK method (DIFFERENTIAL OCTAL PHASE SHIFT KEYING: differential octal phase shift keying).

The IFFT processing unit 242 outputs the modulated data obtained by performing signal processing such as IFFT in the orthogonal frequency division multiplexing scheme (OFDM: orthogonal Frequency Division Multiplexing) on the modulated data received from the mapper 241 to the DAC 251. In OFDM, a signal can be transmitted well even in a state where the signal-to-noise ratio is close to zero dB.

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

The BPF252 outputs an analog signal obtained by attenuating a component outside a predetermined frequency band among frequency components of the analog signal received from the DAC251 to the transmission amplifier 253.

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

[ Receiving section ]

The receiving unit 260 includes a High pass filter (HPF: high-PASS FILTER) 271, a receiving amplifier 272, an ADC (Analog Digital Converter: analog-to-digital converter) 273, a demodulating unit 280 that performs demodulation processing, and an FEC decoder 290 that performs decoding processing in forward error correction. The demodulation unit 280 includes an FFT (Fast Fourier Transform: 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 the communication signal, which is the frequency component of the communication signal received via the signal splitter 110 and has a component equal to or lower than a predetermined frequency, to the reception amplifier 272.

The receiving 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 from the receiving amplifier 272 as an analog signal into a digital signal and outputs the digital signal to the FFT processing section 281.

The FFT processing unit 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, for example, demodulation data obtained by demodulating the digital signal received from the FFT processing unit 281 by the DBPSK method, and outputs the generated demodulation data to the deinterleaver 291.

The deinterleaver 291 performs repeated decoding processing and deinterleaving processing on the demodulated data received from the demodulator 282, and outputs the processed demodulated data to the decoder 292.

The decoder 292 decodes the demodulated data received from the deinterleaver 291, and outputs the processed demodulated data to the descrambler 293.

The descrambler 293 performs a descrambling process on the demodulated data received from the decoder 292, and outputs the demodulated data after the processing to the data processing section 210.

[ Discharge detection section ]

The discharge detection unit 300 detects 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, in addition to the discharge detection section 300, a reception section 260 in the communication section 200 is shown.

Referring to fig. 12, discharge detection unit 300 includes HPF301, LNA (Low Noise Amplifier: low noise amplifier) 302, ADC303, FFT processing unit 304, filter processing unit 310, AGC (Automatic Gain Control: automatic gain control) amplifier 305, ADC306, detection unit 320, switch control unit 330, and 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 BPF312.

The HPF301 outputs a signal obtained by attenuating a component equal to or lower than a predetermined frequency among frequency components of the analog signal received via the signal splitter 110 to the LNA 302. The analog signal received via the signal splitter 110 includes a plurality of noises 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, for example, a frequency component smaller than 1.6MHz, thereby removing noise contained in the analog signal received via the signal splitter 110.

The LNA302 amplifies the analog signal received from the HPF301 by 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 the 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 according to the switch control signal received from the switch control unit 330.

The pass bands of the three BPFs 312 are respectively different. 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 20MHz.

The switch control unit 330 selects one BPF312 to be the output destination of the analog signal switched by the analog switch 311 from among the three BPFs 312. More specifically, the switch control unit 330 determines the passband having the smallest 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 section 330 selects any one BPF312 from the plurality of BPFs 312 based on the current detected by the electromagnetic coupling section 120 or the electrostatic coupling section 121. More specifically, the switch control unit 330 selects, based on the frequency spectrum received from the detection unit 320, a BPF312 corresponding to a passband having the lowest signal level of the analog signal output from the LNA302 among the passbands of the three BPFs 312.

Here, the current waveform generated by the partial discharge is a surge waveform. Since the components of the impulse waveform in the above-described spectrum are equally distributed in the pass bands of the respective BPFs 312, the difference in spectral level in the respective pass bands due to the components of the impulse waveform is small to a negligible extent. Therefore, based on the above-described frequency spectrum, the passband of the three BPFs 312, which has the lowest signal level of the analog signal output from the LNA302, can be regarded as the passband with the smallest noise component.

The switch control unit 330 outputs a 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 BPF312.

For example, the switch control unit 330 periodically or aperiodically selects the BPF312 based on the frequency 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 for 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 from the ADC306 by the detection unit 320 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 noise component included in the digital signal.

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

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

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

The storage unit 340 stores characteristic data relating to the characteristics of the three BPFs 312, respectively. More specifically, the storage unit 340 stores, as the characteristic data, pulse (impulse) response characteristics of the three BPFs 312, for example, an 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 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 implemented by operating processors such as a CPU (Central Processing Unit: central processing unit) and a DSP (DIGITAL SIGNAL Processor: digital signal Processor) with software, for example. Further, some or all of the functions of the FFT processing unit 304, the detecting unit 320, and the switch control unit 330 are realized by operating a processor such as a CPU and a DSP by software, for example.

Referring to fig. 13, the impulse response waveform Imp of the bpf312 is stored in the storage unit 340 as a digital signal having a 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 maxima and one or more minima.

The detection unit 320 multiplies 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 by the X-th value of the impulse response waveform Imp according to the following expression (1), and adds K values obtained by the multiplication for each sample value, thereby calculating the operation value Y (T).

[ Number 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 an operation value Y (T) corresponding to each start time by shifting each start time of the period T1 by one sample of the digital signal S. The detection unit 320 may calculate the operation value Y (t) by multiplying the digital signal S by the impulse response waveform Imp every time the digital signal S of one sample amount is received from the ADC306, and the detection unit 320 may calculate the operation 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 accumulated sample value by the impulse response waveform Imp.

For example, when the impulse waveform is not included in the digital signal S in the period T1 from the time tk to the time tk+t1, the calculated value Y (tk) becomes 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 a surge waveform, the operation value Y (tm) is a somewhat large value.

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

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

The detection unit 320 calculates a phase (hereinafter, also referred to as a surge phase) of a surge signal generated by partial discharge among high-voltage voltages applied to the conductor 71 of the underground cable 10. More specifically, the data processing unit 210 detects a waveform of 50Hz or 60Hz of the induced current generated by the current flowing through the conductor 71, for example, via the power supply coil mounted on the underground cable 10 as described above. The data processing section 210 detects a zero-cross point (zero-cross point) of a 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 detecting unit 320. The detection unit 320 calculates the impact phase based on the received zero-crossing information and the occurrence timing of the impact 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-crossing 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 of the impact signal generated by the partial discharge detected, the impact phase, and the like, and stores the generated partial discharge information in the storage unit 340. The detection unit 320 updates the threshold ThA based on the partial discharge information stored in the storage unit 340, for example, by using a machine learning method.

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

Specifically, the pass bands of the BPF252 in the transmitting unit 220 and the HPF271 in the receiving unit 260 are 10kHz or more, so that components having a frequency smaller than 10kHz are attenuated, while the pass band of the HPF301 in the discharge detecting unit 300 is 1.6MHz or more, so that components having a frequency smaller than 1.6MHz are attenuated.

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 the discharge detection section 300A, a reception section 260 in the communication section 200 is shown.

Referring to fig. 16, in the discharge detection unit 300A of modification 1, the ADC303 is not included, and the filter processing unit 310 includes the LPF313, as compared to the discharge detection unit 300 shown in fig. 12. More specifically, the discharge detection unit 300A includes an HPF301, an LNA302, an FFT processing unit 304, a filter processing unit 310, an AGC amplifier 305, an ADC306, a detection unit 320, a switch control unit 330, and a storage unit 340. The discharge detection unit 300A is the same as the discharge detection unit 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 of 1/2 or less of the sampling frequency of the ADC 306.

The switch control unit 330 periodically or aperiodically selects the LPF313 as a filter to be set as the 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 LPF313.

The LPF313 outputs an analog signal, which attenuates components of the frequency components of the analog signal received from the analog switch 311, having a predetermined frequency or higher, to the AGC amplifier 305.

The AGC amplifier 305 amplifies the signal received from the LPF313 so that the output level of the analog signal to the ADC306 becomes constant, and outputs the amplified signal to the ADC 306.

The ADC306 converts the analog signal received from the AGC amplifier 305 into a digital signal and outputs the digital signal to the FFT processing section 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 the analog signal output by 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 the output destination of the analog signal switched by the analog switch 311 from among the three BPFs 312 based on the frequency spectrum received from the detection unit 320. The switch control unit 330 outputs a 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 BPF312. The switch control unit 330 outputs selection information indicating that the LPF313 is selected to the detection unit 320.

Modification 2

The communication device 500 may be configured to operate by using power obtained by the 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 the frequency band of the induced current is different from the frequency band of the communication signal transmitted and received by the communication device 500.

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

In the communication system 501, the shield current flowing through the shield layer 75 of the underground cable 10 can be extracted by providing the underground cable 10 with the CT 100.

The communication device 500 includes, for example, a filter for passing a current having a frequency of 60Hz or less. The communication device 500 extracts a low-frequency current of 50Hz or 60Hz from the extracted sheath currents using a filter.

Then, the communication device 500 rectifies and synthesizes the extracted low-frequency currents, thereby generating a power supply current sufficient to operate the communication device 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 partial discharge in the underground cable based on the output of the BPF312 and characteristic data related to physical properties of the BPF312, but the present invention is not limited thereto. The discharge detection unit 300 may be configured to detect partial discharge by other methods.

For example, referring to fig. 12, the discharge detection unit 300 may have the following configuration. That is, the HPF301 outputs an analog signal, which attenuates components equal to or lower than a predetermined frequency, among frequency components of the analog signal received via the signal splitter 110, to the LNA 302. The LNA302 amplifies an analog signal received from the HPF301 with 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 the analog signal output from the HPF301 based on the digital signal received from the FFT processing unit 304, and detects 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 thereto. The filter processing unit 310 may have a configuration with two or less BPFs 312, or may have a configuration with four or more BPFs 312.

The communication device according to the first embodiment of the present invention is configured to be provided in the insulating connecting portion 42 and the ground connecting 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, CT100 of communication device 500 in normal connection portion 41 is assembled so as to pass through toroidal core 101 a cable connected between terminal 81 provided in shield layer 75 and ground node 13.

In the communication device according to the first embodiment of the present invention, the following configuration is adopted: in the discharge detection unit 300, the storage unit 340 stores the impulse response waveform Imp as characteristic data of the BPF312, and the detection unit 320 calculates the operation 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 waveforms of sine waves of frequencies included in the pass band of the BPF 312. The detection unit 320 calculates an operation value Y (t) by multiplying the digital signal S by the waveform of the sine wave in the storage unit 340.

The following configuration may be adopted. That is, in the discharge detection section 300, the storage section 340 stores characteristic data other than the impulse response characteristic as the characteristic data of the BPF 312. The detection section 320 detects 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 transmission of the communication information and the detection of the partial discharge are performed 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 performs transmission of communication information by the communication unit 200 and detection of partial discharge by the discharge detection unit 300 alternately in time.

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 apparatuses 500 in the communication system 501 generates communication data including synchronization information indicating transmission timings of communication signals to be realized by the respective communication apparatuses 500 as communication information, and transmits the communication data to the other communication apparatuses 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 partial discharge at the timing indicated by the synchronization signal. In this way, the data processing unit 210 controls the transmission timing of the communication signal and the detection timing of the partial discharge so as to be different from each other, and thereby performs transmission of the communication information by the communication unit 200 and detection of the partial discharge by the discharge detection unit 300 in a time-sharing manner.

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 50 MHz. The communication band of the communication unit 200 and the detection band of the discharge detection unit 300 may be partially or entirely repeated. In this case, for example, as described above, the communication device 500 alternately performs transmission of communication information performed by the communication section 200 and detection of partial discharge performed by the discharge detection section 300 in time.

In the communication device according to the first embodiment of the present invention, the communication device 500C in the ground connection unit 43 is configured to include the communication unit 200 and the discharge detection unit 300, but the present invention is not limited thereto. The communication device 500C in the ground connection unit 43 may be configured to include the communication unit 200 and not include the 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 measurement information received from the sensor 14 as communication information, but the present invention is not limited thereto. 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 to 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 generates communication data including the ID information of the own communication device 500 as a part of the communication information, but the present invention is not limited thereto. The data processing unit 210 may be configured to generate communication data not including ID information.

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

The discharge detection unit 300 may include an amplifier that can adjust a gain from the outside instead of the AGC amplifier 305. In this case, for example, the detection unit 320 generates a gain control signal from a maximum value of the digital signal S in a predetermined period, for example, a period of several periods 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 the communication device according to the first embodiment of the present invention, the following configuration is adopted: in the discharge detection unit 300, the switch control unit 330 selects one BPF312 to be the output destination of the analog signal switched by the analog switch 311 from among the three BPFs 312, and the detection unit 320 detects partial discharge by an operation using the digital signal S received via the ADC306, which is the output of the selected BPF312, 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 partial discharge based on the result of the operation.

Further, a technique capable of transmitting the 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 section outputs the communication signal from the communication section 200 to the shield layer 75 of the underground cable 10 as communication induction current by inductive coupling, and acquires a change in current flowing in the shield layer 75 or a change in potential of the shield layer 75 as detection induction signal by inductive coupling and outputs the detection induction signal to the discharge detection section 300. The discharge detection section 300 detects partial discharge in the underground cable 10 based on the detection induction signal received from the inductive coupling section.

In this way, the communication signal is outputted to the shield layer 75 as a communication induced current by the inductive coupling, and the change in the current flowing through the shield layer 75 or the change in the potential of the shield layer 75 is acquired as a detection induced signal by the inductive coupling, and the partial discharge in the underground cable 10 is detected based on the acquired detection induced signal, and thus, for example, the detection result of the partial discharge can be transmitted as communication information through the shield layer 75 of the underground cable 10. Thus, for example, information of the detection result of partial discharge can be transmitted well in the underground where transmission and reception of communication information by radio is difficult.

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

With such a 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 there is no need to adjust the relationship between the timing of performing the communication process and the timing of performing the detection process, so that the communication process and the detection process can be simplified.

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

In this way, the detection sensing signal is detected at the connection portion of the underground cable, and the partial discharge is detected based on the detection sensing signal, so that the partial discharge of the underground cable 10 can be detected more accurately in the electric 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 an 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 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 that receives an analog signal based on the detected current; and a storage unit 340 that stores characteristic data of the BPF 312. The discharge detection section 300 detects partial discharge based on the output of the BPF312 and the characteristic data in the storage section 340.

In this way, partial discharge is detected 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, and by such a configuration, the presence or absence of a waveform corresponding to the characteristic data in the analog signal can be sensed. Thereby, for example, the influence of noise components contained in the current flowing through the shielding layer 75 can be reduced, and the current waveform due to partial discharge can be sensed.

Therefore, in the partial discharge detection apparatus of the first embodiment of the present invention, partial discharge in the underground cable 10 can be detected more accurately. In general, in order to detect an impact signal generated by partial discharge by digital signal processing, for example, an ADC capable of high-speed sampling at a sampling frequency of several GHz is required. In contrast, by the configuration of analyzing the analog signal via 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 characteristics of the BPF312 as characteristic data.

With this configuration, a detection device capable of satisfactorily sensing a pulse-like current waveform generated in large amounts by 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 partial discharge based on the output of at least one BPF312 and corresponding characteristic data.

With such a configuration, for example, an appropriate BPF312 corresponding to the laying environment of the underground cable 10 can be selected to detect partial discharge. Thus, partial discharge can be detected more accurately in 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 partial discharge based on the output of the selected BPF312 and corresponding characteristic data.

With such a configuration, for example, partial discharge can be detected more accurately by selecting the BPF312 having the passband in which the noise component is the smallest in the current flowing through the shielding layer 75 among the passbands of the plurality of BPFs 312.

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

< Second embodiment >

The present embodiment relates to a communication device having a configuration in which the receiving unit 260 and the discharge detecting unit 400 of the communication unit 200 share a part as compared with the communication device of the first embodiment. The communication device of the present embodiment is the same as that 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, the receiving section 260 in the communication section 200 is shown in addition to the discharge detecting section 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 receiving section 260 in the communication section 200 has an HPF271, a receiving amplifier 272, an ADC273, a demodulating section 280, and an FEC decoder 290. The demodulation section 280 has an FFT processing section 281 and a demodulator 282.

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

The filter processing section 410 has a switch 411 and BPFs 412A, 412B, 412C as digital filters. Hereinafter, each of the BPFs 412A, 412B, 412C is also referred to as a BPF412.

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 implemented by operating a processor such as a CPU and a DSP by software, for example. The FFT processing unit 281, the detection unit 320, the switch control unit 330, and the filter processing unit 410 are implemented by operating a processor such as a CPU and a DSP with software, for example, in part or in whole.

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

The FFT processing unit 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 detection unit 320 in the discharge detection unit 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 pass bands of the three BPFs 412 are respectively different. 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 20MHz.

The BPF412 outputs a digital signal, which attenuates a component outside the passband of itself, among the frequency components of the digital signal received from the ADC273, 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 switches between the following three according to the switch control signal received from the switch control unit 330: the digital signal received from the BPF412A is output to the detection unit 320; the digital signal received from the BPF412B is output to the detecting unit 320; or outputs the digital signal received from the BPF412C to the detection unit 320.

The switch control unit 330 selects one BPF412 from 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 having the smallest 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 frequency spectrum received from the detection unit 320, a BPF412 corresponding to a passband in which the value of the digital signal output from the ADC273 is smallest among the passbands of the three BPFs 412.

Here, the current waveform generated by the partial discharge is a surge waveform. Since the components of the impulse waveform in the above-described spectrum are equally distributed in the pass bands of the respective BPFs 412, the difference in spectral level in the respective pass bands due to the components of the impulse waveform is small to a negligible extent. Therefore, based on the above-described frequency spectrum, the passband of the three BPFs 412, in which the value of the digital signal output from the ADC273 is smallest, can be regarded as the passband in which the noise component is smallest.

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

For example, the switch control unit 330 periodically or aperiodically selects the BPF412 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 frequency spectrum received from the detection unit 320, and may be configured as follows: the digital signal received from the switch 411 by the detection unit 320 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 partial discharge in the underground cable 10 based on the output of the switch 411 and characteristic data related to the physical properties of the BPF412 selected by the switch control unit 330. The details of the partial discharge detection method 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 smallest, based on the frequency 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 partial discharge in the underground cable 10 based on the output of the switch 411 and characteristic data related to physical properties of the BPF412, but is not limited thereto. The detection unit 320 may be configured as follows: a part of the generated spectrum is extracted, and partial discharge in the underground cable 10 is detected based on the extracted spectrum and characteristic data related to physical properties of a frequency band of the spectrum.

For example, at least a part of the communication band of the communication section 200 is overlapped with the detection band of the discharge detection section 400.

Referring to fig. 18, for example, communication unit 200 and discharge detection unit 400 perform transmission of communication information and detection of partial discharge in a time-sharing manner.

More specifically, the communication device 500 performs transmission of communication information by the communication unit 200 and detection of partial discharge by the discharge detection unit 400 alternately in time.

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 separate the frequency band of the communication induced current used by the communication unit 200 for transmitting the communication information and the frequency band of the detection induced signal used by the discharge detection unit 400 for detecting the partial discharge, and thus the filter circuit, the analog/digital conversion circuit, and the like in the reception unit 260 and the discharge detection unit 400 of the communication unit 200 can be shared.

Further, the processor used for the software processing of a part or all of the respective units can be shared, and thus the cost can be reduced.

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

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

The above description includes the features noted below.

[ Additional note 1]

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

[ Additionally noted 2]

A communication device for a power system provided with an underground cable, the communication device comprising: an electromagnetic coupling unit that is electromagnetically coupled to a shield layer of the underground cable; a communication unit that transmits communication information via the shield layer; and a discharge detection unit that detects 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 that is an induction current flowing through the shield layer received from the electromagnetic coupling unit.

Description of the reference numerals

10: Underground cable

11: Cable terminal

12: Wire rod

13: Grounding node

14: Sensor for detecting a position of a body

15: Grounding node

31: Access hole

41: Common connecting part

42: Insulating connecting part

43: Ground connection part

53: Conductive cable

71: Conductor

72: Inner semiconductive layer

73: Insulation body

74: External semiconducting layer

75: Shielding layer

76: Sheath

77: Insulating cylinder

81: Terminal for connecting a plurality of terminals

100：CT

101: Annular iron core

102: Winding

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 unit

230: FEC encoder

231: Scrambler

232: Encoder with a plurality of sensors

233: Interleaver

240: Modulation unit

241: Mapping device

242: IFFT processing section

251：DAC

252：BPF

253: Transmitting amplifier

260: Receiving part

271：HPF

272: Receiving amplifier

273：ADC

280: Demodulation unit

281: FFT processing unit

282: Demodulator with a plurality of filters

290: FEC decoder

291: De-interleaver

292: Decoder

293: Descrambler

300: Discharge detection unit

301：HPF

302：LNA

303：ADC

304: FFT processing unit

305: AGC amplifier

306：ADC

310: Filtering processing unit

311: Analog switch

312：BPF

313：LPF

320: Detection unit

330: Switch control part

340: Storage unit

400: Discharge detection unit

410: Filtering processing unit

411: Switch

412：BPF

500: Communication device

501: Communication system

502: An electric power transmission system.

Claims

1. A communication device for a power system provided with an underground cable, the communication device comprising:

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

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

A discharge detection unit configured to detect partial discharge in the underground cable based on the detection induction signal received from the inductive coupling unit,

The inductive coupling part includes:

A current transformer or a metal foil electrode inductively coupled to the shielding layer; and

A signal distributor connected between the current transformer or the metal foil electrode and the communication part and the discharge detection part,

A current corresponding to the communication signal transmitted from the communication section flows to the current transformer or the metal foil electrode via the signal distributor,

The communication section acquires the communication information from the analog signal received via the signal distributor,

The discharge detection section detects the partial discharge in the underground cable based on an analog signal received via the signal distributor.

2. The communication device of claim 1, wherein,

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

3. The communication device according to claim 1 or 2, wherein,

The communication unit and the discharge detection unit perform transmission of the communication information and detection of the partial discharge at the same time.

4. The communication device according to claim 1 or 2, wherein,

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

The inductive coupling portion is inductively coupled with the shielding layer at a connection portion of the underground cable.

5. The communication device according to claim 3, wherein,

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