Distribution cable fault sensing and positioning system based on high-speed data acquisition

Abstract

The invention discloses a power distribution cable fault sensing and positioning system based on high-speed data acquisition, and belongs to the technical field of cable fault detection, and the system comprises a sensor and a traveling wave fault monitoring terminal which are installed on a power distribution network cable line node, and the sensor is used for collecting the high-frequency transient state, the traveling wave current and the power frequency current of an incoming and outgoing cable grounding wire; the traveling wave fault monitoring terminal is used for acquiring high-frequency transient current, traveling wave current and power frequency current acquired by the sensor and sending the acquired information; the remote fault diagnosis and analysis master station system is used for receiving and analyzing the high-frequency transient current, the traveling wave current and the power frequency current sent by the traveling wave fault monitoring terminal to realize online research and judgment, fault line selection and accurate fault positioning of cable faults; and the communication network is used for realizing data transmission between the traveling wave fault monitoring terminal and the remote fault diagnosis and analysis master station system. The insulation health state of the cable can be evaluated in real time, and observability, controllability and predictability of the insulation health state of a cable line are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of cable fault detection, and in particular to a distribution cable fault sensing and positioning system based on high-speed data acquisition. Background Art

[0002] The power distribution cable has a long power supply line, a complex structure, and is laid underground. The operating environment is harsh. Power cables are not maintenance-free, and cable failures occur from time to time. Once a cable fails, a lot of manpower and material resources are required to repair the cable, and the power supply restoration time is long, which seriously affects the reliability of power supply. Timely discovery and elimination of faults and potential fault hazards is the best way to ensure the reliable operation of the cable supply and distribution system. The power cable fault accurate positioning and early warning device and technology can effectively support the refined operation, maintenance and management of distribution cables.

[0003] However, there are the following technical bottlenecks in online monitoring and accurate positioning of 10kV distribution cable faults:

[0004] (1) The operating environment and structure of 10kV distribution cables are complex, with many branches, making online monitoring, accurate positioning and early warning of distribution network cable faults very difficult;

[0005] (2) Existing traveling wave fault distance measurement technology has been widely used in high-voltage transmission lines, but its ranging resolution is hundreds of meters, which is obviously not suitable for direct online monitoring and precise positioning of faults in 10kV distribution cables;

[0006] (3) The distribution cables are three-core cables, most of which are laid in pipes or directly buried. It is not possible to directly install partial discharge, temperature measurement and other devices, and the fault warning technical means are weak. Summary of the invention

[0007] In view of this, the present invention aims at the deficiencies in the prior art and provides a distribution cable fault sensing and positioning system based on high-speed data acquisition.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is: a distribution cable fault sensing and positioning system based on high-speed data acquisition, comprising:

[0009] Sensors are installed at the nodes of the distribution network cable lines to collect high-frequency transient and traveling wave currents and power frequency currents of the grounding wires of the incoming and outgoing cables;

[0010] A traveling wave fault monitoring terminal is installed on a node of a distribution network cable line and connected to the sensor to obtain the high-frequency transient and traveling wave currents and power frequency currents collected by the sensor and send the obtained information;

[0011] The remote fault diagnosis and analysis master station system is used to receive the high-frequency transient and traveling wave currents and power frequency currents sent by the traveling wave fault monitoring terminal, and analyze them to achieve online analysis and judgment of cable faults, fault line selection and accurate fault location;

[0012] The communication network is used to realize data transmission between the traveling wave fault monitoring terminal and the remote fault diagnosis and analysis main station system.

[0013] Furthermore, the distribution network cable line node includes a switch station, a ring network cabinet, a switch station and a branch box.

[0014] Furthermore, the sensor includes a broadband high-frequency current sensor and an industrial frequency voltage sensor. The acquisition bandwidth of the broadband high-frequency current sensor is 1kHz-25 MHz, and the acquisition bandwidth of the industrial frequency voltage sensor is 0Hz-1kHz. The sampling frequency of the broadband high-frequency current sensor reaches 10MHz, and the sampling accuracy reaches 5%; the industrial frequency sampling accuracy of the industrial frequency voltage sensor reaches 1%.

[0015] Furthermore, the communication network adopts optical fiber, GPRS or 4G communication mode.

[0016] Furthermore, the online analysis method of the remote fault diagnosis and analysis master station system for cable faults includes:

[0017] The transient faults are analyzed and judged by the characteristic frequency band method and the amplitude and polarity of high-frequency transient traveling waves;

[0018] The permanent fault is analyzed and judged by the power frequency steady-state zero-sequence voltage or the line three-phase voltage, the characteristic frequency band method and the amplitude and polarity of the high-frequency transient traveling wave;

[0019] The ground fault is analyzed and judged by the power frequency steady-state zero-sequence voltage or line three-phase voltage, characteristic frequency band method and the amplitude and polarity of high-frequency transient traveling wave;

[0020] The short-circuit fault is analyzed and judged by the power frequency steady-state zero-sequence voltage, the line three-phase voltage and the power frequency circulating current of the grounding wire, the characteristic frequency band method and the amplitude and polarity of the high-frequency transient traveling wave.

[0021] Furthermore, the method for selecting a fault line for a cable fault by the remote fault diagnosis and analysis master station system includes: selecting the fault line by the polarity and amplitude of the high-frequency transient traveling wave.

[0022] Furthermore, the remote fault diagnosis and analysis master station system adopts a wide-area dual-end traveling wave ranging method to achieve accurate fault positioning.

[0023] Furthermore, when a fault occurs at a certain point in the cable, the fault point generates a high-frequency traveling wave signal, which propagates to both ends of the cable. When the sensors at both ends of the cable detect the high-frequency traveling wave signal, the traveling wave fault monitoring terminals at both ends of the cable record the arrival time of the high-frequency traveling wave signal. The remote fault diagnosis and analysis main station system calculates the time difference recorded by the two traveling wave fault monitoring terminals, combined with the known cable length and traveling wave propagation speed, to achieve accurate positioning of the fault point.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention is a distribution cable fault sensing and positioning system based on high-speed data acquisition. By installing sensors and traveling wave fault monitoring terminals on the cable line nodes of the distribution network, the traveling wave fault monitoring terminals transmit the high-frequency transient and traveling wave currents and power frequency currents collected by the sensors to the remote fault diagnosis and analysis main station system in real time for analysis and calculation, thereby realizing online analysis and judgment of cable faults, fault line selection and accurate fault positioning, thereby evaluating the insulation health status of the cable in real time, realizing the observable, controllable and predictable insulation health status of the cable line, guiding the operation and maintenance personnel to carry out rapid and proactive repairs, timely eliminating potential fault hazards, preventing the occurrence of power outages, and providing technical support and reference basis for the status inspection and maintenance of distribution lines.

[0026] Through the implementation of the present invention, the safety, power supply reliability and operation and maintenance efficiency of the distribution network can be improved, and the traditional blind and passive operation and maintenance can be transformed into active operation and maintenance. At the same time, through the implementation of the present invention, the digital and intelligent management level of the cable of the State Grid Nanyang Power Supply Company can be improved, and the development of intelligent digital distribution network can be promoted. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic structural diagram of an embodiment of the present invention;

[0028] Figure 2 is a steady-state and transient waveform diagram in an embodiment of the present invention;

[0029] Figure 3 is a waveform diagram of a high-frequency transient traveling wave in an embodiment of the present invention;

[0030] Figure 4 is a schematic diagram of a fault line selection principle in an embodiment of the present invention;

[0031] Figure 5 is a schematic diagram of the principle of double-terminal traveling wave ranging in an embodiment of the present invention;

[0032] In the figure: 1- ring main unit, 2- branch box, 3- traveling wave fault monitoring terminal, 4- remote fault diagnosis and analysis master station system, 5- broadband high frequency current sensor, 6- power frequency voltage sensor. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0034] Example

[0035] like Figure 1 As shown, the distribution cable fault sensing and positioning system based on high-speed data acquisition includes:

[0036] The sensor is installed at the nodes of the distribution network cable line (switch station, ring main unit 1, switch station and branch box 2, etc.) to collect the high-frequency transient and traveling wave currents and power frequency currents of the grounding wires of the incoming and outgoing cables;

[0037] The traveling wave fault monitoring terminal 3 is installed on the distribution network cable line node (switch station, ring network cabinet 1, switch station and branch box 2, etc.), connected to the sensor, and is used to obtain the high-frequency transient and traveling wave current and power frequency current collected by the sensor, and send the obtained information; the traveling wave fault monitoring terminal uses GPS / Beidou precise timing to ensure the accurate synchronization of the time of each traveling wave fault monitoring terminal;

[0038] The remote fault diagnosis and analysis master station system 4 is used to receive the high-frequency transient and traveling wave currents and power frequency currents sent by the traveling wave fault monitoring terminal, and analyze them to achieve online analysis and judgment of cable faults, fault line selection and accurate fault location;

[0039] The communication network is used to realize data transmission between the traveling wave fault monitoring terminal and the remote fault diagnosis and analysis main station system.

[0040] The sensor comprises a broadband high-frequency current sensor 5 and an industrial frequency voltage sensor 6. The acquisition bandwidth of the broadband high-frequency current sensor is 1kHz-25 MHz, and the acquisition bandwidth of the industrial frequency voltage sensor is 0Hz-1kHz. The sampling frequency of the broadband high-frequency current sensor reaches 10MHz, and the sampling accuracy reaches 5%; the industrial frequency sampling accuracy of the industrial frequency voltage sensor reaches 1%.

[0041] The communication network adopts optical fiber, GPRS or 4G communication mode.

[0042] The online analysis method of the remote fault diagnosis and analysis master station system for cable faults includes:

[0043] a) Analysis of transient faults (such as insulation discharge, defect discharge, tree barriers, lightning strikes, etc.)

[0044] The transient fault is analyzed and judged by the amplitude and polarity of transient state (characteristic frequency band method) and high-frequency transient traveling wave;

[0045] b) Permanent fault analysis

[0046] The permanent fault is analyzed and judged by the amplitude and polarity of steady state (power frequency steady state zero sequence voltage or line three-phase voltage), transient state (characteristic frequency band method) and high-frequency transient traveling wave;

[0047] c) Analysis of small current single-phase grounding fault (main insulation fault)

[0048] The ground fault (main insulation fault) is analyzed and judged by the amplitude and polarity of steady state (power frequency steady state zero sequence voltage or line three-phase voltage), transient state (characteristic frequency band method) and high-frequency transient traveling wave;

[0049] d) Short circuit fault analysis

[0050] The short-circuit fault is judged by the amplitude and polarity of steady-state (power frequency steady-state zero-sequence voltage, line three-phase voltage and grounding line power frequency circulating current), transient (characteristic frequency band method) and high-frequency transient traveling wave. Figure 2 As shown, the high-frequency transient traveling wave waveform is as follows Figure 3 shown.

[0051] like Figure 4 As shown, the fault line selection method for the remote fault diagnosis and analysis master station system for cable faults includes: selecting the fault line through the polarity and amplitude of the high-frequency transient traveling wave.

[0052] like Figure 5 As shown, the remote fault diagnosis and analysis main station system adopts a wide-area two-end traveling wave ranging method to achieve accurate fault positioning: when a fault occurs at a certain point in the cable, the fault point generates a high-frequency traveling wave signal, which propagates to both ends of the cable. When the sensors at both ends of the cable detect the high-frequency traveling wave signal, the traveling wave fault monitoring terminals at both ends of the cable record the arrival time of the high-frequency traveling wave signal. The remote fault diagnosis and analysis main station system calculates the time difference recorded by the two traveling wave fault monitoring terminals, combined with the known cable length and traveling wave propagation speed, to achieve accurate positioning of the fault point.

[0053] The present invention combines the development of digital intelligent distribution network, and studies the distribution cable fault perception and positioning system based on high-speed data acquisition for the cable distribution network, and uses Beidou precise timing, high-speed data acquisition, wide-area traveling wave ranging and artificial intelligence and other technologies to realize online monitoring of distribution cable faults, accurate fault positioning and fault warning. The sampling rate is 10Mhz, the Beidou timing accuracy is less than 10ns, the single-phase grounding fault judgment and line selection accuracy of the small current grounding system reaches more than 95%, and the fault location error is within 10 meters. The operation and maintenance personnel can quickly and accurately find and find the fault point through mobile phone text messages or APP, thereby improving the power supply reliability and operation and maintenance efficiency of the distribution cable. At the same time, the fault diagnosis and analysis service platform of the present invention records and diagnoses and analyzes the transient discharge characteristic waveform, evaluates the insulation health status of the cable in real time, realizes the observable, controllable and predictable insulation health status of the cable line, guides the operation and maintenance personnel to quickly and actively repair, timely eliminates fault hazards, and prevents the occurrence of power outages, providing technical support and reference basis for the state maintenance of the distribution line.

[0054] The distribution cable fault perception and precise positioning system developed by the present invention based on high-speed data acquisition and artificial intelligence technology is applied to 10kV distribution cable scenarios. After adjusting the judgment threshold and field test calibration, it can be further extended to transmission cable lines and other power distribution cable scenarios in factories, mines, petrochemicals, etc. It has very important scientific and technological significance and broad application prospects.

[0055] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, a person skilled in the art can still modify or make equivalent substitutions to the specific implementations of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the scope of protection of the claims of the present invention.

Claims

1. A distribution cable fault sensing and positioning system based on high-speed data acquisition, characterized in that: include: Sensors are installed at the nodes of the distribution network cable lines to collect high-frequency transient and traveling wave currents and power frequency currents of the grounding wires of the incoming and outgoing cables; A traveling wave fault monitoring terminal is installed on a node of a distribution network cable line and connected to the sensor to obtain the high-frequency transient and traveling wave currents and power frequency currents collected by the sensor and send the obtained information; The remote fault diagnosis and analysis master station system is used to receive the high-frequency transient and traveling wave currents and power frequency currents sent by the traveling wave fault monitoring terminal, and analyze them to achieve online analysis and judgment of cable faults, fault line selection and accurate fault location; The communication network is used to realize data transmission between the traveling wave fault monitoring terminal and the remote fault diagnosis and analysis main station system.

2. The distribution cable fault sensing and positioning system based on high-speed data acquisition according to claim 1 is characterized in that: The distribution network cable line nodes include switch stations, ring network cabinets, switch stations and branch boxes.

3. The distribution cable fault sensing and positioning system based on high-speed data acquisition according to claim 1 is characterized in that: The sensor includes a broadband high-frequency current sensor and an industrial frequency voltage sensor. The acquisition bandwidth of the broadband high-frequency current sensor is 1kHz-25 MHz, and the acquisition bandwidth of the industrial frequency voltage sensor is 0Hz-1kHz. The sampling frequency of the broadband high-frequency current sensor reaches 10MHz, and the sampling accuracy reaches 5%; the industrial frequency sampling accuracy of the industrial frequency voltage sensor reaches 1%.

4. The distribution cable fault sensing and positioning system based on high-speed data acquisition according to claim 1 is characterized in that: The communication network adopts optical fiber, GPRS or 4G communication mode.

5. The distribution cable fault sensing and positioning system based on high-speed data acquisition according to claim 1 is characterized in that: The online analysis method of the remote fault diagnosis and analysis master station system for cable faults includes: The transient faults are analyzed and judged by the characteristic frequency band method and the amplitude and polarity of high-frequency transient traveling waves; The permanent fault is analyzed and judged by the power frequency steady-state zero-sequence voltage or the line three-phase voltage, the characteristic frequency band method and the amplitude and polarity of the high-frequency transient traveling wave; The ground fault is analyzed and judged by the power frequency steady-state zero-sequence voltage or line three-phase voltage, characteristic frequency band method and the amplitude and polarity of high-frequency transient traveling wave; The short-circuit fault is analyzed and judged by the power frequency steady-state zero-sequence voltage, the line three-phase voltage and the power frequency circulating current of the grounding wire, the characteristic frequency band method and the amplitude and polarity of the high-frequency transient traveling wave.

6. The distribution cable fault sensing and positioning system based on high-speed data acquisition according to claim 1 is characterized in that: The method for selecting a fault line for a cable fault by a remote fault diagnosis and analysis master station system comprises: selecting a fault line by the polarity and amplitude of a high-frequency transient traveling wave.

7. The distribution cable fault sensing and positioning system based on high-speed data acquisition according to claim 1 is characterized in that: The remote fault diagnosis and analysis master station system adopts a wide-area dual-end traveling wave ranging method to achieve accurate fault positioning.

8. The distribution cable fault sensing and positioning system based on high-speed data acquisition according to claim 7 is characterized in that: When a fault occurs at a certain point in the cable, a high-frequency traveling wave signal is generated at the fault point and propagates to both ends of the cable. When the sensors at both ends of the cable detect the high-frequency traveling wave signal, the traveling wave fault monitoring terminals at both ends of the cable record the arrival time of the high-frequency traveling wave signal. The remote fault diagnosis and analysis master station system calculates the time difference recorded by the two traveling wave fault monitoring terminals, combined with the known cable length and traveling wave propagation speed, to accurately locate the fault point.

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