CN111999597A - Traveling wave fault positioning device of hybrid power transmission line - Google Patents

Traveling wave fault positioning device of hybrid power transmission line Download PDF

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CN111999597A
CN111999597A CN202010858345.6A CN202010858345A CN111999597A CN 111999597 A CN111999597 A CN 111999597A CN 202010858345 A CN202010858345 A CN 202010858345A CN 111999597 A CN111999597 A CN 111999597A
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fault
traveling wave
transmission line
time
wave
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CN111999597B (en
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成林
刘健
毕闯
卢江平
吴经锋
吴健
耿鹏杰
郭安祥
徐伟锋
方玉鑫
高峰
马雪杰
王辰曦
吴子豪
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State Grid Corp of China SGCC
University of Electronic Science and Technology of China
Electric Power Research Institute of State Grid Shaanxi Electric Power Co Ltd
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State Grid Corp of China SGCC
University of Electronic Science and Technology of China
Electric Power Research Institute of State Grid Shaanxi Electric Power Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/08—Locating faults in cables, transmission lines, or networks
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/08—Locating faults in cables, transmission lines, or networks
    • G01R31/088—Aspects of digital computing
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S11/00—Systems for determining distance or velocity not using reflection or reradiation
    • G01S11/02—Systems for determining distance or velocity not using reflection or reradiation using radio waves
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
    • Y04S10/00—Systems supporting electrical power generation, transmission or distribution
    • Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
    • Y04S10/52—Outage or fault management, e.g. fault detection or location

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Abstract

The invention discloses a traveling wave fault positioning device of a hybrid power transmission line, belonging to the technical field of high-voltage power transmission lines of power electronics; the device comprises: the device comprises a current extraction module, a signal conditioning circuit, an A/D conversion module, a GPS high-precision synchronous clock module, a DSP central processing unit module, a GPRS communication module and a PC master station comprehensive analysis module; seven traveling wave extraction devices are installed in the whole hybrid power transmission line and are respectively arranged at two ends of the hybrid line, the middle point of the overhead line, the middle point of the GIL, the middle point of the cable line, the joint of the overhead line and the GIL and the joint of the GIL and the cable. According to the invention, the GPS is utilized to perform time synchronization on the traveling wave extraction devices at each end in the power transmission line, so that the fault positioning precision is improved; and the DSP chip is utilized to realize the processing of the fault signal, thereby realizing the rapid identification and positioning of the fault in the hybrid power transmission line.

Description

Traveling wave fault positioning device of hybrid power transmission line
Technical Field
The invention belongs to the technical field of fault location of high-voltage hybrid power transmission lines, and particularly relates to a traveling wave fault location device of a hybrid power transmission line.
Background
Due to different structural characteristics of the overhead line, the gas insulated transmission line (GIL) and the cable, the laying arrangement of a power transmission system under different conditions can be met, and the adaptability and the flexibility of the whole transmission line are improved. However, for the novel overhead line-GIL-cable hybrid transmission line, the traditional single-end and double-end ranging cannot achieve a good effect.
In order to detect the transient traveling wave phenomenon in the line on the secondary side, the traveling wave component in the line needs to be accurately extracted, and meanwhile, the fault analog signal acquisition speed has higher requirements for ensuring the fault positioning precision.
In the traditional fault location method based on the traveling wave, the location is carried out by depending on the time when the wave heads of the first traveling wave and the second traveling wave reach each detection point, however, because of the difference of the parameters of the overhead line, the GIL and the cable line, a plurality of wave impedance discontinuous points can appear in the mixed line of the current traveling wave, which causes the phenomenon of traveling wave refraction and reflection, and the traveling wave reaching the detection device is difficult to be judged as the wave head of the first traveling wave or the traveling wave signal obtained by subsequent reflection.
For the multi-terminal ranging method based on the traveling wave, the accurate time of the initial traveling wave reaching each recording device needs to be obtained on the basis of data synchronous sampling. And because the time of each device of the transmission line always appears the difference, lead to the time not synchronous, will influence the precision of finding range at last.
In summary, a new traveling wave fault positioning device for a hybrid power transmission line based on a GPS reference time difference is needed.
Disclosure of Invention
In order to solve the problem of ranging of a novel overhead line-gas insulated transmission line (GIL) -cable hybrid transmission line, the invention improves the existing traveling wave ranging device, provides a traveling wave fault location device of the hybrid transmission line, and can improve the precision of fault location by utilizing a GPS to perform time synchronization on traveling wave extraction devices distributed in the transmission line; the DSP chip is used for processing the fault information at a high speed, so that the fault signal processing speed is increased; and the GPRS is utilized to realize the sending of the fault data packet, and the automation and the accuracy of communication are improved.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention relates to a traveling wave fault positioning device of a hybrid power transmission line, which comprises:
the current extraction module is used for extracting a line fault traveling wave signal;
the signal conditioning circuit module is used for adjusting the fault traveling wave signal obtained by the current extraction module to a range conforming to the A/D conversion module to obtain an adjusted fault traveling wave signal;
the A/D conversion module is used for processing the fault traveling wave signal adjusted by the signal conditioning circuit module into a fault traveling wave digital signal;
the DSP central processing unit module is used for processing the fault traveling wave digital signals output by the A/D conversion module to obtain the time for the fault traveling wave signals to reach each current extraction module;
and the PC master station comprehensive analysis module is embedded with a fault distance measurement algorithm and is used for completing fault positioning based on the time obtained by the DSP central processor module.
The invention further improves the method and also comprises the following steps:
and the GPS synchronous clock module is used for providing a uniform time reference for the traveling wave fault positioning device.
The invention further improves the method and also comprises the following steps:
and the GPRS communication module is used for transmitting the fault information obtained after the processing of the DSP central processing module to the PC master station comprehensive analysis module.
The invention has the further improvement that the current extraction modules are respectively arranged at two ends of the hybrid line, the midpoint of the overhead line, the midpoint of the GIL, the midpoint of the cable line, the joint of the overhead line and the GIL and the joint of the GIL and the cable line;
the current extraction module includes: the current transformer is used for converting a current signal at the primary side of the power transmission line into a current signal convenient to collect and measure through the secondary side current transformer; the collected current signals are three-phase current signals of circuit faults.
In a further development of the invention, the conditioning circuit module comprises: a pi-type filter circuit and an analog amplifying circuit.
The invention has the further improvement that in the DSP central processing unit, firstly, the collected fault current traveling wave signal is subjected to phase-mode conversion to obtain an alpha line-mode component; and performing wavelet transformation on the extracted alpha line mode component, and analyzing the mode maximum value of the alpha line mode component to obtain the time of the fault traveling wave signal reaching each current extraction module.
The invention is further improved in that, in the DSP central processing unit,
the expression for the continuous wavelet transform on the alpha component is:
Figure BDA0002647246090000031
wherein χ (t) is a current signal, a is a scaling factor, b is a transfer factor,
Figure BDA0002647246090000032
is the complex conjugate of the selected mother wavelet.
The further improvement of the invention is that the fault location algorithm embedded in the PC master station comprehensive analysis module is as follows: judging a fault occurring section according to a minimum time method and an adjacent measuring point time difference comparison method based on the time of the fault traveling wave signal reaching each current extraction module; calculating a wave speed and a fault starting time based on the obtained section where the fault occurs; and determining the fault position based on the wave speed and the fault starting time obtained by calculation, and completing fault positioning.
The further improvement of the invention lies in that in the fault location algorithm embedded in the PC master station comprehensive analysis module:
when time t ismWhen the fault is minimum, the fault occurs in the first half section of the overhead line;
when time t isaAt minimum, if tb>tmThe fault occurs in the first half section of the overhead line; otherwise, the fault occurs in the second half section of the overhead line;
when time t isbAt minimum, if td-tc＝tc-tbThe fault occurs in the second half section of the overhead line; otherwise, the fault occurs in the first half section of the gas insulated transmission line;
when time t iscAt minimum, if tb<tdThe fault occurs in gas insulated transmissionThe first half of the electric line; otherwise, the fault occurs in the second half section of the gas insulated transmission line;
when time t isdAt minimum, if te-td＝tn-teThe fault occurs in the second half section of the gas insulated transmission line; otherwise, the fault occurs in the front half section of the cable;
when time t iseAt minimum, if tn>tdThe fault occurs in the front half section of the cable; otherwise, the fault occurs in the rear half section of the cable;
when time t isnWhen the fault is minimum, the fault occurs in the rear half section of the cable;
wherein, tmThe first wave head arrival time t of the traveling wave probe at the position m of the terminalaThe first wave head arrival time, t, of the travelling wave probe in the neutral point of the overhead linebThe first wave head arrival time t of the traveling wave probe at the joint of the overhead line and the gas insulated transmission linecThe first wave head arrival time t of the traveling wave probe at the midpoint of the gas insulated transmission linedThe first wave head arrival time t of the traveling wave probe at the joint of the gas insulated transmission line and the cableeThe arrival time of the first wave head of the cable midpoint traveling wave probe is tnThe time of arrival of the first wave head of the traveling wave probe at the terminal n.
A further development of the invention is that,
(1) the fault occurs in the first half section of the overhead line, and the wave speed and the fault starting time t are calculated0The expression of (a) is:
Figure BDA0002647246090000041
the expression for determining the fault location is: d ═ tm-t0)v1；
(2) The fault occurs in the second half section of the overhead line, and the wave speed and the fault starting time t are calculated0The expression of (a) is:
Figure BDA0002647246090000042
the expression for determining the fault location is: d ═ l1+(ta-t0)v1；
(3) The fault occurs in the first half section of the gas insulated transmission line, and the wave speed and the fault starting time t are calculated0The expression of (a) is:
Figure BDA0002647246090000043
the expression for determining the fault location is: d 2l1+(tb-t0)v2；
(4) The fault occurs in the second half section of the gas insulated transmission line, and the wave speed and the fault starting time t are calculated0The expression of (a) is:
Figure BDA0002647246090000051
the expression for determining the fault location is: d 2l1+l2+(tc-t0)；
(5) The fault occurs in the first half section of the cable, the wave speed and the fault starting time t are calculated0The expression of (a) is:
Figure BDA0002647246090000052
the expression for determining the fault location is: d 2l1+2l2+(td-t0)v3；
(6) The fault occurs in the second half section of the cable, and the wave speed and the fault starting time t are calculated0The expression of (a) is:
Figure BDA0002647246090000053
the expression for determining the fault location is: d 2l1+2l2+l3+(te-t0)v3；
In the formula I1Is half the length of the overhead line,/2Is half of the length of the gas insulated transmission line3Is half the length of the cable, v1Is the propagation velocity, v, of a travelling wave in an overhead line2For the propagation velocity, v, of a travelling wave in a gas-insulated power transmission line3D is the distance from the fault location to the terminal m, which is the propagation speed of the traveling wave in the cable.
Compared with the prior art, the invention has the following beneficial effects:
the traveling wave fault positioning device of the hybrid power transmission line based on the GPS reference time difference utilizes the GPS to perform time synchronization on the traveling wave extraction devices distributed in the power transmission line, so that the fault positioning precision can be improved; the DSP chip is used for processing the fault information at a high speed, so that the fault signal processing speed is increased; and the GPRS is utilized to realize the sending of the fault data packet, and the automation and the accuracy of communication are improved. The invention can meet the fault location of the novel power transmission line of overhead line-gas insulated transmission line (GIL) -cable hybrid power transmission line, and is also suitable for fault location and distance measurement of the traditional single power transmission line and overhead line-cable hybrid power transmission line. The fault location can be realized by only analyzing the time of the first wave head, and comparing the time values of different measuring points to determine the fault occurrence time, so that the problem of refraction and reflection of traveling waves is reduced, and the accuracy of fault location is ensured. Meanwhile, the device utilizes the GPS reference time difference to carry out time synchronization and calibration on each traveling wave extraction device in the power transmission line, thereby improving the reliability of distance measurement of the device.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art are briefly introduced below; it is obvious that the drawings in the following description are some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.
Fig. 1 is a schematic structural diagram of a traveling wave fault positioning device of a hybrid power transmission line based on a GPS reference time difference according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a traveling wave collecting and processing system according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a signal conditioning circuit according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a GPS high-precision synchronous clock module according to an embodiment of the present invention;
fig. 5 is a schematic working flow diagram of a traveling wave fault location device of a hybrid power transmission line based on a GPS reference time difference according to an embodiment of the present invention.
Detailed Description
In order to make the purpose, technical effect and technical solution of the embodiments of the present invention clearer, the following clearly and completely describes the technical solution of the embodiments of the present invention with reference to the drawings in the embodiments of the present invention; it is to be understood that the described embodiments are only some of the embodiments of the present invention. Other embodiments, which can be derived by one of ordinary skill in the art from the disclosed embodiments without inventive faculty, are intended to be within the scope of the invention.
Referring to fig. 1, a traveling wave fault location device of a hybrid power transmission line based on a GPS reference time difference according to an embodiment of the present invention is used for locating a fault of an overhead line-gas insulated transmission line (GIL) -cable hybrid line based on a GPS. The traveling wave fault locating device comprises: the device comprises a current extraction module, a signal conditioning circuit module, an A/D conversion module, a GPS high-precision synchronous clock module, a DSP central processing unit module, a GPRS communication module and a PC master station comprehensive analysis module; seven traveling wave extraction devices are installed in the whole hybrid power transmission line and are respectively arranged at two ends of the hybrid line, the middle point of the overhead line, the middle point of the GIL, the middle point of the cable line, the joint of the overhead line and the GIL and the joint of the GIL and the cable.
In the embodiment of the invention, the current transformer is utilized to extract the current of the power transmission line in real time, and the current transformer converts a large-current signal from the primary side of the power transmission line into a small-current signal convenient to collect and measure
When a line fails, the DSP detects a current signal with sudden change, and then controls the A/D conversion chip and the GPS interface unit to sample a fault current traveling wave signal within a preset time;
the signal conditioning circuit module adjusts a small current signal at the secondary side of the current transformer to be within the range of the measuring range of the A/D conversion chip under the undistorted condition; meanwhile, the signal conditioning circuit is used for realizing the electrical isolation between the digital quantity and the analog quantity and avoiding the heavy current from being connected in series with the low-voltage element.
The GPS high-precision synchronous clock module is used for providing a uniform and accurate time reference for the whole fault positioning device. Specifically, the GPS high-precision synchronous clock module is suitable for carrying out clock synchronization on each receiving module in a power grid, ensures high-precision synchronous operation of clocks at each position of the device, outputs high-precision second clock signals and sends the second clock signals to the DSP module.
The traveling wave collecting and processing system needs to record the complete waveform of the current initial traveling wave signal when the current initial traveling wave signal reaches the bus measuring position, the frequency is relatively high, and in order to ensure accurate restoration of the current traveling wave signal and facilitate analysis of a PC (personal computer) processor, the traveling wave collecting and processing system needs to be supported by a data memory SDRAM with a large capacity.
And recording the waveforms and data of the time signals and fault circuit traveling wave signals with the accuracy reaching us level through a data bus and an address bus.
The DSP central processing unit firstly carries out phase-mode conversion on the collected fault current traveling wave signal to obtain an alpha linear-mode component. And performing wavelet transformation on the extracted alpha line mode component, and analyzing the mode maximum value of the alpha line mode component, thereby obtaining the time of the fault traveling wave signal reaching each current extraction module. Optionally, processing the discrete fault signal, specifically including applying wavelet transform to perform modulus maximum analysis on the signal, identifying first extreme value information, performing clock synchronization by using a GPS, and extracting accurate arrival time of a first traveling wave head; the SDRAM space in the DSP chip is required to be large enough, so that data coverage caused in the conversion process of external faults and internal faults can be avoided, and the reliability of the system is improved.
The GPRS communication module converts the serial port data into IP data and transmits the IP data to the PC processor through a wireless communication network. Specifically, the GPRS communication module is suitable for communication between the traveling wave acquisition and processing system and the PC master station comprehensive analysis module, and fault information obtained after processing by the DSP central processing module is sent to the PC master station comprehensive analysis module.
And the PC master station analysis module receives fault information sent by GPRS communication, and data analysis processing and fault positioning calculation are realized by MATLAB programming. The PC master station comprehensive analysis module is suitable for receiving and storing fault reports, receives data processed by the DSP central processing unit module, starts an upper computer program, and achieves automation of traveling wave fault location.
In the embodiment of the invention, in the DSP central processing unit, the expression of the continuous wavelet transformation on the alpha component is as follows:
Figure BDA0002647246090000081
wherein χ (t) is a current signal, a is a scaling factor, b is a transfer factor,
Figure BDA0002647246090000082
is the complex conjugate of the selected mother wavelet.
In the embodiment of the invention, the fault location algorithm embedded in the PC master station comprehensive analysis module is as follows: judging a fault occurring section according to a minimum time method and an adjacent measuring point time difference comparison method based on the time of the fault traveling wave signal reaching each current extraction module; calculating a wave speed and a fault starting time based on the obtained section where the fault occurs; and determining the fault position based on the wave speed and the fault starting time obtained by calculation, and completing fault positioning.
The further improvement of the invention lies in that in the fault location algorithm embedded in the PC master station comprehensive analysis module:
when time t ismWhen the fault is minimum, the fault occurs in the first half section of the overhead line;
when time t isaAt the minimum, iftb>tmThe fault occurs in the first half section of the overhead line; otherwise, the fault occurs in the second half section of the overhead line;
when time t isbAt minimum, if td-tc＝tc-tbThe fault occurs in the second half section of the overhead line; otherwise, the fault occurs in the first half section of the gas insulated transmission line;
when time t iscAt minimum, if tb<tdThe fault occurs in the first half section of the gas insulated transmission line; otherwise, the fault occurs in the second half section of the gas insulated transmission line;
when time t isdAt minimum, if te-td＝tn-teThe fault occurs in the second half section of the gas insulated transmission line; otherwise, the fault occurs in the front half section of the cable;
when time t iseAt minimum, if tn>tdThe fault occurs in the front half section of the cable; otherwise, the fault occurs in the rear half section of the cable;
when time t isnWhen the fault is minimum, the fault occurs in the rear half section of the cable;
wherein, tmThe first wave head arrival time t of the traveling wave probe at the position m of the terminalaThe first wave head arrival time, t, of the travelling wave probe in the neutral point of the overhead linebThe first wave head arrival time t of the traveling wave probe at the joint of the overhead line and the gas insulated transmission linecThe first wave head arrival time t of the traveling wave probe at the midpoint of the gas insulated transmission linedThe first wave head arrival time t of the traveling wave probe at the joint of the gas insulated transmission line and the cableeThe arrival time of the first wave head of the cable midpoint traveling wave probe is tnThe time of arrival of the first wave head of the traveling wave probe at the terminal n.
In the embodiment of the present invention, the first and second substrates,
(1) the fault occurs in the first half section of the overhead line, and the wave speed and the fault starting time t are calculated0The expression of (a) is:
Figure BDA0002647246090000091
the expression for determining the fault location is: d ═ tm-t0)v1；
(2) The fault occurs in the second half section of the overhead line, and the wave speed and the fault starting time t are calculated0The expression of (a) is:
Figure BDA0002647246090000092
the expression for determining the fault location is: d ═ l1+(ta-t0)v1；
(3) The fault occurs in the first half section of the gas insulated transmission line, and the wave speed and the fault starting time t are calculated0The expression of (a) is:
Figure BDA0002647246090000093
the expression for determining the fault location is: d 2l1+(tb-t0)v2；
(4) The fault occurs in the second half section of the gas insulated transmission line, and the wave speed and the fault starting time t are calculated0The expression of (a) is:
Figure BDA0002647246090000101
the expression for determining the fault location is: d 2l1+l2+(tc-t0)；
(5) The fault occurs in the first half section of the cable, the wave speed and the fault starting time t are calculated0The expression of (a) is:
Figure BDA0002647246090000102
the expression for determining the fault location is: d 2l1+2l2+(td-t0)v3；
(6) The fault occurs in the second half section of the cable, and the wave speed and the fault starting time t are calculated0The expression of (a) is:
Figure BDA0002647246090000103
the expression for determining the fault location is: d 2l1+2l2+l3+(te-t0)v3；
In the formula I1Is half the length of the overhead line,/2Is half of the length of the gas insulated transmission line3Is half the length of the cable, v1Is the propagation velocity, v, of a travelling wave in an overhead line2For the propagation velocity, v, of a travelling wave in a gas-insulated power transmission line3D is the distance from the fault location to the terminal m, which is the propagation speed of the traveling wave in the cable.
The device of the embodiment of the invention has the advantages that: the fault location method can meet the fault location of the novel power transmission line of an overhead line-gas insulated transmission line (GIL) -cable hybrid power transmission line, and is also suitable for fault location and distance measurement of the traditional single power transmission line and the overhead line-cable hybrid power transmission line. The fault location can be realized by only analyzing the time of the first wave head, and comparing the time values of different measuring points to determine the fault occurrence time, so that the problem of refraction and reflection of traveling waves is reduced, and the accuracy of fault location is ensured. Meanwhile, the device utilizes the GPS reference time difference to carry out time synchronization and calibration on each traveling wave extraction device in the power transmission line, thereby improving the reliability of distance measurement of the device.
Referring to fig. 1, a schematic structural diagram of a fault location device for an overhead line-gas insulated transmission line (GIL) -cable hybrid transmission line based on a GPS reference time difference according to an embodiment of the present invention is shown in fig. 1, where the fault location device includes: the system comprises a distributed traveling wave acquisition and processing device, a GPRS communication module and a PC master station comprehensive analysis module; the distributed traveling wave acquisition device modules are respectively arranged at two ends of the hybrid line, the middle point of the overhead line, the middle point of the GIL, the middle point of the cable line, the connecting position of the overhead line and the GIL and the connecting position of the GIL and the cable.
Referring to fig. 2 and 3, the structure of the traveling wave collecting and processing system is shown in fig. 2. The current transformer connected into the secondary loop is used for carrying out real-time current extraction on the power transmission line, and a large-current signal from the primary side of the power transmission line is converted into a small-current signal convenient to collect and measure. And then filtering and amplifying the high-frequency small current signal, inputting the high-frequency small current signal to an A/D conversion module, and carrying out digital processing on analog data. The current acquisition and processing circuit is shown in fig. 3. In order to prevent the aliasing phenomenon of the signal, the high-frequency component in the signal needs to be filtered by a low-pass filter before the current signal is sampled; by adjusting R in the amplifying circuit1And R2The value of (a) changes the amplification factor so as to achieve the standard signal required by the a/D converter.
And inputting the scattered fault signals into a DSP central processing unit for analysis. After sampling is finished, the DSP central processing unit firstly carries out phase-mode transformation on the collected fault current traveling wave signal to obtain an alpha line-mode component, specifically comprises the steps of carrying out mode maximum analysis on the signal by applying wavelet transformation, identifying first extreme value information, carrying out clock synchronization by utilizing a GPS (global positioning system), and extracting accurate arrival time of a first traveling wave head. And the DSP records the waveform and data of the time signal with the accuracy reaching us level and the traveling wave signal of the fault circuit through a data bus and an address bus. The SDRAM space in the DSP chip is required to be large enough, so that data coverage caused in the conversion process of external faults and internal faults can be avoided, and the reliability of the system is improved.
A GPS synchronous clock module in the system is utilized to provide a uniform and accurate time reference for a distributed traveling wave method high-voltage transmission line fault positioning system, and an accurate time scale is marked for the collected fault current traveling wave signal to be used as a time basis for analyzing the fault current traveling wave signal later.
Referring to fig. 4, a GPS receiver in the GPS synchronous clock module outputs a 1PPS second pulse signal, which is stabilized by a phase-locked loop and then output to the CPLD control module, and the other signal input is a 1PPS second pulse obtained by frequency division of a constant-temperature high-precision crystal oscillator, which is counted, and the second pulse signal obtained by the GPS receiver is precision compensated, and is processed by the CPLD to obtain a corrected 1PPS second pulse signal, which provides a uniform clock signal for the system. The workflow is shown in fig. 4.
Referring to fig. 5, a data packet processed by the DSP central processing module is sent to the PC master station comprehensive analysis module through a GPRS network and a public network, the PC master station comprehensive analysis module is composed of a PC master controller, the module enters a fault processing program after a fault occurs, data exchange between the traveling wave acquisition module and the PC master station comprehensive analysis module is realized through a communication network, and a fault location algorithm is embedded in the PC master station comprehensive analysis module, so that a location result can be automatically displayed and fault information can be actively reported. The workflow is shown in fig. 5.
In summary, the embodiment of the invention discloses a fault positioning device for an overhead line-gas insulated transmission line (GIL) -cable hybrid transmission line based on a GPS reference time difference, and belongs to the technical field of high-voltage transmission lines of power electronics; the device comprises a current extraction module, a signal conditioning circuit, an A/D conversion module, a GPS high-precision synchronous clock module, a DSP central processing unit module, a GPRS communication module and a PC master station comprehensive analysis module; seven traveling wave extraction devices are installed in the whole hybrid power transmission line and are respectively arranged at two ends of the hybrid line, the middle point of the overhead line, the middle point of the GIL, the middle point of the cable line, the joint of the overhead line and the GIL and the joint of the GIL and the cable. The invention is characterized in that: time synchronization is carried out on the traveling wave extraction devices at all ends in the power transmission line by using a GPS, so that the fault positioning precision is improved; and the DSP chip is utilized to realize the processing of the fault signal, thereby realizing the rapid identification and positioning of the fault in the hybrid power transmission line.
Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can make modifications and equivalents to the embodiments of the present invention without departing from the spirit and scope of the present invention, which is set forth in the claims of the present application.

Claims (10)

1. The utility model provides a traveling wave fault locating device of hybrid transmission line which characterized in that includes:
the current extraction module is used for extracting a line fault traveling wave signal;
the signal conditioning circuit module is used for adjusting the fault traveling wave signal obtained by the current extraction module to a range conforming to the A/D conversion module to obtain an adjusted fault traveling wave signal;
the A/D conversion module is used for processing the fault traveling wave signal adjusted by the signal conditioning circuit module into a fault traveling wave digital signal;
the DSP central processing unit module is used for processing the fault traveling wave digital signals output by the A/D conversion module to obtain the time for the fault traveling wave signals to reach each current extraction module;
and the PC master station comprehensive analysis module is embedded with a fault distance measurement algorithm and is used for completing fault positioning based on the time obtained by the DSP central processor module.
2. The traveling wave fault locating device of a hybrid transmission line according to claim 1, further comprising:
and the GPS synchronous clock module is used for providing a uniform time reference for the traveling wave fault positioning device.
3. The traveling wave fault locating device of a hybrid transmission line according to claim 1, further comprising:
and the GPRS communication module is used for transmitting the fault information obtained after the processing of the DSP central processing module to the PC master station comprehensive analysis module.
4. The traveling wave fault location device of a hybrid transmission line according to claim 1,
the current extraction modules are respectively arranged at two ends of the hybrid line, the middle point of the overhead line, the middle point of the GIL, the middle point of the cable, the connecting position of the overhead line and the GIL and the connecting position of the GIL and the cable;
the current extraction module includes:
the current transformer is used for converting a current signal at the primary side of the power transmission line into a current signal convenient to collect and measure through the secondary side current transformer; the collected current signals are three-phase current signals of circuit faults.
5. The traveling wave fault location device of a hybrid transmission line according to claim 1,
the conditioning circuit module includes: a pi-type filter circuit and an analog amplifying circuit.
6. The traveling wave fault location device of a hybrid power transmission line according to claim 1, wherein the DSP central processing unit first performs phase-mode conversion on the collected fault current traveling wave signal to obtain an α -line-mode component; and performing wavelet transformation on the extracted alpha line mode component, and analyzing the mode maximum value of the alpha line mode component to obtain the time of the fault traveling wave signal reaching each current extraction module.
7. The traveling wave fault location device of a hybrid power transmission line according to claim 6, wherein, in the DSP central processing unit,
the expression for the continuous wavelet transform on the alpha component is:
Figure FDA0002647246080000021
wherein χ (t) is a current signal, a is a scaling factor, b is a transfer factor,
Figure FDA0002647246080000022
is the complex conjugate of the selected mother wavelet.
8. The traveling wave fault location device of a hybrid power transmission line of claim 1, wherein the fault location algorithm embedded in the PC master station comprehensive analysis module is: judging a fault occurring section according to a minimum time method and an adjacent measuring point time difference comparison method based on the time of the fault traveling wave signal reaching each current extraction module; calculating a wave speed and a fault starting time based on the obtained section where the fault occurs; and determining the fault position based on the wave speed and the fault starting time obtained by calculation, and completing fault positioning.
9. The traveling wave fault location device of a hybrid power transmission line of claim 4, wherein in the fault location algorithm embedded in the PC master station comprehensive analysis module:
when time t ismWhen the fault is minimum, the fault occurs in the first half section of the overhead line;
when time t isaAt minimum, if tb>tmThe fault occurs in the first half section of the overhead line; otherwise, the fault occurs in the second half section of the overhead line;
when time t isbAt minimum, if td-tc＝tc-tbThe fault occurs in the second half section of the overhead line; otherwise, the fault occurs in the first half section of the gas insulated transmission line;
when time t iscAt minimum, if tb<tdThe fault occurs in the first half section of the gas insulated transmission line; otherwise, the fault occurs in the second half section of the gas insulated transmission line;
when time t isdAt minimum, if te-td＝tn-teThe fault occurs in the second half section of the gas insulated transmission line; otherwise, the fault occurs in the front half section of the cable;
when time t iseAt minimum, if tn>tdThe fault occurs in the front half section of the cable; otherwise, the fault occurs in the rear half section of the cable;
when time t isnWhen the fault is minimum, the fault occurs in the rear half section of the cable;
wherein, tmThe first wave head arrival time t of the traveling wave probe at the position m of the terminalaThe first wave head arrival time, t, of the travelling wave probe in the neutral point of the overhead linebPower transmission for overhead lines and gas insulationTime of arrival, t, of the first wave head of a travelling-wave probe at a line connectioncThe first wave head arrival time t of the traveling wave probe at the midpoint of the gas insulated transmission linedThe first wave head arrival time t of the traveling wave probe at the joint of the gas insulated transmission line and the cableeThe arrival time of the first wave head of the cable midpoint traveling wave probe is tnThe time of arrival of the first wave head of the traveling wave probe at the terminal n.
10. The traveling wave fault location device of a hybrid transmission line according to claim 9,
(1) the fault occurs in the first half section of the overhead line, and the wave speed and the fault starting time t are calculated0The expression of (a) is:
Figure FDA0002647246080000031
the expression for determining the fault location is: d ═ tm-t0)v1；
(2) The fault occurs in the second half section of the overhead line, and the wave speed and the fault starting time t are calculated0The expression of (a) is:
Figure FDA0002647246080000032
the expression for determining the fault location is: d ═ l1+(ta-t0)v1；
(3) The fault occurs in the first half section of the gas insulated transmission line, and the wave speed and the fault starting time t are calculated0The expression of (a) is:
Figure FDA0002647246080000033
the expression for determining the fault location is: d 2l1+(tb-t0)v2；
(4) The fault occurs in the second half section of the gas insulated transmission line, and the wave speed and the fault starting time t are calculated0The expression of (a) is:
Figure FDA0002647246080000041
the expression for determining the fault location is: d 2l1+l2+(tc-t0)；
(5) The fault occurs in the first half section of the cable, the wave speed and the fault starting time t are calculated0The expression of (a) is:
Figure FDA0002647246080000042
the expression for determining the fault location is: d 2l1+2l2+(td-t0)v3；
(6) The fault occurs in the second half section of the cable, and the wave speed and the fault starting time t are calculated0The expression of (a) is:
Figure FDA0002647246080000043
the expression for determining the fault location is: d 2l1+2l2+l3+(te-t0)v3；
In the formula I1Is half the length of the overhead line,/2Is half of the length of the gas insulated transmission line3Is half the length of the cable, v1Is the propagation velocity, v, of a travelling wave in an overhead line2For the propagation velocity, v, of a travelling wave in a gas-insulated power transmission line3D is the distance from the fault location to the terminal m, which is the propagation speed of the traveling wave in the cable.
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