Cable partial discharge detection method and system based on photon lantern and few-mode fiber

Abstract

The invention discloses a cable partial discharge detection system based on a photon lantern and a few-mode optical fiber. The cable partial discharge detection system comprises a few-mode optical fiber setting module, a multi-mode partial discharge detection module, a signal fusion module and a partial discharge judgment module, the few-mode optical fiber setting module is used for winding a few-mode optical fiber on the power cable to be detected according to a set number of turns; the multi-mode partial discharge detection module is used for carrying out multi-mode partial discharge detection on the cable to obtain a multi-mode partial discharge detection value; the signal fusion module is used for carrying out weighted fusion on the multi-mode partial discharge detection values obtained by the multi-mode partial discharge detection module to obtain final cable partial discharge detection data; and the partial discharge judgment module is used for inputting the final cable partial discharge detection data into a set partial discharge criterion and judging whether partial discharge occurs at the current monitoring point or not. The method also has the outstanding advantages of high practicability, large application range and the like.

Description

Technical Field

[0001] The present invention relates to the field of cable partial discharge detection, and in particular to a cable partial discharge detection method and system based on photon lanterns and few-mode optical fibers. Background Art

[0002] Due to the long distance and invisible buried characteristics of power cables, continuous monitoring is required throughout the entire length of the cable to obtain real-time operation information of the power cables. Distributed detection can quickly and accurately locate the fault point, reducing the frequency of emergency repairs and replacements. Partial discharge is an important problem faced during the operation of power cables. Partial discharge can cause aging, defects or even failure of insulation materials, resulting in power outages. Effective detection of partial discharge is an important task in the operation and maintenance of power cables.

[0003] Fiber optic sensing is widely used in the field of power equipment status monitoring due to its advantages of anti-electromagnetic interference, high sensitivity, small size, good resistance to high temperature and corrosion, good insulation performance, and long-distance transmission. Phase-sensitive optical time domain reflectometer is an important method for power cable status monitoring and positioning. In practical applications, phase-sensitive optical time domain reflectometers may be affected by coherent fading, introducing detection errors and detection blind spots, resulting in reduced detection accuracy and inaccurate fault location. Few-mode fiber is an optical fiber that supports transmission of a few modes. Compared with multi-mode fiber, it can effectively reduce interference between modes. Photon lanterns can convert multiple modes in few-mode fibers into single modes in multiple single-mode fibers, improve signal quality, and reduce the impact of coherent fading on detection results. The use of few-mode fibers and photon lanterns can significantly reduce the impact of coherent fading, thereby improving the measurement accuracy of phase-sensitive optical time domain reflectometers.

[0004] CN116754910A discloses a cable partial discharge monitoring method, system and equipment based on multi-channel optical fiber differential. The method includes obtaining a timing pulse signal and coherent light, modulating the coherent light into three pulse lights with different pulse widths according to the timing pulse signal; using two optical signals of the pulse light to detect partial discharge in the cable area to obtain N groups of pulse data; performing denoising, phase extraction, and smoothing classification processing on the N groups of pulse data in turn to obtain three corresponding groups of phase data; performing discretization and dimension change processing on each group of phase data to obtain three groups of one-dimensional arrays, and judging whether partial discharge occurs in the cable area according to the three groups of one-dimensional arrays. In this patent, only one mode of light is used for partial discharge detection. -OTDR detection, different modes -OTDR signals are different and independent. Due to the spatial differences in the fading positions of different modes, the fusion of the three modes -OTDR is used to suppress coherent fading, which makes the invention less practical and has a smaller scope of application. Summary of the invention

[0005] In order to solve the shortcomings of the prior art, such as low practicability and small application scope, the present invention provides a cable partial discharge detection method and system based on photon lanterns and few-mode optical fibers.

[0006] The present invention adopts the following technical solution.

[0007] On one hand, the present invention discloses a cable partial discharge detection system based on photon lanterns and few-mode optical fibers, including a few-mode optical fiber setting module, a multi-mode partial discharge detection module, a signal fusion module and a partial discharge discrimination module;

[0008] The few-mode optical fiber setting module is used to wind the few-mode optical fiber around the power cable to be detected according to a set number of turns;

[0009] The multi-mode partial discharge detection module performs multi-mode partial discharge detection on the cable based on the photon lantern and the set few-mode optical fiber to obtain a multi-mode partial discharge detection value;

[0010] The signal fusion module performs weighted fusion on the multi-mode partial discharge detection values ​​obtained by the multi-mode partial discharge detection module to obtain final cable partial discharge detection data;

[0011] The partial discharge determination module inputs the final cable partial discharge detection data into a set partial discharge determination criterion to determine whether partial discharge occurs at the current monitoring point.

[0012] More preferably,

[0013] In the multi-mode partial discharge detection module, the multi-modes include a fundamental mode LP01 mode, a high-order mode LP11a mode in the few-mode optical fiber, and a high-order mode LP11b mode in the few-mode optical fiber.

[0014] More preferably,

[0015] The multi-mode partial discharge detection module comprises a narrow linewidth coherent laser (1); the output end of the narrow linewidth coherent laser (1) is connected to the input end of a first optical coupler (2); the two output ends of the first optical coupler (2) are respectively connected to the first input end of an acousto-optic modulator (4) and the input end of a one-to-three coupler (13); the second input end of the acousto-optic modulator (4) is connected to a waveform generator (3), and the output end is connected to the input end of an erbium-doped fiber amplifier (5); the output end of the erbium-doped fiber amplifier (5) is connected to the input end of an optical bandpass filter (6); the output end of the optical bandpass filter (6) is connected to the input end of a one-to-three coupler (7); the three output ends of the one-to-three coupler (7) are respectively connected to the first ends of a first optical fiber circulator (9), a second optical fiber circulator (10) and a third optical fiber circulator (11); the first optical fiber circulator (9), the second optical fiber circulator (10) and the third optical fiber circulator The second end of the optical fiber circulator (11) is respectively connected to the first end, the second end and the third end of the photon lantern (8); the fourth end and the fifth end of the photon lantern (8) are respectively connected to the input end and the output end of the few-mode optical fiber (12); the third end of the first optical fiber circulator (9) is connected to the second input end of the first balanced photodetector (14); the third end of the second optical fiber circulator (10) is connected to the second input end of the second balanced photodetector (15); the third end of the third optical fiber circulator (11) is connected to the second input end of the third balanced photodetector (16); the three output ends of the one-to-three coupler (13) are respectively connected to the first input ends of the balanced photodetector (14), the balanced photodetector (15) and the balanced photodetector (16); the output ends of the balanced photodetector (14), the balanced photodetector (15) and the balanced photodetector (16) are all connected to a data acquisition card (17).

[0016] More preferably,

[0017] The one-to-three coupler (7) divides the pulse filtered by the optical bandpass filter (6) into a first branch pulse, a second branch pulse and a third branch pulse, a total of three branch pulses; the spatial modes of the three branch pulses are LP01 mode, LP11a mode and LP11b mode respectively.

[0018] More preferably,

[0019] The first end, the second end and the third end of the photon lantern (8) respectively receive the first branch pulse, the second branch pulse and the third branch pulse emitted by the second end of the first optical fiber circulator (9), the second optical fiber circulator (10) and the third optical fiber circulator (11), convert the three modes corresponding to the branch pulses of the three modes into multiple modes of the few-mode optical fiber, and transmit them from the fourth end of the photon lantern (8) to the input end of the few-mode optical fiber;

[0020] The fifth end of the photon lantern (8) receives the output signal of the few-mode optical fiber, converts the multiple modes of the few-mode optical fiber into the single modes of three single-mode optical fibers, and outputs the obtained three signals from the first end, the second end, and the third end respectively.

[0021] More preferably,

[0022] The few-mode optical fiber (12) receives the output signal of the fourth end of the photon lantern (8), is used to sense the local discharge signal of the power cable at the winding position, and outputs a signal carrying the local discharge detection information of the cable at the detected position to the fifth end of the photon lantern (8).

[0023] More preferably,

[0024] In the signal fusion module, the multi-mode partial discharge detection values ​​obtained by the multi-mode partial discharge detection module are weighted and fused to obtain the final cable partial discharge detection data as shown in the following formula:

[0025] S(t)=w 01 (t)S 01 (t)+w 11a (t)S 11a (t)+w 11b (t)S 11b (t);

[0026] Where S(t) is the final cable partial discharge detection value at time t; w 01 (t) is the partial discharge weight of LP01 mode at time t; S 01 (t) is the partial discharge detection value of LP01 mode at time t; w 11a (t) is the partial discharge weight of LP11a mode at time t; S 11a (t) is the partial discharge detection value of LP11a mode at time t; w 11b (t) is the partial discharge weight of LP11b mode at time t; S 11b (t) is the partial discharge detection value of LP11b mode at time t.

[0027] More preferably,

[0028] The partial discharge weight of LP01 mode at time t is as follows:

[0029]

[0030] Among them, max[·] means to find the maximum value in the brackets; min[·] means to find the minimum value in the brackets; is the partial discharge phase of LP01 mode at time t; is the partial discharge phase of LP01 mode at time t-1; δ is the phase correlation coefficient; t represents the tth sampling point; N Z is the total number of sampling points of multi-mode partial discharge; e is the natural base; λ 1 is the first weight correlation coefficient; 2 is the second weighted correlation coefficient;

[0031] The partial discharge weight of LP11a mode at time t is as follows:

[0032]

[0033] in, is the partial discharge phase of LP11a mode at time t; is the partial discharge phase of LP11a mode at time t-1;

[0034] The partial discharge weight of LP11b mode at time t is as follows:

[0035]

[0036] in, is the partial discharge phase of LP11b mode at time t; It is the partial discharge phase of LP11b mode at time t-1.

[0037] Another aspect of the present invention discloses a cable partial discharge detection method based on a cable partial discharge detection system, comprising:

[0038] Wind the few-mode optical fiber around the power cable to be tested according to the set number of turns;

[0039] Based on the photon lantern and the set few-mode optical fiber, the multi-mode partial discharge detection of the cable is carried out to obtain the multi-mode partial discharge detection value;

[0040] The multi-mode partial discharge detection values ​​obtained by the multi-mode partial discharge detection module are weighted and integrated to obtain the final cable partial discharge detection data;

[0041] The final cable partial discharge detection data is input into the set partial discharge criterion to determine whether partial discharge occurs at the current monitoring point.

[0042] On the other hand, the present application discloses an electronic device, including a processor and a storage medium; the characteristics are:

[0043] The storage medium is used to store instructions;

[0044] The processor is used to operate according to the instructions to execute the above-mentioned cable partial discharge detection method.

[0045] The present application also discloses a computer-readable storage medium on which a computer program is stored, wherein the program implements the cable partial discharge detection method when executed by a processor.

[0046] The beneficial effects of the present invention are as follows:

[0047] Few-mode fiber is a fiber that supports a few modes of transmission. Compared with multimode fiber, it can effectively reduce interference between modes. Photon lanterns can convert multiple modes in few-mode fiber into a single mode in multiple single-mode fibers, improve signal quality, and reduce the impact of coherent fading on detection results by fusing signals of different modes. The use of few-mode fiber and photon lanterns can significantly reduce the impact of coherent fading, thereby improving the measurement accuracy of phase-sensitive optical time domain reflectometers.

[0048] The invention also has outstanding advantages such as strong practicability and wide application range. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 Schematic diagram of the detection principle based on photon lanterns and few-mode optical fibers. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in this application are only part of the embodiments of the present invention, not all of them. Based on the spirit of the present invention, other embodiments obtained by ordinary technicians in this field without creative work are all within the scope of protection of the present invention.

[0051] The present application discloses a cable partial discharge detection system based on photon lanterns and few-mode optical fibers, including a few-mode optical fiber setting module, a multi-mode partial discharge detection module, a signal fusion module and a partial discharge discrimination module;

[0052] The few-mode fiber setting module is to wind the few-mode fiber around the power cable to be tested according to a set number of turns; in a preferred embodiment of the present invention, the few-mode fiber is evenly wound around the power cable for 150 turns;

[0053] The multi-mode partial discharge detection module performs multi-mode partial discharge detection on the cable based on the photon lantern and the set few-mode optical fiber to obtain a multi-mode partial discharge detection value;

[0054] Preferably, the multimode includes a fundamental mode LP01 mode, a high-order mode LP11a mode in a few-mode optical fiber, and a high-order mode LP11b mode in a few-mode optical fiber;

[0055] The multi-mode partial discharge detection module comprises a narrow linewidth coherent laser 1; the output end of the narrow linewidth coherent laser 1 is connected to the input end of a first optical coupler 2; the two output ends of the first optical coupler 2 are respectively connected to the first input end of an acousto-optic modulator 4 and the input end of a one-to-three coupler 13; the second input end of the acousto-optic modulator 4 is connected to a waveform generator 3, and the output end is connected to the input end of an erbium-doped fiber amplifier 5; the output end of the erbium-doped fiber amplifier 5 is connected to the input end of an optical bandpass filter 6; the output end of the optical bandpass filter 6 is connected to the input end of a one-to-three coupler 7; the three output ends of the one-to-three coupler 7 are respectively connected to the first ends of a first optical fiber circulator 9, a second optical fiber circulator 10 and a third optical fiber circulator 11; the first optical fiber circulator 9, the second optical fiber circulator 10 and the third optical fiber circulator 11 are respectively connected to the first ends of the first optical fiber circulator 9, the second optical fiber circulator 10 and the third optical fiber circulator 11. The second end of the device 11 is respectively connected to the first end, the second end and the third end of the photon lantern 8; the fourth end and the fifth end of the photon lantern 8 are respectively connected to the input end and the output end of the few-mode optical fiber 12; the third end of the first optical fiber circulator 9 is connected to the second input end of the first balanced photodetector 14; the third end of the second optical fiber circulator 10 is connected to the second input end of the second balanced photodetector 15; the third end of the third optical fiber circulator 11 is connected to the second input end of the third balanced photodetector 16; the three output ends of the one-to-three coupler 13 are respectively connected to the first input ends of the balanced photodetector 14, the balanced photodetector 15 and the balanced photodetector 16; the output ends of the balanced photodetector 14, the balanced photodetector 15 and the balanced photodetector 16 are all connected to the data acquisition card 17.

[0056] The narrow linewidth coherent laser 1 emits a laser of 1550 nm;

[0057] The first optical coupler 2 receives the laser light emitted by the narrow linewidth coherent laser 1, and divides the laser light into signal light and local oscillator light; transmits the signal light to the acousto-optic modulator 4, and transmits the local oscillator light to the one-to-three coupler 13;

[0058] Preferably, the first optical coupler can be a 90:10 optical coupler; in a preferred embodiment of the present invention, the 90:10 optical coupler 2 receives the laser light emitted by the narrow linewidth coherent laser 1, and its output light is divided into two branches through the 90:10 optical coupler 2, namely, signal light and local oscillator light. The proportion of light obtained by the signal light is 90% of the power of the laser light emitted by the laser 1, and the proportion of light obtained by the local oscillator light is 10% of the power of the laser light emitted by the laser 1;

[0059] The waveform generator 3 outputs a waveform for modulating the signal light to the acousto-optic modulator 4;

[0060] The acousto-optic modulator 4 modulates the received signal light with the waveform output by the waveform generator 3 to generate a detection pulse;

[0061] The erbium-doped fiber amplifier 5 receives the detection pulse generated by the acousto-optic modulator 4 and amplifies it;

[0062] The optical bandpass filter 6 performs bandpass filtering on the signal amplified by the erbium-doped fiber amplifier 5;

[0063] Those skilled in the art should know how to set a bandpass filter to filter out noise signals and retain the amplified detection pulse signal;

[0064] The one-to-three coupler 7 divides the pulse filtered by the optical bandpass filter 6 into a first branch pulse, a second branch pulse and a third branch pulse, a total of three branch pulses;

[0065] Those skilled in the art should know that the one-to-three coupler 7 can be used to enable different spatial modes. In the preferred embodiment of the present invention, the spatial modes of the three optical fiber branches are respectively the fundamental mode LP01 mode in the optical fiber, the high-order mode LP11a mode in the few-mode optical fiber, and the high-order mode LP11b mode in the few-mode optical fiber. That is, the spatial modes of the three branch pulses are respectively the LP01 mode, the LP11a mode, and the LP11b mode;

[0066] The first ends of the first optical fiber circulator 9, the second optical fiber circulator 10 and the third optical fiber circulator 11 receive the first branch pulse, the second branch pulse and the third branch pulse respectively;

[0067] The second ends of the first optical fiber circulator 9, the second optical fiber circulator 10 and the third optical fiber circulator 11 respectively output the branch pulses received at the first ends to the first end, the second end and the third end of the photon lantern 8, and respectively receive the signals outputted from the first end, the second end and the third end of the photon lantern 8;

[0068] The third ends of the first optical fiber circulator 9, the second optical fiber circulator 10 and the third optical fiber circulator 11 output the signals received at the second ends to the first balanced photodetector 14, the second balanced photodetector 15 and the third balanced photodetector 16 respectively;

[0069] The first end, the second end, and the third end of the photon lantern 8 respectively receive the first branch pulse, the second branch pulse, and the third branch pulse emitted by the second ends of the first optical fiber circulator 9, the second optical fiber circulator 10, and the third optical fiber circulator 11, convert the branch pulses of the three modes into multiple modes of the few-mode optical fiber, and transmit them from the fourth end of the photon lantern 8 to the input end of the few-mode optical fiber; the fifth end of the photon lantern 8 receives the signal output by the few-mode optical fiber with the local discharge detection information of the cable at the detected position, and converts the multiple modes of the few-mode optical fiber into single modes of three single-mode optical fibers, and outputs the obtained three signals from the first end, the second end, and the third end respectively;

[0070] The few-mode optical fiber 12 receives the output signal of the fourth end of the photon lantern 8, is used to sense the partial discharge signal of the power cable at the winding position, and outputs a signal with the partial discharge detection information of the cable at the detected position to the fifth end of the photon lantern 8. The photon lantern multiplexes / demultiplexes the three modes of light to ensure good mode conversion between the single-mode optical fiber and the few-mode optical fiber.

[0071] The one-to-three coupler 13 divides the local oscillator light into a first branch local oscillator light, a second branch local oscillator light and a third branch local oscillator light; the output optical signal Rayleigh backscattered light of the third end of the first optical fiber circulator 9, the second optical fiber circulator 10 and the third optical fiber circulator 11 will be mixed with the first branch local oscillator light, the second branch local oscillator light and the third branch local oscillator light respectively.

[0072] The first balanced photodetector 14 performs photoelectric conversion on a mixed signal of the first branch local oscillator light and the Rayleigh backscattered light of the output optical signal of the third end of the first optical fiber circulator 9 to obtain an LP01 mode partial discharge signal;

[0073] The balanced photodetector 15 performs photoelectric conversion on the mixed signal of the second branch local oscillator light and the Rayleigh backscattered light of the third end output optical signal of the second optical fiber circulator 10 to obtain the LP11a mode partial discharge signal;

[0074] The balanced photodetector 16 performs photoelectric conversion on the mixed signal of the third branch local oscillator light and the Rayleigh backscattered light of the third end output optical signal of the third optical fiber circulator 11 to obtain the LP11b mode partial discharge signal;

[0075] Among them, the LP01 mode partial discharge signal, the LP11a mode partial discharge signal, and the LP11b mode partial discharge signal are all electrical signals.

[0076] The data acquisition card 17 respectively collects the output signals of the first balanced photodetector 14, the second balanced photodetector 15 and the third balanced photodetector 16 to obtain the sampling values ​​of the local discharge in the LP01 mode, the LP11a mode and the LP11b mode.

[0077] The pulses are respectively transmitted to the three ports of the photon lantern after passing through the optical fiber circulator 9, the optical fiber circulator 10, and the optical fiber circulator 11, and then enter the few-mode optical fiber 12. The few-mode optical fiber is evenly wound around the power cable for 150 turns to sense the partial discharge signal of the power cable. The light proportion of the second branch is 10%, which is used as the local oscillator light and is divided into three branches by the one-to-three coupler 13.

[0078] Since the OTDR waveforms of the three modes, namely the fundamental mode LP01 mode, the high-order mode LP11a mode in the optical fiber, and the high-order mode LP11b mode in the optical fiber, are different and independent; and the fading positions are different in space, the fading probability on the optical fiber length and time scale can be effectively reduced by fusing the signals of the three modes. Preferably, the three modes have the same functions;

[0079] The signal fusion module performs weighted fusion on the multi-mode partial discharge detection values ​​obtained by the multi-mode partial discharge detection module to obtain final cable partial discharge detection data;

[0080] The partial discharge detection signals in the three modes measured by the data acquisition card 17 are fused to obtain the final cable partial discharge detection data to reduce the fading probability.

[0081] The multi-mode partial discharge detection values ​​obtained by the multi-mode partial discharge detection module are weighted and fused to obtain the final cable partial discharge detection data as shown in the following formula:

[0082] S(t)=w 01 (t)S 01 (t)+w 11a (t)S 11a (t)+w 11b (t)S 11b (t);

[0083] Where S(t) is the final cable partial discharge detection value at time t; w 01 (t) is the partial discharge weight of LP01 mode at time t; S 01 (t) is the partial discharge detection value of LP01 mode at time t; w 11a (t) is the partial discharge weight of LP11a mode at time t; S 11a (t) is the partial discharge detection value of LP11a mode at time t; w 11b (t) is the partial discharge weight of LP11b mode at time t; S 11b (t) is the partial discharge detection value of LP11b mode at time t.

[0084] The partial discharge weight of LP01 mode at time t is as follows:

[0085]

[0086] Among them, max[·] means to find the maximum value in the brackets; min[·] means to find the minimum value in the brackets; is the partial discharge phase of LP01 mode at time t; is the partial discharge phase of LP01 mode at time t-1; δ is the phase correlation coefficient, and its preferred value range is 1 to 2.3; t represents the tth sampling point; NZ is the total number of sampling points of multi-mode partial discharge; e is the natural base; λ 1 is the first weight correlation coefficient, and its preferred value range is 2.8δ~3.2δ; λ 2 is the second weight correlation coefficient, and its preferred value range is 0.55-0.7; wherein the total number of sampling points of multi-mode partial discharge = the total number of sampling points of the data acquisition card 17 collecting LP01 mode partial discharge signals = the total number of sampling points of the data acquisition card 17 collecting LP11a mode partial discharge signals = the total number of sampling points of the data acquisition card 17 collecting LP11b mode partial discharge signals;

[0087] The partial discharge weight of LP11a mode at time t is as follows:

[0088]

[0089] in, is the partial discharge phase of LP11a mode at time t; is the partial discharge phase of LP11a mode at time t-1;

[0090] The partial discharge weight of LP11b mode at time t is as follows:

[0091]

[0092] in, is the partial discharge phase of LP11b mode at time t; It is the partial discharge phase of LP11b mode at time t-1.

[0093] The amplitude and phase information of the cable partial discharge detection data are calculated by the following method.

[0094]

[0095] Where t represents the serial number of the sampling point, i.e. the tth sampling point; Y I (t) is the same direction signal of the final cable partial discharge detection data at time t; Y Q (t) is the orthogonal signal of the final cable partial discharge detection data at time t; E s (t) represents the light field intensity of the information light; E o (t) represents the light field intensity of the local oscillator light; It represents the phase of the final cable partial discharge detection data, which is also the phase of the external disturbance information; S(t) is the final cable partial discharge detection value at time t; Indicates same frequency information; Represents orthogonal information;

[0096] represents the sum frequency term in the same frequency information, It indicates the component of external disturbance information contained in the same frequency information. represents the sum-frequency term in the orthogonal information, It indicates the component of external disturbance information contained in the orthogonal information. The calculation formula is as follows:

[0097] Δω t =2πΔf / f s ;

[0098] Among them, f s represents the sampling rate of the data acquisition card 17, Δf represents the frequency of the waveform for modulating the signal emitted by the waveform generator 3,

[0099] After orthogonal demodulation, the sum frequency terms of the same direction and orthogonal information are obtained and The low-pass filter is used to filter out the double frequency and obtain the information containing external disturbance.

[0100] The result Y of the low-pass filtering of the same-direction signal of the final cable partial discharge detection data at time t I '(t), the orthogonal signal low-pass filtering result of the final cable partial discharge detection data at time t Y Q '(t) and and The relationship is as follows:

[0101]

[0102]

[0103] According to the low-pass filtering, Y' I and Y' Q , the amplitude information of the final cable partial discharge detection data is as follows:

[0104]

[0105] According to the amplitude information, the sampling point number at the vibration point at the amplitude peak is obtained. The sampling point number is multiplied by the sampling interval time and the speed of light, and then divided by the fiber refractive index. The calculated result is divided by 2, which is the distance between the vibration point and the transmitting end.

[0106] The partial discharge determination module inputs the final cable partial discharge detection data into a set partial discharge determination criterion to determine whether partial discharge occurs at the current monitoring point.

[0107] Those skilled in the art should know how to set the partial discharge criterion. Those skilled in the art can set the criterion according to the actual situation. In order to improve the calculation accuracy, the criterion setting proposed in the embodiment of the present invention is only a preferred embodiment, and is not an inevitable limitation for implementing the cable partial discharge detection system and method based on photon lanterns and few-mode optical fibers of the present invention. According to the final cable partial discharge detection data, the specific criterion setting is as follows:

[0108]

[0109] Among them, t 0 represents the sampling time; S(t 0 ) means t 0 Final cable partial discharge detection value at the moment; Y' is the discharge judgment gain coefficient, and its preferred value range is 0.13 to 1.54; I (t) is the result of low-pass filtering of the same-direction signal of the final cable partial discharge detection data at time t; Y' Q (t) is the orthogonal signal low-pass filtering result of the final cable partial discharge detection data at time t; Y' I (t-1) is the result of low-pass filtering of the same-direction signal of the final cable partial discharge detection data at time t-1; Y' Q (t-1) is the orthogonal signal low-pass filtering result of the final cable partial discharge detection data at time t-1; where, when time t is the first sampling time, set Y' I (t-1) = Y' I (t); Y' Q (t-1) = Y' Q (t);

[0110] If the partial discharge criterion is met at time t, it is determined that no partial discharge occurs at time t; otherwise, it is determined that partial discharge occurs at time t.

[0111] The present application also discloses a cable partial discharge detection method based on a cable partial discharge detection system, which is characterized by comprising:

[0112] Wind the few-mode optical fiber around the power cable to be tested according to the set number of turns;

[0113] Based on the photon lantern and the set few-mode optical fiber, the multi-mode partial discharge detection of the cable is carried out to obtain the multi-mode partial discharge detection value;

[0114] The multi-mode partial discharge detection values ​​obtained by the multi-mode partial discharge detection module are weighted and integrated to obtain the final cable partial discharge detection data;

[0115] The final cable partial discharge detection data is input into the set partial discharge criterion to determine whether partial discharge occurs at the current monitoring point.

[0116] The present disclosure may be a system, a method and / or a computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0117] A computer-readable storage medium may be a tangible device that can hold and store instructions used by an instruction execution device. A computer-readable storage medium may be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples of computer-readable storage media (a non-exhaustive list) include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disk read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanical encoding device, such as a punch card or a raised structure in a groove on which instructions are stored, and any suitable combination of the foregoing. As used herein, a computer-readable storage medium is not to be interpreted as a transient signal per se, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., a light pulse through a fiber optic cable), or an electrical signal transmitted through a wire.

[0118] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to each computing / processing device, or downloaded to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network can include copper transmission cables, optical fiber transmissions, wireless transmissions, routers, firewalls, switches, gateway computers, and / or edge servers. The network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions for storage in the computer-readable storage medium in each computing / processing device.

[0119] The computer program instructions for performing the operation of the present disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-related instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages, such as Smalltalk, C++, etc., and conventional procedural programming languages, such as "C" language or similar programming languages. Computer-readable program instructions may be executed completely on a user's computer, partially on a user's computer, as an independent software package, partially on a user's computer, partially on a remote computer, or completely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., using an Internet service provider to connect via the Internet). In some embodiments, an electronic circuit, such as a programmable logic circuit, a field programmable gate array (FPGA), or a programmable logic array (PLA), may be customized by utilizing the state information of the computer-readable program instructions, and the electronic circuit may execute the computer-readable program instructions, thereby realizing various aspects of the present disclosure.

[0120] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A cable partial discharge detection system based on photon lanterns and few-mode optical fibers, characterized in that: It includes a few-mode fiber setting module, a multi-mode partial discharge detection module, a signal fusion module and a partial discharge discrimination module; The few-mode optical fiber setting module is used to wind the few-mode optical fiber around the power cable to be detected according to a set number of turns; The multi-mode partial discharge detection module performs multi-mode partial discharge detection on the cable based on the photon lantern and the set few-mode optical fiber to obtain a multi-mode partial discharge detection value; The signal fusion module performs weighted fusion on the multi-mode partial discharge detection values ​​obtained by the multi-mode partial discharge detection module to obtain final cable partial discharge detection data; The partial discharge determination module inputs the final cable partial discharge detection data into a set partial discharge determination criterion to determine whether partial discharge occurs at the current monitoring point.

2. The cable partial discharge detection system according to claim 1, characterized in that: In the multi-mode partial discharge detection module, the multi-modes include a fundamental mode LP01 mode, a high-order mode LP11a mode in the few-mode optical fiber, and a high-order mode LP11b mode in the few-mode optical fiber.

3. The cable partial discharge detection system according to claim 1, characterized in that: The multi-mode partial discharge detection module comprises a narrow linewidth coherent laser (1); the output end of the narrow linewidth coherent laser (1) is connected to the input end of a first optical coupler (2); the two output ends of the first optical coupler (2) are respectively connected to the first input end of an acousto-optic modulator (4) and the input end of a one-to-three coupler (13); the second input end of the acousto-optic modulator (4) is connected to a waveform generator (3), and the output end is connected to the input end of an erbium-doped fiber amplifier (5); the output end of the erbium-doped fiber amplifier (5) is connected to the input end of an optical bandpass filter (6); the output end of the optical bandpass filter (6) is connected to the input end of a one-to-three coupler (7); the three output ends of the one-to-three coupler (7) are respectively connected to the first ends of a first optical fiber circulator (9), a second optical fiber circulator (10) and a third optical fiber circulator (11); the first optical fiber circulator (9), the second optical fiber circulator (10) and the third optical fiber circulator The second end of the optical fiber circulator (11) is respectively connected to the first end, the second end and the third end of the photon lantern (8); the fourth end and the fifth end of the photon lantern (8) are respectively connected to the input end and the output end of the few-mode optical fiber (12); the third end of the first optical fiber circulator (9) is connected to the second input end of the first balanced photodetector (14); the third end of the second optical fiber circulator (10) is connected to the second input end of the second balanced photodetector (15); the third end of the third optical fiber circulator (11) is connected to the second input end of the third balanced photodetector (16); the three output ends of the one-to-three coupler (13) are respectively connected to the first input ends of the balanced photodetector (14), the balanced photodetector (15) and the balanced photodetector (16); the output ends of the balanced photodetector (14), the balanced photodetector (15) and the balanced photodetector (16) are all connected to a data acquisition card (17).

4. The cable partial discharge detection system according to claim 3, characterized in that: The one-to-three coupler (7) divides the pulse filtered by the optical bandpass filter (6) into a first branch pulse, a second branch pulse and a third branch pulse, a total of three branch pulses; the spatial modes of the three branch pulses are LP01 mode, LP11a mode and LP11b mode respectively.

5. The cable partial discharge detection system according to claim 4, characterized in that: The first end, the second end and the third end of the photon lantern (8) respectively receive the first branch pulse, the second branch pulse and the third branch pulse emitted by the second end of the first optical fiber circulator (9), the second optical fiber circulator (10) and the third optical fiber circulator (11), convert the three modes corresponding to the branch pulses of the three modes into multiple modes of the few-mode optical fiber, and transmit them from the fourth end of the photon lantern (8) to the input end of the few-mode optical fiber; The fifth end of the photon lantern (8) receives the output signal of the few-mode optical fiber, converts the multiple modes of the few-mode optical fiber into the single modes of three single-mode optical fibers, and outputs the obtained three signals from the first end, the second end, and the third end respectively.

6. The cable partial discharge detection system according to claim 5, characterized in that: The few-mode optical fiber (12) receives the output signal of the fourth end of the photon lantern (8), is used to sense the local discharge signal of the power cable at the winding position, and outputs a signal with the local discharge detection information of the cable at the detected position to the fifth end of the photon lantern (8).

7. The cable partial discharge detection system according to claim 1 or 2, characterized in that: In the signal fusion module, the multi-mode partial discharge detection values ​​obtained by the multi-mode partial discharge detection module are weighted and fused to obtain the final cable partial discharge detection data as shown in the following formula: S(t)=w 01 (t)S 01 (t)+w 11a (t)S 11a (t)+w 11b (t)S 11b (t); Where S(t) is the final cable partial discharge detection value at time t; w 01 (t) is the partial discharge weight of LP01 mode at time t; S 01 (t) is the partial discharge detection value of LP01 mode at time t; w 11a (t) is the partial discharge weight of LP11a mode at time t; S 11a (t) is the partial discharge detection value of LP11a mode at time t; w 11b (t) is the partial discharge weight of LP11b mode at time t; S 11b (t) is the partial discharge detection value of LP11b mode at time t.

8. The cable partial discharge detection system according to claim 7, characterized in that: The partial discharge weight of LP01 mode at time t is as follows: Among them, max[·] means to find the maximum value in the brackets; min[·] means to find the minimum value in the brackets; is the partial discharge phase of LP01 mode at time t; is the partial discharge phase of LP01 mode at time t-1; δ is the phase correlation coefficient; t represents the tth sampling point; N Z is the total number of sampling points of multi-mode partial discharge; e is the natural base; λ1 is the first weight correlation coefficient; λ2 is the second weight correlation coefficient; The partial discharge weight of LP11a mode at time t is as follows: in, is the partial discharge phase of LP11a mode at time t; is the partial discharge phase of LP11a mode at time t-1; The partial discharge weight of LP11b mode at time t is as follows: in, is the partial discharge phase of LP11b mode at time t; It is the partial discharge phase of LP11b mode at time t-1.

9. A cable partial discharge detection method using the cable partial discharge detection system according to any one of claims 1 to 8, characterized in that: include: Wind the few-mode optical fiber around the power cable to be tested according to the set number of turns; Based on the photon lantern and the set few-mode optical fiber, the multi-mode partial discharge detection of the cable is carried out to obtain the multi-mode partial discharge detection value; The multi-mode partial discharge detection values ​​obtained by the multi-mode partial discharge detection module are weighted and integrated to obtain the final cable partial discharge detection data; The final cable partial discharge detection data is input into the set partial discharge criterion to determine whether partial discharge occurs at the current monitoring point.

10. An electronic device, comprising a processor and a storage medium; characterized in that: The storage medium is used to store instructions; The processor is configured to operate according to the instructions to execute the cable partial discharge detection method according to claim 9.

11. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the cable partial discharge detection method according to claim 10 is implemented.

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