Cable state multi-parameter distributed detection method and system based on multi-core optical fiber

Abstract

The invention discloses a cable state multi-parameter distributed detection method and system based on a multi-core optical fiber, and the method comprises the steps: placing the multi-core optical fiber in a power cable, collecting the cable state related data in each fiber core, carrying out the fusion of the collected cable state related data, carrying out the preprocessing, and carrying out the detection of the cable state. The method comprises the steps of preprocessing cable state related data to obtain preprocessed cable state related data, constructing a cable state multi-factor composite criterion for cable state judgment based on the preprocessed cable state related data, and substituting the preprocessed data into the cable state multi-factor composite criterion in real time to obtain a cable state judgment result. The method has the outstanding advantages of high comprehensiveness, high practicability, high reliability and the like.

Description

Technical Field

[0001] The present invention relates to the field of power cable detection, and in particular to a method and system for multi-parameter distributed detection of power cable status based on built-in multi-core optical fiber. Background Art

[0002] Power cables are an important part of the power system, and the operating status of power cables is directly related to the stability and safety of the power system. With the continuous increase in power grid load and the complexity of the cable laying environment, the demand for power cable status monitoring is becoming more and more urgent. Traditional monitoring methods are susceptible to electromagnetic interference and have poor reliability in complex environments. Although the single-core optical fiber monitoring method has the advantages of high precision and anti-electromagnetic interference, its number of monitoring channels is limited and cannot meet the needs of large-scale, long-distance, and multi-parameter monitoring. Multi-core optical fiber contains multiple cores, each of which serves as an independent transmission or sensing channel. The multi-channel characteristics of multi-core optical fiber give it unique advantages in large-scale, long-distance, and multi-parameter monitoring scenarios. Multi-core optical fiber can simultaneously monitor multiple physical parameters such as temperature, strain, and vibration, providing comprehensive monitoring information for cable status. Multi-core optical fiber can be built into the cable to realize distributed multi-parameter optical fiber detection.

[0003] CN112798051A discloses an external cable state monitoring system and method based on fiber grating sensing technology, which uses optical signals of various states of the cable sensed by the fiber grating sensor; demodulates the optical signals of various states sensed to obtain monitoring parameters of various states; the monitoring parameters include: cable joint temperature value, interlayer current value, cable operating current value, intrusion vibration waveform, environmental monitoring value and structural monitoring value; compares the monitoring parameters of each state with the preset alarm threshold of the corresponding state one by one; if any state parameter exceeds the corresponding alarm threshold; an alarm is issued, and the linkage mechanism is controlled to move using full fiber grating sensing technology. This patent belongs to external detection, and the patent compares the monitoring parameters of each state with the preset alarm threshold of the corresponding state one by one to determine the cable state, which makes the cable state judgment of the invention less comprehensive and less practical. Summary of the invention

[0004] In order to solve the shortcomings of poor comprehensiveness and weak practicality in the prior art, the present invention provides a multi-parameter distributed detection method and system for cable status based on multi-core optical fiber.

[0005] The present invention adopts the following technical solution.

[0006] The present invention discloses a multi-parameter distributed detection method of cable status based on multi-core optical fiber, comprising:

[0007] Place multi-core optical fibers in power cables and collect data related to the cable status in each fiber core;

[0008] The collected data related to the cable status are integrated and then preprocessed to obtain the preprocessed data related to the cable status;

[0009] Based on the pre-processed cable status related data, a cable status multi-factor composite criterion for cable status judgment is constructed;

[0010] The pre-processed data is substituted into the multi-factor composite judgment criteria of the cable status in real time to obtain the cable status judgment result.

[0011] More preferably,

[0012] The cable status related data include temperature, strain, vibration and partial discharge of each fiber core.

[0013] More preferably,

[0014] The multi-core optical fiber is a seven-core optical fiber. Figure 4 , including a central fiber core 28, a first azimuth fiber core 29, a second azimuth fiber core 30, a third azimuth fiber core 31, a fourth azimuth fiber core 32, a fifth azimuth fiber core 33 and a sixth azimuth fiber core 34 arranged around the central fiber core 28;

[0015] The first azimuth fiber core 29, the third azimuth fiber core 31 and the fifth azimuth fiber core 33 are sequentially connected as a first sensing optical fiber; the first sensing optical fiber collects temperature and strain from three azimuths of the seven-core optical fiber based on the BOTDR system;

[0016] The central fiber core 28, the second azimuth fiber core 30, the fourth azimuth fiber core 32 and the sixth azimuth fiber core 34 are sequentially connected as a second sensing optical fiber; the second sensing optical fiber is based on The system collects vibration and partial discharge from three positions and the center point of the multi-core optical fiber.

[0017] More preferably,

[0018] The data collected from each fiber core are fused, including the fusion of the temperature data of each fiber core, the fusion of the strain data of each fiber core, the fusion of the vibration data of each fiber core, and the fusion of the partial discharge data of each fiber core.

[0019] More preferably,

[0020] Among them, the method for fusing the strain data of each fiber core is:

[0021] Determine the maximum value S of the core strain at time t max (t);

[0022] The core corresponding to the maximum value of the core strain at time t is recorded as the first core at time t; any core other than the first core at time t among the first orientation core 29, the third orientation core 31 and the fifth orientation core 33 is recorded as the second core at time t;

[0023] The core axial position corresponding to the maximum value of the core strain at time t is taken as the strain axial position at time t, and a coordinate axis is established along the radial direction of the seven-core optical fiber at the strain axial position at time t;

[0024] The strain data is fused according to the following formula to obtain the fused strain data S0(t) at time t;

[0025]

[0026] Among them, S max (t) is the maximum value of the core strain at time t; θ1(t) is the angle between the stress direction corresponding to the maximum value of the strain in the first core at time t and the x-axis; e is the natural base; θ2(t) is the angle between the stress direction corresponding to the maximum value of the strain in the second core at time t and the x-axis; S2(t) is the maximum value of the strain in the second core;

[0027] The specific position where the cable generates strain at time t is determined based on the axial position of the strain at time t, the angle between the stress direction corresponding to the maximum strain in the first fiber core at time t and the x-axis, and the angle between the stress direction corresponding to the maximum strain in the second fiber core at time t and the x-axis.

[0028] More preferably,

[0029] The fusion of the vibration data of each fiber core is shown in the following formula:

[0030] V0(t)=w max V max (t)+w mid V mid (t)+w min V min (t);

[0031] Where V0(t) is the fused vibration data at time t; w max is the weight of the maximum value of cable vibration; V max (t) is the maximum value of cable vibration at time t; w mid V is the vibration weight of the central fiber core 28; mid (t) is the maximum vibration value of the central core 28 at time t; w min is the weight of the minimum cable vibration; V min (t) is the minimum value of cable vibration at time t;

[0032] Based on the radial direction of the core corresponding to the maximum cable vibration at time t in the seven-core optical fiber and the axial position of the maximum cable vibration at time t, the specific position where the cable vibration occurs at time t is determined.

[0033] More preferably,

[0034] Among them, the fusion of the partial discharge data of each fiber core is shown in the following formula:

[0035]

[0036] Among them, P0(t) is the fused partial discharge data at time t; is the maximum weight coefficient of cable partial discharge; P max (t) is the maximum value of cable partial discharge at time t; is the local discharge weight coefficient of the central fiber core 28; mid (t) is the maximum value of the local discharge of the central core 28 at time t;

[0037] Based on the radial direction of the core corresponding to the maximum value of the cable partial discharge at time t in the seven-core optical fiber and the axial position of the maximum value of the cable partial discharge at time t, the specific position where the cable partial discharge occurs at time t is determined.

[0038] More preferably,

[0039] The cable status multi-factor composite criterion C 1c (t) is shown in the following formula:

[0040]

[0041] Among them, ε is the state judgment gain coefficient; T'0(t) is the cable temperature data after preprocessing at time t; T'0(t-1) is the cable temperature data after preprocessing at time t-1; S'0(t) is the strain data after preprocessing at time t; S'0(t-1) is the strain data after preprocessing at time t-1; W v is the cable vibration data weight; V0'(t) is the pre-processed cable vibration data at time t; P0(t) is the fused partial discharge data at time t; τ is the upper limit determination coefficient of partial discharge; P e is the rated voltage of the cable;

[0042] When C 1c When (t) < 0.15, the cable is judged to be in excellent condition;

[0043] When 0.15≤C 1c When (t) < 0.6, the cable is judged to be in good condition;

[0044] When 0.6≤C 1c (t), the cable status is judged to be poor.

[0045] More preferably,

[0046] When the cable is judged to be in excellent condition, regular maintenance is sufficient;

[0047] When the cable is judged to be in good condition, the maintenance frequency needs to be increased;

[0048] When it is determined that the cable is in poor condition, the specific location of the poor cable condition is determined and repairs are performed.

[0049] On the other hand, the present invention discloses a cable state multi-parameter distributed detection method based on multi-core optical fiber, a cable state multi-parameter distributed detection system, including a data acquisition module, a data fusion module, a cable state judgment criterion construction module and a cable state judgment module:

[0050] The data acquisition module places a multi-core optical fiber in the power cable to collect data related to the cable status in each fiber core;

[0051] The data fusion module fuses the collected cable status related data, and then performs preprocessing to obtain the preprocessed cable status related data;

[0052] The cable status judgment criterion construction module constructs a cable status multi-factor composite criterion for judging the cable status based on the pre-processed cable status related data;

[0053] The cable status judgment module substitutes the pre-processed data into the cable status multi-factor composite judgment criterion in real time to obtain the cable status judgment result.

[0054] The beneficial effects of the present invention are as follows:

[0055] The present invention uses one optical fiber to cover the detection functions of multiple optical fibers, which is convenient for being built into power cables, providing favorable conditions for multi-parameter fusion sensing of built-in optical fiber power cables. The Brillouin optical time domain reflectometer (BOTDR) is used to detect temperature and strain, and the phase-sensitive optical time domain reflectometer is used to detect temperature and strain. To detect vibration and partial discharge, multiple parameters and detection methods can be integrated into one multi-core optical fiber, thus improving the multiplexing capability of the optical fiber built into the power cable.

[0056] The present invention fuses the data of each core in a multi-core optical fiber according to a set method, thereby improving the reliability of cable status judgment;

[0057] The present invention constructs a cable state multi-factor composite criterion for judging the cable state based on the pre-processed cable state related data, and judges the cable state by combining the data of each fiber core, so that the present invention has high reliability and strong comprehensiveness;

[0058] The present invention can determine the specific position causing the poor cable state when the cable state is poor, so the present invention has strong practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 It is a flow chart of a multi-parameter distributed detection method of cable status based on multi-core optical fiber of the present invention;

[0060] Figure 2 This is a schematic diagram of the BOTDR principle;

[0061] Figure 3 yes Schematic diagram of the principle;

[0062] Figure 4 This is a schematic diagram of the internal structure of a seven-core optical fiber. DETAILED DESCRIPTION

[0063] 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.

[0064] This application discloses a multi-parameter distributed detection method for cable status based on multi-core optical fiber, see the attached Figure 1 ,include:

[0065] Place multi-core optical fibers in power cables and collect data related to the cable status in each fiber core;

[0066] The cable status related data include temperature, strain, vibration and partial discharge of each fiber core.

[0067] The multi-core optical fiber is a seven-core optical fiber. Figure 4 , including a central fiber core 28, a first azimuth fiber core 29, a second azimuth fiber core 30, a third azimuth fiber core 31, a fourth azimuth fiber core 32, a fifth azimuth fiber core 33 and a sixth azimuth fiber core 34 arranged around the central fiber core 28;

[0068] The first azimuth fiber core 29, the third azimuth fiber core 31 and the fifth azimuth fiber core 33 are sequentially connected as a first sensing optical fiber; the first sensing optical fiber collects temperature and strain from three azimuths of the seven-core optical fiber based on the BOTDR system;

[0069] The central fiber core 28, the second azimuth fiber core 30, the fourth azimuth fiber core 32 and the sixth azimuth fiber core 34 are sequentially connected as a second sensing optical fiber; the second sensing optical fiber is based on The system collects vibration and partial discharge from three positions and the center point of the multi-core optical fiber.

[0070] The collected data related to the cable status are integrated and then preprocessed to obtain the preprocessed data related to the cable status;

[0071] The data collected from each fiber core are fused, including the fusion of the temperature data of each fiber core, the fusion of the strain data of each fiber core, the fusion of the vibration data of each fiber core, and the fusion of the partial discharge data of each fiber core.

[0072] Among them, the method for fusing the strain data of each fiber core is:

[0073] Determine the maximum value S of the core strain at time t max (t);

[0074] The core corresponding to the maximum value of the core strain at time t is recorded as the first core at time t; any core other than the first core at time t among the first orientation core 29, the third orientation core 31 and the fifth orientation core 33 is recorded as the second core at time t;

[0075] The core axial position corresponding to the maximum value of the core strain at time t is taken as the strain axial position at time t, and a coordinate axis is established along the radial direction of the seven-core optical fiber at the strain axial position at time t; preferably, the center point is taken as the origin of the coordinate axis; preferably, the x-axis direction of the set coordinate axis is parallel to the line connecting the core corresponding to the maximum value of the strain and the center point of the multi-core optical fiber;

[0076] The strain data is fused according to the following formula to obtain the fused strain data S0(t) at time t;

[0077]

[0078] Among them, S max (t) is the maximum value of the core strain at time t; θ1(t) is the angle between the stress direction corresponding to the maximum value of the strain in the first core at time t and the x-axis; e is the natural base; θ2(t) is the angle between the stress direction corresponding to the maximum value of the strain in the second core at time t and the x-axis; S2(t) is the maximum value of the strain in the second core;

[0079] The specific position where the cable generates strain at time t is determined based on the axial position of the strain at time t, the angle between the stress direction corresponding to the maximum strain in the first fiber core at time t and the x-axis, and the angle between the stress direction corresponding to the maximum strain in the second fiber core at time t and the x-axis.

[0080] The fusion of the vibration data of each fiber core is shown in the following formula:

[0081] V0(t)=w maxV max (t)+w mid V mid (t)+w min V min (t);

[0082] Where V0(t) is the fused vibration data at time t; w max is the weight of the maximum value of cable vibration, and its preferred value range is 0.8~1; V max (t) is the maximum value of cable vibration at time t; w mid V is the vibration weight of the central fiber core 28, and its preferred value range is 0.3 to 0.5; mid (t) is the maximum vibration value of the central core 28 at time t; w min is the weight of the minimum value of cable vibration, and its preferred value range is 0.1~0.15; V min (t) is the minimum value of cable vibration at time t;

[0083] Among them, 1<w max +w mid +w min ≤1.5.

[0084] Based on the radial direction of the core corresponding to the maximum cable vibration at time t in the seven-core optical fiber and the axial position of the maximum cable vibration at time t, the specific position where the cable vibration occurs at time t is determined.

[0085] The fusion of partial discharge data of each fiber core is shown in the following formula:

[0086]

[0087] Among them, P0(t) is the fused partial discharge data at time t; is the maximum value weight coefficient of cable partial discharge, and its preferred value range is 1.01~1.5; max (t) is the maximum value of cable partial discharge at time t; is the partial discharge weight coefficient of the central core 28, and its preferred value range is 0.15 to 0.35; mid (t) is the maximum value of the local discharge of the central core 28 at time t;

[0088] Based on the radial direction of the core corresponding to the maximum value of the cable partial discharge at time t in the seven-core optical fiber and the axial position of the maximum value of the cable partial discharge at time t, the specific position where the cable partial discharge occurs at time t is determined.

[0089] Based on the pre-processed cable status related data, a cable status multi-factor composite criterion for cable status judgment is constructed;

[0090] When the cable condition is judged to be excellent based on the cable condition multi-factor composite criterion, regular maintenance is sufficient;

[0091] When the cable status is judged to be good based on the multi-factor composite criterion of the cable status, the maintenance frequency needs to be increased;

[0092] When the cable condition is judged to be poor based on the multi-factor composite criterion of the cable condition, the specific location of the poor cable condition is determined and repairs are carried out.

[0093] The pre-processed data is substituted into the multi-factor composite judgment criteria of the cable status in real time to obtain the cable status judgment result.

[0094] Example 1

[0095] A multi-parameter distributed detection method for cable status based on multi-core optical fiber.

[0096] Place multi-core optical fibers in power cables and collect data related to the cable status in each fiber core;

[0097] The cable status related data include temperature, strain, vibration and partial discharge of each fiber core.

[0098] The multi-core optical fiber adopts a seven-core optical fiber, see the attached Figure 4 , including a central fiber core 28, a first azimuth fiber core 29, a second azimuth fiber core 30, a third azimuth fiber core 31, a fourth azimuth fiber core 32, a fifth azimuth fiber core 33 and a sixth azimuth fiber core 34 arranged around the central fiber core 28;

[0099] The first azimuth fiber core 29, the third azimuth fiber core 31 and the fifth azimuth fiber core 33 are sequentially connected as the first sensing optical fiber. Figure 2 The sensing optical fiber 3 in the multi-core optical fiber is used to collect temperature and strain from three directions of the seven-core optical fiber based on the BOTDR system. The outer first direction fiber core 29, the third direction fiber core 31, and the fifth direction fiber core 33 can effectively sense the temperature and strain at three times the physical length of the multi-core optical fiber, sense the temperature and strain from three directions, and effectively determine the spatial direction of the temperature or strain according to the temperature or strain at different positions, effectively avoiding the spatial blind area and improving the perception ability of the BOTDR system. The determination method is as follows:

[0100] See attached Figure 2The structure of the BOTDR Brillouin optical time domain reflectometer system is as follows: a narrow linewidth laser 1 emits light of 1550nm wavelength, which is divided into two paths through a 90:10 coupler 2, with the ratio of the two paths being 90% and 10% respectively. The 90% path is used as a detection path to generate detection pulses entering the sensing optical fiber 3, and the 10% path is used as a reference path to generate reference light. The light entering the detection path is reduced in power to below the maximum incident power of the semiconductor optical amplifier 5 by an adjustable optical attenuator 4, and then enters the semiconductor optical amplifier 5 to modulate the pulse. The pulse peak power output by the semiconductor optical amplifier 5 is relatively low, and enters the pulse erbium-doped fiber amplifier 6 to be amplified to a certain power, and then the detection pulse with the spontaneous radiation noise filtered out by the fiber Bragg grating 7 enters the sensing optical fiber 3 through the fiber circulator 8. The Brillouin scattering signal generated in the sensing optical fiber 3 enters the erbium-doped fiber amplifier 9 through the output end of the fiber circulator 8, is amplified, and then filtered out by the fiber Bragg grating 10 to remove the spontaneous radiation noise, and enters the 50:50 coupler 11 to beat with the reference light. The light of the reference path changes its polarization state through the polarization scrambler 12, thereby eliminating the polarization fading noise caused by different polarization states. The photodetector 13 converts the optical signal into an electrical signal.

[0101] The electrical signal output by the photodetector 13 enters the low noise amplifier 14 for amplification, and then enters the mixer 15 to mix with the sinusoidal signal generated by the microwave local oscillator 16, thereby realizing down-conversion. The down-converted signal is frequency-selectively filtered by the bandpass filter 17 and the power information of the single-frequency signal is extracted by the detector 18. The output frequency of the microwave local oscillator 16 can be adjusted in steps to complete the frequency scanning of the Brillouin scattering signal to reconstruct the Brillouin scattering spectrum. By extracting the center frequency of the Brillouin scattering spectrum along the sensing optical fiber 3, the temperature and strain information at different positions of the sensing optical fiber 3 can be demodulated.

[0102] The central fiber core 28, the second azimuth fiber core 30, the fourth azimuth fiber core 32 and the sixth azimuth fiber core 34 are sequentially connected as the second sensing optical fiber. Figure 3 The sensing optical fiber 25 in the embodiment of the present invention; the second sensing optical fiber is based on The system collects vibration and partial discharge from three positions and the center point of the multi-core optical fiber.

[0103] The central fiber core 28, the second azimuth fiber core 30, the fourth azimuth fiber core 32, and the sixth azimuth fiber core 34 of the OTDR system can achieve four times the effective perception over the physical length of the multi-core optical fiber. The central fiber core 28 can measure the vibration at the center of the optical fiber, and the second azimuth fiber core 30, the fourth azimuth fiber core 32, and the sixth azimuth fiber core 34 can locate the vibration experienced by the optical fiber.

[0104] See attached Figure 3 , The structure of the phase-sensitive optical time domain reflectometer system is as follows: the laser 20 is divided into two branches through a 90:10 coupler 21. The branch with a ratio of 90 passes through an acousto-optic modulator 22 and an erbium-doped fiber amplifier 23, and then enters the optical fiber circulator 24. The return end of the circulator 24 enters the 2×2 coupler 26 together with the branch with a ratio of 10, and then enters the balanced photodetector 27.

[0105] The collected data related to the cable status are integrated and then preprocessed to obtain the preprocessed data related to the cable status;

[0106] The data collected from each fiber core are fused, including the fusion of the temperature data of each fiber core, the fusion of the strain data of each fiber core, the fusion of the vibration data of each fiber core, and the fusion of the partial discharge data of each fiber core.

[0107] The fusion of each fiber core temperature data is shown in the following formula:

[0108] T max (t) = max(T 29 (t),T 31 (t),T 33 (t));

[0109] Among them, T 29 (t) is the maximum temperature of the fiber core 29 at sampling time t, T 31 (t) is the maximum temperature of the core 31 at time t, T 33 (t) is the maximum temperature of the core 33 at time t, and max(·) indicates the maximum value in the brackets; T max (t) is the maximum value of the cable temperature at time t;

[0110] The radial direction of the core corresponding to the maximum value of the cable temperature at moment t in the seven-core optical fiber is taken as the radial direction in which the cable temperature is generated at moment t; the specific position where the cable temperature is generated at moment t is determined based on the radial direction in which the cable temperature is generated at moment t and the axial position of the maximum value of the cable temperature at moment t in the seven-core optical fiber; the maximum value of the cable temperature at moment t is taken as the fused cable temperature data T0(t) at moment t.

[0111] Among them, the method for fusing the strain data of each fiber core is:

[0112] Determine the maximum value S of the core strain at time t max (t);

[0113] The core corresponding to the maximum value of the core strain at time t is recorded as the first core at time t; any core other than the first core at time t among the first orientation core 29, the third orientation core 31 and the fifth orientation core 33 is recorded as the second core at time t;

[0114] The core axial position corresponding to the maximum value of the core strain at time t is taken as the strain axial position at time t, and a coordinate axis is established along the radial direction of the seven-core optical fiber at the strain axial position at time t; preferably, the center point is taken as the origin of the coordinate axis; preferably, the x-axis direction of the set coordinate axis is parallel to the line connecting the core corresponding to the maximum value of the strain and the center point of the multi-core optical fiber;

[0115] The strain data is fused according to the following formula to obtain the fused strain data S0(t) at time t;

[0116]

[0117] Among them, S max (t) is the maximum value of the core strain at time t; θ1(t) is the angle between the stress direction corresponding to the maximum value of the strain in the first core at time t and the x-axis; e is the natural base; θ2(t) is the angle between the stress direction corresponding to the maximum value of the strain in the second core at time t and the x-axis; S2(t) is the maximum value of the strain in the second core;

[0118] The specific position where the cable generates strain at time t is determined based on the axial position of the strain at time t, the angle between the stress direction corresponding to the maximum strain in the first fiber core at time t and the x-axis, and the angle between the stress direction corresponding to the maximum strain in the second fiber core at time t and the x-axis.

[0119] Preferably, the maximum value of the core strain at time t is set according to the following formula:

[0120] S max (t) = max(S 29 (t),S 31 (t),S 33 (t));

[0121] Among them, S 29 (t) is the maximum strain of the fiber core 29 at time t, S 31 (t) is the maximum strain value of the core 31 at time t, S 33 (t) is the maximum strain value of the core 33 at time t, S max (t) is the maximum value of the core strain at time t.

[0122] Preferably, the specific position where the cable generates strain at time t is determined, that is, the coordinate position (x(t), y(t)) where the strain is generated in the cable at time t is calculated according to the following formula:

[0123]

[0124] Wherein, x2(t) is the x-axis coordinate of the second fiber core at time t; y2(t) is the y-axis coordinate of the second fiber core at time t; and the angle is (0, 360°).

[0125] The fusion of the vibration data of each fiber core is shown in the following formula:

[0126] V0(t)=w max V max (t)+w mid V mid (t)+w min V min (t);

[0127] Where V0(t) is the fused vibration data at time t; w max is the weight of the maximum value of cable vibration, and its preferred value range is 0.8~1; V max (t) is the maximum value of cable vibration at time t; w mid V is the vibration weight of the central fiber core 28, and its preferred value range is 0.3 to 0.5; mid (t) is the maximum vibration value of the central core 28 at time t; w min is the weight of the minimum value of cable vibration, and its preferred value range is 0.1~0.15; V min (t) is the minimum value of cable vibration at time t;

[0128] Among them, 1<w max +w mid +w min ≤1.5.

[0129] Preferably, the maximum value of cable vibration is set according to the following formula:

[0130] V max (t)=max(V 30 (t),V 32 (t),V 34 (t))

[0131] Among them, V 30 (t) is the maximum vibration value of the fiber core 30 at time t, V 32 (t) is the maximum vibration value of the fiber core 32 at time t, V 34 (t) is the maximum vibration value of the fiber core 34 at time t, V max (t) is the maximum value of the cable vibration at time t.

[0132] Based on the radial direction of the core corresponding to the maximum cable vibration at time t in the seven-core optical fiber and the axial position of the maximum cable vibration at time t, the specific position where the cable vibration occurs at time t is determined.

[0133] The fusion of partial discharge data of each fiber core is shown in the following formula:

[0134]

[0135] Among them, P0(t) is the fused partial discharge data at time t; is the maximum value weight coefficient of cable partial discharge, and its preferred value range is 1.01~1.5; max (t) is the maximum value of cable partial discharge at time t; is the partial discharge weight coefficient of the central core 28, and its preferred value range is 0.15 to 0.35; mid (t) is the maximum value of the local discharge of the central core 28 at time t;

[0136] Preferably, the maximum value of cable partial discharge is set according to the following formula:

[0137] P max (t) = max(P 30 (t),P 32 (t),P 34 (t))

[0138] Among them, P 30 (t) is the maximum value of the local discharge of the fiber core 30 at time t, P 32 (t) is the maximum value of the local discharge of the fiber core 32 at time t, P 34 (t) is the maximum value of the local discharge of the fiber core 34 at time t, P max (t) is the maximum value of cable partial discharge at time t; max(·) means taking the maximum value in brackets;

[0139] Based on the radial direction of the core corresponding to the maximum value of the cable partial discharge at time t in the seven-core optical fiber and the axial position of the maximum value of the cable partial discharge at time t, the specific position where the cable partial discharge occurs at time t is determined.

[0140] Based on the above method, the temperature, strain and vibration of the built-in multi-core optical fiber power cable can be detected and positioned radially and axially, thereby realizing multi-parameter distributed detection of the cable.

[0141] Preferably, the preprocessing is to clean the outliers and fill the missing values ​​in all the data after fusion, as well as normalize the data;

[0142] Based on the pre-processed cable status related data, a cable status multi-factor composite criterion for cable status judgment is constructed;

[0143] The cable status multi-factor composite criterion C 1c (t) is shown in the following formula:

[0144]

[0145] Wherein, ε is the state judgment gain coefficient, and its preferred value range is 3 to 5; T'0(t) is the cable temperature data after preprocessing at time t; T0'(t-1) is the cable temperature data after preprocessing at time t-1; S'0(t) is the strain data after preprocessing at time t; S'0(t-1) is the strain data after preprocessing at time t-1; W v is the cable vibration data weight, and its preferred value range is 0.3-0.5; V0'(t) is the cable vibration data after preprocessing at time t; P0(t) is the local discharge data after fusion at time t; τ is the local discharge upper limit determination coefficient, and its preferred value range is 1.03-1.5; P e is the rated voltage of the cable;

[0146] Preferably, when t=1, T'0(t-1)=T'0(t);

[0147] Preferably, when t=1, S'0(t-1)=S'0(t);

[0148] When C 1c When (t) < 0.15, the cable is in good condition. If the cable is in good condition, regular maintenance is sufficient.

[0149] When 0.15≤C 1c When (t) < 0.6, the cable is judged to be in good condition; when the cable is judged to be in good condition, the maintenance frequency needs to be increased; preferably, the original maintenance frequency is increased by 15%;

[0150] When 0.6≤C 1c (t), the cable is judged to be in poor condition; when the cable is judged to be in poor condition, the specific location of the poor cable condition is determined and repairs are performed.

[0151] Determine the exact location of a bad cable as follows:

[0152] when When the cable temperature is generated at time t, the specific location where the cable temperature is generated is determined to be the specific location where the cable state is poor;

[0153] Wherein, t represents the number of sampling points, i.e., the tth sampling point; s is an integer, and s∈[1,t]; T0'(t) is the preprocessed cable temperature data at time t; T0'(s) is the preprocessed cable temperature data at time s;

[0154] when When the cable is strained at time t, the specific location where the cable is in poor condition is determined;

[0155] Wherein, S'0(t) is the strain data after preprocessing at time t; S'0(s) is the strain data after preprocessing at time s; ψ is the cable strain determination coefficient, and its preferred value range is 1.2 to 1.35;

[0156] when When the cable vibration occurs at time t, the specific location where the cable is in poor condition is determined;

[0157] Where V'0(t) is the preprocessed cable vibration data at time t; V e is the rated vibration value of the cable; V0(s) is the fused vibration data at time s;

[0158] When P0(t)>1.1τP e When the cable is in poor condition, the specific location where the partial discharge occurs at time t is determined to be the specific location where the cable is in poor condition;

[0159] The pre-processed data is substituted into the multi-factor composite judgment criteria of the cable status in real time to obtain the cable status judgment result.

[0160] Example 2

[0161] A multi-parameter distributed detection method for cable status based on multi-core optical fiber.

[0162] Place multi-core optical fibers in power cables and collect data related to the cable status in each fiber core;

[0163] The cable status related data include temperature, strain, vibration and partial discharge of each fiber core.

[0164] The multi-core optical fiber adopts a seven-core optical fiber, see the attached Figure 4 , including a central fiber core 28, a first azimuth fiber core 29, a second azimuth fiber core 30, a third azimuth fiber core 31, a fourth azimuth fiber core 32, a fifth azimuth fiber core 33 and a sixth azimuth fiber core 34 arranged around the central fiber core 28;

[0165] The first azimuth fiber core 29, the third azimuth fiber core 31 and the fifth azimuth fiber core 33 are sequentially connected as the first sensing optical fiber. Figure 2The sensing optical fiber 3 in the BOTDR system collects temperature and strain from three directions of the seven-core optical fiber; the outer first direction fiber core 29, the third direction fiber core 31, and the fifth direction fiber core 33 can effectively sense the temperature and strain from three directions on the physical length of the multi-core optical fiber, and can effectively determine the spatial direction of the temperature or strain according to the temperature or strain at different positions, effectively avoiding the spatial blind area and improving the perception ability of the BOTDR system. The determination method is as follows: See the attached Figure 2 The structure of the BOTDR Brillouin optical time domain reflectometer system is as follows: a narrow linewidth laser 1 emits light of 1550nm wavelength, which is divided into two paths through a 90:10 coupler 2, with the ratio of the two paths being 90% and 10% respectively. The 90% path is used as a detection path to generate detection pulses entering the sensing optical fiber 3, and the 10% path is used as a reference path to generate reference light. The light entering the detection path is reduced in power to below the maximum incident power of the semiconductor optical amplifier 5 by an adjustable optical attenuator 4, and then enters the semiconductor optical amplifier 5 to modulate the pulse. The pulse peak power output by the semiconductor optical amplifier 5 is relatively low, and enters the pulse erbium-doped fiber amplifier 6 to be amplified to a certain power, and then the detection pulse with the spontaneous radiation noise filtered out by the fiber Bragg grating 7 enters the sensing optical fiber 3 through the fiber circulator 8. The Brillouin scattering signal generated in the sensing optical fiber 3 enters the erbium-doped fiber amplifier 9 through the output end of the fiber circulator 8, is amplified, and then filtered out by the fiber Bragg grating 10 to remove the spontaneous radiation noise, and enters the 50:50 coupler 11 to beat with the reference light. The light of the reference path changes its polarization state through the polarization scrambler 12, thereby eliminating the polarization fading noise caused by different polarization states. The photodetector 13 converts the optical signal into an electrical signal.

[0166] The electrical signal output by the photodetector 13 enters the low noise amplifier 14 for amplification, and then enters the mixer 15 to mix with the sinusoidal signal generated by the microwave local oscillator 16, thereby realizing down-conversion. The down-converted signal is frequency-selectively filtered by the bandpass filter 17 and the power information of the single-frequency signal is extracted by the detector 18. The output frequency of the microwave local oscillator 16 can be adjusted in steps to complete the frequency scanning of the Brillouin scattering signal to reconstruct the Brillouin scattering spectrum. By extracting the center frequency of the Brillouin scattering spectrum along the sensing optical fiber 3, the temperature and strain information at different positions of the sensing optical fiber 3 can be demodulated.

[0167] The central fiber core 28, the second azimuth fiber core 30, the fourth azimuth fiber core 32 and the sixth azimuth fiber core 34 are sequentially connected as the second sensing optical fiber. Figure 3 The sensing optical fiber 25 in the embodiment of the present invention; the second sensing optical fiber is based on The system collects vibration and partial discharge from three positions and the center point of the multi-core optical fiber.

[0168] The central fiber core 28, the second azimuth fiber core 30, the fourth azimuth fiber core 32, and the sixth azimuth fiber core 34 of the OTDR system can achieve four times the effective perception over the physical length of the multi-core optical fiber. The central fiber core 28 can measure the vibration at the center of the optical fiber, and the second azimuth fiber core 30, the fourth azimuth fiber core 32, and the sixth azimuth fiber core 34 can locate the vibration experienced by the optical fiber.

[0169] See attached Figure 3 , The structure of the phase-sensitive optical time domain reflectometer system is as follows: the laser 20 is divided into two branches through a 90:10 coupler 21. The branch with a ratio of 90 passes through an acousto-optic modulator 22 and an erbium-doped fiber amplifier 23, and then enters the optical fiber circulator 24. The return end of the circulator 24 enters the 2×2 coupler 26 together with the branch with a ratio of 10, and then enters the balanced photodetector 27.

[0170] The collected data related to the cable status are integrated and then preprocessed to obtain the preprocessed data related to the cable status;

[0171] The data collected from each fiber core are fused, including the fusion of the temperature data of each fiber core, the fusion of the strain data of each fiber core, the fusion of the vibration data of each fiber core, and the fusion of the partial discharge data of each fiber core.

[0172] The fusion of each fiber core temperature data is shown in the following formula:

[0173] T max (t) = max(T 29 (t),T 31 (t),T 33 (t));

[0174] Among them, T 29 (t) is the maximum temperature of the fiber core 29 at sampling time t, T 31 (t) is the maximum temperature of the core 31 at time t, T 33 (t) is the maximum temperature of the core 33 at time t, and max(·) indicates the maximum value in the brackets; T max (t) is the maximum value of the cable temperature at time t;

[0175] The radial direction of the core corresponding to the maximum value of the cable temperature at moment t in the seven-core optical fiber is taken as the radial direction in which the cable temperature is generated at moment t; the specific position where the cable temperature is generated at moment t is determined based on the radial direction in which the cable temperature is generated at moment t and the axial position of the maximum value of the cable temperature at moment t in the seven-core optical fiber; the maximum value of the cable temperature at moment t is taken as the fused cable temperature data T0(t) at moment t.

[0176] Among them, the method for fusing the strain data of each fiber core is:

[0177] Determine the maximum value S of the core strain at time t max (t);

[0178] The core corresponding to the maximum value of the core strain at time t is recorded as the first core at time t; any core other than the first core at time t among the first orientation core 29, the third orientation core 31 and the fifth orientation core 33 is recorded as the second core at time t;

[0179] The core axial position corresponding to the maximum value of the core strain at time t is taken as the strain axial position at time t, and a coordinate axis is established along the radial direction of the seven-core optical fiber at the strain axial position at time t; preferably, the center point is taken as the origin of the coordinate axis; preferably, the x-axis direction of the set coordinate axis is parallel to the line connecting the core corresponding to the maximum value of the strain and the center point of the multi-core optical fiber;

[0180] The strain data is fused according to the following formula to obtain the fused strain data S0(t) at time t;

[0181]

[0182] Among them, S max (t) is the maximum value of the core strain at time t; θ1(t) is the angle between the stress direction corresponding to the maximum value of the strain in the first core at time t and the x-axis; e is the natural base; θ2(t) is the angle between the stress direction corresponding to the maximum value of the strain in the second core at time t and the x-axis; S2(t) is the maximum value of the strain in the second core;

[0183] The specific position where the cable generates strain at time t is determined based on the axial position of the strain at time t, the angle between the stress direction corresponding to the maximum strain in the first fiber core at time t and the x-axis, and the angle between the stress direction corresponding to the maximum strain in the second fiber core at time t and the x-axis.

[0184] The fusion of the vibration data of each fiber core is shown in the following formula:

[0185] V0(t)=w max V max (t)+w mid V mid (t)+w min V min (t);

[0186] Where V0(t) is the fused vibration data at time t; w max is the weight of the maximum value of cable vibration; V max (t) is the maximum value of cable vibration at time t; w mid V is the vibration weight of the central fiber core 28;mid (t) is the maximum vibration value of the central core 28 at time t; w min is the weight of the minimum cable vibration; V min (t) is the minimum value of cable vibration at time t;

[0187] Based on the radial direction of the core corresponding to the maximum cable vibration at time t in the seven-core optical fiber and the axial position of the maximum cable vibration at time t, the specific position where the cable vibration occurs at time t is determined.

[0188] The fusion of partial discharge data of each fiber core is shown in the following formula:

[0189]

[0190] Among them, P0(t) is the fused partial discharge data at time t; is the maximum weight coefficient of cable partial discharge; P max (t) is the maximum value of cable partial discharge at time t; is the local discharge weight coefficient of the central fiber core 28; mid (t) is the maximum value of the local discharge of the central core 28 at time t;

[0191] Based on the radial direction of the core corresponding to the maximum value of the cable partial discharge at time t in the seven-core optical fiber and the axial position of the maximum value of the cable partial discharge at time t, the specific position where the cable partial discharge occurs at time t is determined.

[0192] Based on the above method, the temperature, strain and vibration of the built-in multi-core optical fiber power cable can be detected and positioned radially and axially, thereby realizing multi-parameter distributed detection of the cable.

[0193] Preferably, the preprocessing is to clean the outliers and fill the missing values ​​in all the data after fusion;

[0194] Based on the pre-processed cable status related data, a cable status multi-factor composite criterion for cable status judgment is constructed;

[0195] Cable status judgment criterion C 2c (t) is shown in the following formula:

[0196]

[0197] Wherein, λ is the local discharge gain coefficient, and its preferred value range is 3 to 5; P'0(t) is the local discharge data after preprocessing at time t; τ is the local discharge upper limit determination coefficient, and its preferred value range is 1.05 to 1.3; P eis the rated voltage of the cable; χ is the strain, vibration, and partial discharge fusion gain coefficient, and its preferred value range is 9 to 11; S'0(t) is the strain data after preprocessing at time t; S'0(t-1) is the strain data after preprocessing at time t-1; V0'(t) is the cable vibration data after preprocessing at time t; V e is the rated vibration value of the cable; T0'(t) is the pre-processed cable temperature data at time t; T'0(t-1) is the pre-processed cable temperature data at time t-1; min(·) means taking the minimum value in brackets;

[0198] Preferably, when t=1, T'0(t-1)=T'0(t);

[0199] Preferably, when t=1, S'0(t-1)=S'0(t);

[0200] When C 2c (t)<0.1V e When the cable is in good condition, regular maintenance is sufficient.

[0201] When 0.1V e ≤C 2c (t)<0.5V e When the cable is in good condition, it is judged that the cable is in good condition; when the cable is judged to be in good condition, the maintenance frequency needs to be increased; preferably, the original maintenance frequency is increased by 15%;

[0202] When 0.5V e ≤C 2c (t), the cable is judged to be in poor condition. When the cable is judged to be in poor condition, the specific location of the poor cable condition is determined and repaired.

[0203] Determine the exact location of a bad cable as follows:

[0204] when When the cable temperature is generated at time t, the specific location where the cable temperature is generated is determined to be the specific location where the cable state is poor;

[0205] Wherein, t represents the number of sampling points, i.e., the tth sampling point; s is an integer, and s∈[1,t]; T0'(t) is the preprocessed cable temperature data at time t; T0'(s) is the preprocessed cable temperature data at time s;

[0206] when When the cable is strained at time t, the specific location where the cable is in poor condition is determined;

[0207] Among them, S'0(t) is the strain data after preprocessing at time t; S max (s) is the maximum value of the core strain at time s;

[0208] When V0'(t)>V e When the cable vibration occurs at time t, the specific location where the cable is in poor condition is determined;

[0209] Where V'0(t) is the preprocessed cable vibration data at time t; V e is the rated vibration value of the cable;

[0210] When P'0(t)>1.1τP e When the cable is in poor condition, the specific location where the partial discharge occurs at time t is determined to be the specific location where the cable is in poor condition;

[0211] Wherein, P0'(t) is the pre-processed partial discharge data at time t;

[0212] The pre-processed data is substituted into the multi-factor composite judgment criteria of the cable status in real time to obtain the cable status judgment result.

[0213] The present application also discloses a cable state multi-parameter distributed detection method and a cable state multi-parameter distributed detection system based on a multi-core optical fiber, including a data acquisition module, a data fusion module, a cable state judgment criterion construction module and a cable state judgment module:

[0214] The data acquisition module places a multi-core optical fiber in the power cable to collect data related to the cable status in each fiber core;

[0215] The data fusion module fuses the collected cable status related data, and then performs preprocessing to obtain the preprocessed cable status related data;

[0216] The cable status judgment criterion construction module constructs a cable status multi-factor composite criterion for judging the cable status based on the pre-processed cable status related data;

[0217] The cable status judgment module substitutes the pre-processed data into the cable status multi-factor composite judgment criterion in real time to obtain the cable status judgment result.

[0218] 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.

[0219] 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.

[0220] 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.

[0221] 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.

[0222] 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 multi-parameter distributed detection method for cable status based on multi-core optical fiber, characterized in that: include: Place multi-core optical fibers in power cables and collect data related to the cable status in each fiber core; The collected data related to the cable status are integrated and then preprocessed to obtain the preprocessed data related to the cable status; Based on the pre-processed cable status related data, a cable status multi-factor composite criterion for cable status judgment is constructed; The pre-processed data is substituted into the multi-factor composite judgment criteria of the cable status in real time to obtain the cable status judgment result.

2. The cable status multi-parameter distributed detection method according to claim 1, characterized in that: The cable status related data include temperature, strain, vibration and partial discharge of each fiber core.

3. The cable status multi-parameter distributed detection method according to claim 1, characterized in that: The multi-core optical fiber is a seven-core optical fiber, comprising a central fiber core (28), a first azimuth fiber core (29) arranged around the central fiber core (28), a second azimuth fiber core (30), a third azimuth fiber core (31), a fourth azimuth fiber core (32), a fifth azimuth fiber core (33) and a sixth azimuth fiber core (34); The first azimuth fiber core (29), the third azimuth fiber core (31) and the fifth azimuth fiber core (33) are sequentially connected as a first sensing optical fiber; the first sensing optical fiber collects temperature and strain from three azimuths of the seven-core optical fiber based on a BOTDR system; The central fiber core (28), the second azimuth fiber core (30), the fourth azimuth fiber core (32) and the sixth azimuth fiber core (34) are sequentially connected to form a second sensing optical fiber; the second sensing optical fiber is based on -OTDR system collects vibration and partial discharge from three positions and the center point of the multi-core optical fiber.

4. The cable status multi-parameter distributed detection method according to claim 1, characterized in that: The data collected from each fiber core are fused, including the fusion of the temperature data of each fiber core, the fusion of the strain data of each fiber core, the fusion of the vibration data of each fiber core, and the fusion of the partial discharge data of each fiber core.

5. The cable status multi-parameter distributed detection method according to claim 3 or 4, Features: Among them, the method for fusing the strain data of each fiber core is: Determine the maximum value S of the core strain at time t max (t); The core corresponding to the maximum value of the core strain at time t is recorded as the first core at time t; any core other than the first core at time t among the first orientation core (29), the third orientation core (31) and the fifth orientation core (33) is recorded as the second core at time t; The core axial position corresponding to the maximum value of the core strain at time t is taken as the strain axial position at time t, and a coordinate axis is established along the radial direction of the seven-core optical fiber at the strain axial position at time t; The strain data is fused according to the following formula to obtain the fused strain data S0(t) at time t; Among them, S max (t) is the maximum value of the core strain at time t; θ1(t) is the angle between the stress direction corresponding to the maximum value of the strain in the first core at time t and the x-axis; e is the natural base; θ2(t) is the angle between the stress direction corresponding to the maximum value of the strain in the second core at time t and the x-axis; S2(t) is the maximum value of the strain in the second core; The specific position where the cable generates strain at time t is determined based on the axial position of the strain at time t, the angle between the stress direction corresponding to the maximum strain in the first fiber core at time t and the x-axis, and the angle between the stress direction corresponding to the maximum strain in the second fiber core at time t and the x-axis.

6. The cable status multi-parameter distributed detection method according to claim 3 or 4, Features: The fusion of the vibration data of each fiber core is shown in the following formula: V0(t)=w max V max (t)+w mid V mid (t)+w min V min (t); Where V0(t) is the fused vibration data at time t; w max is the weight of the maximum value of cable vibration; V max (t) is the maximum value of cable vibration at time t; w mid is the vibration weight of the central fiber core (28); V mid (t) is the maximum vibration value of the central fiber core (28) at time t; w min is the weight of the minimum cable vibration; V min (t) is the minimum value of cable vibration at time t; Based on the radial direction of the core corresponding to the maximum cable vibration at time t in the seven-core optical fiber and the axial position of the maximum cable vibration at time t, the specific position where the cable vibration occurs at time t is determined.

7. The cable status multi-parameter distributed detection method according to claim 3 or 4, characterized in that: in, The fusion of partial discharge data of each fiber core is shown in the following formula: Among them, P0(t) is the fused partial discharge data at time t; is the maximum weight coefficient of cable partial discharge; P max (t) is the maximum value of cable partial discharge at time t; is the partial discharge weight coefficient of the central fiber core (28); mid (t) is the maximum value of the local discharge of the central core (28) at time t; Based on the radial direction of the core corresponding to the maximum value of the cable partial discharge at time t in the seven-core optical fiber and the axial position of the maximum value of the cable partial discharge at time t, the specific position where the cable partial discharge occurs at time t is determined.

8. The cable status multi-parameter distributed detection method according to claim 1 or 2, characterized in that: The cable status multi-factor composite criterion C 1c (t) is shown in the following formula: Among them, ε is the state judgment gain coefficient; T'0(t) is the cable temperature data after preprocessing at time t; T'0(t-1) is the cable temperature data after preprocessing at time t-1; S'0(t) is the strain data after preprocessing at time t; S'0(t-1) is the strain data after preprocessing at time t-1; W v is the cable vibration data weight; V'0(t) is the pre-processed cable vibration data at time t; P0(t) is the fused partial discharge data at time t; τ is the upper limit determination coefficient of partial discharge; P e is the rated voltage of the cable; When C 1c When (t) < 0.15, the cable is judged to be in excellent condition; When 0.15≤C 1c When (t) < 0.6, the cable is judged to be in good condition; When 0.6≤C 1c (t), the cable status is judged to be poor.

9. The cable status multi-parameter distributed detection method according to claim 8, characterized in that: When the cable is judged to be in excellent condition, regular maintenance is sufficient; When the cable is judged to be in good condition, the maintenance frequency needs to be increased; When it is determined that the cable is in poor condition, the specific location of the poor cable condition is determined and repairs are performed.

10. A cable status multi-parameter distributed detection system using the cable status multi-parameter distributed detection method according to any one of claims 1 to 9, characterized in that: It includes data acquisition module, data fusion module, cable status judgment criterion building module and cable status judgment module: The data acquisition module places a multi-core optical fiber in the power cable to collect data related to the cable status in each fiber core; The data fusion module fuses the collected cable status related data, and then performs preprocessing to obtain the preprocessed cable status related data; The cable status judgment criterion construction module constructs a cable status multi-factor composite criterion for judging the cable status based on the pre-processed cable status related data; The cable status judgment module substitutes the pre-processed data into the cable status multi-factor composite judgment criterion in real time to obtain the cable status judgment result.

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