Submarine cable state identification method and system based on typhoon effect and tidal excitation

Abstract

The invention provides a submarine cable state identification method and system based on typhoon effect and tidal excitation, and relates to the technical field of submarine cable monitoring. The method comprises the following steps: performing multi-moment acquisition and demodulation processing on a first optical fiber signal along a submarine cable during a typhoon to obtain temperature data; taking the first group of temperature data as reference data, and subtracting each group of temperature data at other moments from the reference data to obtain the temperature difference of each region of the submarine cable along with the time change; the maximum value of the temperature difference is compared with a preset exposure threshold value, if the maximum value of the temperature difference is larger than the preset exposure threshold value, the area is an exposed area, and otherwise, the area is a non-exposed area; respectively performing first processing and second processing on the exposed area so as to divide the exposed area according to the exposed duration and the exposed state; and further judging whether the suspended exposed area is a continuous suspended exposed area or a new suspended exposed area. According to the invention, high-precision on-line identification of exposed and suspended states of the submarine cable is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of submarine cable monitoring, and in particular to a submarine cable state identification method and system based on typhoon effect and tidal excitation. BACKGROUND

[0002] As an important infrastructure of modern society's power transmission and communication network, submarine cables are widely used in cross-sea power transmission, offshore wind power grid connection, transoceanic communication and other fields. In order to reduce the risk of being hooked and dragged by ship anchors, natural disasters and marine biological damage, and to avoid corrosion damage caused by direct exposure of the cable to seawater, while reducing the impact of heat release on the marine ecological environment during operation, submarine cables are usually buried at a depth of 1-3 meters below the seabed. The integrity and safety of the buried state are the key to ensuring the long-term stable operation of the cable and improving system reliability.

[0003] However, the submarine environment is complex and changeable, and the cable will be affected by multiple external factors such as submarine geological changes, tidal and wave erosion, marine biological attachment and biting, ship anchoring, trawling operations and extreme weather during service. These effects can cause the cable to be partially exposed, suspended or shallowly buried, etc. Once the above conditions occur, the mechanical protection capability of the cable is significantly reduced, which is easy to be directly exposed to the corrosive seawater environment, accelerating the aging of the sheath and insulation layer, and even causing fatigue damage and rupture under the repeated action of waves, tides and flow fields, posing a serious threat to the safe operation of power transmission and communication systems.

[0004] Traditional submarine cable buried state detection technologies mainly include: 1) acoustic monitoring technology, which identifies the buried state of the cable through multi-beam echo sounding (MBES), side scan sonar (SSS) and other acoustic imaging means. This method has high accuracy, but has poor adaptability to complex terrain, and the measurement results are easily affected by water depth, current and bottom conditions, making it difficult to be widely applied due to high cost and insufficient real-time performance. 2) Artificial diving patrol / ROV inspection: state information is obtained by direct imaging through divers or remotely operated vehicles. This method has high accuracy, but is low in efficiency and expensive, and is greatly limited by weather and sea conditions, making it difficult to meet the needs of long-distance cable regular inspection.

[0005] With the expansion of the scale and the increase of the laying depth of submarine cables, the limitations of the above traditional methods become more prominent, especially in terms of large-scale, long-term, real-time monitoring and intelligent management, which cannot effectively meet the engineering needs. In recent years, distributed fiber optic sensing (DFOS) technology has been gradually applied to submarine cable monitoring, which can use the communication cable body to realize long-distance, full-line and all-weather vibration and strain signal acquisition, and has the advantages of uninterrupted communication, no additional sensors and low operation and maintenance cost. Among them, phase-sensitive optical time domain reflectometer (Φ-OTDR) has shown high sensitivity in monitoring ocean dynamic processes.

[0006] The prior art research finds that the submarine cable state detection related research mainly concentrates on the following several types: 1) tidal current monitoring based on DFOS: can capture the low frequency, periodic flow velocity and vibration changes caused by tides, and is used for long-term observation of ocean dynamics. 2) typhoon / extreme weather observation based on DFOS: can detect significant broadband vibration and flow velocity signal changes during typhoon process, and is used for analyzing the ocean response mechanism of extreme weather. 3) buried state detection based on DFOS: some technologies use single power source (such as normal flow, trawl disturbance) signal characteristics to identify abnormal burial depth, but the discrimination logic is relatively single, and lacks multi-source power feature fusion.

[0007] In summary, although the tidal response and typhoon response have been used for ocean dynamics observation, there is currently no systematic joint use of tidal (periodic low frequency stable excitation) and typhoon (short time high amplitude excitation) two types of natural power signals, and the response characteristics under different power conditions are fused, and a high-precision online identification and risk warning method for the exposed, suspended and shallow buried state of submarine cable is realized. On the premise of not increasing the cost of offshore operation, the real-time and accurate state discrimination of the whole submarine cable is realized, and the operation safety and maintenance efficiency are improved. SUMMARY

[0008] In view of the above problems, the present application provides a submarine cable state identification method and system based on typhoon effect and tidal excitation.

[0009] According to one aspect of the present application, a submarine cable state identification method based on typhoon effect and tidal excitation is provided, which comprises:

[0010] A first distributed optical fiber sensing system arranged in a submarine cable communication optical fiber is used to collect first optical fiber signals along the submarine cable at multiple times during a typhoon, and the first optical fiber signals are demodulated to obtain temperature data at multiple times;

[0011] Taking the first group of temperature data as reference data, each group of temperature data at other times is subtracted from the reference data to obtain the temperature difference of each region of the submarine cable with time;

[0012] For a plurality of temperature differences corresponding to each region of the submarine cable, the maximum temperature difference is compared with a preset exposure threshold value, if the maximum temperature difference corresponding to a region is greater than the preset exposure threshold value, the region is an exposed region, otherwise it is a non-exposed region;

[0013] The exposed region of the submarine cable is subjected to a first treatment to divide the exposed region into an existing continuous exposed region or a newly exposed region according to the exposed duration;

[0014] The exposed area of the submarine cable is subjected to a second treatment to divide the exposed area into a suspended exposed area or a non-suspended exposed area according to the exposed state.

[0015] Further, the first distributed optical fiber sensing system is a Brillouin optical time domain analyzer, a Brillouin optical time domain reflectometer or a distributed optical fiber Raman temperature sensor.

[0016] Further, the first treatment of the exposed area of the submarine cable to divide the exposed area into an existing continuous exposed area or a newly exposed area according to the exposed duration includes:

[0017] A sliding window operation is performed on the temperature data corresponding to the exposed area, and a time sequence and a temperature sequence in each sliding window are extracted; based on the time sequence and the temperature sequence, a slope in the sliding window is calculated using a linear regression method to obtain a plurality of slope values; the slope value is a ratio of temperature to time; the absolute value of the slope value is compared with a preset slope threshold value, if the absolute value of the slope value is greater than the preset slope threshold value, a temperature change interval is determined based on the slope value, and the next determination step is entered, otherwise the exposed area is determined as an existing continuous exposed area; the temperature change interval is subjected to a sliding window operation again, a local sliding window slope of the temperature change interval is calculated, and a plurality of local sliding window slopes are averaged to obtain a mean slope; the mean slope is compared with a preset overall slope threshold value, if the mean slope is lower than the preset overall slope threshold value, the exposed area is determined as a newly exposed area; otherwise, the exposed area is determined as an existing continuous exposed area.

[0018] Further, the determination of the temperature change interval based on the slope value includes: determining a time index point corresponding to a slope absolute value greater than a preset slope threshold value from the plurality of slope values, and taking the time index point as a starting point of temperature change; traversing the temperature data from the starting point to determine a time index point with the lowest temperature in the sliding window as an end point of temperature change; and determining the temperature change interval according to the starting point and the end point of temperature change.

[0019] Further, the second treatment of the exposed area of the submarine cable to divide the exposed area into a suspended exposed area or a non-suspended exposed area according to the exposed state includes:

[0020] The second distributed optical fiber sensing system laid in the submarine cable communication optical fiber is used to collect second optical fiber signals along the submarine cable at multiple time instants after a typhoon period, the second optical fiber signals are demodulated to obtain vibration intensity data at multiple time instants;

[0021] The vibration intensity data at adjacent sampling time instants are processed to obtain vibration features;

[0022] identify a plurality of independent suspension regions of the submarine cable based on the vibration characteristics;

[0023] determine an overlapping region between the plurality of independent suspension regions and the exposed region of the submarine cable identified based on the temperature change as a suspension exposed region, and a non-overlapping region as a non-suspension exposed region.

[0024] Further, the second distributed optical fiber sensing system is a phase-sensitive optical time domain reflectometer; and the processing of the vibration intensity data at adjacent sampling time points to obtain vibration characteristics includes: performing differential operation on the vibration intensity data at adjacent sampling time points to obtain a differential signal; and averaging the differential signal in a time window to obtain a vibration differential mean curve.

[0025] Further, the identifying of the plurality of independent suspension regions of the submarine cable based on the vibration characteristics includes: comparing each differential mean value on the vibration differential mean curve with a preset threshold value, defining a label of a position point corresponding to the differential mean value as 1 if the differential mean value is greater than or equal to the preset threshold value, and defining the label as 0 otherwise; the position point with the label equal to 1 is an abnormal point, and the position point with the label equal to 0 is a normal point; finding a continuous section composed of a plurality of abnormal points according to the label; and performing spatial clustering and merging on the plurality of continuous sections to obtain the plurality of independent suspension regions.

[0026] Further, the performing of spatial clustering and merging on the plurality of continuous sections to obtain the plurality of independent suspension regions includes: calculating a physical distance interval between adjacent continuous sections, merging the adjacent continuous sections into one section if the physical distance interval is less than or equal to a preset merging threshold value, and keeping the adjacent continuous sections as independent sections otherwise; and repeating the above process until the plurality of continuous sections cannot be merged to obtain the plurality of independent suspension regions; wherein a calculation formula of the physical distance of each continuous section is:

[0027] ;

[0028] wherein s and e are a starting position point and an ending position point of the continuous section; denotes a spatial sampling interval; 、 denote a starting distance and an ending distance of the continuous section, respectively.

[0029] Further, the method further comprises: after determining the suspended bare area, further determining whether the suspended bare area is a sustained suspended bare area or a new suspended bare area; collecting the optical fiber signal of the submarine cable at multiple time points before the typhoon period by using a second distributed optical fiber sensing system arranged in the submarine cable communication optical fiber, demodulating the optical fiber signal to obtain vibration intensity data at multiple time points before the typhoon period; processing the vibration intensity data at adjacent sampling time points to obtain vibration characteristics; identifying multiple independent suspended areas of the submarine cable before the typhoon period based on the vibration characteristics; comparing the multiple independent suspended areas before and after the typhoon period, if an independent suspended area only appears after the typhoon period, the independent suspended area is a new suspended bare area; and if an independent suspended area appears before and after the typhoon period, the independent suspended area is a sustained suspended bare area.

[0030] According to another aspect of the present application, a submarine cable state recognition system based on typhoon effect and tidal excitation is provided, which is used to implement the above-mentioned submarine cable state recognition method based on typhoon effect and tidal excitation; the system comprises:

[0031] a temperature data acquisition module configured to collect the first optical fiber signal of the submarine cable at multiple time points during the typhoon by using a first distributed optical fiber sensing system arranged in the submarine cable communication optical fiber, and demodulate the first optical fiber signal to obtain temperature data at multiple time points;

[0032] a bare area recognition module configured to take the first group of temperature data as reference data, and subtract each group of temperature data at the remaining time points from the reference data to obtain the temperature difference of each region of the submarine cable with time; for the multiple temperature differences corresponding to each region of the submarine cable, compare the maximum temperature difference with a preset bare area threshold value, if the maximum temperature difference corresponding to a region is greater than the preset bare area threshold value, the region is a bare area, otherwise it is a non-bare area;

[0033] a bare area time recognition module configured to perform first processing on the bare area of the submarine cable to divide the bare area into an existing sustained bare area or a new bare area according to the bare duration;

[0034] a suspended bare area recognition module configured to perform second processing on the bare area of the submarine cable to divide the bare area into a suspended bare area or a non-suspended bare area according to the bare state.

[0035] According to another aspect of the present application, an electronic device is also provided, which comprises at least one processor and a memory storing a computer program; when the computer program is read and executed by the processor, the electronic device performs the above-mentioned submarine cable state recognition method based on typhoon effect and tidal excitation.

[0036] According to another aspect of the present application, there is also provided a readable storage medium storing a computer program, which, when read and executed by an electronic device, causes the electronic device to perform a method for identifying the state of a submarine cable based on typhoon effect and tidal excitation as described above.

[0037] The beneficial technical effects of the present application are:

[0038] The present application firstly combines the tidal signal with the typhoon signal characteristics, combines the periodic low-frequency stable excitation with the short-time high-amplitude excitation, constructs a multi-scale and multi-condition submarine cable response feature model, and realizes high-precision online identification of the submarine cable exposed, suspended and shallow buried state. Compared with the existing methods which rely on a single power source signal or post-investigation, the present application can have high sensitivity and high robustness under extreme weather and normal ocean dynamic conditions, not only improves the accuracy and real-time performance of state identification, but also significantly reduces the false negative and false positive rates. Since the distributed optical fiber sensing technology is used to collect signals, there is no need to add new sensors on the sea and lay additional lines, so the present application has the advantages of convenient deployment, low operation cost and wide application range. The present application can realize all-weather, long-period and continuous monitoring of the submarine cable, is suitable for operation and maintenance management of deep-sea and large-scale submarine cable networks, can effectively reduce the mechanical damage and corrosion failure risk caused by the exposed or suspended state, significantly improves the operation safety and service life of the submarine cable, and provides a new technical path for intelligent monitoring of marine engineering infrastructure. BRIEF DESCRIPTION OF DRAWINGS

[0039] The above and other objects, features and advantages of the present application will become more apparent from the following detailed description read in conjunction with the accompanying drawings, in which several embodiments of the present application are shown by way of example, and in which:

[0040] Figure 1 A flowchart of a method for identifying the state of a submarine cable based on typhoon effect and tidal excitation according to an embodiment of the present application;

[0041] Figure 2 A flowchart for determining the new exposed area and the existing continuous exposed area according to an embodiment of the present application;

[0042] Figure 3 A schematic diagram of the temperature characteristics and vibration characteristics of different regions of a submarine cable according to an embodiment of the present application;

[0043] Figure 4 An example diagram of the state identification result of a submarine cable according to an embodiment of the present application;

[0044] Figure 5A temperature and vibration data example diagram of a suspended area of a submarine cable in an embodiment of the present application is shown in the figure;

[0045] Figure 6 A structural schematic diagram of a submarine cable state recognition system based on typhoon effect and tidal excitation according to the present application is shown in the figure. DETAILED DESCRIPTION

[0046] The principles and spirits of the present application will be described below with reference to several exemplary embodiments. It should be understood that these embodiments are given only to enable those skilled in the art to better understand and implement the present application, and do not limit the scope of the present application in any way. On the contrary, these embodiments are provided to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0047] In the field of submarine cable monitoring, accurate identification of the exposed area and the suspended area of the submarine cable is a key link to ensure the safe and stable operation of the cable. The present application adopts a joint analysis method of temperature signals and vibration signals to effectively distinguish the characteristic differences between the exposed area and the suspended area, and to realize the identification of the risk level. Specifically, the exposed state and the suspended state of the submarine cable may be converted to each other during the process of severe water flow scouring, and the temperature signal is particularly sensitive to the response of the sediment coverage state. The sudden rapid cooling feature during the typhoon can distinguish the deep buried area, the shallow buried area, the existing exposed area and the newly exposed area, but it is difficult to accurately determine whether there is a suspended state caused by the scouring pit below, depending on the temperature signal alone. In comparison, the vibration signal is more significant in response to the suspended area which lacks physical support of the sediment. When the submarine cable is affected by the tidal current, the suspended section is prone to forced vibration due to the lack of soil support, and the vibration intensity increases with the increase of the tidal current velocity. The buried section is weakly vibrated due to the constraint of the soil body. The suspended section produces high-amplitude vibration response under the action of the sea current and the wave, while the section filled with sediment or exposed but not suspended has a significantly lower vibration amplitude due to the buffering effect. Through the joint analysis of temperature and vibration information, the accurate identification of the exposed state and the suspended state of the submarine cable can be realized.

[0048] Based on the above principles, an embodiment of the present application proposes a submarine cable state recognition method based on typhoon effect and tidal excitation, as shown in the figure, which comprises the following steps: Figure 1

[0049] S1, using a first distributed optical fiber sensing system arranged in the communication optical fiber of the submarine cable to collect the first optical fiber signal along the line of the submarine cable at multiple times during the typhoon, demodulating the first optical fiber signal to obtain temperature data at multiple times;

[0050] ​S2, taking the first group of temperature data as reference data, and respectively subtracting each group of temperature data at other time from the reference data to obtain temperature differences of each region of the submarine cable changing over time;

[0051] S3, comparing the maximum value of the temperature differences corresponding to each region of the submarine cable with a preset exposure threshold value, if the maximum value of the temperature differences corresponding to a region is greater than the preset exposure threshold value, the region is an exposed region, otherwise, the region is a non-exposed region;

[0052] S4, performing first processing on the exposed region of the submarine cable to divide the exposed region into an existing continuous exposed region or a newly exposed region according to an exposed duration;

[0053] S5, performing second processing on the exposed region of the submarine cable to divide the exposed region into a suspended exposed region or a non-suspended exposed region according to an exposed state.

[0054] The method starts from S1. In S1, a first distributed optical fiber sensing system arranged in a communication optical fiber of the submarine cable is used to collect first optical fiber signals of the submarine cable along a line at multiple time points during a typhoon, and the first optical fiber signals are demodulated to obtain temperature data at multiple time points.

[0055] According to the embodiment of the present application, the existing composite optical fiber of the submarine cable or an external submarine cable closely combined with the submarine cable is used as a distributed optical fiber sensor, and a first distributed optical fiber sensing system (including a Brillouin optical time domain analyzer (BOTDA), a Brillouin domain optical time domain reflectometer (BOTDR) or a distributed optical fiber Raman temperature sensor (DTS)) is used to collect optical fiber signals and demodulate the collected optical fiber signals to obtain temperature data. Since the sensing optical fiber and the submarine cable to be measured are integrated or bound as a whole, the submarine cable can cover the entire line, including the buried section, the exposed section and the special marine topography region, and the monitoring equipment can be located in the communication room.

[0056] Then S2 is performed, in which the first group of temperature data is taken as reference data, and each group of temperature data at other time is respectively subtracted from the reference data to obtain temperature differences of each region of the submarine cable changing over time.

[0057] According to the embodiment of the present application, the first group of temperature data collected at 0 o'clock every day is taken as reference data , and each group of data collected later is respectively subtracted from the reference data to obtain a temperature difference curve of each time point of the entire cable .

[0058] Then, S3 is performed, in which, for each region of the submarine cable, the maximum temperature difference is compared with a preset exposure threshold value. If the maximum temperature difference of a region is greater than the preset exposure threshold value, the region is an exposed region; otherwise, the region is a non-exposed region.

[0059] According to the embodiment of the present application, when a typhoon passes through a marine area, due to the combined effect of strong wind and rainfall, the temperature of seawater decreases rapidly, and the temperature of the exposed submarine cable decreases faster than that of the buried submarine cable. During the period of the typhoon and before and after the period, the temperature of the exposed submarine cable changes more than that of the buried submarine cable. The temperature difference between the exposed submarine cable and the buried submarine cable provides a significant physical basis for identifying the exposed region.

[0060] Since the temperature change of the seabed and the sea bed is small under normal weather conditions, the temperature difference is small, and the absolute value of the temperature difference is used to determine the threshold value to determine whether each position is in a deep buried area, a shallow buried area or an exposed area. When a typhoon arrives, the temperature of the exposed submarine cable decreases significantly higher than the soil due to the temperature drop of seawater caused by the typhoon. The heat insulation effect of the soil makes its response to the temperature change of seawater small and has a hysteresis effect, and the temperature of the exposed submarine cable is significantly lower than that of the buried submarine cable. In this embodiment, 4℃ is used as the judgment threshold value (i.e. the preset exposure threshold value) of exposure, and greater than 4℃ is an exposed region, greater than 2℃ and less than 4℃ is a shallow buried region, and less than 1℃ is a deep buried region.

[0061] Then, S4 is performed, in which the exposed region of the submarine cable is subjected to a first processing to divide the exposed region into an existing continuous exposed region or a newly exposed region according to the duration of exposure; the first processing includes:

[0062] S41, a sliding window operation is performed on the temperature data corresponding to the exposed region to extract the time series and temperature series in each sliding window;

[0063] S42, based on the time series and the temperature series, a linear regression method is used to calculate the slope in the sliding window to obtain a plurality of slope values; the slope value is the ratio of temperature to time;

[0064] S43, the absolute value of the slope value is compared with a preset slope threshold value. If the absolute value of the slope value is greater than the preset slope threshold value, the temperature change interval is determined based on the slope value, and the next determination step is entered; otherwise, the exposed region is determined to be an existing continuous exposed region;

[0065] S44, the sliding window operation is performed again on the temperature change interval to calculate the local sliding window slope of the temperature change interval, and the average slope is obtained by averaging a plurality of local sliding window slopes;

[0066] S45, compare the average slope with a preset overall slope threshold value, if the average slope is lower than the preset overall slope threshold value, determine that the exposed area is a new exposed area; otherwise, determine that the exposed area is an existing continuous exposed area.

[0067] According to the embodiment of the present application, for the position reduced to 4℃, it is further divided into gradually reduced to 4℃ or suddenly reduced to 4℃, and according to the temperature difference change rate, it is distinguished whether it is a continuous exposed area or a new exposed area. In this embodiment, the method of sliding window slope calculation is adopted, as shown in the following figure, and the specific steps are as follows: Figure 2

[0068] 1) Data loading and preprocessing: load the original temperature difference data and time labels of each time of the exposed area position point; initialize the sliding window size and the slope threshold value of temperature change and other parameters.

[0069] 2) Sliding window slope calculation: perform sliding window operation on the temperature data, and the window length is a preset value, for example, the window size is set to 5; in each window, extract the time series and temperature series in the window; calculate the slope in the window by using the linear regression method (least square method in this embodiment), and record all the window slope results (slope array).

[0070] 3) Temperature change starting point detection: select the index point from the slope array that satisfies the condition that the absolute value of the slope is greater than the preset slope threshold value, and the preset slope threshold value is set to 0.3℃ / hour in this embodiment; determine the first time index point that satisfies the condition as the starting point of temperature change; if there is no time index point that satisfies the condition, it is determined that no obvious temperature change is detected, and the algorithm is exited.

[0071] 4) Temperature change end point detection: traverse the temperature data from the starting point to determine the time index position of the lowest temperature point in the interval; record the time index point of the lowest temperature point as the end point of temperature change.

[0072] 5) Change interval feature extraction: extract the temperature data segment and the corresponding time series between the starting point and the end point (referred to as the change interval); perform sliding window operation again to calculate the local sliding window slope of the change interval, and obtain the average slope.

[0073] 6) Change trend determination: compare the average slope of the change interval with a preset overall slope threshold value, if the average slope is lower than the preset overall slope threshold value, determine that it is a new exposed area, otherwise, determine that it is an existing continuous exposed area; the preset overall slope threshold value is set to 1℃ / hour in this embodiment.

[0074] Then S5 is performed, in which the exposed area of the submarine cable is subjected to a second processing to divide the exposed area into a suspended exposed area or a non-suspended exposed area according to the exposed state; the second processing comprises:​

[0075] S51, collecting second optical fiber signals along the submarine cable at multiple times after the typhoon period by using a second distributed optical fiber sensing system arranged in the submarine cable communication optical fiber, demodulating the second optical fiber signals to obtain vibration intensity data at multiple times;

[0076] S52, processing vibration intensity data at adjacent sampling times to obtain vibration characteristics;

[0077] S53, identifying multiple independent suspension regions of the submarine cable based on the vibration characteristics;

[0078] S54, determining an overlapping region of the multiple independent suspension regions in the exposed region of the submarine cable identified based on the temperature change in S3 as a suspended exposure, and determining a non-overlapping region as a non-suspended exposure.

[0079] According to the embodiment of the present application, in S51, after the typhoon period, the optical fiber signal is collected by using the second distributed optical fiber sensing system (phase sensitive optical time domain reflectometer), and the vibration intensity data is obtained by demodulating the collected optical fiber signal, that is, based on the vibration intensity time domain curve of the collected submarine cable along the line, the intensity-distance curve is generated wherein represents the vibration intensity of the i-th position point at time t, and N represents the total number of position points. The sampling time covers at least one complete tidal period to ensure that sufficient low-frequency excitation response information is obtained.

[0080] In S52, the vibration characteristics are obtained by processing the vibration intensity signals at adjacent sampling times, including:

[0081] First, for the vibration intensity time domain data, the adjacent time data is subjected to difference operation:

[0082] ;

[0083] wherein, represents the difference signal; represents the sampling time interval. The difference operation effectively highlights the dynamic change characteristics in the vibration signal and suppresses the interference of static background and slow-changing trend.

[0084] Then, the difference signal in a time window is averaged to obtain the vibration difference mean curve:

[0085] ;

[0086] wherein, represents the difference mean value of the i-th position point; M represents the number of time points in the window; represents the m-th sampling time. This step improves the spatial consistency and robustness of the signal, effectively enhancing the saliency of the vibration characteristics of the suspended area.

[0087] In S53, multiple independent suspended areas of the submarine cable are identified based on the vibration characteristics, including:

[0088] S531, compare each differential mean value on the vibration differential mean curve with a preset threshold value, if a certain differential mean value is greater than or equal to the preset threshold value, the label of the position point corresponding to the differential mean value is defined as 1, otherwise it is defined as 0; the position point with a label equal to 1 is an abnormal point, and the position point with a label equal to 0 is a normal point; wherein the preset threshold value T is determined according to the statistical distribution of historical monitoring data or combined with artificial experience, and can adopt a fixed threshold value or a dynamic threshold value; the dynamic threshold value can be calculated based on the mean μ and standard deviation σ of the interval composed of multiple position points: T = μ + k σ, wherein μ represents the intensity mean of the current interval position point; σ represents the intensity standard deviation of the current interval position point; k represents an experience coefficient (2 or 3); judge each differential mean value of the differential mean curve to obtain the label as follows:

[0089] ;

[0090] wherein, represents the label of whether the i-th position point is an abnormal point. Thus a sequence of binary labels is obtained , wherein a value of 1 indicates that the position point is an abnormal point.

[0091] S532, find a continuous section composed of multiple abnormal points according to the label; specifically, find a continuous section with a value of 1 from the label sequence , define it as an abnormal candidate interval , s and e are the starting position point and the ending position point of the continuous section; convert the index to physical distance: , wherein, , respectively represent the starting and ending distances of the continuous section; represents the spatial sampling interval (such as 4m).

[0092] S533, spatially cluster and merge multiple continuous sections to obtain multiple independent suspended areas; specifically, calculate the interval of the physical distance between adjacent continuous sections: , represents the starting position point of the n+1-th candidate continuous section, represents the ending position point of the n candidate continuous section; if ( If the merging threshold is specified (e.g., 20 m), then the two segments are merged into a new segment; otherwise, they are retained as independent segments. The above process is repeated until no further merging is possible, thus obtaining multiple independent suspended regions of the submarine cable.

[0093] In S54, the exposed area of ​​the submarine cable identified based on temperature change is compared with multiple independent suspended areas identified based on vibration intensity: the overlapping area of ​​the two is determined as the suspended exposed area, and the non-overlapping area is determined as the non-suspended exposed area.

[0094] Furthermore, following S5, the exposed areas are further assessed to determine whether they are persistent or newly exposed. Specifically, a second distributed optical fiber sensing system deployed in the submarine cable's communication optical fiber is used to collect optical fiber signals along the submarine cable at multiple times before the typhoon season. These signals are then demodulated to obtain pre-typhoon vibration intensity data. After processing according to S52 and S53, multiple independent exposed areas before the typhoon season are obtained. These independent exposed areas before and after the typhoon season are compared. If an independent exposed area only appears after the typhoon season, it is a newly exposed area. If an independent exposed area appears both before and after the typhoon season, it is a persistent exposed area. If an independent exposed area only appears before the typhoon season, it is a disappeared exposed area, which may have been filled with sediment and is no longer exposed, or it may be a non-exposed area. Figure 3 Schematic diagrams of temperature and vibration characteristics in different regions are provided.

[0095] The method proposed in this embodiment of the invention is further verified by combining the multibeam echo sounding results from September 27, 2024.

[0096] like Figure 4 As shown, vibration data obtained based on tidal modulation successfully identified the suspended zone, and the expansion or recession of the suspended zone was dynamically monitored in conjunction with strong sediment transport during the typhoon. The vibration intensity curves show extreme vibration intensity points at both ends of the suspended zone, exhibiting a catenary-like vibration curve. This is because the submarine cable vibrates under the scouring of ocean currents, and the water-sediment interface at the support point generates a large bending moment, resulting in the most intense vibration; this area is also prone to failure. Using these extreme points to locate the suspended segments allows for accurate determination of the length of each suspended segment. Vibration data from regions DS1 and DS2 indicate that the suspended zone existed before the typhoon, but disappeared afterward. Temperature data at corresponding locations showed a temperature drop, indicating that sediment transport during the typhoon caused the suspended zone to become exposed. Post-typhoon multibeam bath data confirmed that the area was no longer suspended.

[0097] Further by Figure 5It is seen that the temperature data corresponding to the suspended area CS3 region shows that the temperature drop range of this section is from 4.52115 km to 4.54628 km, with a total length of 25.13 meters, of which the new exposed area from 4.52115 km to 4.52993 km is about 8.78 meters long and caused by the typhoon, and the existing exposed area from 4.52993 km to 4.54628 km is about 16.35 meters long. The corresponding vibration data shows that the distance between the two vibration maximum points of this section before the typhoon is from 4.5236 km to 4.53994 km, a total of 16.34 meters, which is the existing suspended area. After the typhoon, the vibration data shows that the suspended area is expanded to about 25 meters from 4.519 km to 4.544 km, which is consistent with the newly generated exposed area shown by the temperature data. Combined with the vibration data, it is shown that not only exposure occurs in this section under the influence of the typhoon, but also a suspension is formed. The multi-beam sounding data shows that the length of the suspension is 25.15 meters, and the suspension height is 1.02 meters, verifying the accuracy of the vibration identification. The suspended area is the end of the original riprap dam, which is formed by erosion, and the maximum vibration intensity point is located at the junction of the two ends of the suspension, further confirming the effectiveness of the temperature and vibration data.

[0098] Similarly, the temperature data corresponding to the suspended area CS4 region shows a temperature anomaly of 19.3 meters from 4.6312 km to 4.6505 km. Before the typhoon, the distance between the two vibration maximum points is about 16 meters from 4.648 km to 4.654 km. After the typhoon, the vibration data shows that the length of the suspension is about 16 meters. The multi-beam sounding confirms that the length of the suspension is 15.61 meters, and the suspension height is 0.24 meters. The suspended area at this place is also the end of the original riprap dam, which is formed by erosion. The maximum vibration intensity point is located at the end of the suspension, and there is a partially exposed but not suspended area at the end of the suspension.

[0099] The multi-beam data of the suspended area NS region shows a suspended length of about 16.33 meters. The temperature data shows only a shallow burial state during the typhoon period due to the interruption of the optical cable. It is inferred that the typhoon and the residual wave process caused continuous erosion in this area, leading to exposure and further suspension. The vibration data after the typhoon shows that the length of the suspension is up to 40 meters, indicating that the typhoon caused the formation of a new suspended area.

[0100] The temperature data of the suspended area CS1 region shows multiple continuous exposed and suspended sections, with a buried section between the two exposed areas. The vibration data shows that the interface is the vibration maximum point, verifying that the vibration intensity of the interface is the most significant. The length of Z1 to Z2 section is 16.3 meters, which is basically consistent with the length of the exposed area measured by the multi-beam, which is 15.6 meters. Due to the low overhanging height, the multi-beam determines it as an exposed area, but in fact it is also a suspension under the state of sea current erosion.

[0101] The overhanging area CS2 region is measured about 21.3 meters overhanging, which is a naked overhanging area formed by the collapse of the original riprap dam. The vibration data and the temperature data both show that the area is a continuous naked area, and the overhanging is the existing state, which has existed before the typhoon. The multi-beam data shows that the naked length is 22.8 meters. Because the overhanging height is small, the actual overhanging state is determined to be naked.

[0102] The cross verification result of the multi-beam sounding proves that the dual-mode monitoring method for identifying the naked state based on the temperature drop and the overhanging state based on the vibration signal has good accuracy and reliability, and can provide high-precision and high-reliability technical support for the state evaluation of the submarine cable after the extreme event.

[0103] Another embodiment of the present application provides a submarine cable state identification system based on the typhoon effect and the tidal excitation, which is used to realize the submarine cable state identification method based on the typhoon effect and the tidal excitation as described in the above embodiment, as shown in the figure, the system comprises: Figure 6

[0104] The temperature data acquisition module 610 is configured to collect the first optical fiber signals of the submarine cable along the line at multiple time points during the typhoon by using the first distributed optical fiber sensing system arranged in the submarine cable communication optical fiber, demodulate the first optical fiber signals, and obtain the temperature data at multiple time points.

[0105] The naked identification module 620 is configured to take the first group of temperature data as the reference data, subtract each group of temperature data at the remaining time points from the reference data, and obtain the temperature difference of each region of the submarine cable changing with time. For the multiple temperature differences corresponding to each region of the submarine cable, the maximum value of the temperature difference is compared with the preset naked threshold value. If the maximum value of the temperature difference corresponding to a region is greater than the preset naked threshold value, the region is a naked region, otherwise it is a non-naked region.

[0106] The naked time identification module 630 is configured to perform a first processing on the naked region of the submarine cable, so as to divide the naked region into an existing continuous naked region or a newly born naked region according to the naked duration.

[0107] The overhanging naked identification module 640 is configured to perform a second processing on the naked region of the submarine cable, so as to divide the naked region into an overhanging naked region or a non-overhanging naked region according to the naked state.

[0108] The function of the submarine cable state identification system based on the typhoon effect and the tidal excitation as described in the embodiment of the present application can be explained by the aforementioned submarine cable state identification method based on the typhoon effect and the tidal excitation. Therefore, the system embodiment is not described in detail, and the above method embodiment can be referred to, and will not be described here.

[0109] ​Another embodiment of the present application also provides an electronic device, comprising: at least one processor and a memory storing a computer program; when the computer program is read and executed by the processor, the electronic device performs a method for identifying a state of a submarine cable based on typhoon effect and tidal excitation as described in the foregoing embodiments.

[0110] Another embodiment of the present application also provides a readable storage medium storing a computer program, when the computer program is read and executed by an electronic device, the electronic device performs a method for identifying a state of a submarine cable based on typhoon effect and tidal excitation as described in the foregoing embodiments.

[0111] While the principles and spirit of the application have been described with reference to several specific embodiments, it should be understood that the application is not limited to the specific embodiments disclosed, and the division of aspects is not meant to imply that features from these aspects cannot be combined to benefit, but is merely for the convenience of expression. The present application is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A method for identifying the state of submarine cables based on typhoon effect and tidal excitation, characterized in that, include: During typhoons, the first distributed optical fiber sensing system deployed in the communication optical fiber of the submarine cable is used to collect the first optical fiber signal along the submarine cable at multiple times, and the first optical fiber signal is demodulated to obtain temperature data at multiple times. Using the first set of temperature data as the baseline data, the temperature difference of each set of temperature data at the remaining time points is calculated with the baseline data to obtain the temperature difference of each region of the submarine cable over time. For each area of ​​the submarine cable, the maximum temperature difference is compared with the preset exposure threshold. If the maximum temperature difference of a certain area is greater than the preset exposure threshold, then the area is an exposed area; otherwise, it is a non-exposed area. The exposed areas of submarine cables are first treated to classify them into existing continuous exposed areas or newly exposed areas according to the duration of exposure. The exposed areas of submarine cables undergo a second treatment to classify them into suspended exposed areas or non-suspended exposed areas based on their exposure status.

2. The submarine cable status identification method based on typhoon effect and tidal excitation according to claim 1, characterized in that, The first distributed optical fiber sensing system is a Brillouin optical time domain analyzer, a Brillouin optical time domain reflectometer, or a distributed optical fiber Raman temperature sensor.

3. The submarine cable status identification method based on typhoon effect and tidal excitation according to claim 1, characterized in that, The first processing of the exposed areas of submarine cables to divide the exposed areas into existing continuous exposed areas or newly exposed areas according to the duration of exposure includes: A sliding window operation is performed on the temperature data corresponding to the exposed area to extract the time series and temperature series within each sliding window. Based on the time series and temperature series, a linear regression method is used to calculate the slope within the sliding window, obtaining multiple slope values, where the slope value is the ratio of temperature to time. The absolute value of the slope value is compared with a preset slope threshold. If the absolute value of the slope value is greater than the preset slope threshold, the temperature change range is determined based on the slope value, and the next judgment step is performed; otherwise, the exposed area is determined to be an existing continuous exposed area. The sliding window operation is performed again on the temperature change range to calculate the local sliding window slope of the temperature change range, and the average of multiple local sliding window slopes is taken to obtain the mean slope. The mean slope is compared with a preset overall slope threshold. If the mean slope is lower than the preset overall slope threshold, the exposed area is determined to be a newly exposed area; otherwise, the exposed area is determined to be an existing continuous exposed area.

4. The submarine cable status identification method based on typhoon effect and tidal excitation according to claim 3, characterized in that, The step of determining the temperature change range based on the slope value includes: determining the time index point corresponding to the absolute value of the slope being greater than a preset slope threshold from multiple slope values, and taking this time index point as the starting point of the temperature change; traversing the temperature data from the starting point, and determining the time index point with the lowest temperature within the sliding window as the end point of the temperature change; and determining the temperature change range based on the starting point and the end point of the temperature change.

5. The submarine cable status identification method based on typhoon effect and tidal excitation according to claim 4, characterized in that, The second processing of the exposed areas of submarine cables, to classify the exposed areas into suspended exposed areas or non-suspended exposed areas according to their exposure status, includes: The second distributed optical fiber sensing system deployed in the communication optical fiber of the submarine cable was used to collect the second optical fiber signal along the submarine cable at multiple times after the typhoon season. The second optical fiber signal was demodulated to obtain vibration intensity data at multiple times. The vibration intensity data at adjacent sampling times are processed to obtain vibration characteristics; Based on the vibration characteristics, multiple independent suspended regions of the submarine cable were identified; The overlapping areas between the exposed areas of the submarine cable identified based on temperature changes and the multiple independent suspended areas are defined as suspended exposed areas, and the non-overlapping areas are defined as non-suspended exposed areas.

6. The submarine cable status identification method based on typhoon effect and tidal excitation according to claim 5, characterized in that, The second distributed optical fiber sensing system is a phase-sensitive optical time-domain reflectometer; the process of processing the vibration intensity data at adjacent sampling times to obtain vibration characteristics includes: performing differential operations on the vibration intensity data at adjacent sampling times to obtain differential signals; and calculating the average value of the differential signals within a time window to obtain a vibration differential mean curve.

7. The submarine cable status identification method based on typhoon effect and tidal excitation according to claim 6, characterized in that, The method of identifying multiple independent suspended regions of submarine cables based on the vibration characteristics includes: comparing each mean difference on the vibration difference mean curve with a preset threshold; if a mean difference is greater than or equal to the preset threshold, the label of the location point corresponding to the mean difference is defined as 1, otherwise it is defined as 0; the location point with a label equal to 1 is an anomaly point, and the location point with a label equal to 0 is a normal point; finding a continuous segment composed of multiple anomaly points according to the labels; and performing spatial clustering and merging on multiple continuous segments to obtain multiple independent suspended regions.

8. The submarine cable state identification method based on typhoon effect and tidal excitation according to claim 7, characterized in that, The step of spatially clustering and merging multiple continuous segments to obtain multiple independent suspended regions includes: calculating the physical distance interval between adjacent continuous segments; if the physical distance interval is less than or equal to a preset merging threshold, then the adjacent continuous segments are merged into one segment; otherwise, they are retained as independent segments; repeating the above process until multiple continuous segments cannot be merged, resulting in multiple independent suspended regions; wherein, the formula for calculating the physical distance of each continuous segment is: ； In the formula, s and e are the starting and ending points of the continuous segment; Indicates the spatial sampling interval; , These represent the starting and ending distances of a continuous segment, respectively.

9. The submarine cable status identification method based on typhoon effect and tidal excitation according to claim 8, characterized in that, The method further includes: after determining the suspended exposed area, further judging the suspended exposed area to determine whether it is a persistent suspended exposed area or a newly formed suspended exposed area: using a second distributed optical fiber sensing system deployed in the communication optical fiber of the submarine cable to collect optical fiber signals along the submarine cable at multiple times before the typhoon season, demodulating the optical fiber signals to obtain vibration intensity data at multiple times before the typhoon season; processing the vibration intensity data at adjacent sampling times to obtain vibration characteristics; identifying multiple independent suspended areas of the submarine cable before the typhoon season based on the vibration characteristics; comparing the multiple independent suspended areas before and after the typhoon season, if an independent suspended area only appears after the typhoon season, then the independent suspended area is a newly formed suspended exposed area; if an independent suspended area appears both before and after the typhoon season, then the independent suspended area is a persistent suspended exposed area.

10. A submarine cable status identification system based on typhoon effect and tidal excitation, the system being used to implement the submarine cable status identification method based on typhoon effect and tidal excitation as described in any one of claims 1-9, characterized in that, The system includes: The temperature data acquisition module is configured to use a first distributed optical fiber sensing system deployed in the communication optical fiber of the submarine cable to collect the first optical fiber signal along the submarine cable at multiple times during the typhoon, demodulate the first optical fiber signal, and obtain temperature data at multiple times. The exposed cable identification module is configured to use the first set of temperature data as the reference data, and subtract the temperature data of each set of temperature data at other times from the reference data to obtain the temperature difference of each area of ​​the submarine cable over time; for multiple temperature differences corresponding to each area of ​​the submarine cable, the maximum temperature difference is compared with the preset exposed cable threshold. If the maximum temperature difference corresponding to a certain area is greater than the preset exposed cable threshold, then the area is an exposed area; otherwise, it is a non-exposed area. The exposed time identification module is configured to perform a first processing on the exposed area of ​​the submarine cable to divide the exposed area into existing continuous exposed areas or newly exposed areas according to the duration of exposure. The suspended exposed area identification module is configured to perform a second processing on the exposed area of ​​the submarine cable to classify the exposed area into a suspended exposed area or a non-suspended exposed area according to the exposed state.

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