CN111708093B - A multi-mode submarine cable buried depth detection method and detection system - Google Patents

Abstract

The invention relates to a multi-mode submarine cable buried depth detection method and a multi-mode submarine cable buried depth detection system, wherein the multi-mode submarine cable buried depth detection system comprises a measurement ship, an upper computer, a watertight towed body and a watertight cable, wherein the upper computer is arranged on the measurement ship, and a first triaxial fluxgate, a second triaxial fluxgate, an altimeter, an attitude instrument and a lower computer are arranged in the watertight towed body; the method comprises the following steps: inputting alternating current or direct current to the submarine cable through a current source; connecting the watertight towed body with an upper computer on a measuring ship by using a watertight cable; the measuring ship drags the watertight towed body through the watertight cable to scan the sea area; the first triaxial fluxgate and the second triaxial fluxgate respectively collect three components of a magnetic field, the altimeter collects the distance between the first triaxial fluxgate and the seabed and the Euler angle collected by the attitude instrument, and data are transmitted to the upper computer through the watertight cable; and the upper computer calculates the submarine cable burial depth according to the current type input to the submarine cable and the acquired data. The invention has various measuring forms, can measure the submarine cable burial depth for both alternating current and direct current of the submarine cable, and has simple operation.

Description

A multi-mode submarine cable buried depth detection method and detection system

technical field

The invention relates to the field of submarine cable operation and maintenance, and relates to a multi-mode submarine cable buried depth detection method and detection system, which are used to improve the efficiency of submarine cable buried depth measurement.

Background technique

Submarine cable depth detection is an indispensable link in the operation and maintenance of submarine cables. When the submarine cable fails, the accuracy and measurement efficiency of the buried depth data of the submarine cable will affect the time cost and economic cost of maintenance. At present, the buried depth of the submarine cable is determined by receiving the magnetic field changes generated by the submarine cable in space through the receiving coil instrument. Commonly used probes to measure the buried depth of submarine cables and multi-coils to measure the buried depth.

Probes for detecting the buried depth of submarine cables are as disclosed in the patent number CN105044784A. The double-probe submarine cable detection system includes a probe induction module, a module for filtering out interference signals, a peak signal extraction module, a core processor module, a keyboard module, and a liquid crystal display. Module and power module; the probe induction module adopts a double probe structure. The two probes are connected by a connecting rod of a fixed length. The axis directions of the two probes are parallel to each other, and the axis directions are perpendicular to the connecting rod. The detection method Including the detection of the position, direction and buried depth of the submarine cable.

Multi-coil buried depth measurement as disclosed in the patent number CN110850484A is a coil submarine cable detection device and a detection method. The detection device includes three sets of induction coils for detecting the induced electromotive force of the submarine cable. Each group of induction coils is a toroidal coil, and the detection device further includes a data transmission module and a host computer, three groups of induction coils, data transmission modules and the host computer are connected in sequence for communication; the three groups of induction coils will acquire the corresponding induced electromotive force transmission To the data transmission module, the data transmission module processes and transmits the information of the maximum induced electromotive force to the upper computer.

Using the above two methods to measure the buried depth of the submarine cable is only applicable to the case where the submarine cable is connected to alternating current, and is not applicable to the case that the submarine cable is connected to direct current. The structure also affects the selection of its optimal operating frequency. The determination of the coil structure means the determination of its optimal operating frequency; generally, one of 25Hz, 50Hz, and 133Hz is selected for measurement, and the measurement frequency is discontinuous.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a multi-mode submarine cable buried depth detection method and detection system in view of the defects of single application range and discontinuous measurement frequency in the prior art for submarine cable buried depth measurement.

In order to achieve the purpose, the technical scheme provided by the invention is:

The invention relates to a multi-mode submarine cable buried depth detection method, comprising the following steps:

1) Input alternating current or direct current to the submarine cable through the current source;

2) Use watertight cables to connect the watertight tow body with the first three-axis fluxgate, the second three-axis fluxgate, an altimeter, an attitude indicator and a lower computer to the upper computer on the surveying ship;

3) Place the watertight tow body in the sea water, and the survey ship drags the watertight tow body through the watertight cable and scans the sea area until the submarine cable is located directly below the survey ship, and the survey ship hovers above the submarine cable;

4) The first three-axis fluxgate collects the three _- component magnetic field at its position E1, the second three-axis fluxgate collects the three-component magnetic field at its position _E2 , and the altimeter collects the first three-axis fluxgate and the seabed. Distance h ₀ , the attitude meter collects Euler angles in the directions of X, Y, and Z axes, and the collected data is transmitted to the upper computer through the lower computer and the watertight cable;

5) The host computer calculates the buried depth of the submarine cable according to the type of current input to the submarine cable and the collected data.

The purpose of the current source described in step 1) of the present invention is to input alternating current or direct current to the submarine cable, which may refer to either the current source that comes with the submarine cable or a current source provided separately. Specifically, an alternating current source or a direct current can be used. source.

Preferably, in the described step 2), the second three-axis fluxgate is located directly below the first three-axis fluxgate, the altimeter is at the same height as the first three-axis fluxgate, the first three-axis fluxgate, The second three-axis fluxgate, the altimeter and the attitude meter are all connected to the lower computer, and the lower computer is connected to the upper computer through a watertight cable.

Preferably, in the step 1), what is input through the current source is alternating current, and the current value I is recorded after the submarine cable outputs the sinusoidal current signal of the stable frequency ω. In the step 5), the specific details of the buried depth of the submarine cable are calculated. Steps include:

5.1) According to the collected Euler angles in the directions of X, Y, and Z axes, form Euler rotation matrices R _X (α), R _Y (β), R _Z (γ), and Euler rotation matrix R _X (α ), R _Y (β), R _Z (γ) are calculated as:

Among them, α, β, γ are the Euler angle of the X axis, the Euler angle of the Y axis and the Euler angle of the Z axis;

5.2) Correct the three components of the magnetic field at the first three-axis fluxgate and the second three-axis fluxgate through the Euler rotation matrix, and the corrected counting method is:

Among them, B _x1 , B _Y1 , and B _Z1 are the three components of the magnetic field collected by the first three-axis fluxgate, B _x2 , B _Y2 , and B _Z2 are the three components of the magnetic field collected by the second three-axis fluxgate, and B _x1 ', B _Y1 ', B _Z1 ', B _x2 ', B _Y2 ', B _Z2 ' are the three components of the corrected magnetic field;

5.3) Perform Fourier transform on the three components of the corrected magnetic field respectively, and take the amplitudes A _x1 , A _Y1 , and A _Z1 of the X, Y, and Z-axis magnetic field vectors of the two three-axis fluxgates at the fixed frequency ω respectively. , A _x2 , A _Y2 , A _Z2 ;

5.4) Calculate the distance between the first three-axis fluxgate and the submarine cable. The calculation method of the distance is:

R ₁ =R ₂ +d ₀ (7);

where μ ₀ is the vacuum permeability, R ₁ is the distance between the first three-axis fluxgate and the submarine cable, R ₂ is the distance between the second three-axis fluxgate and the submarine cable, and d ₀ is the first three-axis magnetic flux the distance between the gate and the second three-axis fluxgate;

5.5) Calculate the buried depth h of the submarine cable, and the calculation formula is:

h=R ₁ -h ₀ (8);

Among them, h ₀ is the distance between the first three-axis fluxgate and the seabed, that is, the output of the altimeter.

Preferably, in the step 1), the input through the current source is direct current, and the specific steps of calculating the buried depth of the submarine cable in the step 5) include:

5.1) According to the collected Euler angles in the directions of X, Y, and Z axes, form Euler rotation matrices R _X (α), R _Y (β), R _Z (γ), and Euler rotation matrix R _X (α ), R _Y (β), R _Z (γ) are calculated as:

Among them, α, β, γ are the Euler angle of the X axis, the Euler angle of the Y axis and the Euler angle of the Z axis;

5.2) Correct the three components of the magnetic field at the first three-axis fluxgate and the second three-axis fluxgate through the Euler rotation matrix, and the corrected counting method is:

Among them, B _x1 , B _Y1 , and B _Z1 are the three components of the magnetic field collected by the first three-axis fluxgate, B _x2 , B _Y2 , and B _Z2 are the three components of the magnetic field collected by the second three-axis fluxgate, and B _x1 ', B _Y1 ', B _Z1 ', B _x2 ', B _Y2 ', B _Z2 ' are the three components of the corrected magnetic field;

5.3) Calculate the total magnetic fields B ₁ and B ₂ according to the three components of the corrected magnetic field, and the calculation formula is:

5.4) Calculate the distance between the first three-axis fluxgate and the submarine cable according to the total magnetic fields B ₁ and B ₂ , the calculation formula is:

R ₁ =R ₂ +d ₀ (13);

Among them, k is the proportional coefficient, R ₁ is the distance between the first three-axis fluxgate and the submarine cable, R ₂ is the distance between the second three-axis fluxgate and the submarine cable, and d ₀ is the first three-axis fluxgate and the submarine cable. The distance between the second and third axis fluxgates;

5.5) Calculate the buried depth h of the submarine cable, and the calculation formula is:

h=R ₁ -h ₀ (8);

h ₀ is the distance between the first three-axis fluxgate and the seabed, that is, the output of the altimeter.

Preferably, in the step 3), the measuring vessel drags the watertight tow body through the watertight cable and uses the S-shaped route to quickly scan the sea area. During the scanning process, the three-axis fluxgate continuously measures the X-axis magnetic field, and passes the watertight The cable is transmitted to the host computer, and the host computer generates the X-axis magnetic field waveform according to the continuously measured X-axis magnetic field. When the X-axis magnetic field waveform has a peak value, it indicates that the submarine cable is located directly under the measuring vessel.

Preferably, when alternating current is input to the submarine cable, step 6) is further included, and step 6) is: adjusting the frequency ω of the current, repeating steps 1) to 5) to obtain the buried depth of the submarine cable at continuous frequencies.

The invention also relates to a multi-mode submarine cable buried depth detection system, comprising a survey vessel, a host computer, a watertight tow body and a watertight cable; the host computer is arranged on the survey vessel; the watertight tow body communicates with the measurement vessel through the watertight cable. The ship is connected, and the watertight tow body is provided with a first three-axis fluxgate and a second three-axis fluxgate for collecting the three components of the magnetic field, and an altimeter for collecting the distance h ₀ between the first three-axis fluxgate and the seabed , an attitude meter for collecting Euler angles in the X, Y, and Z axis directions and a lower computer for receiving and transmitting data, the first three-axis fluxgate, the second three-axis fluxgate, an altimeter and an attitude meter They are all connected to the lower computer for communication, and the lower computer communicates with the upper computer through a watertight cable.

Preferably, the second three-axis fluxgate is located directly below the first three-axis fluxgate, and the height of the altimeter is the same as that of the first three-axis fluxgate.

Preferably, the watertight drag body includes a non-metallic watertight bin, and the first three-axis fluxgate, the second three-axis fluxgate, the altimeter, the attitude indicator and the lower computer are all fixed in the non-metallic watertight bin.

Preferably, it also includes a current source for inputting current to the submarine cable, and the current source is an alternating current source or a direct current source.

Adopting the technical scheme provided by the present invention, compared with the prior art, has the following beneficial effects:

1. The present invention selects the corresponding algorithm according to the type of current input to the submarine cable, and calculates the buried depth of the submarine cable according to the collected data. For the AC and DC currents of the submarine cable, the buried depth of the submarine cable can be measured, and the scope of application is wider. wide.

2. When AC power is input to the submarine cable, the buried depth of the submarine cable can be obtained by adjusting the frequency ω of the current and repeatedly measuring the buried depth of the submarine cable.

3. The present invention only needs to operate the high-power alternating current source, the watertight drag body and the upper computer, and the operation is simple.

Description of drawings

1 is a structural block diagram of a multi-mode submarine cable buried depth detection system involved in Embodiment 1;

2 is a structural block diagram of a multi-mode submarine cable buried depth detection system involved in Embodiments 2 and 3;

Fig. 3 is the structural block diagram of the water surface drag body;

FIG. 4 is a schematic diagram of the relative positions of the measuring vessel, the submarine cable and the two fluxgates of the present invention.

Notes: 1-current source, 2-watertight drag body, 3-first three-axis fluxgate, 4-second three-axis fluxgate, 5-altimeter, 6-attitude meter, 7-lower computer, 8- Watertight cable, 9-host computer, 10-measurement vessel, 11-submarine cable.

Detailed ways

In order to deepen the understanding of the present invention, the embodiments of the present invention are described in detail. The following examples are implemented on the premise of the technical solutions of the present invention, and provide detailed implementations, but the protection scope of the present invention is not limited to the following Example.

Example 1

1 and 3, the present embodiment relates to a multi-mode submarine cable buried depth detection system, including a survey vessel 10, a host computer 9, a watertight tow body 2 and a watertight cable 8; the host computer 9 is arranged in the measurement On the ship 10; the watertight drag body 2 is connected with the measuring vessel through the watertight cable 8, the watertight drag body 2 includes a non-metallic watertight warehouse, and the watertight drag body 2 is provided with a first three-axis fluxgate for collecting the three components of the magnetic field 3 and the second three-axis fluxgate 4. An altimeter for collecting the distance h ₀ between the first three-axis fluxgate and the seabed 5. An attitude meter for collecting Euler angles in the X, Y, and Z axis directions 6 and the lower computer 7 for receiving and transmitting data, the second three-axis fluxgate 4 is located directly below the first three-axis fluxgate 3, and the altimeter 5 is the same height as the first three-axis fluxgate 3 , the first three-axis fluxgate 3, the second three-axis fluxgate 4, the altimeter 5 and the attitude indicator 6 are all connected with the lower computer 7 in communication, and the lower computer 7 is connected with the upper computer 9 through the watertight cable 8 in communication, and the first three The axial fluxgate 3, the second three-axis fluxgate 4, the altimeter 5, the attitude indicator 6 and the lower computer 7 are all fixed in the non-metallic watertight bin.

The first three-axis fluxgate 3 and the second three-axis fluxgate 4 are Mag-13 three-axis fluxgates produced by British Bartington Company; the attitude indicator 6 adopts a three-dimensional attitude indicator; the non-metallic watertight cabin is composed of carbon fiber materials ; Watertight cable 8 uses multi-core Kevlar cable; altimeter 5 uses Valeport's VA500 seabed altimeter.

In this embodiment, the above-mentioned multi-mode submarine cable buried depth detection system is used to detect the buried depth of the submarine cable in normal operation. Under normal operation, the interior of the submarine cable is AC current, and the multi-mode submarine cable buried depth detection method includes the following steps:

1) In this embodiment, the submarine cable works normally, and there is no need to additionally input current to the submarine cable 11, and the current value I during normal operation is recorded;

2) Use watertight cable 8 to connect the watertight drag body 2 with the first three-axis fluxgate 3, the second three-axis fluxgate 4, the altimeter 5, the attitude meter 6 and the lower computer 7 and the upper position on the measuring vessel 10. machine 9 to connect;

3) The watertight tow body 2 is placed in seawater, the measuring vessel 10 drags the watertight tow body 2 through the watertight cable 8 and uses the S-shaped route to quickly scan the sea area. During the scan process, the three-axis fluxgate continuously measures the X-axis. The magnetic field is transmitted to the host computer through the watertight cable, and the host computer generates the X-axis magnetic field waveform according to the X-axis magnetic field measured continuously. After 11 is located directly under the surveying vessel 10, the surveying vessel 10 hovers above the submarine cable 11. At this time, the positions of the surveying vessel 10, the first three-axis fluxgate 3, the second three-axis fluxgate 4 and the submarine cable 11 are The relationship is shown in Figure 4, the measuring vessel 10, the first three-axis fluxgate 3, the second three-axis fluxgate 4 and the submarine cable 11 are located on the same vertical line, and the second three-axis fluxgate 4 is located on the submarine cable. 11, the first three-axis fluxgate 3 is located directly above the second three-axis fluxgate 4, and the measuring vessel 10 is located directly above the first three-axis fluxgate 3;

4) The first three-axis fluxgate 3 collects the three _- component magnetic field at its position E1, the second three-axis fluxgate 4 collects the three-component magnetic field at its position _E2 , and the altimeter 5 collects the first three-axis fluxgate 3 The distance h ₀ from the seabed, the attitude meter 6 collects Euler angles in the X, Y, and Z axis directions, and the collected data is transmitted to the upper computer 9 through the lower computer 7 and the watertight cable 8;

5) In this embodiment, the internal current of the submarine cable 11 is alternating current. The buried depth of the submarine cable 11 is calculated according to the current type, the collected data and the recorded current value I, and the calculation steps of the buried depth include:

5.1) According to the collected Euler angles in the directions of X, Y, and Z axes, form Euler rotation matrices R _X (α), R _Y (β), R _Z (γ), and Euler rotation matrix R _X (α ), R _Y (β), R _Z (γ) are calculated as:

Among them, α, β, γ are the Euler angle of the X axis, the Euler angle of the Y axis and the Euler angle of the Z axis;

5.2) Correct the three components of the magnetic field at the first three-axis fluxgate 3 and the second three-axis fluxgate 4 through the Euler rotation matrix, that is, convert the three components of the AC magnetic field to the geographic coordinate system, and the corrected counting method is as follows: :

Among them, B _x1 , B _Y1 , and B _Z1 are the three components of the magnetic field collected by the first three-axis fluxgate 3 , and B _x2 , B _Y2 , and B _Z2 are the three components of the magnetic field collected by the second three-axis fluxgate 4 , B _x1 ', B _Y1 ', B _Z1 ', B _x2 ', B _Y2 ', B _Z2 ' are the three components of the corrected magnetic field;

5.3) Perform Fourier transform on the three components of the corrected magnetic field respectively, and take the amplitudes A _x1 , A _Y1 , and A _Z1 of the X, Y, and Z-axis magnetic field vectors of the two three-axis fluxgates at the fixed frequency ω respectively. , A _x2 , A _Y2 , A _Z2 ;

5.4) Calculate the distance between the first three-axis fluxgate 3 and the submarine cable 11. The calculation method of the distance is:

R ₁ =R ₂ +d ₀ (7);

Wherein μ ₀ is the vacuum permeability, R ₁ is the distance between the first three-axis fluxgate 3 and the submarine cable 11, R ₂ is the distance between the second three-axis fluxgate 4 and the submarine cable 11, and d ₀ is the first The distance between the three-axis fluxgate 3 and the second three-axis fluxgate 4, d ₀ is measured when the watertight drag body 2 is installed;

5.5) Calculate the buried depth h of the submarine cable 11, and the calculation formula is:

h=R ₁ -h ₀ (8);

Wherein, h ₀ is the distance between the first three-axis fluxgate 3 and the seabed, that is, the output of the altimeter 6;

The buried depth h of the submarine cable 11 is finally calculated and displayed on the host computer 9 .

Embodiment 2

2 and 3, the present embodiment relates to a multi-mode submarine cable buried depth detection system, including a current source 1, a measuring vessel 10, a host computer 9, a watertight drag body 2 and a watertight cable 8. The current source 1 is connected to the submarine cable, and the current source 1 is an alternating current source or a direct current source, which is used to input alternating current or direct current to the submarine cable 11; the upper computer 9 is arranged on the measuring vessel 10; the watertight tow The body 2 is connected to the measuring vessel through a watertight cable 8. The watertight drag body 2 includes a non-metallic watertight bin. The watertight drag body 2 is provided with a first three-axis fluxgate 3 and a second three-axis fluxgate for collecting the three components of the magnetic field. 4. An altimeter 5 used to collect the distance h ₀ between the first three-axis fluxgate and the seabed, an attitude meter 6 used to collect Euler angles in the X, Y, and Z axis directions, and an altimeter 6 used to receive and transmit data The lower computer 7, the second three-axis fluxgate 4 is located directly below the first three-axis fluxgate 3, the altimeter 5 is the same height as the first three-axis fluxgate 3, and the first three-axis fluxgate 3 , the second three-axis fluxgate 4, the altimeter 5 and the attitude meter 6 are all connected with the lower computer 7, the lower computer 7 is connected with the upper computer 9 through the watertight cable 8, the first three-axis fluxgate 3, the second three The axis fluxgate 4, the altimeter 5, the attitude indicator 6 and the lower computer 7 are all fixed in the non-metallic watertight bin.

The first three-axis fluxgate 3 and the second three-axis fluxgate 4 are Mag-13 three-axis fluxgates produced by British Bartington Company; the attitude indicator 6 adopts a three-dimensional attitude indicator; the non-metallic watertight cabin is composed of carbon fiber materials ; Watertight cable 8 uses multi-core Kevlar cable; altimeter 5 uses Valeport's VA500 seabed altimeter.

In this embodiment, the above-mentioned multi-mode submarine cable buried depth detection system is used to detect the buried depth of an abnormally working submarine cable, and the multi-mode submarine cable buried depth detection method includes the following steps:

1) In this embodiment, the current source 1 is used to input alternating current to the submarine cable 11. The current source is a high-power alternating current source. The current source 1 adopts the programmable alternating current power source of All Sky Technology. Direct current can be output, this embodiment only outputs alternating current, and the current value I is recorded after the submarine cable outputs a sinusoidal current signal with a stable frequency ω;

2) Use watertight cable 8 to connect the watertight drag body 2 with the first three-axis fluxgate 3, the second three-axis fluxgate 4, the altimeter 5, the attitude meter 6 and the lower computer 7 and the upper position on the measuring vessel 10. machine 9 to connect;

3) The watertight tow body 2 is placed in seawater, the measuring vessel 10 drags the watertight tow body 2 through the watertight cable 8 and uses the S-shaped route to quickly scan the sea area. During the scan process, the three-axis fluxgate continuously measures the X-axis. The magnetic field is transmitted to the host computer through the watertight cable, and the host computer generates the X-axis magnetic field waveform according to the X-axis magnetic field measured continuously. After 11 is located directly under the surveying vessel 10, the surveying vessel 10 hovers above the submarine cable. At this time, the positional relationship between the surveying vessel 10, the first three-axis fluxgate 3, the second three-axis fluxgate 4 and the submarine cable 11 As shown in FIG. 4 , the measuring vessel 10 , the first three-axis fluxgate 3 , the second three-axis fluxgate 4 and the submarine cable 11 are located on the same vertical line, and the second three-axis fluxgate 4 is located on the submarine cable 11 Right above, the first three-axis fluxgate 3 is located just above the second three-axis fluxgate 4, and the measuring vessel 10 is located just above the first three-axis fluxgate 3;

4) The first three-axis fluxgate 3 collects the three _- component magnetic field at its position E1, the second three-axis fluxgate 4 collects the three-component magnetic field at its position _E2 , and the altimeter 5 collects the first three-axis fluxgate 3 The distance h ₀ from the seabed, the attitude meter 6 collects Euler angles in the X, Y, and Z axis directions, and the collected data is transmitted to the upper computer 9 through the lower computer 7 and the watertight cable 8;

5) In the present embodiment, the internal current of the submarine cable 11 is alternating current, and the buried depth of the submarine cable 11 is calculated according to the current type, the collected data and the recorded current value I, and the calculation steps of the buried depth include:

5.1) According to the collected Euler angles in the directions of X, Y, and Z axes, form Euler rotation matrices R _X (α), R _Y (β), R _Z (γ), and Euler rotation matrix R _X (α ), R _Y (β), R _Z (γ) are calculated as:

Among them, α, β, γ are the Euler angle of the X axis, the Euler angle of the Y axis and the Euler angle of the Z axis;

5.2) Correct the three components of the magnetic field at the first three-axis fluxgate 3 and the second three-axis fluxgate 4 through the Euler rotation matrix, that is, convert the three components of the AC magnetic field to the geographic coordinate system, and the corrected counting method is as follows: :

Among them, B _x1 , B _Y1 , and B _Z1 are the three components of the magnetic field collected by the first three-axis fluxgate 3 , and B _x2 , B _Y2 , and B _Z2 are the three components of the magnetic field collected by the second three-axis fluxgate 4 , B _x1 ', B _Y1 ', B _Z1 ', B _x2 ', B _Y2 ', B _Z2 ' are the three components of the corrected magnetic field;

5.3) Perform Fourier transform on the three components of the corrected magnetic field respectively, and take the amplitudes A _x1 , A _Y1 , and A _Z1 of the X, Y, and Z-axis magnetic field vectors of the two three-axis fluxgates at the fixed frequency ω respectively. , A _x2 , A _Y2 , A _Z2 ;

5.4) Calculate the distance between the first three-axis fluxgate 3 and the submarine cable 11. The calculation method of the distance is:

R ₁ =R ₂ +d ₀ (7);

Wherein μ ₀ is the vacuum permeability, R ₁ is the distance between the first three-axis fluxgate 3 and the submarine cable 11, R ₂ is the distance between the second three-axis fluxgate 4 and the submarine cable 11, and d ₀ is the first The distance between the three-axis fluxgate 3 and the second three-axis fluxgate 4, d ₀ is measured when the watertight drag body 2 is installed;

5.5) Calculate the buried depth h of the submarine cable 11, and the calculation formula is:

h=R ₁ -h ₀ (8);

Among them, h ₀ is the distance between the first three-axis fluxgate and the seabed, that is, the output of the altimeter;

6) Adjust the frequency ω of the current, and repeat steps 1) to 5) to obtain the buried depth of the submarine cable under the continuous frequency;

The buried depth h of the submarine cable 11 is finally calculated and displayed on the host computer 9 .

Embodiment 3

The structure of the multi-mode submarine cable buried depth detection system in this embodiment is the same as that of the second embodiment, and this embodiment will not be described again. For detection, the multi-mode submarine cable buried depth detection method includes the following steps:

1) In this embodiment, direct current is input to the submarine cable 11 through the current source 1. The current source is a high-power direct current source. Output direct current, this embodiment only outputs direct current;

2) Use watertight cable 8 to connect the watertight drag body 2 with the first three-axis fluxgate 3, the second three-axis fluxgate 4, the altimeter 5, the attitude meter 6 and the lower computer 7 and the upper position on the measuring vessel 10. machine 9 to connect;

3) The watertight tow body 2 is placed in seawater, the measuring vessel 10 drags the watertight tow body 2 through the watertight cable 8 and uses the S-shaped route to quickly scan the sea area. During the scan process, the three-axis fluxgate continuously measures the X-axis. The magnetic field is transmitted to the host computer through the watertight cable, and the host computer generates the X-axis magnetic field waveform according to the X-axis magnetic field measured continuously. After 11 is located directly under the surveying vessel 10, the surveying vessel 10 hovers above the submarine cable. At this time, the positional relationship between the surveying vessel 10, the first three-axis fluxgate 3, the second three-axis fluxgate 4 and the submarine cable 11 As shown in FIG. 4 , the measuring vessel 10 , the first three-axis fluxgate 3 , the second three-axis fluxgate 4 and the submarine cable 11 are located on the same vertical line, and the second three-axis fluxgate 4 is located on the submarine cable 11 Right above, the first three-axis fluxgate 3 is located just above the second three-axis fluxgate 4, and the measuring vessel 10 is located just above the first three-axis fluxgate 3;

4) The first three-axis fluxgate 3 collects the three _- component magnetic field at its position E1, the second three-axis fluxgate 4 collects the three-component magnetic field at its position _E2 , and the altimeter 5 collects the first three-axis fluxgate 3 The distance h ₀ from the seabed, the attitude meter 6 collects Euler angles in the X, Y, and Z axis directions, and the collected data is transmitted to the upper computer 9 through the lower computer 7 and the watertight cable 8;

5) In this embodiment, the internal current of the submarine cable 11 is direct current, and the buried depth of the submarine cable 11 is calculated according to the current type and the collected data. The calculation steps of the buried depth include:

5.1) According to the collected Euler angles in the directions of X, Y, and Z axes, form Euler rotation matrices R _X (α), R _Y (β), R _Z (γ), and Euler rotation matrix R _X (α ), R _Y (β), R _Z (γ) are calculated as:

Among them, α, β, γ are the Euler angle of the X axis, the Euler angle of the Y axis and the Euler angle of the Z axis;

5.2) Correct the three components of the magnetic field at the first three-axis fluxgate 3 and the second three-axis fluxgate 4 through the Euler rotation matrix, and the corrected counting method is:

Among them, B _x1 , B _Y1 , and B _Z1 are the three components of the magnetic field collected by the first three-axis fluxgate 3 , and B _x2 , B _Y2 , and B _Z2 are the three components of the magnetic field collected by the second three-axis fluxgate 4 , B _x1 ', B _Y1 ', B _Z1 ', B _x2 ', B _Y2 ', B _Z2 ' are the three components of the corrected magnetic field;

5.3) Calculate the total magnetic fields B ₁ and B ₂ according to the three components of the corrected magnetic field, and the calculation formula is:

5.4) Calculate the distance between the first three-axis fluxgate 3 and the submarine cable 11 according to the total magnetic fields B ₁ and B ₂ , and the calculation formula is:

R ₁ =R ₂ +d ₀ (13);

Among them, k is the proportional coefficient, R ₁ is the distance between the first three-axis fluxgate 3 and the submarine cable 11, R ₂ is the distance between the second three-axis fluxgate 4 and the submarine cable 11, and d ₀ is the first three-axis fluxgate. The distance between the fluxgate 3 and the second three-axis fluxgate 4, d ₀ is measured when the watertight drag body 2 is installed;

5.5) Calculate the buried depth h of the submarine cable, and the calculation formula is:

h=R ₁ -h ₀ (8);

h ₀ is the distance between the first three-axis fluxgate 3 and the seabed, that is, the output of the altimeter 6;

The buried depth h of the submarine cable 11 is finally calculated and displayed on the host computer 9 .

Through the above-mentioned three embodiments, the working principle of the present invention is summarized as follows:

When measuring the buried depth by AC, if the submarine cable is working normally, the current value I will be recorded in real time; if the submarine cable is not working normally, connect one end of the submarine cable to the current source, and adjust the high-power current source to output a sinusoidal current signal with a stable frequency ω. Record the current value I, two three-axis fluxgate magnetometers measure the three components of the magnetic field, convert the three-component AC magnetic field to the geographic coordinate system through the angle data provided by the attitude meter, and then go through Fourier transformation to obtain the three-axis magnetic flux The three components of the door are finally substituted into the AC submarine cable buried depth equation to calculate the submarine cable buried depth. The working mechanism of the submarine cable's normal working buried depth measurement is basically the same as the AC buried depth measurement, but the method of obtaining the current value is different;

When measuring the buried depth with DC, connect one end of the submarine cable to the current source, adjust the high-power current source to output a stable DC current signal, and two three-axis fluxgate magnetometers measure the three components of the magnetic field, and use the angle provided by the attitude meter. The data converts the three components of the AC magnetic field into the geographic coordinate system, and obtains the three components of the three-axis fluxgate. Finally, it is substituted into the buried depth equation of the DC submarine cable to calculate the buried depth of the submarine cable.

The present invention has been described in detail above with reference to the embodiments, but the above contents are only preferred embodiments of the present invention and cannot be considered to limit the implementation scope of the present invention. All equivalent changes and improvements made according to the scope of the application of the present invention should still fall within the scope of the patent of the present invention.

Claims (8)

1. a multi-mode submarine cable buried depth detection method, is characterized in that: it comprises the following steps: 1) Input alternating current or direct current to the submarine cable through the current source; 2) Use watertight cables to connect the watertight tow body with the first three-axis fluxgate, the second three-axis fluxgate, an altimeter, an attitude indicator and a lower computer to the upper computer on the surveying ship; 3) Place the watertight tow body in the sea water, and the survey ship drags the watertight tow body through the watertight cable and scans the sea area until the submarine cable is located directly below the survey ship, and the survey ship hovers above the submarine cable; 4) The first three-axis fluxgate collects the three _- component magnetic field at its position E1, the second three-axis fluxgate collects the three-component magnetic field at its position _E2 , and the altimeter collects the first three-axis fluxgate and the seabed. Distance h ₀ , the attitude meter collects Euler angles in the directions of X, Y, and Z axes, and the collected data is transmitted to the upper computer through the lower computer and the watertight cable; 5) The host computer calculates the buried depth of the submarine cable according to the type of current input to the submarine cable and the collected data; When the input through the current source in step 1) is alternating current, the current value I is recorded after the submarine cable outputs the sinusoidal current signal of the stable frequency ω, and the concrete steps of calculating the buried depth of the submarine cable in the described step 5) include: 5.1) According to the collected Euler angles in the directions of X, Y, and Z axes, form Euler rotation matrices R _X (α), R _Y (β), R _Z (γ), and Euler rotation matrix R _X (α ), R _Y (β), R _Z (γ) are calculated as:

Among them, α, β, γ are the Euler angle of the X axis, the Euler angle of the Y axis and the Euler angle of the Z axis; 5.2) Correct the three components of the magnetic field at the first three-axis fluxgate and the second three-axis fluxgate through the Euler rotation matrix, and the corrected counting method is:

Among them, B _x1 , B _Y1 , and B _Z1 are the three components of the magnetic field collected by the first three-axis fluxgate, B _x2 , B _Y2 , and B _Z2 are the three components of the magnetic field collected by the second three-axis fluxgate, and B _x1 ', B _Y1 ', B _Z1 ', B _x2 ', B _Y2 ', B _Z2 ' are the three components of the corrected magnetic field; 5.3) Perform Fourier transform on the three components of the corrected magnetic field respectively, and take the amplitudes A _x1 , A _Y1 , and A _Z1 of the X, Y, and Z-axis magnetic field vectors of the two three-axis fluxgates at the fixed frequency ω respectively. , A _x2 , A _Y2 , A _Z2 ; 5.4) Calculate the distance between the first three-axis fluxgate and the submarine cable. The calculation method of the distance is:

R ₁ =R ₂ +d ₀ (7); where μ ₀ is the vacuum permeability, R ₁ is the distance between the first three-axis fluxgate and the submarine cable, R ₂ is the distance between the second three-axis fluxgate and the submarine cable, and d ₀ is the first three-axis magnetic flux the distance between the gate and the second three-axis fluxgate; 5.5) Calculate the buried depth h of the submarine cable, and the calculation formula is: h=R ₁ -h ₀ (8); Among them, h ₀ is the distance between the first three-axis fluxgate and the seabed, that is, the output of the altimeter; When the direct current is input through the current source in step 1), the specific steps of calculating the buried depth of the submarine cable in step 5) include: 5.1) According to the collected Euler angles in the directions of X, Y, and Z axes, form Euler rotation matrices R _X (α), R _Y (β), R _Z (γ), and Euler rotation matrix R _X (α ), R _Y (β), R _Z (γ) are calculated as:

Among them, α, β, γ are the Euler angle of the X axis, the Euler angle of the Y axis and the Euler angle of the Z axis; 5.2) Correct the three components of the magnetic field at the first three-axis fluxgate and the second three-axis fluxgate through the Euler rotation matrix, and the corrected counting method is:

Among them, B _x1 , B _Y1 , and B _Z1 are the three components of the magnetic field collected by the first three-axis fluxgate, B _x2 , B _Y2 , and B _Z2 are the three components of the magnetic field collected by the second three-axis fluxgate, and B _x1 ', B _Y1 ', B _Z1 ', B _x2 ', B _Y2 ', B _Z2 ' are the three components of the corrected magnetic field; 5.3) Calculate the total magnetic fields B ₁ and B ₂ according to the three components of the corrected magnetic field, and the calculation formula is:

5.4) Calculate the distance between the first three-axis fluxgate and the submarine cable according to the total magnetic fields B ₁ and B ₂ , the calculation formula is:

R ₁ =R ₂ +d ₀ (13); Among them, k is the proportional coefficient, R ₁ is the distance between the first three-axis fluxgate and the submarine cable, R ₂ is the distance between the second three-axis fluxgate and the submarine cable, and d ₀ is the first three-axis fluxgate and the submarine cable. The distance between the second and third axis fluxgates; 5.5) Calculate the buried depth h of the submarine cable, and the calculation formula is: h=R ₁ -h ₀ (8); h ₀ is the distance between the first three-axis fluxgate and the seabed, that is, the output of the altimeter. 2. The multi-mode submarine cable buried depth detection method according to claim 1, characterized in that: in the step 2), the second three-axis fluxgate is located directly below the first three-axis fluxgate, and the altimeter The same height as the first three-axis fluxgate, the first three-axis fluxgate, the second three-axis fluxgate, the altimeter and the attitude meter are all connected to the lower computer, and the lower computer is connected to the upper computer through a watertight cable. 3. multi-mode submarine cable buried depth detection method according to claim 1, is characterized in that: in described step 3), surveying vessel drags watertight drag body by watertight cable and adopts S-type route to carry out fast scanning to sea area, During the scanning process, the three-axis fluxgate continuously measures the X-axis magnetic field, and transmits it to the host computer through a watertight cable. The host computer generates the X-axis magnetic field waveform according to the continuously measured X-axis magnetic field. Indicates that the submarine cable is directly below the survey vessel. 4. The multi-mode submarine cable buried depth detection method according to claim 1, characterized in that: when the input to the submarine cable is alternating current, it also includes step 6), and step 6) is: adjusting the frequency ω of the current, repeating In steps 1) to 5), the buried depth of the submarine cable under the continuous frequency is obtained. 5. The multi-mode submarine cable buried depth detection method according to claim 1 is characterized in that: it is realized based on a multi-mode submarine cable buried depth detection system, and the multi-mode submarine cable buried depth detection system comprises a survey vessel, a host The upper computer is set on the measuring vessel; the watertight towing body is connected with the measuring vessel through the watertight cable, and the inside of the watertight towing body is provided with a first three-axis magnetic field for collecting the three components of the magnetic field. A pass gate and a second three-axis fluxgate, an altimeter for collecting the distance h ₀ of the first three-axis fluxgate and the seabed, an attitude meter for collecting Euler angles in the X, Y, and Z axis directions, and The lower computer used to receive and transmit data, the first three-axis fluxgate, the second three-axis fluxgate, the altimeter and the attitude meter are all connected to the lower computer, and the lower computer communicates with the upper computer through a watertight cable. 6 . The multi-mode submarine cable buried depth detection method according to claim 5 , wherein the second three-axis fluxgate is located directly below the first three-axis fluxgate, and the altimeter is connected to the first three-axis fluxgate. 7 . Fluxgate contour. 7. The multi-mode submarine cable buried depth detection method according to claim 6, wherein the watertight drag body comprises a non-metallic watertight bin, the first three-axis fluxgate, the second three-axis magnetic fluxgate The door, altimeter, attitude indicator and lower computer are all fixed in the non-metallic watertight compartment. 8. The multi-mode submarine cable buried depth detection method according to claim 6, characterized in that: it further comprises a current source for inputting current to the submarine cable, and the current source is an alternating current source or a DC current source .

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