Submarine Cable Laying Control Method and System Based on Constant Catenary Length

Abstract

This invention relates to the field of submarine cable laying technology, specifically disclosing a submarine cable laying control method and system based on a constant catenary length. This invention utilizes real-time measurement of the vertical water depth H below the cable exit point of the cable-laying vessel. c 1. The vertical water depth H above the plowshare is burying the plow. l The angle θ of the submarine cable entering the water at the point where the cable-laying vessel exits the water. c The entry angle θ of the submarine cable at the point where the plough enters the plough head. l The horizontal distance D between the cable-laying vessel's cable exit point and the burial plow's entry point is determined based on H at each moment. c H l θ c θ l D calculates the catenary length L at each moment, and further compares L with the preset catenary length L e The length deviation value ΔL is obtained by subtracting the length deviation value ΔL, and then the cable-laying speed of the cable-laying vessel is controlled according to the length deviation value ΔL. This invention ensures the smooth laying of submarine cables with a fixed slack by estimating the catenary length in real time and adjusting the cable-laying speed in real time.

Description

Technical Field

[0001] This invention relates to the field of submarine cable laying technology, and in particular to a submarine cable laying control method and system based on a constant catenary length. Background Technology

[0002] Submarine cables are cables wrapped in insulating materials and laid on the seabed. They are divided into submarine communication cables and submarine power cables. Modern submarine communication cables use optical fibers as materials to transmit telephone and Internet signals for telecommunications transmission.

[0003] In submarine cable construction, cables need to be buried on the seabed. The catenary method is currently a mainstream laying method, using a cable-laying vessel in conjunction with a burial plow. During catenary laying, the burial plow is towed by the cable-laying vessel, requiring careful control of cable tension. Excessive tension can cause mechanical damage, while insufficient tension can lead to cable twisting. The laying speed directly determines the cable tension. In flat seabed areas, cable tension can also be measured by the catenary length. By comparing the catenary length between the cable-laying vessel's exit point and the burial plow's entry point with a predetermined catenary length, the laying speed can be controlled, achieving a certain amount of slack in the laying process. However, currently, there is a lack of a precise method for measuring the catenary length, making it difficult to guarantee the smooth implementation of this method. Summary of the Invention

[0004] This invention provides a method and system for controlling submarine cable laying based on a constant catenary length. The technical problem it solves is how to accurately estimate the length of the catenary between the cable-laying vessel's cable exit point and the burial plow's entry point, so as to ensure the smooth laying of submarine cables with a fixed allowance.

[0005] To solve the above technical problems, the present invention provides a submarine cable laying control system based on a constant catenary length, comprising the following steps:

[0006] S1. The vertical water depth below the cable-laying vessel's cable exit point is measured in real time and recorded as H. c The vertical water depth above the plowshare, measured in real time, is recorded as H. l The angle of entry of the submarine cable into the water at the point where the cable-laying vessel exits the water is measured in real time and recorded as θ. c The angle of entry of the submarine cable into the plough at the ploughing point is measured in real time and recorded as θ. l The horizontal distance between the cable-laying vessel's cable exit point and the burial plow's entry point, measured in real time, is denoted as D.

[0007] S2, based on H at the current time c H l θ c θ l D calculates the length L of the catenary at the current moment;

[0008] S3. Compare the current catenary length L with the preset catenary length L e The difference is calculated to obtain the length deviation value ΔL;

[0009] S4. Control the cable-laying speed of the cable-laying vessel according to the length deviation value ΔL.

[0010] Further, in step S2, the length L of the catenary at the current moment is calculated based on the following formula:

[0011]

[0012] Furthermore, in step S3, the preset catenary length L e Set to:

[0013]

[0014] These are empirical parameter values.

[0015] Further, step S4 specifically includes:

[0016] When ΔL is greater than 0, decrease the cable laying speed; when ΔL = 0, keep the cable laying speed constant; when ΔL is less than 0, increase the cable laying speed.

[0017] Furthermore, the cable laying speed is controlled based on the PID control principle according to ΔL.

[0018] The present invention also provides a submarine cable laying control system based on a constant catenary length, the key features of which are: a water depth detection unit, an angle measurement unit, a distance measurement unit, a catenary length calculation unit, a catenary length comparison unit, and a cable laying machine control unit;

[0019] The water depth detection unit is used to measure the vertical water depth below the cable-laying vessel's cable-laying point in real time, denoted as H. c And the real-time measurement of the vertical water depth above the plowshare, denoted as H. l ;

[0020] The angle measuring unit is used to measure the water entry angle of the submarine cable at the cable-laying vessel's cable exit point in real time, denoted as θ. c The angle of entry of the submarine cable into the plough at the ploughing point is measured in real time and denoted as θ. l ;

[0021] The distance measurement unit is used to measure the horizontal distance between the cable-laying vessel's cable exit point and the burial plow's entry point in real time, denoted as D.

[0022] The catenary length calculation unit is used to calculate the length of the catenary based on the current H. c H l θ c θ lD calculates the length L of the catenary at the current moment;

[0023] The catenary length comparison unit is used to compare the current catenary length L with a preset catenary length L. e The difference is calculated to obtain the length deviation value ΔL;

[0024] The cable-laying machine control unit is used to control the cable-laying speed of the cable-laying vessel based on the length deviation value ΔL.

[0025] Specifically, the catenary length calculation unit calculates the current catenary length L based on the following formula:

[0026]

[0027] Specifically, the preset catenary length L e Set to:

[0028]

[0029] These are empirical parameter values.

[0030] Specifically, the cable-laying machine control unit is used to control the cable-laying speed of the cable-laying vessel according to the length deviation value ΔL, specifically:

[0031] When ΔL is greater than 0, decrease the cable laying speed; when ΔL = 0, keep the cable laying speed constant; when ΔL is less than 0, increase the cable laying speed.

[0032] Preferably, the cable-laying machine control unit adopts the PID control principle to control the cable-laying speed according to ΔL.

[0033] The present invention provides a method and system for controlling submarine cable laying based on a constant catenary length, which measures the vertical water depth H below the cable-laying vessel at the cable exit point in real time. c 1. The vertical water depth H above the plowshare is burying the plow. l The angle θ of the submarine cable entering the water at the point where the cable-laying vessel exits the water. c The entry angle θ of the submarine cable at the point where the plough enters the plough head. l The horizontal distance D between the cable-laying vessel's cable exit point and the burial plow's entry point is determined based on H at each moment. c H l θ c θ l D calculates the catenary length L at each moment, and further compares L with the preset catenary length L eThe length deviation value ΔL is obtained by subtracting the length deviation value. The cable-laying speed of the cable-laying vessel is then controlled based on this value. Specifically, when ΔL is 0 or close to 0, the original cable-laying speed is maintained; when ΔL is less than 0, the cable-laying speed is increased; and when ΔL is greater than 0, the cable-laying speed is decreased. This invention ensures the smooth laying of submarine cables with a fixed slack by estimating the catenary length in real time and adjusting the cable-laying speed accordingly. Attached Figure Description

[0034] Figure 1 This is a flowchart of a submarine cable laying control method based on a constant catenary length provided in an embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram illustrating the shape and related parameter definitions of the submarine cable between the cable-laying vessel and the burying plow, provided in an embodiment of the present invention. Detailed Implementation

[0036] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. The embodiments are given for illustrative purposes only and should not be construed as limiting the present invention. The accompanying drawings are for reference and illustration only and do not constitute a limitation on the scope of patent protection of the present invention, because many changes can be made to the present invention without departing from the spirit and scope of the present invention.

[0037] The submarine cable laying control method based on constant catenary length provided in this embodiment of the invention, such as... Figure 1 As shown in the flowchart, this embodiment includes the following steps:

[0038] S1. The vertical water depth below the cable-laying vessel's cable exit point is measured in real time and recorded as H. c The vertical water depth above the plowshare, measured in real time, is recorded as H. l The angle of entry of the submarine cable into the water at the point where the cable-laying vessel exits the water is measured in real time and recorded as θ. c The angle of entry of the submarine cable into the plough at the ploughing point is measured in real time and recorded as θ. l The horizontal distance between the cable-laying vessel's cable exit point and the burial plow's entry point, measured in real time, is denoted as D. Figure 2 As shown;

[0039] S2, based on H at the current time c H l θ c θ l D calculates the length L of the catenary at the current moment;

[0040] S3. Compare the current catenary length L with the preset catenary length L e The difference is calculated to obtain the length deviation value ΔL;

[0041] S4. Control the cable-laying speed of the cable-laying vessel according to the length deviation value ΔL.

[0042] In this embodiment, in step S2, the length L of the catenary at the current moment is calculated based on the following formula:

[0043]

[0044] The above formula is obtained using geometric calculation methods. Please refer to the following formula:

[0045]

[0046] Using geometric calculation methods, the vertical water depth below the cable-laying vessel's cable-laying point is measured in real time at each moment and denoted as H. ci The vertical water depth above the plowshare, measured in real time, is recorded as H. li The vertical water depth below the point where the cable-laying vessel leaves the cable is projected onto the vertical water depth below the point where the cable-laying vessel leaves the cable in the vertical direction, and the difference h is calculated. i =H ci -H ci The angle of entry of the submarine cable into the water at the point where the cable-laying vessel exits the water is measured in real time and recorded as θ. ci The horizontal distance between the cable-laying vessel's cable exit point and the burial plow's entry point is Di. The actual horizontal length of the cable is X. i =D i +h i ·tanθ ci By measuring the insertion angle θ of the submarine cable at the tangent position of the ploughing cut in real time... li By combining the method of infinitesimal elements with geometric concepts, the length L of the catenary at each time step can be obtained. i =X i / cosθ li , where i represents the i-th time.

[0047] In step S3, the preset catenary length L e Set to:

[0048]

[0049] In the formula, This is an empirical parameter value, representing the preset catenary compensation length.

[0050] The cable is submerged in seawater. Ignoring other complex factors such as currents and tides, the cable dangles from the support structure on the laying vessel, forming a triangle. Within this triangle, the water depth is H. c It is one side of a right triangle, the horizontal distance D is the other side, and the cable length L is... e The slant side, in practical applications, needs to be adjusted or have some redundancy added according to specific water depth and other conditions to ensure that the cable can adapt to various environmental conditions and remain safe and reliable.

[0051] Furthermore, the present invention can control the cable-laying speed of the cable-laying vessel based on the length deviation value ΔL, specifically as follows:

[0052] When ΔL is greater than 0, reduce the cable laying speed and the length of the submarine cable catenary to achieve a constant catenary length; when ΔL = 0, keep the cable laying speed constant to achieve a constant catenary length; when ΔL is less than 0, increase the cable laying speed to achieve a constant catenary length.

[0053] More specifically, the PID control principle is used to control the cable laying speed based on ΔL, that is, the PID control is used to control the deviation of the submarine cable length. The output is adjusted according to the error between the set value and the actual value so that the system can achieve the desired target. Refer to the following process:

[0054] [1] When the length deviation is large, the response of the control output can be increased by increasing the proportional (P) parameter of the PID controller. Increasing the P parameter can quickly reduce the deviation and thus approach the set value more quickly.

[0055] This will result in a larger control output from the system, accelerating the adjustment speed.

[0056] [2] If the length deviation is small: When the length deviation is small, the static error can be reduced by increasing the integral (I) parameter, making the system more accurately stable near the set value. Integral control acts on the cumulative deviation value. If there is a continuous small deviation, the integral term will gradually increase the control output, making the system more stable.

[0057] For a smooth and reliable speed regulation method, a closed-loop feedback system based on PID control can be used, with the specific settings as shown below.

[0058] 1) Set the target speed; set the desired target speed as the set value.

[0059] 2) Sensor feedback: Sensors are used to measure the actual speed in real time, and this feedback signal will be used to calculate the speed deviation.

[0060] 3) PID controller; The PID controller is used to calculate speed deviation. The output of the PID controller is a control signal used to adjust the input of the actuator (such as a motor) to control the speed.

[0061] 4) Actuator control: Adjust the actuator input based on the output of the PID controller so that the actual speed gradually approaches the set value.

[0062] 5) Cyclic Feedback: The above steps are a cyclic process. By continuously measuring the actual speed, calculating the speed deviation, and adjusting the actuator input, the system is made to continuously approach the set value.

[0063] 6) Parameter tuning: The performance of a PID controller is affected by its parameters (P, I, D). To obtain optimal performance, tuning and parameter optimization are usually required.

[0064] This closed-loop feedback system based on PID control can smoothly and reliably adjust the speed when the speed deviation is large or small. By appropriately adjusting the PID parameters, fast response, low static error, and stable control performance can be obtained.

[0065] Corresponding to the above method, this embodiment of the invention also provides a submarine cable laying control system based on a constant catenary length, including a water depth detection unit, an angle measurement unit, a catenary length calculation unit, a catenary length comparison unit, and a cable laying machine control unit.

[0066] The water depth detection unit is used to measure the vertical water depth below the cable-laying vessel's cable exit point in real time, denoted as H. c And the real-time measurement of the vertical water depth above the plowshare, denoted as H. l ;

[0067] The angle measurement unit is used to measure the water entry angle of the submarine cable at the cable-laying vessel's exit point in real time, denoted as θ. c The angle of entry of the submarine cable into the plough at the ploughing point is measured in real time and denoted as θ. l ;

[0068] The catenary length calculation unit is used to calculate the length of the catenary based on the current time H. c H l θ c θ l D calculates the length L of the catenary at the current moment;

[0069] The catenary length comparison unit is used to compare the current catenary length L with the preset catenary length L. e The difference is calculated to obtain the length deviation value ΔL;

[0070] The cable-laying machine control unit is used to control the cable-laying speed of the cable-laying vessel based on the length deviation value ΔL.

[0071] In this embodiment, the water depth detection unit uses a depth gauge. The angle measurement unit calculates the angle by taking photos using an image acquisition device and then processing the images. The distance measurement unit uses the Ultra-Short Baseline Positioning (USBL) method to determine the horizontal distance D between the cable exit point of the cable-laying vessel and the point before the burial plow enters the plowshare.

[0072] Similarly, the catenary length calculation unit calculates the current catenary length L based on equation (1). The preset catenary length L... eThe setting is as shown in equation (3). The cable-laying machine control unit is used to control the cable-laying speed of the cable-laying vessel according to the length deviation value ΔL. Specifically, when ΔL is greater than 0, the cable-laying speed is reduced; when ΔL = 0, the cable-laying speed is kept constant; when ΔL is less than 0, the cable-laying speed is increased. Similarly, the cable-laying machine control unit uses the PID control principle to control the cable-laying speed according to ΔL.

[0073] In summary, the submarine cable laying control method and system based on a constant catenary length provided in this invention control method and system achieves this by real-time measurement of the vertical water depth H below the cable-laying vessel's cable exit point. c 1. The vertical water depth H above the plowshare is burying the plow. l The angle θ of the submarine cable entering the water at the point where the cable-laying vessel exits the water. c The entry angle θ of the submarine cable at the point where the plough enters the plough head. l The horizontal distance D between the cable-laying vessel's cable exit point and the burial plow's entry point is determined based on H at each moment. c H l θ c θ l D calculates the catenary length L at each moment, and further compares L with the preset catenary length L e The length deviation value ΔL is obtained by subtracting the length deviation value. The cable-laying speed of the cable-laying vessel is then controlled based on this value. Specifically, when ΔL is 0 or close to 0, the original cable-laying speed is maintained; when ΔL is less than 0, the cable-laying speed is increased; and when ΔL is greater than 0, the cable-laying speed is decreased. This invention ensures the smooth laying of submarine cables with a fixed slack by estimating the catenary length in real time and adjusting the cable-laying speed accordingly.

[0074] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for controlling submarine cable laying based on constant catenary length, characterized in that, Including the following steps: S1. The vertical water depth below the cable-laying vessel's cable exit point is measured in real time and recorded as... The vertical water depth above the plowshare, measured in real time, is recorded as follows: The angle of entry of the submarine cable into the water at the point where the cable-laying vessel exits the water is measured in real time and recorded as follows: The angle at which the submarine cable enters the plow at the plow's entry point is measured in real time and recorded as... The horizontal distance between the cable-laying vessel's cable exit point and the burial plow's entry point, measured in real time, is recorded as follows: ; S2, based on the current time , , , , Calculate the length of the catenary at the current moment. ; S3. Calculate the current catenary length. With the preset catenary length The difference is calculated to obtain the length deviation value. ; S4. Based on the length deviation value Controlling the cable-laying speed of the cable-laying vessel, specifically: when When the value is greater than 0, decrease the cable laying speed; when When =0, the cable laying speed remains constant; when When the value is less than 0, increase the cable laying speed.

2. The submarine cable laying control method based on constant catenary length according to claim 1, characterized in that, In step S3, the preset catenary length Set to: ， These are empirical parameter values.

3. The submarine cable laying control method based on constant catenary length according to claim 1, characterized in that, The PID control principle is adopted according to Control the cable laying speed.

4. A submarine cable laying control system based on a constant catenary length, characterized in that: It includes a water depth detection unit, an angle measurement unit, a distance measurement unit, a catenary length calculation unit, a catenary length comparison unit, and a cable laying machine control unit; The water depth detection unit is used to measure the vertical water depth below the cable-laying vessel's cable-laying point in real time, denoted as... And the real-time measurement of the vertical water depth above the plowshare is recorded as... ; The angle measuring unit is used to measure the water entry angle of the submarine cable at the cable-laying vessel's cable exit point in real time, denoted as... And the angle of entry of the submarine cable at the point where the plough enters the plough mouth is measured in real time and recorded as ; The distance measurement unit is used to measure the horizontal distance between the cable-laying vessel's cable exit point and the burial plow's entry point in real time, denoted as [missing information]. ; The catenary length calculation unit is used to calculate the length based on the current time. , , , , Calculate the length of the catenary at the current moment. ; The catenary length comparison unit is used to compare the current catenary length. With the preset catenary length The difference is calculated to obtain the length deviation value. ; The cable-laying machine control unit is used to determine the length deviation value. Controlling the cable-laying speed of the cable-laying vessel, specifically: when When the value is greater than 0, decrease the cable laying speed; when When =0, the cable laying speed remains constant; when When the value is less than 0, increase the cable laying speed.

5. The submarine cable laying control system based on a constant catenary length according to claim 4, characterized in that, Preset catenary length Set to: ， These are empirical parameter values.

6. The submarine cable laying control system based on constant catenary length according to claim 5, characterized in that: The cable-laying machine control unit adopts the PID control principle. Control the cable laying speed.

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