Submarine cable laying bottoming tension control system and method

Abstract

The present invention discloses a bottom-touching tension control system and method for submarine cable laying, which belongs to the field of marine cable construction. The bottom-touching tension control system for submarine cable laying includes a cable laying machine, a water-entering bridge and a processor arranged on a cable laying vessel, as well as a plurality of horizontal rollers arranged between the cable laying machine and the water-entering bridge. The submarine cable forms a first catenary after being separated from the cable laying machine, and forms a second catenary after being separated from the water-entering bridge. The preset formula in the processor can calculate the difference between the corrected submarine cable tension at the bottom-touching point of the seabed and the minimum allowable tension of the submarine cable, and accordingly adjust the cable laying speed of the cable laying machine to make it approach 0, so as to make it consistent with the minimum allowable tension of the submarine cable. T R Matching can achieve refined control of the bottom tension of the submarine cable and can also achieve precise control of the cable laying speed of the cable laying machine.

Description

Technical Field

[0001] The invention relates to a bottoming tension control system and method for laying a submarine cable, and belongs to the field of marine submarine cable construction. Background Art

[0002] As offshore wind farms are becoming saturated, offshore wind farms are gradually developing in the deep sea. For the construction of ultra-long-distance submarine cables in the deep sea, the lay-first-then-bury construction process can effectively reduce reliance on high-quality construction windows and shorten the construction period of ultra-long-distance submarine cables. The lay-first-then-bury submarine cable laying method generally adopts the catenary method. By controlling the speed of the cable-laying vessel, the cable-laying machine's cable-releasing speed, and the speed of the cable turntable, the submarine cable touches the bottom in a catenary manner with less tension. When the tension of the submarine cable touching the bottom is too large, in areas with uneven seabeds, the submarine cable is easily suspended in the air, resulting in long-term residual stress. If the tension of the submarine cable touching the bottom is too small, the submarine cable will be compressed, the cable bending radius will be too small, and it will be easy to cause dangerous circling, affecting the subsequent ROV post-burial operations.

[0003] There are several forms of tension control in the current submarine cable laying process, but all of them have certain shortcomings:

[0004] (1) A Bragg grating (FBG) sensor is placed on the cable sheath to collect local strain in real time. The fiber optic demodulator converts the strain signal into a digital signal and transmits it to the calculation unit. Combined with the known cable stress-strain relationship, the cable tension data can be obtained. However, since submarine cable laying is a dynamic process, what needs to be measured is the cable tension at the bottom point, which is constantly changing. The optical fiber cannot sense this position, which poses a great challenge to measuring submarine cable tension using optical fiber.

[0005] (2) Calculate the cable tension by monitoring the cable's underwater shape and combining it with theoretical formulas. Due to the complex working environment of laying cables, it is difficult to accurately monitor the cable's shape due to the influence of various factors such as waves, uneven seabed, and the stirring of seabed sediment by the laying plow.

[0006] (3) Control the cable bottoming tension by monitoring the cable entry angle. During actual offshore operations, due to the influence of waves, the cable-laying vessel sways violently, making it difficult to measure the cable entry angle. In addition, due to the constant shaking of the cable, the measurement accuracy is also difficult to guarantee. Summary of the Invention

[0007] In response to the problems existing in the prior art, the present invention provides a submarine cable laying bottom tension control system and method, which can obtain real-time submarine cable bottom tension based on the catenary shape equation, and automatically adjust the cable laying speed of the cable laying machine through the processor to make the submarine cable bottom tension meet the requirements.

[0008] In order to solve the above technical problems, the present invention includes the following technical solutions:

[0009] A bottom-touching tension control system for laying submarine cables comprises a cable laying machine, a water-launching bridge, and a processor arranged on a cable laying vessel, and a plurality of horizontal rollers arranged between the cable laying machine and the water-launching bridge;

[0010] The point where the submarine cable separates from the cable laying machine is marked as A, and the point where the submarine cable contacts the first horizontal roller is marked as B. The submarine cable forms the first catenary between points A and B.

[0011] The launching bridge is arc-shaped and is located at the stern of the cable-laying vessel. Several compactly arranged circular roller pressure sensors are installed at the curved edge of the launching bridge. The lowest pressure sensor can be used to determine the cable's suspension point F. The point where the cable touches the seabed is marked as E, and the cable forms a second catenary between points F and E.

[0012] Preset formula in the processor:

[0013] ;

[0014] ;

[0015] ;

[0016] ;

[0017] Where, T wdown is the cable tension at the point where it touches the seabed; is the correction value; T’ wdown The cable tension corrected for the point where the seabed touches the bottom; is the vertical load per unit length of the submarine cable in the air; is the vertical load per unit length of submarine cable in water; is the height of the first catenary, which is a fixed value; is the horizontal projection length of the first catenary, which is the measured value; for F The distance from the point to the sea level is the measured value; is the distance between point E and sea level, which is the measured value; R R is the minimum permissible curvature radius of the submarine cable, which is a fixed value; T R is the minimum allowable tension of the submarine cable; for and T R Difference;

[0018] The processor can Control the cable laying speed of the cable laying machine to tends to 0, making and T R match.

[0019] Furthermore, a horizontal distance meter is set on one side of the cable laying machine to measure .

[0020] Furthermore, the depth D from the sea level to the seabed is measured using sonar equipment.

[0021] Furthermore, a distance meter is set up on the cable-laying vessel to measure the distance D3 between point B and the sea level;

[0022] After the pressure sensor of the water-entering bridge determines the suspension point F of the submarine cable, the height difference D2 between point B and point F is determined. D 1= D 3- D 2.

[0023] Furthermore, the processor can Generate error signal ; Built-in speed adjustment in the processor The PID algorithm formula is:

[0024] ;

[0025] In the formula K p 、 K i 、 K d is the PID parameter;

[0026] The processor collects the current motor speed of the cable laying machine in real time , the processor outputs the motor target speed :

[0027] .

[0028] Furthermore, the processor adopts a programmable controller.

[0029] Correspondingly, the present invention also provides a method for controlling the bottoming tension of a submarine cable laying using the above-mentioned bottoming tension control system, comprising:

[0030] Step 1: Collect the parameters of the submarine cable, including the vertical load per unit length of the submarine cable in the air , Vertical load per unit length of underwater submarine cable , Minimum allowable curvature radius of submarine cable R R ;Measure the height difference of the first catenary D a , real-time measurement of the horizontal length of the first catenary La , seabed depth D and the suspension point at the submarine cable entry bridge F Vertical distance from sea level D 1. Setting value;

[0031] Step 2: The processor calculates according to the preset formula ;

[0032] Step 3: Processor Control the cable laying speed of the cable laying machine to Approaching 0, and T R match.

[0033] Further, in step 3, the processor Control the cable laying speed of the cable laying machine to Approaching 0, specifically:

[0034] when When the cable is released, increase the cable laying machine speed to reduce the bottom tension of the submarine cable. ;when When the cable is released, reduce the cable laying machine speed to increase the bottom tension of the submarine cable. ; Keep the cable release speed constant.

[0035] Further, in step 3, the processor Control the cable laying speed of the cable laying machine to Approaching 0, specifically:

[0036] Processor according to Generate error signal ; Built-in speed adjustment in the processor The PID algorithm formula is:

[0037] ;

[0038] In the formula K p 、 K i 、 K d is the PID parameter;

[0039] The processor collects the current motor speed of the cable laying machine in real time , the processor outputs the motor target speed :

[0040] .

[0041] Furthermore, the processor is preset ,when When, through K p Quickly correct the speed deviation when When the integral coefficient K i or K d Correct speed deviation.

[0042] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art: the present invention provides a control system and method for the bottoming tension of a submarine cable, a preset formula in the processor, based on the catenary equation of the first catenary of the submarine cable, can calculate the approximate tension value of the submarine cable at the bottom of the first catenary Ignoring the friction between the submarine cable and the pressure sensors of the horizontal roller and the circular roller of the water bridge, the tension at the top of the second catenary of the submarine cable is equal to Based on the tension expression of the second catenary of the submarine cable, the bottom tension of the submarine cable is obtained T wdown , and T wdown After correction, we get T’ wdown Therefore, only the horizontal length of the first catenary needs to be measured in real time L a , seabed depth D And the vertical distance between the suspension point of the submarine cable entry bridge and the sea level D 1. Combined with the known parameters of the submarine cable, the real-time bottoming tension of the submarine cable can be obtained, which has the advantages of less measurement data, simple operation, and the ability to obtain accurate bottoming tension of the submarine cable in real time. The present invention also obtains the minimum allowable tension of the submarine cable based on the minimum curvature radius of the second catenary of the submarine cable. T R By controlling the cable laying speed of the cable laying machine, the corrected submarine cable will touch the bottom tension. T wdown and T R Matching can achieve refined control of the bottoming tension of the submarine cable, which can avoid problems caused by excessive or insufficient bottoming tension of the submarine cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 Schematic diagram of a bottoming tension control system for laying a submarine cable in one embodiment of the present invention;

[0044] Figure 2 Schematic diagram of a catenary in one embodiment of the present invention.

[0045] The numbers in the figure are as follows:

[0046] 1-cable-laying vessel; 2-submarine cable; 3-cable-laying machine; 4-first catenary; 5-horizontal contact section; 6-arc-shaped contact section; 7-second catenary; 8-water-entry bridge; 9-pressure sensor; 10-roller; 11-distance meter; 12-sea level; 13-seabed. DETAILED DESCRIPTION

[0047] The following is a detailed description of the submarine cable installation bottom tension control system and method provided by the present invention, with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are highly simplified and not to exact scale, and are intended solely to facilitate and clarify the purpose of illustrating the embodiments of the present invention.

[0048] Example 1

[0049] This embodiment provides a bottoming tension control system for submarine cable laying, such as Figure 1 As shown, it includes a cable laying machine 3, a water-entering bridge 8 and a processor (not shown) arranged on a cable laying vessel 1, and a plurality of horizontal rollers 10 arranged between the cable laying machine 3 and the water-entering bridge 8. Figure 1 As shown, the submarine cable 2 is laid using a cable laying vessel 1. The cable laying vessel 1 is usually provided with a carrying turntable (not shown) for placing the submarine cable 2, and the submarine cable 2 is wound on the carrying turntable. The cable laying vessel 1 is also provided with a cable laying machine 3 and a water-entry bridge 8. The water-entry bridge 8 is arc-shaped and is provided at the tail of the cable laying vessel 1. A number of horizontal rollers 10 are provided between the cable laying machine 3 and the water-entry bridge 8. The cable laying machine 3 drives the submarine cable to move, lifts the submarine cable 2 from the carrying turntable and transports it to the horizontal rollers 10, then enters the seawater through the water-entry bridge 8, and completes the laying after touching the bottom of the seabed. The submarine cable 2 forms a first catenary 4 between the cable laying machine 3 and the rollers, then forms a horizontal contact section 5 on the horizontal roller 10, forms an arc-shaped contact section 6 on the water-entry bridge 8, and forms a second catenary 7 between the suspension point of the submarine cable 2 on the water-entry bridge 8 and the point where it touches the seabed 13. The horizontal projection length of the first catenary 4 is recorded as L a , the height is recorded as D a The contact point between the first catenary 4 and the first horizontal roller 10 is recorded as point B, the suspension point of the submarine cable 2 on the water-entering bridge 8 at the top of the second catenary 7 is recorded as F, the distance between the sea level 12 and the seabed is recorded as D, the height difference between point F and the sea level 12 is recorded as D1, the height difference between point B and point F is recorded as D2, and the height difference between point B and the sea level 12 is recorded as D3.

[0050] Cable laying machine 3 controls the speed of laying out submarine cable 2 v , v Increase, L a Reduce, submarine cable 2 is suspended at the water bridge 8F Move down, D 2 increases, the tension of submarine cable 2 decreases; v Reduce, L a Increase, submarine cable 2 is suspended at the water bridge 8 F Move up, D 2 Decreases, and the tension of the submarine cable 2 increases. The water entry bridge 8 can guide the lowering of the submarine cable 2 and make the lowering bending radius of the submarine cable 2 meet the requirements to prevent the submarine cable 2 from being damaged. Since the hanging point F of the submarine cable 2 will change dynamically, in order to measure the position of the hanging point of the submarine cable 2, a pressure sensor 9 with several compactly arranged circular rollers is set on the water entry bridge 8. The contact point between the lowest point pressure sensor 9 with pressure measurement and the submarine cable 2 is regarded as point F. Since the relative height of point B remains unchanged, D2 can be calculated. In addition, a vertical rangefinder is set near each horizontal roller 10 within a preset distance from the cable laying machine 3. By measuring the distance of the submarine cable 2, the position of point B can be obtained, thereby obtaining the distance L a , D a As a known number, a horizontal distance meter 11 can also be set to measure the distance of the submarine cable at a height close to the upper edge of the horizontal roller to obtain the distance L a In addition, by setting a distance meter on the cable laying vessel 1, the D 3.

[0051] Preset formula in the processor: ; ; ; The processor is capable of computing real-time ,according to Control the cable laying speed of the cable laying machine 3 so that Approaching 0, and T R Match. Where, D a is a fixed value; is the vertical load per unit length of the submarine cable in the air; is the vertical load per unit length of submarine cable in water, R R The minimum permissible curvature radius of the submarine cable. After the submarine cable is determined, R R 、 、 is a fixed value; is a correction value, which is preset based on experience; T Ris the minimum allowable tension of the submarine cable, calculated according to the formula. is the horizontal projection length of the first catenary, for F The distance from the point to the sea level is the measured value, is the distance between point E and sea level, 、 、 The real-time measurement value. T wdown is the cable tension at the point where it touches the seabed; T’ wdown The cable tension corrected for the point where the seabed touches the bottom; for T’ wdown and T R Difference.

[0052] By way of example and not limitation, Figure 1 As shown, when point F is determined, the vertical distance between F and point B can be obtained D 2. Arrange a rangefinder on the deck to measure the horizontal roller's height 12 degrees from the sea level. D 3, so we can get the height of the submarine cable 2 hanging point from the sea level 12 D 1= D 3- D 2. The cable-laying vessel's sonar equipment measures the depth of the seabed D .

[0053] The following is a further explanation of the preset formula in the processor:

[0054] For a submarine cable 2 that is considered to bear vertical load and has a constant weight per unit length, if Figure 2 As shown, the origin of the coordinate axis is set at the lowest point of the catenary, the X axis is horizontal, and the Y axis is vertically downward. The classic catenary equation is expressed as follows:

[0055] (1)

[0056] The vertical load per unit length is , the horizontal component of tension is (Because it only bears vertical load, constant).

[0057] For the first catenary 4, when x=L a hour, y=-D a , substitute into formula (1) to solve the tension of submarine cable 2 at point B T adown :

[0058] (2)

[0059] Where, ω a is the vertical load per unit length of the submarine cable in the air, which is a fixed value.

[0060] Since a horizontal roller 10 is provided on the deck and a roller pressure sensor 9 is provided on the water-entering bridge 8, both the horizontal contact section 5 and the arc-shaped contact section 6 of the submarine cable 2 are sliding friction, and the friction force can be ignored, the following is obtained:

[0061] T adown =T wtop (3)

[0062] in T wtop is the tension of the submarine cable 2 at point F. D Larger, deep sea submarine cable 2 unit length vertical load in water Also large, leading to T wtop larger; D a It is usually designed to be relatively small, that is, the first catenary meets the small sag condition, so <<1, will Perform Taylor expansion and take the first two terms to get:

[0063] (4)

[0064] Substituting into formula (2) we can get:

[0065] (5)

[0066] Establishing catenary tension T The expression:

[0067] (6)

[0068] Substitution y=- ( D 1 +D )hour, T=T wtop , H = T wdown , = , we can get:

[0069] (7)

[0070] The above formula uses Taylor expansion. Ignoring the vertical load of a short section of submarine cable 2 from the suspension point to the sea level 12, it is equal to the weight per unit length in water. Taking into account the above calculation approximation, the tension at the bottoming point is corrected:

[0071] (8)

[0072] In the formula T’ wdown The tension of the submarine cable 2 corrected at the point where the seabed 13 touches the bottom; For experience value.

[0073] The minimum allowable tension is calculated from the minimum allowable curvature radius of the submarine cable. The mathematical expression of the curvature radius is:

[0074] (9)

[0075] According to the catenary theory, the minimum curvature radius is at the lowest point of the catenary. Substituting Department , we can get the minimum curvature radius of the catenary R min expression:

[0076] (10)

[0077] Minimum allowable curvature radius of submarine cable 2 R R The submarine cable 2 has been calibrated before leaving the factory. For example, for a submarine cable 2 with an outer diameter of 0.1823m, the submarine cable parameters given at the factory are R R is 3.663m, substitute in the above formula R min = R R 、 = 、 H = T R , we can get:

[0078] (11)

[0079] Find the bottom point tension With the minimum allowable tension T R Difference :

[0080] (12)

[0081] The processor can Control the cable laying speed of the cable laying machine 3 so that Approaches 0, specifically, when When the cable is released, the cable laying machine 3 is increased to reduce the tension of the submarine cable 2 touching the bottom. ;when When the cable is released, the cable laying machine 3 is reduced to increase the bottom tension of the submarine cable 2. ; Keep the cable release speed constant.

[0082] It should be noted that the processor uses a programmable controller (PLC). The PLC has a built-in PID module, which integrates a functional module with a PID (proportional-integral-differential) control algorithm. PID (proportional-integral-differential) control is a widely used engineering control technology that adjusts system errors through proportional, integral, and differential control methods to achieve precise control. The processor is based on Generate error signal , according to the error Output speed adjustment :

[0083] (13)

[0084] when When the deviation is large, by increasing the proportional coefficient K p To increase the response of the control output and quickly correct the speed deviation; when When the deviation is small, by increasing the integral coefficient K i To speed up the elimination of steady-state errors and make the system more stable near the set value. ,for example =5kN, when When, through K p To quickly correct the speed deviation, when When the integral coefficient K i or K d Correct speed deviation.

[0085] The motor of the cabling machine 3 can feed back the current speed to the processor For example, the encoder inside the motor can monitor the speed in real time. The processor outputs the motor target speed. :

[0086] (14)

[0087] During the laying process of submarine cable 2, measurement data, bottom tension data, and rotation speed data are updated in real time to form a PID-based closed-loop control.

[0088] Example 2

[0089] This embodiment provides a method for controlling the bottoming tension of a submarine cable laying using the submarine cable laying bottoming tension control system described in the first embodiment, comprising:

[0090] Step 1: Collect the parameters of submarine cable 2, including the vertical load per unit length of submarine cable 2 in the air , Vertical load per unit length of submarine cable in water , Minimum allowable curvature radius of submarine cable 2 R R ; Measure the height difference of the first catenary 4 D a , real-time measurement of the horizontal length of the first catenary 4 L a , seabed depth D and 8 suspension points at the submarine cable 2 water bridge F 12 vertical distance from sea level D 1. Setting value;

[0091] Step 2: The processor calculates according to the preset formula ;

[0092] Step 3: Processor Control the cable laying speed of the cable laying machine 3 so that Approaching 0, and T R match.

[0093] In one embodiment, in step 3, the processor Control the cable laying speed of the cable laying machine 3 so that Approaching 0, specifically:

[0094] when When the cable is released, the cable laying machine 3 is increased to reduce the tension of the submarine cable 2 touching the bottom. ;when When the cable is released, the cable laying machine 3 is reduced to increase the bottom tension of the submarine cable 2. ; Keep the cable release speed constant.

[0095] In one embodiment, in step 3, the processor Control the cable laying speed of the cable laying machine 3 so that Approaching 0, specifically:

[0096] Processor according to Generate error signal ; Built-in speed adjustment in the processor The PID algorithm formula is:

[0097] ;

[0098] In the formula K p 、 K i 、 K d is the PID parameter;

[0099] The processor collects the current speed of the motor of the cable laying machine 3 in real time , the processor outputs the motor target speed :

[0100] .

[0101] In one embodiment, the processor is preset ,when When, through K p Quickly correct the speed deviation when When the integral coefficient K i or K d Correct speed deviation.

[0102] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0103] The above-described embodiments merely illustrate several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that a person skilled in the art would be able to make numerous modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A submarine cable laying bottom tension control system, characterized in that: It includes a cable laying machine, a launching bridge and a processor installed on a cable laying vessel, and a number of horizontal rollers installed between the cable laying machine and the launching bridge; The point where the submarine cable separates from the cable laying machine is marked as A, and the point where the submarine cable contacts the first horizontal roller is marked as B. The submarine cable forms the first catenary between points A and B. The launching bridge is arc-shaped and is located at the stern of the cable-laying vessel. Several compactly arranged circular roller pressure sensors are installed at the curved edge of the launching bridge. The lowest pressure sensor can be used to determine the cable's suspension point F. The point where the cable touches the seabed is marked as E, and the cable forms a second catenary between points F and E. Preset formula in the processor: ； ； ； ； Where, T wdown is the cable tension at the point where it touches the seabed; is the correction value; T’ wdown The cable tension corrected for the point where the seabed touches the bottom; is the vertical load per unit length of the submarine cable in the air; is the vertical load per unit length of submarine cable in water; is the height of the first catenary, which is a fixed value; is the horizontal projection length of the first catenary, which is the measured value; for F The distance from the point to the sea level is the measured value; is the distance between point E and sea level, which is the measured value; R R is the minimum permissible curvature radius of the submarine cable, which is a fixed value; T R is the minimum allowable tension of the submarine cable; for and T R Difference; The processor can Control the cable laying speed of the cable laying machine to tends to 0, making and T R match.

2. The submarine cable laying bottoming tension control system according to claim 1, characterized in that: A horizontal distance meter is set on one side of the cable laying machine to measure .

3. The submarine cable laying bottoming tension control system according to claim 1, characterized in that: The depth D from sea level to seabed is measured by sonar equipment.

4. The submarine cable laying bottoming tension control system according to claim 3, characterized in that: A distance meter is set up on the cable-laying vessel to measure the distance D3 between point B and the sea level; After the pressure sensor of the water-entering bridge determines the suspension point F of the submarine cable, the height difference D2 between point B and point F is determined. D 1= D 3- D 2.

5. The submarine cable laying bottoming tension control system according to claim 1, characterized in that: The processor can Generate error signal ; Built-in speed adjustment in the processor The PID algorithm formula is: ； In the formula K p 、 K i 、 K d is the PID parameter; The processor collects the current motor speed of the cable laying machine in real time , the processor outputs the motor target speed : 。 6. The submarine cable laying bottoming tension control system according to claim 1, characterized in that: The processor adopts a programmable controller.

7. A method for controlling the bottoming tension of a submarine cable using the bottoming tension control system for submarine cable laying according to any one of claims 1 to 6, characterized in that: include: Step 1: Collect the parameters of the submarine cable, including the vertical load per unit length of the submarine cable in the air , Vertical load per unit length of underwater submarine cable , Minimum allowable curvature radius of submarine cable R R ;Measure the height difference of the first catenary D a , real-time measurement of the horizontal length of the first catenary L a , seabed depth D and the suspension point at the submarine cable entry bridge F Vertical distance from sea level D 1. Setting value; Step 2: The processor calculates according to the preset formula ; Step 3: Processor Control the cable laying speed of the cable laying machine to Approaching 0, and T R match.

8. The method for controlling the bottoming tension of a submarine cable as claimed in claim 7, wherein: In step 3, the processor Control the cable laying speed of the cable laying machine to Approaching 0, specifically: when When the cable is released, increase the cable laying machine speed to reduce the bottom tension of the submarine cable. ;when When the cable is released, reduce the cable laying machine speed to increase the bottom tension of the submarine cable. ; Keep the cable release speed constant.

9. The method for controlling the bottoming tension of a submarine cable as claimed in claim 7, wherein: In step 3, the processor Control the cable laying speed of the cable laying machine to Approaching 0, specifically: Processor according to Generate error signal ; Built-in speed adjustment in the processor The PID algorithm formula is: ； In the formula K p 、 K i 、 K d is the PID parameter; The processor collects the current motor speed of the cable laying machine in real time , the processor outputs the motor target speed : 。 10. The method for controlling the bottoming tension of a submarine cable as claimed in claim 7, wherein: Preset in processor ,when When, through K p Quickly correct the speed deviation when When the integral coefficient K i or K d Correct speed deviation.

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