A method, device and equipment for detecting leakage of submarine oil-filled cable

Abstract

The present invention discloses a leakage detection method, device and equipment for a submarine oil-filled cable. The method comprises the following steps: obtaining a route elevation change curve and first environmental data corresponding to the submarine oil-filled cable; constructing a one-dimensional pipeline laminar flow model according to a discretization result of the route elevation change curve in combination with the first environmental data; performing steady-state simulation using the one-dimensional pipeline laminar flow model to determine a stable flow rate of insulating oil; responding to second environmental data and a monitored flow rate monitored in real time, calculating a real-time insulating oil flow rate corresponding to the one-dimensional pipeline laminar flow model according to the second environmental data and the stable flow rate of insulating oil; if a deviation value between the real-time insulating oil flow rate and the monitored flow rate exceeds a preset leakage threshold, it is determined that a leakage occurs in the submarine oil-filled cable, thereby improving the calculation efficiency of the real-time insulating oil flow rate through a digital twin method, being able to detect subtle flow leakage at an early stage of leakage, and effectively improving the accuracy of leakage detection.

Description

Technical Field

[0001] The present invention relates to the technical field of leakage detection, and in particular to a leakage detection method, device and equipment for a submarine oil-filled cable. Background Art

[0002] Submarine oil-filled cable refers to an oil-filled cable used for submarine high-voltage power transmission. It adopts oil-immersed insulation technology, that is, the insulation performance of the submarine cable is improved by filling insulating oil to eliminate the air gap between cable layers. A typical oil-filled cable usually contains an insulating oil channel, a copper conductor, insulating oil paper, a lead sheath, and an outer sheath. The insulation performance of the oil-filled cable is extremely good, it can withstand a very high working electric field strength, has very low dielectric loss, good heat dissipation, and reliable sheath protection. Therefore, the oil-filled cable is generally used for cross-sea high-voltage power transmission.

[0003] The traditional leak detection method is to judge cable or pipeline leakage through the law of conservation of fluid mass, that is, to judge whether the mass of the inflow and outflow at both ends is the same. However, for leak detection, this method can only be used when a large-scale leak occurs or in the later stage of a leak. At the same time, continuous positioning is required to find the location of the leak, and the detection accuracy is low. Summary of the invention

[0004] The present invention provides a leakage detection method, device and equipment for submarine oil-filled cables, which solves the technical problem that the traditional leakage detection method is to judge the leakage of cables or pipelines by the conservation of fluid mass, that is, to judge whether the inflow and outflow masses at both ends are the same. However, for leakage detection, this method can only be used when a large-scale leakage occurs or in the late stage of leakage, and continuous positioning is required to find the location of the leakage point, resulting in low detection accuracy.

[0005] A first aspect of the present invention provides a method for detecting leakage of a submarine oil-filled cable, comprising:

[0006] Obtaining a route elevation change curve and first environmental data corresponding to the submarine oil-filled cable;

[0007] According to the discretization result of the route elevation change curve, a one-dimensional pipeline laminar flow model is constructed in combination with the first environmental data;

[0008] performing a steady-state simulation on the one-dimensional pipeline laminar flow model to determine a steady flow rate of the insulating oil;

[0009] In response to the second environmental data monitored in real time and the monitored flow rate, the real-time insulating oil flow rate corresponding to the one-dimensional pipeline laminar flow model is calculated according to the second environmental data and the insulating oil stable flow rate;

[0010] If the deviation value between the real-time insulating oil flow rate and the monitored flow rate exceeds a preset leakage threshold, it is determined that the submarine oil-filled cable has a leakage.

[0011] Optionally, it also includes:

[0012] If the deviation value between the real-time insulating oil flow rate and the monitored flow rate does not exceed a preset leakage threshold, it is determined that no leakage occurs in the submarine oil-filled cable.

[0013] Optionally, the step of constructing a one-dimensional pipeline laminar flow model based on the discretization result of the route elevation change curve in combination with the first environmental data includes:

[0014] Discretizing the route elevation change curve according to preset intervals to obtain a plurality of discrete points;

[0015] Performing a discrete density convergence check on the discrete points with the insulating oil flow rate as the result to determine whether the intervals between the discrete points meet the convergence condition;

[0016] If not, the intervals between the discrete points are reduced according to a preset step size to obtain multiple new discrete points;

[0017] Jump to the step of performing discrete density convergence check on the discrete points with the insulating oil flow rate as the result, and judging whether the intervals between the discrete points meet the convergence condition;

[0018] If the conditions are met, each of the discrete points is connected and boundary conditions are set according to the first environmental data to generate a one-dimensional pipeline laminar flow model.

[0019] Optionally, it also includes:

[0020] Obtaining a position of an oil flow restrictor in the submarine oil-filled cable;

[0021] A one-dimensional valve node is added to the one-dimensional pipeline laminar flow model according to the position of the oil flow restrictor to obtain a new one-dimensional pipeline laminar flow model.

[0022] Optionally, the boundary conditions include pressure boundary conditions and temperature boundary conditions; if the conditions are met, the step of connecting the discrete points and setting the boundary conditions according to the first environmental data to generate a one-dimensional pipeline laminar flow model comprises:

[0023] If the convergence condition is met, then the discrete points are connected to generate an initial pipeline laminar flow model;

[0024] Extracting the oil pump pressures at both ends, the oil tank temperatures at both ends and the seawater temperature from the first environmental data;

[0025] Using the oil pump pressures at both ends as pressure boundary conditions at both ends of the oil channel in the initial pipeline laminar flow model;

[0026] Using the oil tank temperatures at both ends as temperature boundary conditions at both ends of the oil channel in the initial pipeline laminar flow model;

[0027] The seawater temperature is used as a temperature boundary condition of the outer surface of the cable in the initial pipeline laminar flow model to generate a one-dimensional pipeline laminar flow model.

[0028] Optionally, the step of calculating the real-time insulating oil flow rate corresponding to the one-dimensional pipeline laminar flow model in response to the second environmental data monitored in real time and the monitored flow rate according to the second environmental data and the insulating oil stable flow rate comprises:

[0029] In response to the real-time monitored second environmental data and the monitored flow rate, the boundary conditions of the one-dimensional pipeline laminar flow model are updated using the second environmental data;

[0030] The insulating oil steady flow rate is used as input to perform transient simulation on the one-dimensional pipeline laminar flow model to determine the corresponding real-time insulating oil flow rate.

[0031] Optionally, the second environmental data includes thermal conductivity and conductor current; the step of taking the insulating oil steady flow rate as input, performing transient simulation on the one-dimensional pipeline laminar flow model, and determining the corresponding real-time insulating oil flow rate includes:

[0032] Calculating the heat permeability per unit length along the cable in the one-dimensional pipeline laminar flow model according to the thickness of each layer of the cable in the one-dimensional pipeline laminar flow model and the thermal conductivity;

[0033] The heat generated by the cable is calculated by using the conductor current combined with Joule's law;

[0034] The insulating oil steady flow rate, the heat permeability per unit length and the cable heat generation are substituted into a preset conservation formula group to calculate the real-time insulating oil flow corresponding to the one-dimensional pipeline laminar flow model.

[0035] Optionally, the conservation formula group includes:

[0036]

[0037]

[0038]

[0039] Where, t is time, A is the cross-sectional area of ​​the pipeline, ρ is the fluid density, u is the steady flow rate of the insulating oil, p is the fluid pressure, and d h is the pipe diameter, fD is the friction coefficient, F is the volume force, T is the temperature of the fluid, C p is the specific heat of the fluid, k is the thermal conductivity of the fluid, Q is the heat generated by the cable per unit length of the cable conductor, Q wall It is the heat permeability per unit length.

[0040] A second aspect of the present invention provides a leakage detection device for a submarine oil-filled cable, comprising:

[0041] A data acquisition module, used to acquire a route elevation change curve and first environmental data corresponding to the submarine oil-filled cable;

[0042] A model building module, used to build a one-dimensional pipeline laminar flow model according to the discretization result of the route elevation change curve and in combination with the first environmental data;

[0043] A steady flow rate calculation module, used to perform steady-state simulation on the one-dimensional pipeline laminar flow model to determine the steady flow rate of the insulating oil;

[0044] A real-time flow calculation module, configured to respond to the second environmental data monitored in real time and the monitored flow, and calculate the real-time insulating oil flow corresponding to the one-dimensional pipeline laminar flow model according to the second environmental data and the insulating oil stable flow rate;

[0045] The flow deviation judgment module is used to determine that the submarine oil-filled cable has a leak if the deviation value between the real-time insulating oil flow and the monitored flow exceeds a preset leakage threshold.

[0046] A third aspect of the present invention provides an electronic device, comprising a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the leakage detection method for a submarine oil-filled cable as described in any one of the first aspects of the present invention.

[0047] It can be seen from the above technical solutions that the present invention has the following advantages:

[0048] The present invention obtains a route elevation change curve and first environmental data corresponding to a submarine oil-filled cable; constructs a one-dimensional pipeline laminar flow model according to a discretization result of the route elevation change curve and the first environmental data; uses the one-dimensional pipeline laminar flow model to perform steady-state simulation and determine a stable flow rate of the insulating oil; responds to real-time monitored second environmental data and a monitored flow, and calculates a real-time insulating oil flow corresponding to the one-dimensional pipeline laminar flow model according to the second environmental data and the stable flow rate of the insulating oil; if the deviation value between the real-time insulating oil flow and the monitored flow exceeds a preset leakage threshold, it is determined that a leakage occurs in the submarine oil-filled cable, thereby improving the calculation efficiency of the real-time insulating oil flow through a digital twin method, and considering the influence of the second environmental data, it is possible to detect a slight flow leakage caused by the flow caused by thermal expansion and contraction of the insulating oil, discover the existence of a leakage point in the early stage of leakage, and effectively improve the accuracy of leakage detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0050] Figure 1 A flowchart of the steps of a method for detecting leakage of a submarine oil-filled cable provided in Embodiment 1 of the present invention;

[0051] Figure 2 A flow chart of the steps of a method for detecting leakage of a submarine oil-filled cable provided in Embodiment 2 of the present invention;

[0052] Figure 3 A schematic diagram of a one-dimensional pipeline laminar flow model in an embodiment of the present invention;

[0053] Figure 4 This is a structural block diagram of a leakage detection device for a submarine oil-filled cable provided in Embodiment 3 of the present invention. DETAILED DESCRIPTION

[0054] The embodiments of the present invention provide a leakage detection method, device and equipment for a submarine oil-filled cable, which are used to solve the technical problem that the traditional leakage detection method is to judge the leakage of the cable or pipeline by the conservation of fluid mass, that is, to judge whether the inflow and outflow masses at both ends are the same. However, for leakage detection, this method can only be used when a large-scale leakage occurs or in the late stage of leakage, and continuous positioning is required to find the location of the leakage point, resulting in low detection accuracy.

[0055] The conductor inside the current submarine oil-filled cable is made of a spirally wound copper strip to form a hollow pipe. The gaps on the surface of the conductor allow the insulating oil to pass freely. When the cable is working, the two sides are pressurized and the inside of the pipe is filled with insulating oil. If the cable leaks, the pressure inside the oil channel will squeeze the insulating oil out of the leak point, thereby preventing seawater from entering the cable and causing a short circuit in the conductor.

[0056] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0057] See also Figure 1 , Figure 1 A flowchart of the steps of a method for detecting leakage of a submarine oil-filled cable provided in Embodiment 1 of the present invention.

[0058] The present invention provides a method for detecting leakage of a submarine oil-filled cable, comprising:

[0059] Step 101, obtaining a route elevation change curve and first environmental data corresponding to a submarine oil-filled cable;

[0060] The route elevation change curve refers to the height change curve between the submarine oil-filled cable and the horizontal plane or other assumed reference plane.

[0061] The first environmental data refers to the data used to set the boundary conditions of the one-dimensional pipeline laminar flow model, which includes but is not limited to parameter data such as temperature, pressure or flow rate obtained by temperature fiber optic sensors set along the submarine oil-filled cable, oil pump pressure, oil tank thermometers, etc.

[0062] In an embodiment of the present invention, in order to obtain a data basis for leak detection of a submarine oil-filled cable, a route elevation change curve and first environmental data corresponding to the submarine oil-filled cable may be first obtained from a preset database or other software.

[0063] Step 102, constructing a one-dimensional pipeline laminar flow model based on the discretization result of the route elevation change curve and the first environmental data;

[0064] After obtaining the route elevation change curve, since it is necessary to simulate the flow characteristics of the entire submarine cable oil channel, the route elevation change curve can be further discretized according to preset intervals to determine multiple discrete points, and after performing a convergence analysis of the discrete density in combination with the first environmental data, a one-dimensional pipeline laminar flow model is constructed.

[0065] It should be noted that the one-dimensional pipeline laminar flow model can be generated by using the nonisothermal pipe flow module (Nonisothermal Pipe Flow) of the computational fluid dynamics software COMSOL and setting the boundary conditions of the model with the first environmental data while taking heat transfer into consideration.

[0066] Step 103, performing steady-state simulation on the one-dimensional pipeline laminar flow model to determine the steady flow rate of the insulating oil;

[0067] In the embodiment of the present invention, after the one-dimensional pipeline laminar flow model is created, a steady-state simulation can be performed on it to determine the steady flow rate of the insulating oil after the flow reaches stability, which serves as the initial condition for the subsequent transient simulation.

[0068] Step 104, in response to the second environmental data monitored in real time and the monitored flow, calculate the real-time insulating oil flow corresponding to the one-dimensional pipeline laminar flow model according to the second environmental data and the stable flow rate of the insulating oil;

[0069] In an embodiment of the present invention, the environment in which the submarine oil-filled cable is located can be monitored in real time to obtain second environmental data such as the oil pump pressure and oil tank temperature at both ends of the submarine oil-filled cable, and the optical fiber temperature along the cable. At the same time, the monitoring flow of the oil pipeline in which the submarine oil-filled cable is located can also be obtained.

[0070] The second environment data is used to update the boundary conditions in the one-dimensional pipeline laminar flow model, and the steady flow rate of the insulating oil is used as input to calculate the real-time insulating oil flow corresponding to the model.

[0071] Step 105: If the deviation between the real-time insulating oil flow rate and the monitored flow rate exceeds a preset leakage threshold, it is determined that the submarine oil-filled cable has a leakage.

[0072] After calculating the real-time insulating oil flow, the deviation between the real-time insulating oil flow and the monitored flow can be further calculated. If the deviation exceeds a preset leakage threshold, such as 10%, it is determined that the submarine oil-filled cable is leaking.

[0073] In an embodiment of the present invention, a route elevation change curve and first environmental data corresponding to the submarine oil-filled cable are obtained; a one-dimensional pipeline laminar flow model is constructed according to the discretization result of the route elevation change curve and the first environmental data; a steady-state simulation is performed using the one-dimensional pipeline laminar flow model to determine the stable flow rate of the insulating oil; in response to the second environmental data and the monitored flow monitored in real time, the real-time insulating oil flow corresponding to the one-dimensional pipeline laminar flow model is calculated according to the second environmental data and the stable flow rate of the insulating oil; if the deviation value between the real-time insulating oil flow and the monitored flow exceeds a preset leakage threshold, it is determined that a leakage occurs in the submarine oil-filled cable, thereby improving the calculation efficiency of the real-time insulating oil flow through a digital twin method, and considering the influence of the second environmental data, it is possible to detect subtle flow leakage caused by the flow caused by thermal expansion and contraction of the insulating oil, discover the existence of the leakage point in the early stage of the leakage, and effectively improve the accuracy of leakage detection.

[0074] See also Figure 2 , Figure 2 A flow chart showing the steps of a method for detecting leakage of a submarine oil-filled cable according to a second embodiment of the present invention is shown.

[0075] An embodiment of the present invention provides a method for detecting leakage of a submarine oil-filled cable, comprising:

[0076] Step 201, obtaining a route elevation change curve and first environmental data corresponding to a submarine oil-filled cable;

[0077] In the embodiment of the present invention, the specific implementation process of step 201 is similar to step 101 and will not be repeated here.

[0078] Step 202, constructing a one-dimensional pipeline laminar flow model based on the discretization result of the route elevation change curve and combining it with the first environmental data;

[0079] See also Figure 3 , Figure 3 A model schematic diagram of a one-dimensional pipeline laminar flow model in an embodiment of the present invention is shown, where the thick black solid line is the elevation change curve of an imaginary submarine cable, and the points enclosed by other white circles are discrete points of the elevation curve.

[0080] Optionally, step 202 may include the following sub-steps S11-S15:

[0081] S11, discretizing the route elevation change curve according to a preset interval to obtain a plurality of discrete points;

[0082] In this embodiment, the route elevation change curve can be discretized according to a preset interval to obtain multiple discrete points, such as Figure 3 The points in the free part provide the data basis for the subsequent discrete density convergence verification.

[0083] S12, performing discrete density convergence check on discrete points with insulating oil flow as the result, and judging whether the interval between discrete points meets the convergence condition;

[0084] After obtaining multiple discrete points, a discrete density convergence check can be performed to determine whether the interval of the insulating oil flow calculated for the line composed of the multiple discrete points meets the convergence condition.

[0085] Specifically, the process of discrete density convergence verification is to perform grid convergence analysis in this case, that is, to determine when the elevation discrete density increases to a certain extent and the flow calculation result no longer changes. By associating each discrete point and solving the conservation formula group, the insulating oil flow corresponding to the current discrete point can be determined, and the difference between the two adjacent insulating oil flows can be calculated to determine whether the difference is greater than the preset convergence threshold.

[0086] If it is greater than, it indicates that the interval between the discrete points does not meet the convergence condition at this time, and step S13 can be executed at this time.

[0087] S13, if not satisfied, reducing the intervals between discrete points according to a preset step length to obtain multiple new discrete points;

[0088] If the interval between the discrete points does not meet the convergence condition, the interval between the discrete points can be reduced according to a preset step size to update multiple new discrete points.

[0089] In order to reduce the consumption of computing resources, multiple specific interval values ​​can be set, such as 1 meter, 5 meters and 10 meters, and discrete density convergence check can be performed at the specific interval value. If the convergence condition is not met, it can be directly adjusted to a smaller specific interval value.

[0090] S14, jump to execute the step of performing discrete density convergence check on discrete points with insulating oil flow as the result, and judging whether the interval between discrete points meets the convergence condition;

[0091] S15. If satisfied, connect each discrete point and set boundary conditions according to the first environment data to generate a one-dimensional pipeline laminar flow model.

[0092] In one example of the present invention, the boundary conditions include pressure boundary conditions and temperature boundary conditions, and S15 may include the following sub-steps:

[0093] If the convergence condition is met, each discrete point is connected to generate an initial pipeline laminar flow model;

[0094] Extracting the oil pump pressures at both ends, the oil tank temperatures at both ends and the seawater temperature from the first environmental data;

[0095] The oil pump pressure at both ends is used as the pressure boundary condition at both ends of the oil channel in the initial pipeline laminar flow model;

[0096] The temperatures of the oil tanks at both ends are used as the temperature boundary conditions at both ends of the oil channel in the initial pipeline laminar flow model;

[0097] The seawater temperature is used as the temperature boundary condition of the outer surface of the cable in the initial pipeline laminar flow model to generate a one-dimensional pipeline laminar flow model.

[0098] In the embodiment of the present invention, if the difference between the insulating oil flow rates is less than or equal to , it is determined that the interval meets the convergence condition, and at this time, each discrete point can be connected to generate an initial pipeline laminar flow model.

[0099] At the same time, it is also necessary to set the boundary conditions of the model. The oil pump pressures at both ends, the oil tank temperatures at both ends and the seawater temperature can be extracted from the first environmental data; the oil pump pressures at both ends are used as the pressure boundary conditions at both ends of the oil channel in the initial pipeline laminar flow model; the oil tank temperatures at both ends are used as the temperature boundary conditions at both ends of the oil channel in the initial pipeline laminar flow model; the seawater temperature is used as the temperature boundary condition for the outer surface of the cable in the initial pipeline laminar flow model to generate a one-dimensional pipeline laminar flow model.

[0100] In the specific implementation, the pressure of the oil pumps at both ends of the oil-filled cable can be used as the pressure boundary conditions at both ends of the oil channel, the temperature of the oil tank thermometers at both ends can be used as the temperature boundary conditions at both ends of the oil channel, and the temperature fiber optic sensors laid along the oil-filled cable can be used to measure the seawater temperature along the cable as the temperature boundary conditions of the cable outer surface. The equivalent heat transfer coefficient of the cable can also be calculated based on the thickness and thermal conductivity of each layer of the cable, and then the heat per unit length along the cable can be calculated, the conductor current can be monitored, and the heat generated by the conductor can be calculated using Joule's law as the heat source term in the flow model.

[0101] Furthermore, step 202 may also include the following sub-steps:

[0102] Obtain the location of the oil flow restrictor in the subsea oil-filled cable;

[0103] In the one-dimensional pipeline laminar flow model, one-dimensional valve nodes are added according to the position of the oil flow restrictor to obtain a new one-dimensional pipeline laminar flow model.

[0104] In the specific implementation, in order to consider the resistance effect of the oil flow restrictor in the oil channel on the flow, a one-dimensional valve node (valve node in COMSOL) is added at the position of the oil flow restrictor. The flow damper is modeled by computational fluid dynamics to obtain its pressure drop at different flow rates, which is used to set the pressure loss coefficient of the valve node in COMSOL.

[0105] Among them, the pressure loss coefficient k is:

[0106]

[0107] Where Δp is the pressure drop and u is the flow rate.

[0108] Step 203, performing steady-state simulation on the one-dimensional pipeline laminar flow model to determine the steady flow rate of the insulating oil;

[0109] Steady-state simulation is the simulation of a steady-state system. The focus is on the stability and other behavioral characteristics of the system when the simulation time tends to infinity. The simulation time is required to be long enough to obtain high-quality estimation results. In order to eliminate the influence of the initial state of the simulation on the simulation results, it is usually necessary to set a sufficiently long warm-up period, during which no statistical information is collected. It is usually also necessary to have enough repeated runs to obtain good simulation results.

[0110] Since it is necessary to obtain the stable flow rate of the insulating oil in the pipeline under a stable state, a steady-state simulation can be performed on the one-dimensional pipeline laminar flow model. The pressure of the oil pumps at both ends of the oil-filled cable is used as the pressure boundary condition at both ends of the oil channel. The temperature of the oil tank thermometers at both ends is used as the temperature boundary condition at both ends of the oil channel. The temperature fiber optic sensor laid along the oil-filled cable is used to measure the seawater temperature along the cable as the temperature boundary condition of the outer surface of the cable until the flow reaches a stable state, and the stable flow rate of the insulating oil at this time is determined.

[0111] At the same time, the steady flow rate of insulating oil is also used as the initial condition for subsequent transient simulations.

[0112] It should be noted that when conducting steady-state simulation, the highest temperature and the lowest temperature of seawater are taken as the temperature boundary values ​​of the outer surface of the cable. At the same time, in actual use, the pressure at both ends of the oil-filled cable and the current of the cable conductor are kept constant, and then the initial conditions of the insulating oil flow are calculated.

[0113] Step 204, in response to the second environmental data monitored in real time and the monitored flow, the boundary conditions of the one-dimensional pipeline laminar flow model are updated using the second environmental data;

[0114] In this embodiment, the pipeline in which the one-dimensional pipeline laminar flow model is located can be monitored in real time to obtain real-time monitoring flow and second environmental data. The boundary conditions of the one-dimensional pipeline laminar flow model are updated through the second environmental data to obtain real-time changes in the environment in which the cable is located.

[0115] The data type of the second environmental data is the same as that of the first environmental data, including the oil pump pressure at both ends, the oil tank temperature at both ends, the temperature of the optical fiber along the cable, and the thermal conductivity and conductor current.

[0116] Step 205, using the insulating oil steady flow rate as input, performing transient simulation on the one-dimensional pipeline laminar flow model to determine the corresponding real-time insulating oil flow rate;

[0117] Transient simulation refers to the process of simulating and calculating the real-time insulating oil flow rate at a certain moment by taking the steady flow rate of insulating oil as the initial condition of input and combining it with the real-time boundary corresponding to the second environment data. It can be set up and implemented through COMSOL software.

[0118] Optionally, the second environmental data includes thermal conductivity and conductor current; step 205 may include the following sub-steps S21-S23:

[0119] S21. Calculate the heat permeability per unit length along the cable in the one-dimensional pipeline laminar flow model according to the thickness and thermal conductivity of each layer of the cable in the one-dimensional pipeline laminar flow model;

[0120] In this embodiment, the second environmental data may also include thermal conductivity and conductor current. The heat permeability per unit length along the cable in the one-dimensional pipeline laminar flow model is calculated by the thickness and thermal conductivity of each layer of the cable. The specific process may be as follows:

[0121] Heat per unit length Q wall It can be calculated based on the equivalent heat transfer coefficient of the submarine cable:

[0122] Q wall =(hZ) eff (T ext -T)[W / m]

[0123] Where (hZ) eff is the equivalent heat transfer coefficient, which is obtained by multiplying the heat transfer coefficient h by the circumference of the submarine cable Z. ext is the ambient temperature measured by the temperature optical fiber. The equivalent heat transfer coefficient can be estimated by the thermal conductivity and thickness of each layer of the submarine cable:

[0124]

[0125] Where r0 is the inner diameter of the pipe, r N is the outer diameter of the pipe, r n is the outer diameter of the nth layer of pipe, k n is the thermal conductivity of the nth layer of pipe. int is the convection heat transfer coefficient of the internal insulating oil, which can be calculated by the following formula:

[0126]

[0127] Nu int =3.66

[0128] Where k is the thermal conductivity of the insulating oil, Nu intis the Nusselt number of insulating oil flow (a dimensionless number that characterizes the intensity of convective heat transfer).

[0129] h ext is the convective heat transfer coefficient of external seawater, which can be calculated by the following formula:

[0130]

[0131]

[0132] where k s is the thermal conductivity of seawater, Nu ext is the Nusselt number of seawater flow, Re is the Reynolds number of seawater, and the current velocity u around the submarine cable is used. s (can be obtained from marine meteorological reports), seawater density ρ s 、Seawater viscosity μ s Find:

[0133]

[0134] Pr is the Prandtl number, which can be obtained from the specific heat of seawater C p , k s , μ s Find:

[0135] Pr=C p μ s / k s

[0136] It should be noted that the physical property constants (density, viscosity, specific heat, thermal conductivity) of insulating oil and seawater should be interpolated from the average interface temperature. int , the average temperature is 0.5(T+T0); for h ext , the average temperature is 0.5(T ext +T N ).

[0137] The above is for Q wall The calculation can be realized in COMSOL. Engineers can set the corresponding material properties of the cable layers, insulating oil and seawater, as well as the external environment temperature T in the software. ext (measured by temperature optical fiber) and ocean current velocity u s

[0138] S22. Use conductor current combined with Joule's law to calculate the heating value of the cable;

[0139] In the specific implementation, the conductor current of the current cable conductor can be monitored in real time, and the heat generated by the cable per unit length can be calculated based on Joule's law:

[0140] Q=I 2 R

[0141] Among them, I is the conductor current and R is the conductor resistance.

[0142] S23, using the insulating oil steady flow rate, the heat permeability per unit length and the cable heat generation to substitute into the preset conservation formula group, calculate the real-time insulating oil flow corresponding to the one-dimensional pipeline laminar flow model.

[0143] Furthermore, the conservation formula group includes:

[0144]

[0145]

[0146]

[0147] Where, t is time, A is the cross-sectional area of ​​the pipeline, ρ is the fluid density, u is the steady flow rate of the insulating oil, p is the fluid pressure, and d h is the pipe diameter, f D is the friction coefficient, F is the volume force, T is the temperature of the fluid, C p is the specific heat of the fluid, k is the thermal conductivity of the fluid, Q is the heat generated by the cable per unit length of the cable conductor, Q wall It is the heat permeability per unit length.

[0148] In an embodiment of the present invention, the conservation formula group includes mass conservation, momentum conservation and energy conservation equations. By substituting the existing insulating oil stable flow rate, heat permeability per unit length and cable heat generation into the preset conservation formula group and solving the formula group, the real-time insulating oil flow rate is obtained, that is, the product of the cross-sectional area of ​​the pipeline and the insulating oil stable flow rate.

[0149] Where, the friction coefficient f D The Reynolds number-friction coefficient curve actually measured in the pipeline test can be set using a user-defined equation, or set as a preset parameter, which is not limited in the embodiment of the present invention.

[0150] When the method described in the embodiment of the present invention is used, compared with the traditional method of judging cable or pipeline leakage by fluid mass conservation, the method based on digital twins can consider the flow caused by thermal expansion and contraction of insulating oil due to changes in marine environmental temperature and conductor current. This method can detect subtle leakage flow and discover the existence of leakage points in the early stage of leakage; a transient one-dimensional pipeline laminar flow model considering heat transfer is established to simulate the flow of insulating oil in the oil channel of oil-filled submarine cables. This model has similar accuracy to the three-dimensional model in simulating such uniform laminar flow problems with low Reynolds numbers, but its computational efficiency is much higher than that of the three-dimensional model, which can significantly improve its response speed as a digital twin model.

[0151] Step 206: If the deviation between the real-time insulating oil flow rate and the monitored flow rate exceeds a preset leakage threshold, it is determined that the submarine oil-filled cable has a leakage.

[0152] Furthermore, the method further comprises the following steps:

[0153] If the deviation value between the real-time insulating oil flow rate and the monitored flow rate does not exceed the preset leakage threshold, it is determined that no leakage occurs in the submarine oil-filled cable.

[0154] In this embodiment, the deviation value can be obtained by calculating the difference between the real-time insulating oil flow and the monitored flow and taking the absolute value. If the deviation value does not exceed the preset leakage threshold, it is determined that the submarine oil-filled cable has no leakage.

[0155] In an embodiment of the present invention, a route elevation change curve and first environmental data corresponding to the submarine oil-filled cable are obtained; a one-dimensional pipeline laminar flow model is constructed according to the discretization result of the route elevation change curve and the first environmental data; a steady-state simulation is performed using the one-dimensional pipeline laminar flow model to determine the stable flow rate of the insulating oil; in response to the second environmental data and the monitored flow monitored in real time, the real-time insulating oil flow corresponding to the one-dimensional pipeline laminar flow model is calculated according to the second environmental data and the stable flow rate of the insulating oil; if the deviation value between the real-time insulating oil flow and the monitored flow exceeds a preset leakage threshold, it is determined that a leakage occurs in the submarine oil-filled cable, thereby improving the calculation efficiency of the real-time insulating oil flow through a digital twin method, and considering the influence of the second environmental data, it is possible to detect subtle flow leakage caused by the flow caused by thermal expansion and contraction of the insulating oil, discover the existence of the leakage point in the early stage of the leakage, and effectively improve the accuracy of leakage detection.

[0156] See also Figure 4 , Figure 4 This is a structural block diagram of a leakage detection device for a submarine oil-filled cable provided in Embodiment 3 of the present invention.

[0157] An embodiment of the present invention provides a leakage detection device for a submarine oil-filled cable, comprising:

[0158] The data acquisition module 401 is used to acquire the route elevation change curve and the first environmental data corresponding to the submarine oil-filled cable;

[0159] A model building module 402 is used to build a one-dimensional pipeline laminar flow model based on the discretization result of the route elevation change curve and the first environmental data;

[0160] A steady flow rate calculation module 403 is used to perform a steady-state simulation on a one-dimensional pipeline laminar flow model to determine a steady flow rate of insulating oil;

[0161] A real-time flow calculation module 404 is used to respond to the second environmental data and the monitored flow rate monitored in real time, and calculate the real-time insulating oil flow rate corresponding to the one-dimensional pipeline laminar flow model according to the second environmental data and the stable flow rate of the insulating oil;

[0162] The flow deviation judgment module 405 is used to judge that the submarine oil-filled cable has a leak if the deviation value between the real-time insulating oil flow and the monitored flow exceeds a preset leakage threshold.

[0163] Optionally, the device further comprises:

[0164] The non-leakage determination module is used to determine that there is no leakage in the submarine oil-filled cable if the deviation value between the real-time insulating oil flow rate and the monitored flow rate does not exceed a preset leakage threshold.

[0165] Optionally, the model building module 402 includes:

[0166] The discrete submodule is used to discretize the route elevation change curve according to a preset interval to obtain multiple discrete points;

[0167] The convergence judgment submodule is used to perform discrete density convergence check on discrete points with insulating oil flow as the result, and judge whether the interval between discrete points meets the convergence condition;

[0168] The interval reduction submodule is used to reduce the interval between discrete points according to a preset step size to obtain multiple new discrete points if the condition is not satisfied;

[0169] A jump submodule is used to jump to the step of performing a discrete density convergence check on discrete points with the insulating oil flow rate as the result, and judging whether the interval between the discrete points meets the convergence condition;

[0170] The model generation submodule is used to connect the discrete points and set the boundary conditions according to the first environmental data to generate a one-dimensional pipeline laminar flow model if the conditions are met.

[0171] Optionally, the model building module 402 further includes:

[0172] A limiter position acquisition submodule is used to acquire the position of the oil flow limiter in the submarine oil-filled cable;

[0173] The model updating submodule is used to add a one-dimensional valve node according to the position of the oil flow restrictor in the one-dimensional pipeline laminar flow model to obtain a new one-dimensional pipeline laminar flow model.

[0174] Optionally, the boundary conditions include pressure boundary conditions and temperature boundary conditions; the model generation submodule is specifically used for:

[0175] If the convergence condition is met, each discrete point is connected to generate an initial pipeline laminar flow model;

[0176] Extracting the oil pump pressures at both ends, the oil tank temperatures at both ends and the seawater temperature from the first environmental data;

[0177] The oil pump pressure at both ends is used as the pressure boundary condition at both ends of the oil channel in the initial pipeline laminar flow model;

[0178] The temperatures of the oil tanks at both ends are used as the temperature boundary conditions at both ends of the oil channel in the initial pipeline laminar flow model;

[0179] The seawater temperature is used as the temperature boundary condition of the outer surface of the cable in the initial pipeline laminar flow model to generate a one-dimensional pipeline laminar flow model.

[0180] Optionally, the real-time traffic calculation module 404 includes:

[0181] A boundary condition updating submodule, for responding to the second environmental data monitored in real time and the monitored flow, and updating the boundary conditions of the one-dimensional pipeline laminar flow model using the second environmental data;

[0182] The insulating oil flow calculation submodule is used to perform transient simulation on the one-dimensional pipeline laminar flow model with the steady flow rate of insulating oil as input to determine the corresponding real-time insulating oil flow rate.

[0183] Optionally, the second environmental data includes thermal conductivity and conductor current; the insulating oil flow calculation submodule is specifically used for:

[0184] According to the thickness and thermal conductivity of each layer of the cable in the one-dimensional pipeline laminar flow model, the heat permeability per unit length along the cable in the one-dimensional pipeline laminar flow model is calculated;

[0185] The heat generated by the cable is calculated by using the conductor current combined with Joule's law;

[0186] The steady flow rate of insulating oil, the heat permeability per unit length and the heat generated by the cable are substituted into the preset conservation formula group to calculate the real-time insulating oil flow corresponding to the one-dimensional pipeline laminar flow model.

[0187] Optionally, the conservation formula group includes:

[0188]

[0189]

[0190]

[0191] Where, t is time, A is the cross-sectional area of ​​the pipeline, ρ is the fluid density, u is the steady flow rate of the insulating oil, p is the fluid pressure, and d h is the pipe diameter, f D is the friction coefficient, F is the volume force, T is the temperature of the fluid, C pis the specific heat of the fluid, k is the thermal conductivity of the fluid, Q is the heat generated by the cable per unit length of the cable conductor, Q wall It is the heat permeability per unit length.

[0192] An embodiment of the present invention provides an electronic device, including a memory and a processor, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the processor executes the steps of the leakage detection method for a submarine oil-filled cable as described in any embodiment of the present invention.

[0193] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described devices and modules can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0194] In the several embodiments provided by the present invention, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the modules is only a logical function division. There may be other division methods in actual implementation, such as multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or modules, which can be electrical, mechanical or other forms.

[0195] The modules described as separate components may or may not be physically separated, and the components shown as modules may or may not be physical modules, that is, they may be located in one place or distributed on multiple network modules. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0196] In addition, each functional module in each embodiment of the present invention may be integrated into one processing module, or each module may exist physically separately, or two or more modules may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of software functional modules.

[0197] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for detecting leakage of a submarine oil-filled cable, characterized in that: include: Obtaining a route elevation change curve and first environmental data corresponding to the submarine oil-filled cable; According to the discretization result of the route elevation change curve, a one-dimensional pipeline laminar flow model is constructed in combination with the first environmental data; performing a steady-state simulation on the one-dimensional pipeline laminar flow model to determine a steady flow rate of the insulating oil; In response to the second environmental data monitored in real time and the monitored flow rate, the real-time insulating oil flow rate corresponding to the one-dimensional pipeline laminar flow model is calculated according to the second environmental data and the insulating oil stable flow rate; If the deviation between the real-time insulating oil flow rate and the monitored flow rate exceeds a preset leakage threshold, it is determined that the submarine oil-filled cable has a leakage; The step of constructing a one-dimensional pipeline laminar flow model based on the discretization result of the route elevation change curve and combining the first environmental data includes: Discretizing the route elevation change curve according to preset intervals to obtain a plurality of discrete points; Performing a discrete density convergence check on the discrete points with the insulating oil flow rate as the result to determine whether the intervals between the discrete points meet the convergence condition; If not, the intervals between the discrete points are reduced according to a preset step size to obtain multiple new discrete points; Jump to the step of performing discrete density convergence check on the discrete points with the insulating oil flow rate as the result, and judging whether the intervals between the discrete points meet the convergence condition; If so, each of the discrete points is connected and boundary conditions are set according to the first environmental data to generate a one-dimensional pipeline laminar flow model.

2. The method according to claim 1, characterized in that Also includes: If the deviation value between the real-time insulating oil flow rate and the monitored flow rate does not exceed a preset leakage threshold, it is determined that no leakage occurs in the submarine oil-filled cable.

3. The method according to claim 1, characterized in that Also includes: Obtaining a position of an oil flow restrictor in the submarine oil-filled cable; A one-dimensional valve node is added to the one-dimensional pipeline laminar flow model according to the position of the oil flow restrictor to obtain a new one-dimensional pipeline laminar flow model.

4. The method according to claim 1, characterized in that: The boundary conditions include pressure boundary conditions and temperature boundary conditions; if the conditions are met, the steps of connecting the discrete points and setting the boundary conditions according to the first environmental data to generate a one-dimensional pipeline laminar flow model include: If the convergence condition is met, then the discrete points are connected to generate an initial pipeline laminar flow model; Extracting the oil pump pressures at both ends, the oil tank temperatures at both ends and the seawater temperature from the first environmental data; Using the oil pump pressures at both ends as pressure boundary conditions at both ends of the oil channel in the initial pipeline laminar flow model; Using the oil tank temperatures at both ends as temperature boundary conditions at both ends of the oil channel in the initial pipeline laminar flow model; The seawater temperature is used as a temperature boundary condition of the outer surface of the cable in the initial pipeline laminar flow model to generate a one-dimensional pipeline laminar flow model.

5. The method according to claim 1, characterized in that The step of calculating the real-time insulating oil flow rate corresponding to the one-dimensional pipeline laminar flow model in response to the second environmental data monitored in real time and the monitored flow rate according to the second environmental data and the insulating oil stable flow rate comprises: In response to the real-time monitored second environmental data and the monitored flow rate, the boundary conditions of the one-dimensional pipeline laminar flow model are updated using the second environmental data; The insulating oil steady flow rate is used as input to perform transient simulation on the one-dimensional pipeline laminar flow model to determine the corresponding real-time insulating oil flow rate.

6. The method according to claim 5, characterized in that The second environmental data includes thermal conductivity and conductor current; the step of taking the insulating oil steady flow rate as input, performing transient simulation on the one-dimensional pipeline laminar flow model, and determining the corresponding real-time insulating oil flow rate includes: Calculating the heat permeability per unit length along the cable in the one-dimensional pipeline laminar flow model according to the thickness of each layer of the cable in the one-dimensional pipeline laminar flow model and the thermal conductivity; The heat generated by the cable is calculated by using the conductor current combined with Joule's law; The insulating oil steady flow rate, the heat permeability per unit length and the cable heat generation are substituted into a preset conservation formula group to calculate the real-time insulating oil flow corresponding to the one-dimensional pipeline laminar flow model.

7. The method according to claim 6, characterized in that The conservation formula group includes: ； ； ； in, For time, is the cross-sectional area of ​​the pipe, is the fluid density, To stabilize the flow rate of insulating oil, is the fluid pressure, is the pipe diameter, is the friction coefficient, is the volume force, is the temperature of the fluid, is the specific heat of the fluid, is the thermal conductivity of the fluid, is the heat generated per unit length of the cable conductor, It is the heat permeability per unit length.

8. A leakage detection device for a submarine oil-filled cable, characterized in that: include: A data acquisition module, used to acquire a route elevation change curve and first environmental data corresponding to the submarine oil-filled cable; A model building module, used to build a one-dimensional pipeline laminar flow model according to the discretization result of the route elevation change curve and in combination with the first environmental data; A steady flow rate calculation module, used to perform steady-state simulation on the one-dimensional pipeline laminar flow model to determine the steady flow rate of the insulating oil; A real-time flow calculation module, configured to respond to the second environmental data monitored in real time and the monitored flow, and calculate the real-time insulating oil flow corresponding to the one-dimensional pipeline laminar flow model according to the second environmental data and the insulating oil stable flow rate; A flow deviation judgment module, configured to judge that leakage occurs in the submarine oil-filled cable if the deviation value between the real-time insulating oil flow and the monitored flow exceeds a preset leakage threshold; The model building module comprises: A discrete submodule, used for discretizing the route elevation change curve according to a preset interval to obtain a plurality of discrete points; A convergence judgment submodule is used to perform a discrete density convergence check on the discrete points with the insulating oil flow rate as the result, and judge whether the interval between the discrete points meets the convergence condition; An interval reduction submodule is used to reduce the interval between the discrete points according to a preset step size to obtain multiple new discrete points if the condition is not satisfied; A jump submodule, used for jumping to the step of performing discrete density convergence check on the discrete points with the insulating oil flow as the result, and judging whether the interval between the discrete points meets the convergence condition; The model generation submodule is used to connect the discrete points and set boundary conditions according to the first environmental data to generate a one-dimensional pipeline laminar flow model if the conditions are met.

9. An electronic device, characterized in that: It comprises a memory and a processor, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the processor executes the steps of the leakage detection method for the submarine oil-filled cable as described in any one of claims 1 to 7.

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