An OPGW ice-melting current and optical fiber critical temperature rise optimization calculation method and system

Abstract

The application discloses an OPGW ice-melting current and optical fiber critical temperature rise optimization calculation method and system. The method comprises the following steps: establishing a calculation expression of the Joule heat consumption of the OPGW in the ice-melting process; obtaining the calculation expression of the OPGW ice-melting current from the energy conservation equation in the OPGW direct-current ice-melting process; obtaining the on-site icing line model and the detection parameters of the on-site online monitoring device, and then combining the on-site specified ice-melting time to obtain the OPGW required ice-melting current value according to the calculation expression of the OPGW ice-melting current; and according to the OPGW required ice-melting current value, the maximum value of the OPGW internal optical fiber temperature before ice shedding and the steady-state value of the OPGW internal optical fiber temperature after ice shedding are calculated, and the maximum value of the former two is taken as the OPGW internal optical fiber critical temperature rise value. The application effectively supports the on-site icing monitoring and timely response to faults of the high-voltage transmission line without relying on the finite element modeling simulation calculation.

Description

Technical Field

[0001] This invention belongs to the field of power grid transmission lines and relates to the optimized calculation of OPGW de-icing current and optical fiber critical temperature rise. Specifically, it is an optimized calculation method and system for OPGW de-icing current and optical fiber critical temperature rise that combines online monitoring parameters and adapts to the complex on-site icing environment. Background Technology

[0002] As power grid transmission lines gradually develop towards ultra-high voltage, large capacity, and long distance, the line corridors are becoming increasingly dense, and fault events caused by line icing occur frequently, affecting the reliability of power supply.

[0003] Currently, in the design of OPGW de-icing solutions, the determination of key parameters such as the required de-icing current, current generator capacity, and maximum fiber temperature often requires finite element simulation calculations. This involves a significant investment of time and manpower in modeling and simulation, resulting in low efficiency. Furthermore, it is difficult to respond promptly to on-site icing faults, and the reliability of high-voltage transmission line operation cannot be guaranteed. Summary of the Invention

[0004] The technical problem this invention aims to solve is to address the needs of on-site production lines by providing an optimized calculation method and system for OPGW de-icing current and fiber critical temperature rise based on on-site parameters. This method simplifies the calculation expression of OPGW de-icing current with respect to Joule heat consumption to obtain the OPGW de-icing current. It calculates the maximum value of the internal fiber temperature of the OPGW before de-icing and the steady-state value of the internal fiber temperature of the OPGW after de-icing, taking the maximum of the two as the critical temperature rise value of the internal fiber of the OPGW. This eliminates the need for finite element simulation calculations, effectively supporting on-site icing monitoring and timely fault response for high-voltage transmission lines. It also provides a reference for the design of subsequent OPGW DC de-icing schemes.

[0005] Therefore, the present invention adopts the following technical solution: an optimized calculation method for OPGW de-icing current and optical fiber critical temperature rise, comprising:

[0006] Step a) Establish a calculation expression for the Joule heat consumption generated by the OPGW during the ice melting process;

[0007] Step b) Based on the calculation expression of Joule heat consumption, the energy conservation equation for the OPGW DC de-icing process is obtained, and from the energy conservation equation for the OPGW DC de-icing process, the calculation expression of the OPGW de-icing current with respect to Joule heat consumption is obtained.

[0008] Step c) Obtain the model of the iced line and the detection parameters of the on-site online monitoring device. Calculate the ice melting area in the cross-section of the iced line, the heat exchange coefficient of the outer surface of the ice layer, the equivalent thermal resistance of the remaining ice layer after the ice layer falls off, and the heat loss of the outer surface of the ice layer. Combined with the ice melting time specified on site, obtain the required ice melting current value of OPGW according to the calculation expression of OPGW ice melting current.

[0009] Step d): Based on the required de-icing current value of OPGW, calculate the maximum value of the internal fiber temperature of OPGW before de-icing and the steady-state value of the internal fiber temperature of OPGW after de-icing.

[0010] Step e) Based on the maximum value of the internal fiber temperature of the OPGW before de-icing and the steady-state value of the internal fiber temperature of the OPGW after de-icing, the maximum value of the former two is taken as the critical temperature rise value of the internal fiber of the OPGW.

[0011] This invention, based on the model of the iced line and the detection parameters of the on-site online monitoring device, obtains the required de-icing current value for the OPGW by using the expression for the Joule heat consumed by the OPGW during the de-icing process and the de-icing current of the OPGW, combined with the de-icing time specified on-site; calculates the maximum value of the internal fiber temperature of the OPGW before de-icing and the steady-state value of the internal fiber temperature of the OPGW after de-icing, and takes the larger of the two as the critical temperature rise value of the internal fiber of the OPGW, thereby completing the optimization calculation of the OPGW de-icing current and the critical temperature rise of the fiber.

[0012] Furthermore, in step a), the Joule heat consumed by the OPGW during the ice melting process includes the heat required for the temperature rise of the melted ice layer, the latent heat absorbed when the ice melts, the heat lost from the outer surface of the ice layer, the heat required for the temperature rise of the unmelted ice layer, and the heat required for the temperature rise of the OPGW; to simplify the calculation, the heat required for the temperature rise of the unmelted ice layer and the heat required for the temperature rise of the OPGW are ignored.

[0013] Furthermore, in step b), the energy conservation equation for the OPGW DC de-icing process simplifies to:

[0014] ,

[0015] In the formula, I This refers to the OPGW de-icing current, in amperes (A). r T for T The resistance per unit length of the OPGW de-icing conductor, in units of / m; T This indicates the temperature of the OPGW de-icing conductor, in °C. t The time for melting ice is expressed in units of 1. s ; P cThis represents the heat lost per unit length of the outer surface of the ice layer, expressed in J / m. ρ i The density of the ice layer is expressed in kg / m³. 3 ; L F Latent heat absorbed when a unit mass of ice melts, expressed in J / kg; S m This represents the area of ​​ice that melts in a cross-section during the melting time, expressed in meters (m²). 2 ; C i This represents the specific heat capacity of the ice layer, expressed in J / (kg·℃). T a The ambient temperature is expressed in °C.

[0016] Furthermore, in step c), the detection parameters of the on-site online monitoring device include ambient temperature, wind speed, and ice thickness. Ambient temperature, wind speed, and ice thickness are the basis for calculating key parameters such as melting area and heat exchange coefficient, and directly affect the calculation results of melting current and fiber optic temperature rise. Ambient temperature is used to determine the temperature difference between the ice layer and the environment for heat exchange, wind speed is used to calculate the Reynolds number and thus determine the heat exchange coefficient, and ice thickness is used to calculate the melting area.

[0017] Furthermore, in step c), the method for calculating the heat loss of the outer surface of the ice layer is as follows: the heat loss of the outer surface of the ice layer is calculated based on the radius of the OPGW, the ice thickness, the heat exchange coefficient of the outer surface of the ice layer, the temperature of the outer surface of the ice layer, the ambient temperature, and the melting time.

[0018] Furthermore, the outer surface temperature of the ice layer T i The formula for calculation is:

[0019] ,

[0020] In the formula, h Surface thermal conductivity, in W / (m²) 2 ·℃); R c The radius of the OPGW is in meters. d The icing thickness of OPGW is given in meters (m). R T1 The equivalent thermal resistance of the remaining ice layer after the ice layer has detached is expressed in m·℃ / W. T a The ambient temperature is expressed in °C.

[0021] Furthermore, the equivalent conductive thermal resistance of the remaining ice layer after the ice layer detaches... R T1 The formula for calculation is:

[0022] ,

[0023] In the formula, This represents the area element in a two-dimensional field of the remaining ice layer after the ice layer has detached; r out This represents the outer radius of the ice layer after it has broken off, in meters. r in This indicates the radius of the contact surface between the remaining ice layer and the OPGW optical fiber, in meters (m). The thermal conductivity of ice, in units of W / ( m ·℃).

[0024] Furthermore, in step d), the formula for calculating the maximum internal fiber temperature of the OPGW before de-icing is:

[0025] ,

[0026] In the formula, T pm This represents the maximum internal fiber temperature of the OPGW before de-icing, in °C. R T0 The equivalent thermal resistance of the air gap is expressed in m·℃ / W. R T2 The equivalent thermal resistance between the internal optical fiber and the surface of the OPGW is expressed in m·℃ / W. I 0 represents the required de-icing current value for the OPGW, in amperes (A). r T for T The resistance per unit length of the OPGW ice-melting conductor, expressed in Ω / m.

[0027] Furthermore, in step d), the steady-state temperature of the internal fiber of the OPGW after de-icing is calculated using the following formula:

[0028] ,

[0029] In the formula, T pn The steady-state temperature of the optical fiber inside the OPGW after de-icing is expressed in °C. r T for T The resistance per unit length of the OPGW ice-melting conductor, expressed in Ω / m; I 0 represents the required de-icing current value for the OPGW, in amperes (A). R T2 The equivalent thermal resistance between the internal optical fiber and the surface of the OPGW is expressed in m·℃ / W. R cThe radius of the OPGW is in meters. T a This refers to the ambient temperature, expressed in °C. h c The heat exchange coefficient of the OPGW surface is expressed in W / (m²). 2 ·℃).

[0030] Another technical solution adopted in this invention is as follows: an optimization calculation system for OPGW de-icing current and optical fiber critical temperature rise, used to implement the above-mentioned optimization calculation method, comprising:

[0031] Unit for establishing the calculation expression for Joule heat consumption: Establish the calculation expression for Joule heat consumption generated by OPGW during the ice melting process;

[0032] Unit for obtaining the calculation expression of melting current: Based on the calculation expression of Joule heat consumption, the energy conservation equation of the OPGW DC melting process is obtained, and the calculation expression of OPGW melting current is obtained from the energy conservation equation of the OPGW DC melting process;

[0033] The de-icing current calculation unit obtains the model of the iced line and the detection parameters of the on-site online monitoring device, calculates the ice melting area in the cross-section of the iced line, the heat exchange coefficient of the outer surface of the ice layer, the equivalent thermal resistance of the remaining ice layer after the ice layer falls off, and the heat loss of the outer surface of the ice layer. Then, combined with the de-icing time specified on site, the required de-icing current value of OPGW is obtained according to the calculation expression of OPGW de-icing current.

[0034] Fiber optic maximum temperature calculation unit: Calculates the maximum fiber temperature inside the OPGW before de-icing based on the required de-icing current value of the OPGW;

[0035] Fiber temperature steady-state value calculation unit: Based on the required de-icing current value of OPGW, calculate the steady-state value of fiber temperature inside OPGW after de-icing;

[0036] Fiber Critical Temperature Rise Acquisition Unit: Based on the maximum value of the fiber temperature inside the OPGW before de-icing and the steady-state value of the fiber temperature inside the OPGW after de-icing, the maximum value of the two is taken as the critical temperature rise value of the fiber inside the OPGW.

[0037] Compared with existing technologies, this invention does not require finite element simulation modeling for iced lines, and can quickly obtain the OPGW de-icing current and the critical temperature rise value of optical fiber, which improves the calculation efficiency of OPGW de-icing current, effectively supports on-site icing monitoring and timely fault response of high-voltage transmission lines, and can also provide a reference for the design of subsequent OPGW DC de-icing schemes. Attached Figure Description

[0038] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0039] Figure 1 This is a flowchart of the optimized calculation method for OPGW de-icing current and optical fiber critical temperature rise according to the present invention;

[0040] Figure 2 This is a flowchart of the OPGW de-icing current calculation method of the present invention;

[0041] Figure 3 This is a cross-sectional view of a field-mounted A-type OPGW line in a specific embodiment of the present invention;

[0042] Figure 4 This is a cross-sectional view of the B-type OPGW line in a specific embodiment of the present invention;

[0043] Figure 5 The graph shows the calculated temperature rise characteristic curves of type A OPGW optical fiber under different ambient temperatures in a specific embodiment of the present invention.

[0044] Figure 6 The graph shows the calculated temperature rise characteristic curves of type B OPGW optical fiber under different ambient temperatures in a specific embodiment of the present invention.

[0045] Figure 7 The figure shows the calculated temperature rise characteristic curves of type A OPGW optical fiber under different wind speeds in a specific embodiment of the present invention.

[0046] Figure 8 The figure shows the calculation results of the temperature rise characteristic curves of type B OPGW optical fiber under different wind speeds in a specific embodiment of the present invention.

[0047] Figure 9 The graph shows the calculated steady-state temperatures of two types of OPGW optical fibers after complete melting under different ambient temperatures in a specific embodiment of the present invention.

[0048] Figure 10 The graph shows the calculation results of the maximum steady-state temperature of two types of OPGW optical fibers after complete de-icing under different wind speeds in a specific embodiment of the present invention.

[0049] Figure 11 This is a diagram showing the composition of the optimization calculation system for OPGW de-icing current and optical fiber critical temperature rise according to the present invention. Detailed Implementation

[0050] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0051] Example 1

[0052] This embodiment presents an optimized calculation method for the OPGW de-icing current and the critical temperature rise of optical fiber, such as... Figure 1 As shown, the steps are as follows:

[0053] Step a) Establish a calculation expression for the Joule heat consumption generated by the OPGW during the ice melting process.

[0054] The formula for calculating the heat consumed by a Joule is as follows:

[0055] ,

[0056] In the formula, P c This represents the heat loss per unit length of the outer surface of the ice layer, expressed in J / m. ρ i The density of the ice layer is expressed in kg / m³. 3 ; L F The latent heat absorbed when a unit mass of ice melts. L F =335000 J / kg; S m This refers to the area of ​​ice that melts in the cross-section of an icing line during the melting period, expressed in meters (m²). 2 ; C i This represents the specific heat capacity of the ice layer, expressed in J / (kg·℃). T a This refers to the ambient temperature, expressed in °C. S i The area of ​​the ice layer that melts in the cross-section of the icing line after de-icing is expressed in m. 2 ; T i This indicates the temperature rise of the remaining ice layer after de-icing of an icing line, expressed in °C. ρ c 、C c and S c These represent the density, specific heat capacity, and cross-sectional area of ​​the material in different parts of the OPGW, respectively, with units of kg / m². 3 J / (kg·℃), m 2 ; Tc This indicates the temperature of the OPGW at the moment of ice shedding, in °C.

[0057] Step b) Based on the calculation expression of Joule heat consumption, the energy conservation equation for the OPGW DC de-icing process is obtained, and from the energy conservation equation for the OPGW DC de-icing process, the calculation expression of the OPGW de-icing current with respect to Joule heat consumption is obtained.

[0058] The expression for calculating the Joule heat consumption generated by the OPGW during the ice-melting process established in step a) follows the law of conservation of energy. The energy conservation equation for the DC ice-melting process of the OPGW is shown in equation (1).

[0059] (1)

[0060] In the formula: I This is the ice-melting current, measured in amperes (A). r T for T The resistance per unit length of the OPGW ice-melting conductor, expressed in Ω / m; T This indicates the temperature of the OPGW de-icing conductor, in °C. t The time for melting ice is expressed in units of 1. s .

[0061] In formula (1), the Joule heat consumed by the OPGW during the actual ice melting process includes the heat required for the temperature rise of the melted ice layer, the latent heat absorbed when the ice melts, the heat lost from the outer surface of the ice layer, the heat required for the temperature rise of the unmelted ice layer, and the heat required for the temperature rise of the OPGW. Since the heat absorbed by the unmelted ice layer and the OPGW during the temperature rise is relatively small, it can be ignored for the convenience of engineering application calculations. Therefore, formula (1) can be simplified to formula (2).

[0062] (2)

[0063] The meanings of the variables in the formula remain consistent with those in formula (1), and will not be repeated here.

[0064] Step c) Obtain the model of the icing line and the detection parameters of the on-site online monitoring device. Calculate the ice melting area in the cross-section of the icing line, the heat exchange coefficient of the outer surface of the ice layer, the equivalent thermal resistance of the remaining ice layer after the ice layer falls off, and the heat loss from the outer surface of the ice layer. Combined with the ice melting time specified on site, obtain the required ice melting current value of the OPGW according to the calculation expression of the OPGW ice melting current.

[0065] The on-site online monitoring device detects parameters including ambient temperature. T a Wind speed V a Ice thicknessd .

[0066] Specifically, in step c), the required de-icing current value for the OPGW is as follows: Figure 2 As shown, obtain it through the following steps:

[0067] Step c1) First, calculate the melting area of ​​the ice layer in the cross-section of the icing line. S m Heat exchange coefficient of the outer surface of the ice layer h Ice surface temperature T i and the heat loss per unit length of the outer surface of the ice layer P c .

[0068] In step c1), the area of ​​ice melting in the cross-section of the icing line. S m The calculation is as follows: when the ice layer displaces downwards s = d At that time, the ice layer detached from the OPGW surface. The area of ​​ice melting in the cross-section... S m The formula for calculation is:

[0069] (3)

[0070] In the formula, Pi; R c The radius of the OPGW is in meters. R s The radius of the outermost aluminum-clad steel wire in OPGW, in meters; d The icing thickness of OPGW is given in meters (m). n This refers to the number of aluminum-clad steel wires in the outermost layer of OPGW.

[0071] In step c1), the heat exchange coefficient of the outer surface of the ice layer h The formula for calculation is:

[0072] (4)

[0073] In the formula, λ a The thermal conductivity of air. λ a =0.0244W / (m·℃); ε For the emissivity of the ice surface, ε =0.9; σ The radiation constant, σ =5.67×10 -8 W / (m 2 ·℃ 4); T a This refers to the ambient temperature, expressed in °C. B , b For the reason G r The determining coefficient; C , n For the reason R e The determining coefficient; R e , P r , G r These are the Reynolds number, Prandlt number, and Grasshof number, respectively. R e , P r , G r The calculations for the three are shown in equation (5).

[0074] (5)

[0075] In the formula, V a The wind speed in the surrounding environment is expressed in m / s. ν The kinematic viscosity of air. ν =1.328×10 -5 m 2 / s; μ Let be the kinetic viscosity coefficient of air. μ =1.72×10 -5 kg / (m·s); C a The specific heat capacity of air. C a =1005J / (kg·℃); ρ a For the density of air, ρ a =1.293kg / m 3 .

[0076] in, R e Typical value range: In laminar flow, R e <2×10 5 In the terminal flow, R e ≥2×10 5 ; Pr Typical value range: In air at room temperature, the default value is... Pr It is a constant. Pr≈0.7; G r Typical value range: In laminar flow, G r <1.41×10 9 In the terminal flow, G r ≥1.41×10 9 ;

[0077] B , b For the reason G r The determining coefficient; C , n For the reason R e The determining coefficients are shown below.

[0078] In laminar flow, that is G r <1.41×10 9 hour, B =0.48, b =0.25; in the terminal flow, that is G r ≥1.41×10 9 At that time, B = 0.10, b = 0.33; in laminar flow, i.e. R e <2×10 5 hour, C =0.664, n =0.5; in the terminal flow, that is R e ≥2×10 5 hour, C =0.0296, n =0.8.

[0079] In step c1), the outer surface temperature of the ice layer T i The formula for calculation is:

[0080] (6)

[0081] In the formula, h Surface thermal conductivity, in W / (m²) 2 ·℃); R T1 The equivalent thermal resistance of the remaining ice layer after the ice layer has detached is expressed in m·℃ / W.

[0082] The equivalent thermal resistance of the remaining ice layer after the ice layer breaks off. R T1 The calculation formula is as follows:

[0083] (7)

[0084] In the formula, This represents the area element in a two-dimensional field of the remaining ice layer after the ice layer has detached; r out This represents the outer radius of the ice layer after it has broken off, in meters. r in This indicates the radius of the contact surface between the remaining ice layer and the OPGW optical fiber, in meters (m). The thermal conductivity of ice, in units of W / ( m ·℃);

[0085] In step c1), the method for calculating the heat loss of the outer surface of the ice layer is as follows: the heat loss of the outer surface of the ice layer is calculated based on the radius of the OPGW, the ice thickness, the heat exchange coefficient of the outer surface of the ice layer, the temperature of the outer surface of the ice layer, the ambient temperature, and the melting time.

[0086] Heat lost from the outer surface of the ice layer P c The formula for calculation is:

[0087] (8)

[0088] In the formula, P c This represents the heat lost per unit length of the outer surface of the ice layer, expressed in J / m. R c The radius of the OPGW is in meters. d The icing thickness of OPGW is given in meters (m). T i This indicates the temperature of the outer surface of the ice layer, in °C. T a The ambient temperature is expressed in °C. t The melting time is expressed in seconds (s).

[0089] Step c2), according to equations (3)-(8), substitute into equation (2) to obtain the energy conservation equation, see equation (9).

[0090] (9)

[0091] The melting time and melting current are obtained by transforming equation (9), as shown in equation (10) and equation (11) respectively.

[0092] (10)

[0093] (11)

[0094] Step c3) Obtain the on-site specified ice melting time. t 0, Substitute into equation (11) to obtain the required de-icing current value for OPGW. I 0, see equation (12).

[0095] (12)

[0096] In the formula, I 0 represents the required de-icing current value for the OPGW, in amperes (A). t 0 represents the on-site ice melting time, measured in seconds (s).

[0097] Step d): Based on the required de-icing current value of the OPGW, calculate the maximum value of the internal fiber temperature of the OPGW before de-icing and the steady-state value of the internal fiber temperature of the OPGW after de-icing.

[0098] In step d), the maximum internal fiber temperature of the OPGW before de-icing. T pm The calculation is shown in equation (13).

[0099] (13)

[0100] In the formula, T pm This represents the maximum internal fiber temperature of the OPGW before de-icing, in °C. R T0 The equivalent thermal resistance of the air gap is expressed in m·℃ / W. R T2 This represents the equivalent thermal resistance between the internal optical fiber and the surface of the OPGW, expressed in m·℃ / W. R T2 It is determined by the model and structural form of the OPGW (the model includes the structural form); I 0 represents the required de-icing current value for the OPGW, in amperes (A). r T for T Resistance per unit length of the OPGW ice-melting conductor at ℃, expressed in Ω / m.

[0101] Equivalent conductive thermal resistance of air gap R T0 The calculation formula is as follows:

[0102] (14)

[0103] In the formula, λ a The thermal conductivity of air. λ a =0.0244 W / (m·℃); Rc The radius of the OPGW is in meters. Represents an area element in a two-dimensional field; The polar equation for the inner surface of the ice layer at the moment of de-icing is expressed as equation (15):

[0104] (15)

[0105] In step d), the steady-state temperature of the optical fiber inside the OPGW after de-icing. T n The calculation is shown in equation (16).

[0106] (16)

[0107] In the formula, T pn The steady-state temperature of the optical fiber inside the OPGW after de-icing is expressed in °C. r T for T The resistance per unit length of the OPGW ice-melting conductor, expressed in Ω / m; I 0 represents the required de-icing current value for the OPGW, in amperes (A). R T2 This represents the equivalent thermal resistance between the internal optical fiber and the surface of the OPGW, expressed in m·℃ / W. R T2 It is determined by the model and structural form of the OPGW (the model includes the structural form); R c The radius of the OPGW is in meters. T a This refers to the ambient temperature, expressed in °C. h c The heat exchange coefficient of the OPGW surface is expressed in W / (m²). 2 ·℃).

[0108] Step e): Based on the maximum value of the internal fiber temperature of the OPGW before de-icing and the steady-state value of the internal fiber temperature of the OPGW after de-icing, take the maximum value of the two as the critical temperature rise value of the internal fiber of the OPGW. T max .

[0109] T max The calculation is shown in equation (17).

[0110] (17)

[0111] In the formula: T max This represents the critical temperature rise of the optical fiber inside the OPGW, in °C.T pm This represents the maximum internal fiber temperature of the OPGW before de-icing, in °C. T pn The steady-state temperature of the internal optical fiber of the OPGW after de-icing is expressed in °C.

[0112] Application examples

[0113] Taking two different types of icing OPGW lines in the field as examples, the following steps apply the optimized calculation method of this invention to calculate the OPGW de-icing current and the critical temperature rise of optical fiber.

[0114] 1) Obtain the model number of the icing-affected line on site. The model number for Type A OPGW lines is OPGW-12B1+2A1a-68, and the cross-sectional diagram is shown below. Figure 3 As shown, the B-type OPGW line model is OPGW-24B1-122, and the cross-sectional diagram is as follows. Figure 4 As shown; obtain the various detection parameters of the on-site online monitoring device. Among them, ambient temperature... T a =-5℃, wind speed V a =5m / s, ice thickness d =15mm.

[0115] 2) Based on the type of icing line and the various detection parameters obtained from the on-site online monitoring device, the Joule heat consumption generated by the OPGW during the de-icing process was calculated. The Joule heat consumption of the type A OPGW line was 5.24 kWh, and the Joule heat consumption of the type B OPGW line was 10.53 kWh.

[0116] 3) Based on the Joule heat consumed by the OPGW during the de-icing process, the de-icing current value of the OPGW is calculated, and the de-icing current value of the type A OPGW line is 250A, and the de-icing current value of the type B OPGW line is 300A.

[0117] 4) Based on the specified on-site de-icing time of 60 minutes, calculate the maximum internal fiber temperature of the OPGW before de-icing. The calculation results of the temperature rise characteristic curves of the two OPGW fiber types under different ambient temperatures are as follows: Figure 5 and Figure 6 As shown in the figure, the calculated results of the temperature rise characteristic curves of the two types of OPGW optical fibers under different wind speeds are as follows: Figure 7 and Figure 8 As shown, the maximum fiber temperature before de-icing for Type A OPGW lines is 82℃, and the maximum fiber temperature before de-icing for Type B OPGW lines is 71℃.

[0118] 5) Based on the specified on-site de-icing time of 60 minutes, calculate the steady-state temperature of the internal fiber optic cable of the OPGW after de-icing. The calculated steady-state temperatures of the two types of OPGW fibers after complete de-icing under different ambient temperatures are as follows: Figure 9 As shown in the figure, the calculated steady-state temperatures of the two types of OPGW optical fibers after complete de-icing at different wind speeds are as follows: Figure 10 As shown, the steady-state temperature of the optical fiber after de-icing in the Type A OPGW line is 44℃, and the steady-state temperature of the optical fiber after de-icing in the Type B OPGW line is 53℃.

[0119] 6) Obtain the maximum value of the internal fiber temperature of the OPGW before de-icing in step d). The maximum value of the fiber temperature before de-icing for type A OPGW lines is 82℃, and the maximum value of the fiber temperature before de-icing for type B OPGW lines is 71℃. Obtain the steady-state value of the internal fiber temperature of the OPGW after de-icing in step e). The steady-state value of the fiber temperature after de-icing for type A OPGW lines is 44℃, and the steady-state value of the fiber temperature after de-icing for type B OPGW lines is 53℃. Comparing the two values ​​for type A OPGW lines, the larger value is 82℃, therefore the critical temperature rise of the internal fiber of type A OPGW is 82℃; comparing the two values ​​for type B OPGW lines, the larger value is 71℃, therefore the critical temperature rise of the internal fiber of type B OPGW is 71℃.

[0120] Example 2

[0121] This embodiment provides an optimized calculation system for OPGW de-icing current and optical fiber critical temperature rise, used to implement the optimized calculation method described in Embodiment 1, such as... Figure 11 As shown, it consists of a unit for establishing the Joule heat consumption calculation expression, a unit for obtaining the ice melting current calculation expression, a unit for calculating the ice melting current value, a unit for calculating the maximum fiber temperature, a unit for calculating the steady-state value of fiber temperature, and a unit for obtaining the critical temperature rise value of fiber.

[0122] The Joule heat consumption calculation expression establishment unit establishes the calculation expression for the Joule heat consumption generated by the OPGW during the ice melting process; it is used to implement step a) in Example 1, and will not be repeated here.

[0123] The unit for obtaining the ice-melting current calculation expression: Based on the calculation expression of the Joule heat consumption, the energy conservation equation of the OPGW DC ice-melting process is obtained, and the calculation expression of the OPGW ice-melting current is obtained from the energy conservation equation of the OPGW DC ice-melting process; this is used to implement step b) in Example 1, which will not be repeated here.

[0124] The de-icing current calculation unit obtains the model of the iced line and the detection parameters of the on-site online monitoring device, calculates the melting area of ​​the ice layer in the cross-section of the iced line, the heat exchange coefficient of the outer surface of the ice layer, the equivalent thermal resistance of the remaining ice layer after the ice layer falls off, and the heat loss of the outer surface of the ice layer. Combined with the de-icing time specified on site, the required de-icing current value of the OPGW is obtained according to the calculation expression of the OPGW de-icing current. This is used to implement step c) in Example 1, which will not be repeated here.

[0125] Fiber optic temperature maximum value calculation unit: Based on the required de-icing current value of OPGW, calculate the maximum value of the fiber temperature inside OPGW before de-icing; used to implement step d) in Example 1, which will not be repeated here.

[0126] Fiber temperature steady-state value calculation unit: Based on the required de-icing current value of OPGW, calculate the steady-state value of the fiber temperature inside OPGW after de-icing; used to implement step d) in Example 1, which will not be repeated here.

[0127] Fiber critical temperature rise value acquisition unit: Based on the maximum value of the fiber temperature inside the OPGW before de-icing and the steady-state value of the fiber temperature inside the OPGW after de-icing, the maximum value of the two is taken as the critical temperature rise value of the fiber inside the OPGW; used to implement step e) in Example 1, which will not be repeated here.

[0128] It should be noted that each module in the aforementioned optimization calculation system for OPGW de-icing current and fiber critical temperature rise can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of a computer device in hardware form or independent of it, or stored in the memory of a computer device in software form, so that the processor can call and execute the corresponding operations of each module. For specific limitations regarding the optimization calculation system for OPGW de-icing current and fiber critical temperature rise, please refer to the limitations of the optimization calculation method for OPGW de-icing current and fiber critical temperature rise described above; both have the same function and role, and will not be repeated here.

[0129] The above description of the embodiments is provided to enable those skilled in the art to understand and apply the present invention. Those skilled in the art can readily make various modifications to the above embodiments and apply the general principles described herein to other embodiments without creative effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made to the present invention by those skilled in the art based on the disclosure thereof should be within the scope of protection of the present invention.

Claims

1. An OPGW ice-melting current and optical fiber critical temperature rise optimization calculation method, characterized in that, The method comprises the following steps: Step a), establishing a calculation expression of the Joule heat consumption generated by the OPGW in the ice melting process; Step b), obtaining a calculation expression of the OPGW ice melting current with respect to the Joule heat consumption according to the energy conservation in the OPGW direct current ice melting process; Step c), obtaining the model of the icing line in the field and the detection parameters of the on-line monitoring device in the field, calculating the ice layer melting area in the cross section of the icing line, the heat exchange coefficient of the outer surface of the ice layer, the equivalent heat conduction thermal resistance of the residual ice layer after the ice layer falls off, and the heat loss of the outer surface of the ice layer, and then combining the ice melting time specified in the field, and obtaining the required ice melting current value of the OPGW according to the calculation expression of the OPGW ice melting current; Step d), calculating the maximum value of the internal optical fiber temperature of the OPGW before ice shedding and the steady-state value of the internal optical fiber temperature of the OPGW after ice shedding according to the required ice melting current value of the OPGW; Step e), taking the maximum value of the maximum value of the internal optical fiber temperature of the OPGW before ice shedding and the steady-state value of the internal optical fiber temperature of the OPGW after ice shedding as the critical temperature rise value of the internal optical fiber of the OPGW.

2. The method of claim 1, wherein the OPGW ice-melting current and the critical temperature rise of the optical fiber are optimized. In step a), the Joule heat consumption generated by the OPGW in the ice melting process includes the heat required for the temperature rise of the melted part of the ice layer, the latent heat absorbed during the ice melting, the heat loss of the outer surface of the ice layer, the heat required for the temperature rise of the unmelted part of the ice layer, and the heat required for the temperature rise of the OPGW; for simplification of calculation, the heat required for the temperature rise of the unmelted part of the ice layer and the heat required for the temperature rise of the OPGW are ignored.

3. The method of claim 2, wherein the OPGW ice-melting current and the critical temperature rise of the optical fiber are optimized. In step b), the calculation expression of the OPGW ice melting current with respect to the Joule heat consumption is: ， In the formula, I is the OPGW ice-melting current, in A; is T is the unit length resistance of the OPGW ice-melting conductor, in / m; T represents the temperature of the OPGW ice-melting conductor, in ℃; t is the ice-melting time, in s ; P c is the heat dissipated per unit length of the outer surface of the ice layer, in J / m; is the density of the ice layer, in kg / m 3 ; L F is the latent heat absorbed per unit mass of the ice during melting, in J / kg; S m is the area of the ice layer melting in the cross section during the ice-melting time, in m 2 ; C i is the specific heat capacity of the ice layer, in J / (kg·℃); T a is the ambient temperature, in ℃.

4. The method of claim 1, wherein the OPGW ice-melting current and the critical temperature rise of the optical fiber are optimized. In step c), the detection parameters of the on-line monitoring device in the field include the environmental temperature, the wind speed, and the ice thickness.

5. The method of claim 1, wherein the OPGW ice-melting current and the critical temperature rise of the optical fiber are optimized. In step c), the calculation method of the heat loss of the outer surface of the ice layer is: according to the radius of the OPGW, the ice thickness, the heat exchange coefficient of the outer surface of the ice layer, the temperature of the outer surface of the ice layer, the environmental temperature, and the ice melting time, the heat loss of the outer surface of the ice layer is calculated.

6. The method of claim 5, wherein the OPGW ice-melting current and the critical temperature rise of the optical fiber are optimized. Ice layer outer surface temperature T i The calculation formula is: ， In the formula, h is the surface heat transfer coefficient, with the unit of W / (m 2 ·℃); R c is the radius of the OPGW, with the unit of m; d is the ice thickness of the OPGW, with the unit of m; R T1 is the equivalent conductive thermal resistance of the remaining ice layer after the ice layer falls off, with the unit of m·℃ / W; T a is the ambient temperature, with the unit of ℃.

7. The method of claim 6, wherein the OPGW ice-melting current and the critical temperature rise of the optical fiber are optimized. Equivalent conductive thermal resistance of residual ice layer after ice layer shedding R T1 The calculation formula is: ， wherein, represents an area element in the two-dimensional field of the remaining ice layer after the ice layer falls off; represents the outer layer radius after the ice layer falls off, in m; represents the contact surface radius of the remaining ice layer and the OPGW optical fiber, in m; is the thermal conductivity of ice, in W / ( m ·℃).

8. The method of claim 1, wherein the OPGW ice-melting current and the critical temperature rise of the optical fiber are optimized. In step d), the calculation formula of the maximum value of the internal optical fiber temperature of the OPGW before ice shedding is: ， wherein, T pm is the maximum value of the internal optical fiber temperature of the OPGW before ice shedding, in units of °C; R T0 is the equivalent conduction thermal resistance of the air gap, in units of m °C / W; R T2 is the equivalent conduction thermal resistance between the internal optical fiber of the OPGW and the surface of the OPGW, in units of m °C / W; I 0 is the required ice-melting current value of the OPGW, in units of A; is T is the unit length resistance of the OPGW ice-melting conductor, in units of Ω / m; T represents the temperature of the OPGW ice-melting conductor, in units of °C.

9. The method of claim 1, wherein the OPGW ice-melting current and the critical temperature rise of the optical fiber are optimized. In step d), the calculation formula of the steady-state value of the internal optical fiber temperature of the OPGW after ice shedding is: ， In the formula, T pn T0 is the steady-state value of the internal optical fiber temperature of OPGW after ice shedding, in units of ℃; R0 is T R0 is the unit length resistance of the OPGW ice melting conductor, in units of Ω / m; T T0 is the temperature of the OPGW ice melting conductor, in units of ℃; I I0 is the required ice melting current value of OPGW, in units of A; R T2 R0 is the equivalent conduction thermal resistance between the internal optical fiber of OPGW and the surface of OPGW, in units of m·℃ / W; R c R0 is the radius of OPGW, in units of m; T a T0 is the ambient temperature, in units of ℃; h c R0 is the heat exchange coefficient of the surface of OPGW, in units of W / (m 2 ·℃).

10. An OPGW ice-melting current and optical fiber critical temperature rise optimization calculation system for implementing the optimization calculation method of any one of claims 1-9, characterized in that, The method comprises the following steps: The Joule heat consumption calculation expression establishing unit: establishing a calculation expression of the Joule heat consumption generated by the OPGW in the ice melting process; The ice melting current calculation expression obtaining unit: obtaining a calculation expression of the OPGW ice melting current with respect to the Joule heat consumption according to the energy conservation in the OPGW direct current ice melting process; The ice melting current value calculation unit: obtaining the model of the icing line in the field and the detection parameters of the on-line monitoring device in the field, calculating the ice layer melting area in the cross section of the icing line, the heat exchange coefficient of the outer surface of the ice layer, the equivalent heat conduction thermal resistance of the residual ice layer after the ice layer falls off, and the heat loss of the outer surface of the ice layer, and then combining the ice melting time specified in the field, and obtaining the required ice melting current value of the OPGW according to the calculation expression of the OPGW ice melting current; The optical fiber temperature maximum value calculation unit: calculating the maximum value of the internal optical fiber temperature of the OPGW before ice shedding according to the required ice melting current value of the OPGW; The optical fiber temperature steady-state value calculation unit calculates the steady-state value of the optical fiber temperature inside the OPGW after ice shedding according to the required ice-melting current value of the OPGW; The optical fiber critical temperature rise value acquisition unit compares the maximum value of the optical fiber temperature inside the OPGW before ice shedding and the steady-state value of the optical fiber temperature inside the OPGW after ice shedding, and takes the maximum value as the critical temperature rise value of the optical fiber inside the OPGW.

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