CN104181193B - Method for calculating thermal resistance of packing layer in compound optical fiber of three-core submarine cable - Google Patents

Abstract

The invention relates to a method for calculating thermal resistance of a packing layer in a compound optical fiber of a three-core submarine cable, belonging to the field of thermodynamic calculation of parameters of a cable material. The method comprises the following steps: firstly, calculating thermal resistance between the inner diameter part of the packing layer and the outer diameter part of an armor layer; subsequently, calculating the temperature of the outer diameter part of the packing layer according to the temperature of the compound optical fiber, then calculating the temperature of the outer diameter part of the armor layer, and subsequently, calculating thermal resistance between two isothermal surfaces according to a temperature difference between the isothermal surface of the optical fiber and the isothermal surface of the outer diameter part of the armor layer and loss of a submarine cable core; and finally, subtracting the thermal resistance between the isothermal surface of the optical fiber and the isothermal surface of the outer diameter part of the armor layer from the thermal resistance between the inner diameter part of the packing layer and the outer diameter part of the armor layer so as to obtain the thermal resistance of the packing layer in the compound optical fiber. The method is capable of solving the problem that thermal resistance of a packing layer in a compound optical fiber cannot be calculated when the temperature of a conductor is calculated based on the temperature of the optical fiber by a thermal circuit method and when current-carrying capacity is calculated; the method has the advantages of being high in speed, being accurate and being universally suitable for all three-core cables.

Description

In three core submarine cables within composite fiber packed layer thermal resistance computational methods

Technical field

The invention belongs in cable material parameter calculation of thermodynamics field, more particularly to three core submarine cables composite fiber with The computational methods of interior packed layer thermal resistance.

Background technology

As China's offshore novel energy exploitation is growing with electricity needs, the demand of transmission of electricity over strait is increasingly urgent, sea Bottom cable application quantity grows with each passing day.Three core submarine cables can reduce route width of corridor condition compared to single submarine cable Lower raising transmission capacity, and have the advantages that to reduce loss, it is widely used in offshore islands and powers and marine wind electric field transmission of electricity. In order to realize the transmission of information, optical fiber is typically all compounded with three core submarine cables, constitutes optical fiber composite submarine cable.

Conductor temperature is the key factor for determining the submarine cable life-span, is also to determine the important evidence of current-carrying capacity, is state The important parameter of monitoring.Utilize Distributed Optical Fiber Sensing Techniques to monitor three core overland cable skin temperatures, enter column conductor temperature The case that degree is calculated.For three-core optical fiber composite submarine cable, because it lays bad environments, it is impossible to individually lay in its epidermis Sensing optic cable, and because three core submarine cable radial structures are asymmetric, using Re Lufa by composite fiber temperature computation conductor temperature Thermal resistance dyscalculia when spending, causes at present to be rarely reported the conductor temperature computational methods of three-core optical fiber composite submarine cable.

For problem above, the present invention proposes the calculating side of packed layer thermal resistance within composite fiber in three core submarine cables Method, solves when calculating conductor temperature according to Re Lufa and fiber optic temperature that packed layer thermal resistance is imponderable within composite fiber asks Topic, to carry out submarine cable status monitoring using composite fiber measured temperature in three core submarine cables and carrying current calculation is provided Effective ways.

The content of the invention

It is an object of the present invention to the computational methods of packed layer thermal resistance within composite fiber in three core submarine cables are proposed, For solving according to Re Lufa, using packed layer thermal resistance is imponderable in composite fiber during fiber optic temperature calculating conductor temperature to ask Topic.

To achieve these goals, technical scheme proposed by the present invention is filled out within composite fiber in three core submarine cables The computational methods of layer thermal resistance are filled, it is characterized in that methods described includes：

Step 1：The thermal resistance of packed layer internal diameter to armor external diameter is calculated, concrete grammar is as follows：

(1) assume that packed layer internal diameter to the thermal resistivity between armor external diameter is all the thermal resistivity of packed layer, calculate Packed layer internal diameter is to the thermal resistance between armor external diameter

Wherein, R is the half of armor external diameter, r₁It is distance of the core center to submarine cable center, n=3 is core Quantity, r is the radius of core, and λ is the heat conductivity for filling layer material；

(2) using thermal resistance sum T of IEC60853 criterion calculation packed layer external diameters to armor external diameter_s", it is equal to pricks The thermal resistance sum of band, brass band, armouring bed course and armor；

(3) assume that packed layer external diameter to the material between armor external diameter is filling layer material, using IEC60853 standards Calculate thermal resistance T_s”’；

(4) packed layer internal diameter is calculated to true thermal resistance sum T between armor external diameter_s=T_s’-(T_s”’-T_s”)；

Step 2：Packed layer outer radius temperature is calculated, concrete grammar is as follows：

As y-axis, y-axis is original with the intersection point of packed layer external diameter to extended line with light unit center to the submarine cable line of centres Point, the tangent line of packed layer external diameter is x-axis at origin, sets up coordinate system；Calculate packed layer outer radius temperature be

Wherein, t (x, y) is the temperature of composite fiber, and Q is the total losses of three cores, and λ is the thermal resistivity of packed layer, y₀For the distance at submarine cable center to packed layer external diameter, x and y is the transverse and longitudinal coordinate at light unit center, and x=0；

Step 3：Armor outer radius temperature is calculated, concrete grammar is as follows：

(1) X is set as lead alloy sheath to material thickness between armor and the ratio of lead alloy sheath external diameter, for each other Discontiguous lead alloy sheath, computational geometry factor

(2) packed layer external diameter is all calculated as follows to the layers of material thermal resistance between armor internal diameter

Wherein, ρ_TIt is thermal resistivity；

(3) armor temperature is calculated

t_a=T_s-Q·T_s1

Wherein, T_s1For the thermal resistance sum of packed layer external diameter to armor internal diameter；

Step 4：Calculating the thermal resistance at composite fiber between isothermal level and armor outer radius isothermal level is

Wherein, Δ t is the temperature difference at optical fiber at isothermal level and armor between isothermal level；

Step 5：Calculate packed layer thermal resistance T within composite fiber_f=T_s-T_fa。

The composite fiber is single mode, multimode or other kinds of optical fiber, and the temperature of composite fiber passes through distribution type fiber-optic Temperature measurement equipment is measured, and these equipment are based on fiber raman scattering, based on optical fiber Brillouin scattering or based on fiber Rayleigh The distributed optical fiber temperature measurement equipment of relevant Cleaning Principle or instrument.

Beneficial effects of the present invention：1st, the invention provides packed layer thermal resistance within composite fiber in three core submarine cables Computational methods；2nd, the method that the present invention is provided is applied to all of three-core optical fiber composite submarine cable or overland cable；3rd, this The method of bright proposition is to set up composite fiber using thermal circuit model to have established theoretical base with conductor temperature relation and carrying current calculation Plinth.

Description of the drawings

Fig. 1 is three-core optical fiber composite submarine cable sectional view；

Fig. 2 is the schematic diagram using composite fiber temperature computation packed layer outer radius temperature.

Specific embodiment

With reference to the accompanying drawings and examples the present invention is described further：

1st, the thermal resistance of packed layer internal diameter to armor external diameter in three core submarine cables is calculated.With ZS-YJQF41 types 18/30/ As a example by the core XLPE insulating optical fiber composite submarine cables of 36kV tri-, its internal structure is as shown in Figure 1.Specifically calculation procedure is：

(1) assume that packed layer internal diameter to the thermal resistivity between armor external diameter is all the thermal resistivity of packed layer, calculate Packed layer internal diameter is to the thermal resistance between armor external diameter

Wherein, R is the half of armor external diameter, r₁It is distance of the core center to submarine cable center, n=3 is core Quantity, r is the radius of core, and λ is the heat conductivity for filling layer material.

(2) using thermal resistance sum T of IEC60853 criterion calculation packed layer external diameters to armor external diameter_s", it is equal to pricks The thermal resistance sum of band, brass band, armouring bed course and armor.

(3) assume that packed layer external diameter to the material between armor external diameter is filling layer material, using IEC60853 standards Calculate thermal resistance T_s”’。

(4) packed layer internal diameter is calculated to true thermal resistance sum T between armor external diameter_s=T_s’-(T_s”’-T_s”)。

2nd, packed layer outer radius temperature is calculated, concrete grammar is as follows：

As shown in Fig. 2 with the extended line of light unit center (i.e. composite fiber) to the submarine cable line of centres as y-axis, y-axis Intersection point with packed layer external diameter is origin, and the tangent line of packed layer external diameter is x-axis at origin, sets up coordinate system；Calculate outside packed layer Temperature at footpath is

Wherein, t (x, y) is the temperature (temperature can be obtained using distributed optical fiber temperature measuring equipment) of composite fiber, Q It is the total losses of three cores, λ is the thermal resistivity of packed layer, y₀For submarine cable center to packed layer external diameter (i.e. origin) Distance, x and y are the transverse and longitudinal coordinates of light unit center (i.e. composite fiber), and x=0.

3rd, armor outer radius temperature is calculated, concrete grammar is as follows：

(1) X is set as lead alloy sheath to material thickness between armor and the ratio of lead alloy sheath external diameter, for each other Discontiguous lead alloy sheath, computational geometry factor

(2) packed layer external diameter is all calculated as follows to the layers of material thermal resistance between armor internal diameter

Wherein, ρ_TIt is thermal resistivity.

(3) armor temperature is calculated

t_a=t_s-Q·T_s1

Wherein, T_s1For the thermal resistance sum of packed layer external diameter to armor internal diameter.

4th, calculating the thermal resistance at composite fiber between isothermal level and armor outer radius isothermal level is

Wherein, Δ t is the temperature difference at optical fiber at isothermal level and armor between isothermal level；

5th, packed layer thermal resistance T within composite fiber is calculated_f=T_s-T_fa。

The above, is only presently preferred embodiments of the present invention, and any pro forma restriction is not made to the present invention, any ripe Professional and technical personnel is known, in the case of without departing from the technology of the present invention essence, any modification that above example is made, Equivalent variations and modification, belong to the protection domain of technical solution of the present invention.

Claims (2)

1. in three core submarine cables within composite fiber packed layer thermal resistance computational methods, it is characterised in that comprise the following steps：

Step 1：The thermal resistance of packed layer internal diameter to armor external diameter is calculated, concrete grammar is as follows：

(1) assume that packed layer internal diameter to the thermal resistivity between armor external diameter is all the thermal resistivity of packed layer, calculate filling Layer internal diameter is to the thermal resistance between armor external diameter

$T_s^{\′}=\frac{ln(R/r_1)-\frac{1}{n}ln(nr/r_1)}{2\mathrm{\π}\mathrm{\λ}}$

Wherein, R is the half of armor external diameter, r₁It is distance of the core center to submarine cable center, n=3 is the number of core Amount, r is the radius of core, and λ is the heat conductivity for filling layer material；

(2) using thermal resistance sum T of IEC60853 criterion calculation packed layer external diameters to armor external diameter_s", it is equal to band, pyrite The thermal resistance sum of band, armouring bed course and armor；

(3) assume that packed layer external diameter to the material between armor external diameter is filling layer material, using IEC60853 criterion calculation Thermal resistance T_s”’；

(4) packed layer internal diameter is calculated to true thermal resistance sum T between armor external diameter_s=T_s’-(T_s”’-T_s”)；

Step 2：Packed layer outer radius temperature is calculated, concrete grammar is as follows：

As y-axis, y-axis is origin with the intersection point of packed layer external diameter to extended line with light unit center to the submarine cable line of centres, The tangent line of packed layer external diameter is x-axis at origin, sets up coordinate system；Calculate packed layer outer radius temperature be

$t_s=t(x,y)-\frac{Q}{2\mathrm{\π}\mathrm{\λ}}ln\sqrt{\frac{x^2+{(y+y_0)}^2}{x^2+{(y-y_0)}^2}}$

Wherein, t (x, y) is the temperature of composite fiber, and Q is the total losses of three cores, and λ is the thermal resistivity of packed layer, y₀For sea To the distance of packed layer external diameter, x and y is the transverse and longitudinal coordinate at light unit center, and x=0 for bottom cable center；

Step 3：Armor outer radius temperature is calculated, concrete grammar is as follows：

(1) set X as lead alloy sheath to material thickness between armor and lead alloy sheath external diameter ratio, for not connecing each other Tactile lead alloy sheath, computational geometry factor

(2) packed layer external diameter is all calculated as follows to the layers of material thermal resistance between armor internal diameter

$T=\frac{{\mathrm{\ρ}}_T}{2\mathrm{\π}}\stackrel{\‾}{G}$

Wherein, ρ_TIt is thermal resistivity；

(3) armor temperature is calculated

t_a=t_s-Q·T_s1

Wherein, T_s1For the thermal resistance sum of packed layer external diameter to armor internal diameter；

Step 4：Calculating the thermal resistance at composite fiber between isothermal level and armor outer radius isothermal level is

$T_{fa}=\frac{\mathrm{\Δ}t}{Q}$

Wherein, Δ t is the temperature difference at optical fiber at isothermal level and armor between isothermal level；

Step 5：Calculate packed layer thermal resistance T within composite fiber_f=T_s-T_fa。

2. according to claim 1 in three core submarine cables within composite fiber packed layer thermal resistance computational methods, its feature It is that composite fiber is single mode, multimode or other kinds of optical fiber, the temperature of composite fiber passes through distributed optical fiber temperature measuring Equipment is measured, and these equipment are based on fiber raman scattering, based on optical fiber Brillouin scattering or based on the relevant detection of fiber Rayleigh The distributed optical fiber temperature measurement equipment of principle or instrument.