CN113255095A - Method for optimizing strength concentration of stress cone field of XLPE cable factory joint - Google Patents

Method for optimizing strength concentration of stress cone field of XLPE cable factory joint Download PDF

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CN113255095A
CN113255095A CN202110291909.7A CN202110291909A CN113255095A CN 113255095 A CN113255095 A CN 113255095A CN 202110291909 A CN202110291909 A CN 202110291909A CN 113255095 A CN113255095 A CN 113255095A
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field strength
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陈向荣
孟繁博
王启隆
黄若彬
韩哲
杨帆
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Ningbo Orient Wires & Cables Co ltd
Zhejiang University ZJU
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Zhejiang University ZJU
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Abstract

本发明公开了一种优化XLPE电缆工厂接头应力锥场强集中的方法,所述方法包括以下步骤:(1)构建XLPE电缆工厂接头物理模型,引入非线性电导率控制层;(2)计算不同位置的本体和恢复层的场强;(3)获得控制层与本体以及恢复绝缘电导率与厚度的关系;(4)控制层长度参数设计。(5)控制层厚度参数设计。(6)确定控制层参数。本发明提供了一种XLPE电缆工厂接头应力锥电场强度集中的优化方法,通过引入非线性电导率控制层,改变其厚度和长度的方式,减少了接头应力锥处的电场强度,有效改善了接头绝缘内部的电场强度分布。本发明方法简单,易于计算和操作,普适性强,为电缆接头的设计和研发提供了有效的解决方法。

Figure 202110291909

The invention discloses a method for optimizing the stress cone field strength concentration of an XLPE cable factory joint. The method includes the following steps: (1) constructing a physical model of the XLPE cable factory joint, and introducing a nonlinear conductivity control layer; (2) calculating different (3) Obtain the relationship between the control layer and the body and the recovery insulation conductivity and thickness; (4) Design the parameters of the length of the control layer. (5) Control layer thickness parameter design. (6) Determine the parameters of the control layer. The invention provides a method for optimizing the electric field intensity concentration of the joint stress cone of an XLPE cable factory. By introducing a nonlinear conductivity control layer and changing its thickness and length, the electric field intensity at the joint stress cone is reduced, and the joint is effectively improved. Electric field strength distribution inside the insulation. The method of the invention is simple, easy to calculate and operate, and has strong universality, and provides an effective solution for the design and research and development of cable joints.

Figure 202110291909

Description

Method for optimizing strength concentration of stress cone field of XLPE cable factory joint
Technical Field
The invention belongs to the technical field of high voltage and insulation, and particularly relates to a method for optimizing strength concentration of an electric field of a joint stress cone of an XLPE cable factory.
Background
With the continuous acceleration of urbanization process and the continuous and rapid development of economy in China, the demand of power consumption is increased sharply, and in order to adapt to the rapidly increasing power transmission demand, new energy and direct current loads are continuously and massively connected into a power system. In the process of power transmission, a Cross-linked Polyethylene (XLPE) cable has become a key power device for long-distance and large-capacity power transmission due to the advantages of excellent electrical performance, small floor area and the like. In recent 20 years, with continuous breakthrough of XLPE cable insulation material technology and continuous progress of cable production technology, XLPE insulated cables have been applied to domestic and foreign projects such as cross-sea power transmission, asynchronous grid interconnection and the like. In a long cable transmission line, a cable joint is used as a key link for connecting cable sections, and the insulation characteristic of the cable joint directly influences the safe and stable operation of the whole cable system. Especially for high-voltage large-capacity power transmission systems, the cable joint technology has become the bottleneck of the development of large-length large-capacity high-voltage cable systems, so that the research on the cable joint technology is the key for developing the large-length large-capacity high-voltage cable power transmission.
At present, the intermediate joint of the cable mainly has three modes of a cold shrinkage mode, a heat shrinkage mode and a prefabrication mode. The joints adopt a shielding tube or a stress cone to control an electric field, and because the XLPE insulation of the cable body is not matched with the electrical parameters of a new insulating material introduced at the joint, charge accumulation and a distorted electric field are easily formed at a composite insulation interface, and insulation breakdown is caused when the electric field is serious. The current factory joint technology adopts the insulation recovery material the same as the insulation material of a cable body, can effectively reduce space charge accumulation caused by interface polarization theoretically, recovers the inner shielding layer and the outer shielding layer of the joint according to the structure of the cable body, and can avoid the problem of electric field concentration around a stress cone and a shielding pipe. In fact, although the recovered insulating material is the same as the insulating material of the cable body, in the vulcanization process of the recovered insulating material, because the environmental conditions such as the process, the temperature and the like cannot be kept consistent with the insulation of the cable body, and the body insulation close to the new and old insulating interfaces has the problem of secondary vulcanization caused by reheating, the electrical properties of the recovered insulation of the factory joints and the insulation of the cable body have different degrees, so that the electric field concentration phenomenon occurs on the new and old insulating interfaces. The existing research shows that the crosslinking temperature and time of the process for manufacturing the factory joint on site are difficult to accurately control, the crosslinking degree of recovered insulation is generally lower than that of body insulation, the conductivity of corresponding XLPE is larger, impurities are easily introduced into the recovered insulation in the process of manufacturing the joint, and in addition, the crosslinking of free radicals caused by insufficient time for recovering insulation and degassing is insufficient, so that the direct current conductivity of the recovered insulation is larger than that of the body insulation, further, an interface electric field of the body and the recovered insulation is influenced, the field intensity concentration at three joint points of the body insulation, the recovered insulation and a shielding layer is easily caused, the insulation degradation and even insulation breakdown are caused under high field intensity after long-time operation, and the safe and stable operation of a cable system is seriously influenced. Therefore, an effective and feasible method is needed to optimize the field intensity concentration at the factory joint interface, improve the electric field distribution of the joint insulation, and further solve the problem of electric field concentration of the XLPE cable factory joint.
Disclosure of Invention
The invention aims to solve the problem of field intensity concentration at a joint stress cone of an XLPE cable factory, and provides a design method of a nonlinear conductivity control layer, which can effectively improve the field intensity at the joint stress cone of the cable factory. The method is realized by introducing a nonlinear conductivity control layer at the interface of a body XLPE insulating layer and a recovery XLPE insulating layer and designing the length and the thickness of the nonlinear conductivity control layer to be proper.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention firstly discloses an optimization design method for field intensity concentration at a joint stress cone of an XLPE cable factory, which comprises the following steps:
step 1: constructing a physical model of an XLPE cable factory joint, and introducing a nonlinear conductivity control layer at the interface of a body XLPE insulating layer and a recovered XLPE insulating layer;
definition of R1iIs the body insulation equivalent resistance, R, between different positions of the nonlinear conductivity control layer and the conductor shielding layer2iRestoring insulation equivalent resistance between different positions of the nonlinear conductivity control layer and the insulation shielding layer; r3iThe equivalent resistance of the control layer is positioned at different positions of the interface; where i ═ 1,2, ·, n, denotes the different positions of the control layer.
Step 2: obtaining bulk XLPE layer field strength E at different positions near the interface1And restoring the field strength E of the XLPE layer2The relational expression of (1);
and step 3: obtaining the relation between the nonlinear conductivity control layer and the bulk XLPE insulating layer and between the conductivity and the thickness of the recovered XLPE insulating layer;
and 4, step 4: nonlinear conductivity control layer length design
Selecting the thickness of the nonlinear conductivity control layer to be unchanged, obtaining the maximum field intensity of the stress cone and the change curve of the maximum field intensity of the nonlinear conductivity control layer along with the length of the nonlinear conductivity control layer by changing the length of the nonlinear conductivity control layer, and selecting the length corresponding to the intersection point of the two change curves as the length of the nonlinear conductivity control layer;
and 5: nonlinear conductivity control layer thickness design
Selecting the length of the nonlinear conductivity control layer as the length determined in the step (4), keeping the length unchanged, obtaining a change curve of the maximum field intensity of the stress cone and the maximum field intensity of the control layer along with the thickness of the nonlinear conductivity control layer by changing the thickness of the nonlinear conductivity control layer, and selecting the thickness corresponding to the intersection point of the two change curves as the thickness of the nonlinear conductivity control layer;
step 6: and (5) introducing a nonlinear conductivity control layer according to the length obtained in the step (4) and the thickness obtained in the step (5) to realize the optimization of the strength concentration of the stress cone of the XLPE cable factory joint.
Further, the step 2 specifically comprises:
setting the voltage between the conductor and the insulation shielding layer to be Udc,E1And σ1Field strength and DC conductivity, E, respectively, of bulk XLPE insulation2And σ2To restore the field strength and DC conductivity, E, respectively, of XLPE insulation3And σ3The field intensity and the direct current conductivity of the nonlinear conductivity control layer are respectively; the bulk XLPE layer field intensity E of different positions near the interface can be obtained according to the formula (1)1And restoring the field strength E of the XLPE layer2The expression (c) of (a),
Figure RE-GDA0003122448750000031
wherein k isσIs the ratio of the recovered insulation conductivity to the insulation conductivity of the body, in formula (1), E3,σ3, k2For unknown parameters, d1,d2,d3A variable that varies with position, d1For controlling the distance of the layer from the conductor shield, d, for non-linear conductivity2For the distance of the nonlinear conductivity control layer from the insulating shield layer, d3For non-linear conductivity control of layer thickness, d1+d2+d3D is the insulation thickness at the joint.
Further, the step 3 specifically comprises:
let the length of the nonlinear conductivity control layer be lm,dmThickness of the layer being controlled for non-linear conductivity, dm= lmSin theta, theta is the angle between the insulating interface and the shielding layer, and P is (1/k)2-1)d3, (kσ-1)d1+P=(kσ-1)dm,kσIs the ratio of the recovered insulation conductivity to the bulk insulation conductivity, and the relationship between the conductivity and the thickness of the nonlinear conductivity control layer and the bulk XLPE insulation layer and the recovered XLPE insulation layer can be obtained according to the formula (2),
Figure RE-GDA0003122448750000041
further, R at different positions1i、R2i、R3iAre different, and therefore the bulk XLPE layer field strength E at different positions1And restoring the field strength E of the XLPE layer2The values of (A) and (B) are different, and the maximum field intensity of the stress cone and the maximum field intensity of the nonlinear conductivity control layer can be obtained by scanning and comparing the electric fields at different positions. The maximum field strength of the stress cone refers to the maximum field strength E of the bulk XLPE insulation layer1maxAnd restoring the maximum field strength E of the XLPE insulation layer2maxThe greater of the two. In addition, the invention introduces the nonlinear conductivity control layer at the interface, when the length and the thickness of the nonlinear conductivity control layer are changed, the maximum field intensity of the stress cone and the maximum field intensity of the nonlinear conductivity control layer are changed.
Furthermore, in the step 4,
the relationship between the length of the nonlinear conductivity control layer and the conductivity is obtained by equation (3),
Figure RE-GDA0003122448750000042
firstly, setting the thickness and the length of a nonlinear conductivity control layer as initial values, and solving the maximum field intensity of a stress cone and the maximum field intensity of the nonlinear conductivity control layer under the initial values through formulas (1) and (2);
then, keeping the thickness unchanged, and solving the maximum field intensity of the stress cone and the maximum field intensity of the nonlinear conductivity control layer by changing the length of the nonlinear conductivity control layer to obtain the change curves of the maximum field intensity of the stress cone of the cable joint and the maximum field intensity of the nonlinear conductivity control layer along with the length of the nonlinear conductivity control layer; and selecting the length corresponding to the intersection point of the two change curves as the length of the nonlinear conductivity control layer.
Furthermore, in the step 5,
the relation formula of the thickness of the nonlinear conductivity control layer and the conductivity is shown as a formula (4);
Figure RE-GDA0003122448750000043
firstly, setting the length of the nonlinear conductivity control layer as the length determined in the step 4, setting the initial thickness, and solving the maximum field intensity of the stress cone and the maximum field intensity of the nonlinear conductivity control layer under the initial thickness value through formulas (1) and (2);
then keeping the length unchanged; solving the maximum field intensity of the stress cone and the maximum field intensity of the nonlinear conductivity control layer by changing the thickness of the nonlinear conductivity control layer, and obtaining the change curves of the maximum field intensity of the stress cone of the cable joint and the maximum field intensity of the nonlinear conductivity control layer along with the thickness of the nonlinear conductivity control layer; and selecting the thickness corresponding to the intersection point of the two change curves as the thickness of the nonlinear conductivity control layer.
Compared with the prior art, the invention has the following beneficial technical effects: the invention provides a method for optimizing the electric field intensity concentration of a stress cone of an XLPE cable factory joint, which reduces the electric field intensity at the position of the stress cone of the cable factory joint by introducing a nonlinear conductivity control layer to change the thickness and the conductivity of the nonlinear conductivity control layer, and effectively improves the electric field intensity distribution in the insulation of the cable factory joint. The method is simple, easy to calculate and operate and strong in universality, reduces the problem of insulation degradation caused by high field intensity at the stress cone through the optimized design of the nonlinear conductivity control layer, and provides an effective solution for the design and research and development of the cable joint.
Drawings
FIG. 1 is a physical model diagram of a XLPE cable plant splice.
Fig. 2 is a graph of the electric field distribution of different nonlinear conductivity control layer lengths and reaction force cones.
Fig. 3 is a graph of the effect of different nonlinear conductivity control layer lengths on their own electric field distribution.
Fig. 4 is a graph of maximum field strength of a cable joint versus control layer length.
Fig. 5 is a graph showing the influence of the thickness of the nonlinear conductivity control layer on the electric field distribution of the reaction force cone.
Fig. 6 is a graph of the thickness of the nonlinear conductivity control layer as a function of its own electric field strength.
Fig. 7 is a graph of maximum field strength of insulation inside a cable joint as a function of thickness of the control layer.
Detailed Description
The present invention will be further described in detail with reference to the following examples of 10kV XLPE cable fusion splices and accompanying drawings.
Step 1: an XLPE cable joint physical model was constructed and a non-linear conductivity control layer was introduced as shown in figure 1. In FIG. 1, E1And σ1Field strength and DC conductivity, E, respectively, of bulk XLPE insulation2And σ2Respectively restoring the field strength and the direct current conductivity of the XLPE insulating layer. E3And σ3The field strength and the direct current conductivity of the nonlinear conductivity control layer are respectively. d1For controlling the distance of the layer from the conductor shield, d, for non-linear conductivity2For the distance of the nonlinear conductivity control layer from the insulating shield layer, d3The layer thickness is controlled for nonlinear conductivity. R1i(i ═ 1,2, · · n) is the bulk insulation equivalent resistance between different locations of the nonlinear conductivity control layer and the conductor shield layer, R2i(i ═ 1,2, · · n) is the recovered insulation equivalent resistance between the different locations of the nonlinear conductivity control layer and the insulating shield layer. R3i(i ═ 1,2, · · n) is the control layer equivalent resistance at different positions of the interface.
Step 2: setting the voltage between the conductor and the insulation shielding layer to be Udc,d1+d2+d3D (d is the insulation thickness at the joint), kσThe insulating DC conductivity being restored to be insulated from the bodyA ratio. Therefore, the bulk XLPE layer field strength E at different positions near the interface can be obtained according to the formula (1)1And restoring the field strength E of the XLPE layer2The relational expression (c) of (c).
Figure RE-GDA0003122448750000061
And step 3: let the length of the nonlinear conductivity control layer be lm,kσ1.5, the dc conductivity of the bulk insulation is 4.3 × 10-15S/m, direct current conductivity of recovered insulation is 4.3kσ×10-15S/m,θ=10°,dm=lmsin θ can obtain the conductivity and thickness relationship between the nonlinear conductivity control layer and the bulk insulation and the recovered insulation according to formula (2).
Figure RE-GDA0003122448750000062
And 4, step 4: nonlinear conductivity control layer length design. Setting the thickness d of the control layer3The relationship between the length of the control layer and the conductivity can be obtained from equation (3) ═ 0.1 mm.
Figure RE-GDA0003122448750000063
FIG. 2 is a graph showing the effect of different lengths of the nonlinear conductivity control layer on the electric field distribution of the reaction force cone. As can be seen from fig. 2, when the nonlinear conductivity control layer is introduced, the electric field distribution of the reaction force cone is more uniform, and the field strength of the reaction force cone gradually decreases as the length of the nonlinear conductivity control layer increases. Fig. 3 illustrates the effect of different nonlinear conductivity control layer lengths on its own electric field distribution. It can be found from fig. 3 that the maximum field strength of the nonlinear conductivity control layer increases with increasing length. Fig. 4 shows the maximum field strength inside the insulation of a cable joint as a function of the length of the control layer. As can be seen from fig. 4, as the length of the nonlinear conductivity control layer increases, the maximum field strength of the reaction force cone becomes smaller and smaller, and the maximum field strength of the control layer becomes larger and larger. When the length of the nonlinear control layer is equal to 5mm, the electric field intensity of the reaction force cone and the nonlinear conductivity control layer is minimum, namely the maximum field intensity of the joint insulation is minimum. The length of the nonlinear conductivity control layer can be selected to be 5 mm.
And 5: and designing the thickness of the nonlinear conductivity control layer. Setting the thickness l of the control layermAnd 5mm, the relation formula of the thickness of the control layer and the conductivity is shown as the formula (4).
Figure RE-GDA0003122448750000071
FIG. 5 is a graph showing the effect of the thickness of the nonlinear conductivity control layer on the electric field distribution of the reaction force cone. As can be seen from fig. 5, as the thickness of the control layer increases, the electric field of the reaction force cone decreases as the thickness of the nonlinear conductivity control layer increases. Fig. 6 shows the relationship between the thickness of the nonlinear conductivity control layer and its own electric field strength, and it can be seen from fig. 6 that the electric field strength inside the control layer is continuously reduced as the thickness of the control layer is increased. Fig. 7 shows the maximum field strength of the insulation inside the cable joint as a function of the thickness of the control layer. As can be seen from fig. 7, the electric field intensity inside the insulation layer is continuously decreased with the increase of the thickness of the nonlinear conductivity control layer, and when the thickness of the control layer is greater than 0.5mm, the maximum field intensity of the reaction force cone is slowly attenuated, and the effect of continuously increasing the thickness is not significant for reducing the field intensity distribution of the reaction force cone. The nonlinear conductivity control layer may thus be chosen to be 0.5mm thick.
Step 6: according to the curve relation between the maximum field intensity of the cable joint and the length and thickness of the nonlinear conductivity control layer, the length of the nonlinear conductivity control layer can be determined to be 5mm, and the thickness value is 0.5 mm. By introducing the nonlinear conductivity control layer, the electric field intensity at the stress cone of the joint of a cable factory can be reduced, and the electric field intensity distribution in the insulation of the joint of the cable factory is effectively improved
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (6)

1.一种优化XLPE电缆工厂接头应力锥场强集中的方法,其特征在于包含以下步骤:1. a method for optimizing XLPE cable factory joint stress cone field strength concentration is characterized in that comprising the following steps: 步骤1:构建XLPE电缆工厂接头物理模型,在本体XLPE绝缘层和恢复XLPE绝缘层交界面处引入非线性电导率控制层;定义R1i为非线性电导率控制层不同位置与导体屏蔽层之间的本体绝缘等效电阻,R2i为非线性电导率控制层不同位置与绝缘屏蔽层之间的恢复绝缘等效电阻;R3i为位于交界面不同位置的控制层等效电阻;其中i=1,2,···,n,表示控制层不同位置;Step 1: Build the physical model of the XLPE cable factory joint, and introduce a nonlinear conductivity control layer at the interface between the body XLPE insulating layer and the recovery XLPE insulating layer; define R 1i as the difference between the nonlinear conductivity control layer and the conductor shielding layer. The body insulation equivalent resistance of , R 2i is the recovery insulation equivalent resistance between different positions of the nonlinear conductivity control layer and the insulating shielding layer; R 3i is the equivalent resistance of the control layer at different positions of the interface; where i=1 ,2,...,n, indicating different positions of the control layer; 步骤2:获得交界面附近不同位置的本体XLPE层场强E1和恢复XLPE层的场强E2的关系表达式;Step 2: Obtain the relational expression of the field strength E 1 of the bulk XLPE layer at different positions near the interface and the field strength E 2 of the restored XLPE layer; 步骤3:获得非线性电导率控制层与本体XLPE绝缘层以及恢复XLPE绝缘层的电导率与厚度的关系;Step 3: Obtain the relationship between the nonlinear conductivity control layer and the bulk XLPE insulating layer and restore the conductivity and thickness of the XLPE insulating layer; 步骤4:非线性电导率控制层长度设计Step 4: Nonlinear Conductivity Control Layer Length Design 选择非线性电导率控制层的厚度不变,通过改变非线性电导率控制层的长度,获取应力锥的最大场强和非线性电导率控制层最大场强随非线性电导率控制层长度的变化曲线,选取两条变化曲线的交点对应的长度作为非线性电导率控制层长度;The thickness of the nonlinear conductivity control layer is selected to remain unchanged, and by changing the length of the nonlinear conductivity control layer, the maximum field strength of the stress cone and the change of the maximum field strength of the nonlinear conductivity control layer with the length of the nonlinear conductivity control layer are obtained. curve, select the length corresponding to the intersection of the two change curves as the length of the nonlinear conductivity control layer; 步骤5:非线性电导率控制层厚度设计Step 5: Nonlinear Conductivity Control Layer Thickness Design 选择非线性电导率控制层的长度为步骤4确定的长度,且保持不变,通过改变非线性电导率控制层的厚度,获取应力锥的最大场强与控制层最大场强随非线性电导率控制层厚度的变化曲线,选取两条变化曲线的交点对应的厚度作为非线性电导率控制层的厚度;Select the length of the nonlinear conductivity control layer as the length determined in step 4, and keep it unchanged. By changing the thickness of the nonlinear conductivity control layer, the maximum field strength of the stress cone and the maximum field strength of the control layer are obtained with the nonlinear conductivity. The change curve of the thickness of the control layer, the thickness corresponding to the intersection of the two change curves is selected as the thickness of the nonlinear conductivity control layer; 步骤6:根据步骤4获得长度和步骤5获得的厚度,引入非线性电导率控制层,实现XLPE电缆工厂接头应力锥场强集中的优化。Step 6: According to the length obtained in step 4 and the thickness obtained in step 5, a nonlinear conductivity control layer is introduced to realize the optimization of the stress cone field intensity concentration of the XLPE cable factory joint. 2.根据权利要求1所述的优化XLPE电缆工厂接头应力锥场强集中的方法,其特征在于所述的步骤2具体为:2. the method for optimizing XLPE cable factory joint stress cone field strength concentration according to claim 1, is characterized in that described step 2 is specifically: 设导体与绝缘屏蔽层之间的电压为Udc,E1和σ1分别为本体XLPE绝缘层的场强和直流电导率,E2和σ2分别为恢复XLPE绝缘层的场强和直流电导率,E3和σ3分别为非线性电导率控制层的场强和直流电导率;可根据公式(1)获得交界面附近不同位置的本体XLPE层场强E1和恢复XLPE层的场强E2的表达式,Let the voltage between the conductor and the insulating shielding layer be U dc , E 1 and σ 1 are the field strength and DC conductivity of the bulk XLPE insulating layer, respectively, E 2 and σ 2 are the field strength and DC conductivity of the restored XLPE insulating layer, respectively E3 and σ3 are the field strength and DC conductivity of the nonlinear conductivity control layer, respectively; the field strength E1 of the bulk XLPE layer at different positions near the interface and the field strength of the recovery XLPE layer can be obtained according to formula ( 1 ). The expression for E2 ,
Figure FDA0002982511960000021
Figure FDA0002982511960000021
其中,kσ是恢复绝缘电导率与本体绝缘电导率的比值,公式(1)中,E3,σ3,k2为未知参数,d1,d2,d3为随位置不同而改变的变量,d1为非线性电导率控制层到导体屏蔽层的距离,d2为非线性电导率控制层到绝缘屏蔽层的距离,d3为非线性电导率控制层厚度,d1+d2+d3=d,d为接头处绝缘厚度。Among them, kσ is the ratio of the recovery insulation conductivity to the bulk insulation conductivity. In formula (1), E 3 , σ 3 , k 2 are unknown parameters, and d 1 , d 2 , and d 3 change with different positions. variable, d 1 is the distance from the nonlinear conductivity control layer to the conductor shielding layer, d 2 is the distance from the nonlinear conductivity control layer to the insulating shielding layer, d 3 is the thickness of the nonlinear conductivity control layer, d 1 +d 2 +d 3 =d, where d is the insulation thickness at the joint.
3.根据权利要求1所述的优化XLPE电缆工厂接头应力锥场强集中的方法,其特征在于所述的步骤3具体为:3. the method for optimizing XLPE cable factory joint stress cone field strength concentration according to claim 1 is characterized in that described step 3 is specifically: 设非线性电导率控制层的长度为lm,dm为非线性电导率控制层的厚度,dm=lm*sinθ,θ是本体绝缘与恢复绝缘界面与内导体屏蔽层的夹角,令P=(1/k2-1)d3,(kσ-1)d1+P=(kσ-1)dm,kσ是恢复绝缘电导率与本体绝缘电导率的比值,可根据公式(2)获得非线性电导率控制层与本体XLPE绝缘层以及恢复XLPE绝缘层的电导率与厚度的关系,Let the length of the nonlinear conductivity control layer be lm, dm is the thickness of the nonlinear conductivity control layer, dm = lm * sinθ , θ is the angle between the bulk insulation and recovery insulation interface and the inner conductor shielding layer, Let P=(1/k 2 -1)d 3 , (k σ -1)d 1 +P=(k σ -1)d m , k σ is the ratio of the recovered insulation conductivity to the bulk insulation conductivity, which can be According to formula (2), the relationship between the conductivity and thickness of the nonlinear conductivity control layer and the bulk XLPE insulating layer and the recovery XLPE insulating layer is obtained,
Figure FDA0002982511960000022
Figure FDA0002982511960000022
4.根据权利要求2所述的优化XLPE电缆工厂接头应力锥场强集中的方法,其特征在于所述的步骤4中,应力锥的最大场强是指本体XLPE绝缘层的最大场强E1max和恢复XLPE绝缘层的最大场强E2max二者的最大值。4. the method for optimizing XLPE cable factory joint stress cone field strength concentration according to claim 2, is characterized in that in described step 4, the maximum field strength of stress cone refers to the maximum field strength E 1max of body XLPE insulating layer and the maximum value of both the maximum field strength E 2max that restores the XLPE insulating layer. 5.根据权利要求4所述的优化XLPE电缆工厂接头应力锥场强集中的方法,其特征在于,所述的步骤4中,5. the method for optimizing XLPE cable factory joint stress cone field strength concentration according to claim 4, is characterized in that, in described step 4, 非线性电导率控制层的长度与电导率关系由公式(3)获得,The relationship between the length of the nonlinear conductivity control layer and the conductivity is obtained by formula (3),
Figure FDA0002982511960000023
Figure FDA0002982511960000023
首先设定非线性电导率控制层的厚度和长度为初始值,求解初始值下的应力锥最大场强和非线性电导率控制层的最大场强;First, set the thickness and length of the nonlinear conductivity control layer as initial values, and solve the maximum field strength of the stress cone and the maximum field strength of the nonlinear conductivity control layer under the initial values; 然后,保持厚度不变,通过改变非线性电导率控制层的长度,求解应力锥最大场强和非线性电导率控制层的最大场强,获取电缆接头应力锥最大场强和非线性电导率控制层最大场强随非线性电导率控制层长度的变化曲线;选取两条变化曲线的交点对应的长度作为非线性电导率控制层长度。Then, keeping the thickness unchanged, by changing the length of the nonlinear conductivity control layer, solve the maximum field strength of the stress cone and the maximum field strength of the nonlinear conductivity control layer, and obtain the maximum field strength of the stress cone of the cable joint and the nonlinear conductivity control The curve of the maximum field strength of the layer with the length of the nonlinear conductivity control layer; the length corresponding to the intersection of the two change curves is selected as the length of the nonlinear conductivity control layer.
6.根据权利要求4所述的优化XLPE电缆工厂接头应力锥场强集中的方法,其特征在于,所述的步骤5中,6. the method for optimizing XLPE cable factory joint stress cone field strength concentration according to claim 4, is characterized in that, in described step 5, 非线性电导率控制层的厚度与电导率关系公式如式(4)所示;The relationship between the thickness of the nonlinear conductivity control layer and the conductivity is shown in formula (4);
Figure FDA0002982511960000031
Figure FDA0002982511960000031
首先设定非线性电导率控制层的长度为步骤4确定的长度,求解初始厚度值下的应力锥最大场强和非线性电导率控制层的最大场强;First, set the length of the nonlinear conductivity control layer as the length determined in step 4, and solve the maximum field strength of the stress cone and the maximum field strength of the nonlinear conductivity control layer under the initial thickness value; 然后保持长度不变;通过改变非线性电导率控制层的厚度,求解应力锥最大场强和非线性电导率控制层的最大场强,获取电缆接头应力锥最大场强和非线性电导率控制层最大场强随非线性电导率控制层厚度的变化曲线;选取两条变化曲线的交点对应的厚度作为非线性电导率控制层厚度。Then keep the length unchanged; by changing the thickness of the nonlinear conductivity control layer, solve the maximum field strength of the stress cone and the maximum field strength of the nonlinear conductivity control layer, and obtain the maximum field strength of the cable joint stress cone and the nonlinear conductivity control layer The curve of the maximum field strength with the thickness of the nonlinear conductivity control layer; the thickness corresponding to the intersection of the two change curves is selected as the thickness of the nonlinear conductivity control layer.
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