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In-Depth Study on Deflection Control Measures of Long-Span Suspended Tubular Busbar
DOI: 10.12677/SG.2023.131003, PDF, HTML, XML, 下载: 253  浏览: 441

Abstract: In recent years, with the wide application of long-span suspended tubular busbar in substations of various voltage levels, the problem of excessive deflection of tubular busbar has become more and more prominent. In this paper, relying on a 750 kV substation, aiming at the problem of excessive deflection of the long-span suspended tubular busbar, a three-dimensional finite element model is established to calculate the deflection and field strength of the tubular busbar, and a new type of tubular busbar suspension system is proposed by means of comprehensive comparative analysis, theoretical calculation and true-type testing, namely, V-shaped insulator string with double-sided auxiliary cable tubular busbar suspension system. And related fitting is developed and manufactured. Compared with the current solution, the tubular busbar deflection in the interval and between the suspension points of adjacent intervals can be greatly reduced to less than 0.5 D (D is the outer diameter of the tubular busbar), and it has the advantages of controllable field strength, simple structure, and convenient construction. Taking a 750 kV substation as an example, it can save about 28% of the investment in the tubular busbar fittings. The research results of the V-shaped insulator string plus double-sided auxiliary cable suspension system and its special fittings provide technical support for the subsequent construction of long-span suspended tubular busbar projects, and it has broad application space and excellent social benefits.

1. 引言

2. 大跨度悬吊式管母挠度控制措施分析

2.1. 依托工程简介

750 kV悬吊式管母相关参数如表1所示：

Table 1. Tube bus parameters

2.2. 控制措施分析

1) 有效降低管母挠度的金具连接体系研究

2) 悬挑型构架横梁挂点设计

3) 多根管母并列架设结构设计

3. V型绝缘子串加双侧辅助拉索的管母悬吊系统

3.1. 设计方案

Figure 1. Pipe bus suspension system with V-shaped insulator string and auxiliary cables on both sides

3.2. 理论分析计算

3.2.1. 悬吊系统结构形式的整体分析

1) 母线向一侧倾斜的问题

Figure 2. Photo of the tubular busbar tilted to one side

Figure 3. Force diagram of the tubular busbar inclined to one side

${F}_{左G}=\left({L}_{1}/L\right)\ast G$ (1)

${F}_{右G}=\left(\left(L-{L}_{1}\right)/L\right)\ast G$ (2)

${F}_{左G1}=\left(\left({L}_{3}+L\right)/L\right)\ast {G}_{1}$ (3)

${F}_{右G1}=-\left({L}_{3}/L\right)\ast {G}_{1}$ (4)

${F}_{左G}+{F}_{左G1}={F}_{右G}+{F}_{右G1}$ (5)

${G}_{1}=\left(\left({L}_{2}\ast {L}_{1}\right)/\left(L+2\ast {L}_{3}\right)\right)\ast G$ (6)

2) 控制管母中部向上拱起的问题

Figure 4. Force diagram of the insulator string at the hanging point on the frame

A点和B点的绝缘子挂点拉力FA和FB可分解为与地面和管母轴线垂直或平行的三个分力。因管母两侧及左右是对称布置，所以FAC与FBC两个力相互抵消，FAG和FBG为绝缘子、管母及金具等所有悬挂件重力的1/4。C点和D点的情况与A点和B点相同。

E点轴螺栓的受力有一个水平分力FES，其大小为：

${F}_{ES}={F}_{AS}+{F}_{BS}=\text{TANG}\left(a\right)\ast G/2$ (7)

Figure 5. Cross-line force diagram

Figure 6. Force diagram of the hanging point of the tubular busbar

Figure 7. Tubular busbar structure diagram

G：绝缘子、管母及金具等悬挂件重力；

a：绝缘子挂点处受力方向在平行于管母轴线的垂直面投影角度。

$M={M}_{F}={M}_{E}={F}_{ES}\ast h$ (8)

$\left({L}_{1}+{L}_{2}/2\right)\ast {L}_{2}\ast 246\ge M+{L}_{1}\ast 60\ast 9.8$ (9)

3.2.2. 悬吊系统设计方案

1) 悬吊系统设计原则

a) 应具有良好的电气性能，满足通流要求。额定电压750 kV，最高运行电压825 kV，额定电流5000 A。

b) 强度可靠、力学性能良好，满足变电工程力学要求。强度安全系数应满足：正常运行时不得小于4.0，安装检修或其他短路状态时不得小于2.5。

Figure 8. Structure diagram of the tower support fittings of the tubular busbar

c) 在晴天夜晚、工频电压(635.1 kV)下，无可见电晕。无线电干扰水平控制在1000 μV以下。电晕损失应小于同长度导线损失的能量。

d) 满足相关国家标准、行业标准及规范要求，结构合理，避免损伤导线；重量轻，便于安装施工。

e) 接续电阻不应大于等长导线电阻值。

f) 线夹对导线的握力：承受全张力的接续金具(耐张线夹等)对导线的握力，应不小于导线拉断力的65%，不承受全张力的接续金具(设备线夹等)对导线的握力，应不小于导线拉断力的10%。

2) 管母三点悬吊金具的结构设计

a) 管母塔架支撑金具的结构设计。

Figure 9. Structure diagram of height adjustment mechanism

3) 管母拉线固定金具的结构设计

Figure 10. Structure diagram of the fixing fittings of the tubular busbar

4) 管母三点悬吊金具的双侧辅助拉索结构设计

Figure 11. Structure diagram of the double-sided auxiliary cable for the three-point suspension hardware of the tubular busbar

5) 悬吊式管母V型绝缘子串的结构设计

Figure 12. Sectional diagram of a typical 750 kV busbar partition in a substation

3.2.3. 悬吊系统仿真计算

1) 管母挠度仿真计算

a) 未配重状态下管母位移最大值为133 mm；

b) 随着配重重量的增加，管母位移最大值呈先减小后增大趋势，最大值由管母中间位置移向端部两侧；

c) 配重约80 kg时挠度最小。

2) 悬吊系统电场分布仿真计算

a) 各悬吊绝缘子均压环、管母抱夹、跳线线夹表面电场强度最大值出现在沉孔边沿倒角处，数值小于2.3 kV/mm；

b) 跳线连接板边沿、连接板螺栓表面电场强度最大值超过2.3 kV/mm，当倒角大于4 mm时，可降至2.0 kV/mm以内。

3.3. 真型试验验证

1) 试验准备

a) 准备试验场地及试验用挂点；

b) 采购铝镁硅合金管母6Z63-300/276；

c) 研制V型绝缘子串加双侧辅助拉索的管母悬吊系统相关金具；

d) 准备光学发光器、水平测量仪等测量工具。

2) 试验挂接参数

3) 试验方法及测量位置

Figure 13. Schematic diagram of the attachment when the span is 48 m and each side of the figure-eight tower is 3.5 m

Figure 14. Schematic diagram of the attachment when the span is 48 m and each side of the figure-eight tower is 4 m

Figure 15. Schematic diagram of measurement location

4) 试验方案

Figure 16. Schematic diagram of the side arm of the double-sided figure-eight tower with the three-point suspension fittings of the tubular busbar

Figure 17. Schematic diagram of the side arm of the three-point suspension fittings of the tubular busbar with the two points 21 and 42 removed

Figure 18. Schematic diagram of the side arm of the three-point suspension fittings of the tubular busbar with the two points 21, 22, 41 and 42 removed

5) 管母变形量的计算方法

Figure 19. Diagram of the method for calculating the deformation of the tubular busbar

6) 试验数据分析

Table 2. Deflection measurement data sheet of tubular busbar (arm extension 3.5 m on each side) mm

a) 跨中心荷载越大，跨中挠度越大；

b) 相对跨中荷载，配重若过大，会造成挠度最大点转移到配重处；

c) 跨中荷载向边侧偏移时，对跨中挠度有利，但对另一侧端头挠度的改善贡献较小；

d) 撤掉三点悬吊金具外侧臂，挠度明显增大，且挠度最大点出现在两侧相邻间隔管母连接处；

e) 撤掉三点悬吊金具两侧臂，即为常规方案，挠度进一步增大，挠度最大点在跨中。

Table 3. Comparison table of deflection measurement data of tubular busbar mm

Figure 20. Comparison diagram of deflection measurement data of tubular busbar

a) 对于48 m跨间隔的6Z63-300/276管母，三点悬吊金具侧臂延伸至3.5 m或4.0 m，均可保证48 m跨间隔挠度降低至0.5 D (150 mm)以内；

b) 三点悬吊金具侧臂延伸越长，对管母挠度越有利；

c) V型绝缘子串加双侧辅助拉索的管母悬吊系统，较常规设计方案，悬吊管母挠度可降低约38.3%；

d) 结合管母挠度、该悬吊系统受力分析、经济性等因素综合考虑，建议该站750 kV母线采用的V型绝缘子串加双侧辅助拉索的管母悬吊系统，两侧臂延伸4.0 m为最优。

3.4. 经济性分析

Table 4. Economic comparison of 750 kV tubular busbar fittings in a 750 kV substation

4. 结论

1) 基于V型绝缘子串加双侧辅助拉索的管母悬吊系统可实现“大幅降低间隔内跨中管母挠度、及相邻间隔悬吊点之间的管母挠度至0.5 D (D为管母外径)以内”的目标。

2) 基于V型绝缘子串加双侧辅助拉索的管母悬吊系统具有场强可控、结构简单、便于施工、利于工程创优等优势。以某750 kV变电站为例，可节约750 kV管母金具投资约28%，经济性高。

3) 基于V型绝缘子串加双侧辅助拉索的管母悬吊系统具有普遍的推广价值和良好的社会效益，可为后续大跨度悬吊式管母工程建设提供重要的技术支持。

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