架空输电线路课程设计 班级 姓名 学号 指导老师
年 月 日
目录
一、设计条件 ····································································································· 二、设计要求 ····································································································· 三、整理已知条件······························································································· 四、比载计算 ····································································································· 五、计算临界档距,判断控制条件 ········································································· 六、判定最大弧垂······························································································· 七、计算各气象条件下的应力和弧垂 ······································································ 八、安装曲线计算······························································································· 九、画应力弧垂曲线与安装曲线 ············································································ 十、感想 ···········································································································
330Kv架空输电线路设计
一、设计条件
1.典型气象区V区
2.导线型号LGJ-400/50 3.电压等级330Kv
二、设计要求
列出各气象条件,计算出比载,判断临界档距,最大弧垂气象,画出应力弧垂曲线及安
装曲线。
三、整理已知条件
1. 气象条件及其作用 气象 最高最低最大项目 气温 气温 风速(强度) 气温 风换算前 速 换算后 冰厚 作用 40 0 0 0 -10 0 0 0 10 30 32.01 0 最大风速(间距) 10 30 32.01 0 覆冰有风(强度) -5 10 10.67 10 覆冰内过外过外过安装事故年均覆冰有风电压 无风 有风 气象 气象 气温 无风 (间距) -5 10 10.67 10 15 15 16.01 0 15 0 0 0 校验地线对档距中央导线的保护 15 10 10.67 0 校验绝缘子风偏后的间距 -5 10 10.67 0 检验安装时条件 -10 0 0 0 15 0 0 0 -5 0 0 10 校验电气间距 校验计算计算校验校验校验校验电气导线强度 电气杆塔电气绝缘间距 强度 间距 强度 间距 子风偏后的间距 表一 检验防微杆塔风震强度 动 2.风速换算
由于此处的风速是高度为10米处的基准风速,而110~330Kv输电线路应取离地面15米处的风速,所以应当进行风速高度换算。采用公式 式中
vh —线路设计高度h处的风速,m/s;
v0 —标准高度10m处的风速,m/s;
?h???????10?z? —风速高度变化系数;z为粗糙度指数;?为修正系数
z0.16在此设计中采用《架空输电线路设计》孟遂民版中表2—6规定,取粗糙度等级为B; 则相应的z=0.16;?=1.0
??h??????10??15?????10??1.067则 最大风速时风速换算值为v=1.067×30=32.01m/s
覆冰有风,外过有风,安装气象时风速换算值为v=1.067×10=10.67m/s
内过电压时风速换算值为v=1.067×15=16.01m/s
73.导线参数
此处采用LGJ-400/50导线,其相应参数如下表二所示 截面积导线直A( mm 2 ) 径d(mm) 451.55 27.63 弹性系温膨数系数E(MPa) ? 69000 19.3×10^-6 计算拉断力(N) 123400 计算质量抗拉强安全(kg/km) 度 ?p系数(MPa) k 1511 259.62 2.5 许用应力 ??0?(MPa) 103.85 年均应力上限 ? ? cp ? (MPa) 64.90 导线的安全系数取2.5,控制微风震动的年均气象条件下的年均运行应力设计安全系数取4 则抗拉强度 许用应力
年均运行应力上限
四、比载计算
1.自重比载 2.冰重比载 3.垂直总比载
?3?3无冰风压比载??1??2?55.93?104. (MPa/m)v(1) 外过电压,安装有风?4??sin?2?10?3(MPa/m) c?f?scdWA此时风速v=10.67m/s ?c?1.0 ?f?1.0 ?sc?1.1
W0.625?10.67(2)内过电压?4??c? f?scdvsin?2?10?3?1.1?27.63??10?3?4.79?10?3(MPa/m)A451.552此时风速v=16.01m/s ?c?1.0 ?f?0.75 ?sc?1.1
2?3?43?)最大风速?c?f?scdvsin( ??10?0.75?1.1?27.63?WA0.625?16.012?10?3?8.09?10?3(MPa/m)451.55此时风速v=32.01m/s ?c?1.0 ?sc?1.1 计算强度时?f?Wv0.625?32.0122?3?3?30.75 ?4??c?f?scdAsin??10?0.75?1.1?27.63?451.55?10?32.33?10(MPa/m)Wv0.625?32.0122?3?3?30.61 ?4??c?f?scdAsin??10?0.61?1.1?27.63?451.55?10?26.29?10(MPa/m)校验电气间距时?f?5.覆冰风压比载
此时风速v=10.67m/s ?c?1.0 ?sc?1.2 计算强度和检验风偏时均可取?f?1.0
6.无冰综合比载
(1)外过电压,安装有风
(2)内过电压 (3)最大风速 计算强度时?6?校验风偏时?6?32.822?32.332?10?3?46.07?10?3(MPa/m) 32.822?26.292?10?3?42.05?10?3(MPa/m)
7.覆冰综合比载
计算强度和校验风偏时?7?项目 自重比载 55.932?9.012?10?3?56.65?10?3(MPa/m)
冰重比载 55.93 无冰综合(强度) 46.07 无冰综合(风偏) 42.05 覆冰综合(强度) 56.65 覆冰综合(风偏) 56.65 各气象条件下的比载计算值列于下表三 数据32.82 (?10?3MPa/m) 五、计算临界档距,判断控制条件
1. 当气象条件变化时,应力随之变化,在应力达到最大时的气象条件即为控制条件,在输电线路设计时,应考虑的四种气象条件分别为最低气温,最大风速,最厚覆冰,年均气温。 这四种气象条件的有关参数如表四所示 条件 项目 许用应力 最大风速 最厚覆冰 最低气温 年均气温 ??0?103.85 103.85 -5 d 103.85 -10 a 64.90 15 c 比载 ?(MPa/m) 温度 t(。c)?/??0?排序 10 b 2.按等高悬点考虑,计算各临界档距 由状态方程式
可得临界档距的计算公式为 所以各临界档距如下:
lab?24???0?b???0?a??Ecos??tb?ta?????bE?????????0b???a??????????0a2????2??cos3???24?19.3?10?6?69000?20??309.16m69000?0.44362?0.31602?10?6??lac?24???0?c???0?a??Ecos??tc?ta?????cE?????????0c???a??????????0a2????2??cos3???24(64.90?103.85?19.3?10?6?69000?25)??虚数22?669000?0.5057?0.3160?10??lad?24???0?d???0?a??Ecos??td?ta?????dE?????????0d???a??????????0a2????2??cos3???24?19.3?10?6?69000?5??108.23m22?669000?0.5455?0.3160?10??lbc?24???0?c???0?b??Ecos??tc?tb?????cE?????????0c???b??????????0b2????2??cos3???24(64.90?103.85?19.3?10?6?69000?5)??虚数69000?0.50572?0.44362?10?6??lbd?24???0?d???0?b??Ecos??td?tb?????dE?????????0d???b??????????0b2????2??cos3???24?19.3?10?6?69000?(?15)??虚数22?669000?0.5455?0.4436?10??lcd?24???0?d???0?c??Ecos??td?tc?????dE?????????0d???c??????????0c2????2??cos3???24(103.85?64.90?19.3?10?6?69000?20)??164.82m22?669000?0.5057?0.3160?10??将结论列于下面表五
可能的控制条件 a(最低气温) 临界档距(m) b(最大风速) c(年均气温) d(最厚覆冰) — 由上表五可得出如下结论:
当代表档距l<164.82m时年均气温是控制条件;当代表档距l>164.82m时最厚覆冰是控制条件。
六、判定最大弧垂
此处最大弧垂是指架空线在无风气象条件下垂直平面内档距中央弧垂的最大值。出现最大弧垂的气象条件是最高气温或覆冰无风,在此设计中采用临界温度法判定最大弧垂。
1. 临界温度法