问题详情

某变电站至1OkV开关站采用LGJ-240架空线路输送电能,架空线长度为3km,单位长度电阻为R0=0.15Ω/km,单位长度电抗X0为0.3412/km,变电站母线电压为10.5kV,要求开关站母线电压不低于10kV,试求cos=0.95时,该开关站最大能送出多少容量的负载?(IGL-240导线在40℃室外温度时载流量为494A)


时间:2021-12-28 18:39 关键词: 配电线路工 线路运行与检修专业考试

答案解析

<p> (1)&Delta;u=10.5-10=0.5(kv)<br> (2)设最大容量为s<br> 则P=COS<img src="http://que-oss.fenziquan.com/web/akimg/asource/2015052917534064313.jpg">S=0.95S,Q=Ssin<img src="http://que-oss.fenziquan.com/web/akimg/asource/2015052917534064313.jpg">=0.31(S)<br> (3)R=R<sub>0</sub>L=0.15&times;3=O.45(&Omega;)<br> X=X<sub>0</sub>L=0.34&times;3=1.02(&Omega;)<br> (4)∵&Delta;U=(PR+QX)/>0.5<br> &there4;(0.95S&times;0.45+0.31S&times;1.02)/10>0.5<br> &there4;S<6.72(MVA.<br> (5)校验载流量∵S=<img src="http://que-oss.fenziquan.com/web/akimg/asource/2015052917543196273.jpg">UIcos<img src="http://que-oss.fenziquan.com/web/akimg/asource/2015052917534064313.jpg"><br> &there4;I=S/<img src="http://que-oss.fenziquan.com/web/akimg/asource/2015052917543196273.jpg">Ucos<img src="http://que-oss.fenziquan.com/web/akimg/asource/2015052917534064313.jpg">=6.729&times;(10<sup>3</sup>/<img src="http://que-oss.fenziquan.com/web/akimg/asource/2015052917543196273.jpg">)&times;10&times;0.95=408A.<br> LGJ240导线在40C室外温度时载流量为494>408,所以最大能送出6.72MVA。</p>