電力系統(tǒng)分析練習(xí)題及其答案

1、[例21]一條220kV的輸電線長180km導(dǎo)線為LGJ400(直徑2.8cm)水平排列相間距7m求該線路的RXB并畫等值電路.解:電阻:kmSr08.04005.311??????4.1418008.01????lrR電抗:cmDeq88270027007003?????kmrDxeq42.04.18.0882lg1445.08.0lg1445.01??????6.7518042.01?????lxX電納:kmSrDbeq107.21

2、04.1882lg58.710lg58.76661?????????SlbB66110486180107.2????????等值電路:[例22]220kV架空線水平排列相間距7m，每相為分裂導(dǎo)線，計算直2402??LGJQ徑21.88mm，分裂間距400mm，求每相單位長度的電阻、電抗和電納。解:電阻:kmSr660.040225.311??＝???電抗:757.62400288.219.0?????dDDssbmmDeq8820700

3、02700070003?????kmDDxsbeq31.0757.628820lg1445.0lg1445.01????電納:151.66400288.21????rdreq與準(zhǔn)確計算相比，電阻誤差0.4%，電抗誤差0.12%，電納誤差0.24%，本例線路長度小于1000km，用實用近似公式計算已能夠滿足精確要求。如果直接取1)(11.22165)ZYKKlj?????11則Z=（rjx這時，電阻誤差達15%，電抗誤差7%，電納誤差3.

4、4%，誤差已較大。例2－4330kV架空線路的參數(shù)為0579.00kmr??316.00kmx??試分別計算長度為100，200，300，400和500線00?g.105.360kmsb???路的π型等值參數(shù)的近視值，修正值和精確值。解首先計算100km線路的參數(shù)（一）??????????)6.3179.5(100)316.00579.0()(00`jjljxrZsjsjljbgY4600`1055.3100)1055.30()(???

5、????????(二)修正參數(shù)計算9963.01001055.3316.031131126200??????????lbxkr9982.0100]316.01055.30579.01055.3316.0[611)06112626200200(??????????????lxbrbxkx0009.11001055.3316.01211121126200??????????lbxkb????????????)5431.317686.5(10

6、0)316.09982.00579.09963.0()(00`jjljxkrkZxrssjljbkYb460`105533.31001055.30009.1??????????（三）精確參數(shù)計算??????????????060000192.58255.300)2201.275914.299()1055.3()316.00579.0()()(jjjjjbgxrZckmbgxrjjjjj146000010)6355.09663.0()10