1、电力系统暂态分析课后答案整理版最新第一章1-2-1对例1-2,取UB2110kV,SB30MVA,用准确和近似计算法计算参数标幺值。解:准确计算法:选取第二段为基本段,取 UB2 110kV,SB 30MVA,则其余两段的电压基准值分别为:UB1kU10.5110kV9.5kV1B2121UB3UB2110k26.6kV1106.6电流基准值:IB1SB301.8kA3UB139.5IB2SB300.16kA3UB23110IB3SB302.62kA3UB336.6各元件的电抗标幺值分别为:发电机:x10.2610.52300.32309.52变压器T1:x20.1051212300.1211
2、10231.52输电线路:x30.480300.0791102变压器T2:x40.1051102300.211521102电抗器:x50.0562.620.46.60.3电缆线路:x60.082.5300.146.6211电源电动势标幺值: E 1.169.5近似算法:取SB30MVA,各段电压电流基准值分别为:UB110.5kV,IB1301.65kA310.5UB2 115kV,IUB3 6.3kV,IB 2B33030.15kA1153032.75kA6.3各元件电抗标幺值:发电机:x10.2610.52300.263010.52变压器T1:x2300.10.10531.5输电线路:x3
3、0.4300.073801152变压器T2:x4300.210.10515电抗器:x50.0562.750.446.30.3电缆线路:x60.082.5300.1516.3211电源电动势标幺值:E1.0510.5习题2解:(1)准确计算:UB3 UB(110)115kVUUB2kB32220115 209.1kV121UB1UB311522010.59.1kVk2k1121242各段的电流基准值为:IB1SB22014.0kA3UB139.1IB2SB2200.6kA3UB23209.1SB2201.1kAIB331153UB3各元件的电抗标幺值分别为:发电机:x10.3010.522200
4、.292400.89.12变压器T1:x20.1410.522200.1430029.12输电线路:x30.422302200.49209.12变压器T2:x40.1422022200.122802209.12(2)近似算法:UB110.5kV,IB122012.10kA310.5UB2231kV,IB22200.55kA3231UB3121kV,IB32201.05kA3121各元件电抗标幺值:发电机:x10.302200.22240/0.8变压器T1:x20.142200.10300220输电线路:x30.422300.402312变压器T2:x40.142200.11280习题3要点:以
5、下摘自国家电网公司电力系统安全稳定计算规定 :2.4.1暂态稳定是指电力系统受到大扰动后, 各同步电机保持同步运行并过渡到新的或恢复到原来稳态运行方式的能力, 通常指保持第一、 第二摇摆不失步的功角稳定, 是电力系统功角稳定的一种形式。2.5.1动态稳定是指电力系统受到小的或大的扰动后,在自动调节和控制装置的作用下,保持较长过程的运行稳定性的能力,通常指电力系统受到扰动后不发生发散振荡或持续的振荡,是电力系统功角稳定的另一种形式。两者均是系统受扰动后恢复的能力,均属于功角的稳定,暂态是偏移正常运行状态很小的暂时的状态,能很快达到正常状态,而动态稳定更多依靠于自动调节和控制装置的作用,时间较长,
6、波动较大。1.3.1(1)Um2*6.3Im9.45KAz0.943(2)arctanxarctan0.79757.64or0.505L0.797Ta0.005R314*0.505Im|0| 0ia 9.45cos(t 27.64o) 9.45cos27.64oe200t或ia9.45cos(t27.64o)8.37e200tib9.45cos(t147.64o)9.45cos147.64oe200tic9.45cos(t92.36o)9.45cos92.36oe200t或:将ua改写成ua2*6.3sin(t90o),带入公式得ia9.45sin(t62.36o)9.45sin62.36oe
7、200tib9.45sin(t57.64o)9.45sin57.64oe200tic9.45sin(t182.36o)9.45sin182.36oe200t(3)a,b,c相初始相角分别|为62.36o,57.64o,177.64o,故a相瞬时电流最大0.01iMImIm*e0.00510.73KA(4)由|90|90得=57.64或-122.361.3.2CIm|0|sin(|0|)Imsin()a相9030)9.45sin(309057.64)8.12KA2*0.18sin(30B相7.86KAc相0.26KA2.2.1取基准值UB13.8kV,SB240MVA,则IBSB2403*UB1
8、0.04kA3*13.8发电机次暂态电抗标幺值UN2*SB0.216xd*xdSN/cosUB2变压器的电抗标幺值xT*US(%)*UTN2*SB0.13100SNUB2电流标幺值Im*12.890.130.216第二章2-2-1一发电机、变压器组的高压侧断路器处于断开状态,发电机空载运行,其端电压为额定电压。试计算变压器高压侧突然三相短路后短路电流交流分量初始值Im。发电机:SMW,N200UN13.8kVcosN0.9xd0.92xd0.32xd0.2变压器:SN240MVA,220kV/13.8kV,US(%)13解:取基准值UB13.8kV,SB240MVA电流基准值IBSB24010
9、.04kA3UB313.8则变压器电抗标幺值xTUS%UTN2SB1313.822400.13100SNUB210024013.82发电机次暂态电抗标幺值UN2SB13.8224020.216xdxdSNUB20.220013.82cosN0.9次暂态电流标幺值I112.86xTxd0.130.22有名值Im22.8610.0438.05kA2-3-1例2-1的发电机在短路前处于额定运行状态。(1)分别用E,E和Eq计算短路电流交流分量 I ,I和Id;(2)计算稳态短路电流 I 。解:(1)U010,I01cos10.85132短路前的电动势:E0U0jxdI01j0.167321.0977
10、.4E0U0jxdI01j0.269321.16611.3Id01sin(41.132)0.957Uq01cos41.10.754Eq0Uq0xdId00.7540.2690.9571.01Eq0Uq0xdId00.7542.260.9572.92所以有:IE0xd1.097/0.1676.57IE0xd1.166/0.2694.33IdEq0xd1.01/0.2693.75(2)IEq0/xd2.92/2.261.292-4-1解:对不计阻尼绕组的情形UdriddqUqriqqdUfrfiffdxdidxadifqxqiqfxadidxfif由定子三相开路:id=iq=0得:Udxaddif
11、dqdtUqqdxadifUf0rfifrfifxfdiffdtUf0rftUf0exf可以解得:ifrfrfrftUf0exf带入得:UdxadrfUf0rftUf0)xadUf0rftUqxad(exf(1exf)rfrfrf可得:Uacossin1UdUbcos(120)sin(120)1UqUccos(120)sin(120)1U0UdcostUqsintUdcos(t120)Uqsin(t120)Udcos(t120)Uqsin(t120)UaxadUf0exfUbxadUf0exfUcxadUf0exfrftxadUf0rftxfcostsint(1exf)rfrftUf0rftx
12、fexfcos(t120)xadsin(t120)(1)rfrftUf0rftxfexfcos(t120)xadsin(t120)(1)rf2-5,6-1Eqmtid(1eTd)xdxLiq0uGdxL*iq0tuGqxL*idEqm*xL(1eTd)xdxL2-5,6-2励磁突增前:I|0|=UG1.317.5jxLEQUGJxqI|0|1.3550.3Iq|0|1.31cos(50.37.5)50.30.9650.3Iq|0|1.31sin(50.37.5)(50.390)0.8939.3而Eq|0|=UG+jxdIdjxqIq1.8450.3由Uf|0|0.1Uf|0|得:Eqm0.18
13、4EqmtTd)tid(1e0.136(1e0.26)xdxqiq0tia0.136(1e0.26)costEqm*xLttuGqTd)0.027(1(1ee0.26)xdxLuGd0tuGa0.027(1e0.26)sint设励磁突增前:UGa|0|2cos(t15)ia|0|2*1.31cos(t7.5)tiaia|0|ia2*1.31cos(t7.5)0.136(1e0.26)cost则有:tUGa2cos(t15)0.027(1e0.26)sint第三章3-1-1j0.15j0.075x1j0.075j0.1-1j0.1-1j0.1x2-1X11j0.15j13;1160j0.2j0.
14、1X2139;1j0.15j170013j0.075j60I1j17.948739j700IG1If13j0.075j4.6154;jj0.07560j13IG2IG30.5If13j60j6.6667;j0.07560IG14.61546015.22683*10.5IG26.66676021.99443*10.53-1-2x7X3+x4+x6-1XX810.17826;110.5(X1X2)X70.5(X3X4X6)10.2565;If1913.898561X9X1X2X8IG1IfX8X21000X1X2X257.758321IG2IG30.5IfX70.5(X3X4X6)X1100010.340.5(X1X2)0.5(X3X4X6)X1X2X23213-1-3(1)SB 1000MVA,平均额定电压为基准值 ;1000X1 250 0.302 0.274;5252XXXXXXif2345861. 1410000.19472010000.217 0.32556001. 92. 121000112010.1794
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