電力系統(tǒng)分析第三章例題7798

第三章電力系統(tǒng)潮流分布計(jì)算3-2已知圖3-2所示輸電線路始末端電壓分別為248kV、220kV，末端有功功率負(fù)荷為220MW，無(wú)功功率負(fù)荷為165MVAR。試求始端功率因數(shù)。8+jUUP=220Q=165MVAR22C×10-4SC×10-4S12習(xí)題圖3-23-2解：···SQ22025.510426.62(MVAR)y2①Sˊ8ˊ②S220k24C×10(S)C-42Q24825.510433.83(MVAR)y11習(xí)題解圖S220j165j26.62220j138.38(MVA)?2求Z中的功率損耗：122202138.382(8j40)11.165j55.83S?122202S220j138.3811.165j55.83231.165j194.21?1S231.165j194.21j33.83231.165j160.38(MVA)?1231.165cos0.8216231.1652160.3823-8額定電壓110kV的輻射形電網(wǎng)各段阻抗及負(fù)荷如圖3-8所示。已知電源A的電壓為121kV，求功率分布和各母線電壓。（注：考慮功率損耗，可以不計(jì)電壓降落的橫分量U）。習(xí)題圖3-83-8解：·20+設(shè)UU01100?ˊS〞20+BASSCCAN40+j30M10+j習(xí)題解圖110282(20j30)0.271j0.4071102S?BCS?S?S?(10j8)0.271j0.4079.793j7.593CBCBS?SS40j309.793j7.95330.207j22.407??BBB30.207222.4072(20j40)2.338j4.676S?AB1102S?SS?30.207j22.4072.338j4.67632.545j27.083?BABA已知U=121kVAU32.5452027.0834014.332kV121ABUUU12114.332106.668kVBAABU(9.793)20(7.593)303.972kV106.668BCUUU106.6683.972110.64kVCBBC3-13由A、B兩端供電的電力網(wǎng)，其線路阻抗和負(fù)荷功率等如圖3-13示。試求當(dāng)A、B兩端供電電壓相等（即U=U）時(shí)，各段線路的輸送功率是多少（不計(jì)線路的功率損耗）ABAUZ=4+j8ΩZ=2+j4ΩZ=3+j6ΩB234aUb··S=30+j15MVAa習(xí)題圖3-133-13解：1、4支路合并，42·2··S等值電路如圖3-13a所示。S1aSb1··S2SZ(3j6)24()習(xí)題解圖314(30j15)(4j8)(20j10)(2j4)20j10S?8j16A(20j10)(6j12)(30j15)(4j8)30j15S?8j16BSS?S?20j10(30j15)(10j5)?abAa6j12ZSS??ZZ(30j15)(6j12)(3j6)20j1014B143j6Z?SS?ZZ(30j15)(6j12)(3j6)10j5B1114輸送功率分布如圖3-13b所示。1U2220+j10a310+j5b2U430+j15習(xí)題解圖3-16發(fā)電廠C的輸出功率、負(fù)荷D及E的負(fù)荷功率以及線路長(zhǎng)度參～～Z=2+j4Ω=1+j2Ω=2+j4ZZB123L=10kmL=5km數(shù)如圖3-16所示。12··S=60+j25MVE?U1120kV，??S=40+j30D當(dāng)CUU，Z=10+j20Ω4L=50kmAB并計(jì)及線路CE上的功率損耗，但不計(jì)其它線路上功率損耗時(shí)，求線路AD、CU4=112kV·CS=100+j50M～CDE、及BE上通過(guò)的功率。習(xí)題圖3-163-16解：PP2Q2R1002502109.965CCU21122CE4CQP2Q2100250X422019.93CCU21122CECS?9.965j19.9510j20CESS?(S?S?)60j25(100j5010j20)(30j5)?EEC如圖3-16所示CEZ=2+j4Z=1+j2E1DA1B···SSSBEAD·S=40DE·S〞ED習(xí)題解圖S(ZZ)SZ3(40j30)(3j6)(30j5)(2j4)12j16?S?D23E212j(424)ADZZZ312SZS(ZZ)(40j30)(2j4)(30j5)(3j6)2j9?S?D1E125j10BEZZZ312?SS10j25?DESS?12j162j910j25?ADBE則S?S?S?(12j16)(40j30)(28j14)DEDAD3-18如圖3-18所示，已知閉式網(wǎng)參數(shù)如下：3Z2j41Z3j62Z4j83L10kmL15kmL20km123??S=10+j5MVAS=30+j15MVABC負(fù)荷參數(shù)：電源參數(shù)：U=110kVA試求閉式網(wǎng)上的潮流分布及B點(diǎn)電壓值（計(jì)算時(shí)，不計(jì)線路上的功率損耗）?！獳U=110kVA1+j31121+ΩA5+j311L33··SLC8+j6習(xí)題圖3-21習(xí)題圖3-183-18解：如圖3-18a等值電路.▽CAˊAZZBSZ4+j23+j12+j1S31習(xí)題指導(dǎo)圖(30j15)(1510)(10j5)10(30j15)25(10j5)10S?20151045Ac18.89j9.44SS?S?(30j15)(18.89j9.44)11.11j5.56?BCCACSS?S?(10j5)(11.11j5.56)21.11j10.56?ABBBC▽C點(diǎn)為功率分點(diǎn)。于是網(wǎng)絡(luò)從C點(diǎn)打開(kāi)，變成兩個(gè)輻射網(wǎng)如圖3-18b所示。AZ3CZ2BZ1Aˊ4SSˊSˊ++10+j5習(xí)題解圖18.8929.442(4j8)0.15j0.3S?311024SS?S?18.89j9.440.15j0.3019.04j9.74?AAC311.1125.562(3j6)0.0127558(3j6)0.0383j0.0765S?21102S?S?S?S?10j511.11j5.560.0383j0.076521.1483j10.6365BBC2B21.1483210.63652(2j4)0.0463(2j4)S?111020.0926j0.1853S?S?S?21.1483j10.63650.0926j0.1853121.2409j10.821821.24j10.82ABPRQX21.24210.82442.4843.280.77690.78UU1101101AUUU1100.78109.22kVBA13-21如圖3-21所示電力系統(tǒng)，已知Z、Z、Z均為1+j3Ω，U=37kV，若不計(jì)線路上122331壓降落的橫分量，求功率分布及最低點(diǎn)電壓。A的功率損耗及電A1+j31121+Ω5+j31138+j6習(xí)題圖3-213-21解：⑴功率分布：(8j6)20(5j3)107j5S?10101013SS?S?(8j6)(7j5)1j1?23313SS?S?(5j3)(1j1)6j4?12223SS?S?