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power systems analysis phần 6

cung cấp cho sinh viên với một kiến thức làm việc của các vấn đề hệ thống điện và kỹ thuật máy tính được sử dụng để giải quyết một số vấn đề. Các chủ đề bao gồm: phân tích dòng tải, công văn tối ưu của các thế hệ, lỗi ba pha đối xứng, các thành phần đối xứng | i. miXMlVLO I E.JXO Example 4.2 A 500-kV three-phase transposed line IS composed of one AC SR 1 272 000-cmil 45 7 Bittern conductor per phase with horizontal conductor configuration as shown in Figure 4.19. The conductors have a diameter of 1.345 m and a GMR of 0.5328 in. Find the inductance and capacitance per phase per kilometer of the line. a b c C3----------- 12 35 ---------- 73 ------- 23 35 --------- n13 - 70 FIGURE 4.19 Conductor layout for Example 4.2. Conductor radius IS r 0.056 ft and GMRl 0.5328 12 0.0444 ft. GMD is obtained using 4 42 GMD 35 X 35 x 70 44.097 ft From 4.58 the inductance per phase IS 44.097 L 0.2 In 7 1.38 mH km 0.0444 and from 4.92 the capacitance per phase IS c - 0-Q 0.0083 juF km ln 0.056 Example 4.3 The line m Example 4.2 IS replaced by two ACSR 636 000-cmĩl 24 7 Rook conductors which have the same total cross-sectional area of aluminum as one Bittern conductor. The line spacing as measured from the center of the bundle IS the same as before and is shown m Figure 4.20. a b c 0 0 O O 0 0 18 - I r---D12 - 35 ---------r 23 - 35 --- - D13 70 - FIGURE 4.20 Conductor layout for Example 4.3. 4.16. imr-ỈP.lT OT H.m l i f ON 1 HU O AHACJ IANUU JLZV The conductors have diameter of 0.977 ir and ư GMR of 0.3924 m. Bundle spacing IS 18 m. Find the inductance and capacilance per phase per kilometer of the line and compare II with that of Example 42. Conductor radius IS r --El 0.4385 in. and irom Example 4.2 GMD 44.097 it. The equivalent geometric mean radius with two conductors per bundle for calculating inductance and capacitance arc g.ven by 4.5 I and 4.88 GMRl --- Si . Ị.22Ỉ47 ft Ĩ.2 to and 9 X 7 x To ii.-mbo GMRC - - 0.2471 ft 12 .2 From 4.58 the inductance per phase IS r 44.097 . L 0.2 In - - 1 .ÍẸ188 mH km 0.22147 and from Í.4 92 the capacitance per phase IS Comparing with the results of Example 4.2 there S a. 23.2 percent reduction in the inductance and a 28.9 percent increase m the capnciiance. The function GMĐ. GMRL GMRC1 - emu IS .