Đang chuẩn bị liên kết để tải về tài liệu:
Electric Machinery Fundamentals Power & Energy_14

Tham khảo tài liệu 'electric machinery fundamentals power & energy_14', kỹ thuật - công nghệ, điện - điện tử phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | a What is the line voltage of the two loads b What is the voltage drop on the transmission lines c Find the real and reactive powers supplied to each load. d Find the real and reactive power losses in the transmission line. e Find the real power reactive power and power factor supplied by the generator. Solution To solve this problem first convert the two deltas to equivalent wyes and get the per-phase equivalent circuit. 0.090 Q 7 0.16 Q 277Z0 V V . . 0 load Z 2.5Z36.87 Q Z 2 1.67Z- 20 Q a The phase voltage of the equivalent Y-loads can be found by nodal analysis. V .-277Z0 V V. V. Zload v _T íálonl__ __T load 0 0.09 j0.16 Q 2.5Z36.87 Q 1.67Z-20 Q _ 5.443Z - 60.6 Vad - 277Z0 v 0.4 Z - 36.87 Vad 0.6Z20 Vad 0 5.955Z-53.34 V load 1508Z-60.6 7 load 253.2Z-7.3 V 281 Therefore the line voltage at the loads is V 3 V 439 V . b The voltage drop in the transmission lines is AV. V. gen - Vjoad 277 0 V - 253.2Z-7.3 41.3Z52 V c The real and reactive power of each load is P 3- -cosỡ 3 253-2V cos 36.87 61.6 kW 1 Z 2.5 Q Q 3- -sinớ 3 253 2 V sin 36.87 46.2 kvar 1 Z 2.5 Q P2 -cosQ 3 253 2 V cos -20 108.4 kW 2 Z 1.67 Q Q2 3- sinớ 3 253.2 V sin -20 -39.5 kvar 2 Z 1.67 Q v d The line current is Ili AV A1 2 1 225Z- 8.6 A line ZUne 0.09 j0.16 Q Therefore the loses in the transmission line are Pine 3IJRline 3 225 a 2 0.09 Q 13.7 kW Qline 3IJXline 3 225 A 2 0.16 Q 24.3 kvar e The real and reactive power supplied by the generator is Pgen Pine P P2 13.7 kW 61.6 kW 108.4 kW 183.7 kW Qgen Ổline Q1 Ố2 24.3 kvar 46.2 kvar - 39.5 kvar 31 kvar The power factor of the generator is PF cos tan-1 Qgen cos tan 1 31 kvar 0.986 lagging Pgen 183.7 kW A-3. Figure PA-2 shows a one-line diagram of a simple power system containing a single 480 V generator and three loads. Assume that the transmission lines in this power system are lossless and answer the following questions. a Assume that Load 1 is Y-connected. What are the phase voltage and currents in that load b Assume that Load 2 is A-connected.