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. Q 7 Q 277Z0 V V . . 0 load Z Q Z 2 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 Q Q Q _ - Vad - 277Z0 v Z - Vad Vad 0 V load 7 load 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 - V c The real and reactive power of each load is P 3- -cosỡ 3 253-2V cos kW 1 Z Q Q 3- -sinớ 3 253 2 V sin kvar 1 Z Q P2 -cosQ 3 253 2 V cos -20 kW 2 Z Q Q2 3- sinớ 3 V sin -20 kvar 2 Z Q v d The line current is Ili AV A1 2 1 225Z- A line ZUne Q Therefore the loses in the transmission line are Pine 3IJRline 3 225 a 2 Q kW Qline 3IJXline 3 225 A 2 Q kvar e The real and reactive power supplied by the generator is Pgen Pine P P2 kW kW kW kW Qgen Ổline Q1 Ố2 kvar kvar - kvar 31 kvar The power factor of the generator is PF cos tan-1 Qgen cos tan 1 31 kvar lagging Pgen 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.
