Full exam for Electric Power Systems in the Energy Engineering degree programme at Politecnico di Milano. The document covers: Electric Power Systems Exam #4: 29/01/2020 1° Part Exercise 1 The power plant PP, depicted in the figure bellow, consists of two identical generation groups (synchronous machine SG1 and SG2) and electric line L and it is characterized by the following data: Electric Line L:
Full exam for Electric Power Systems in the Energy Engineering degree programme at Politecnico di Milano. The document covers: Electric Power Systems Exam #4: 29/01/2020 1° Part Exercise 1 The power plant PP, depicted in the figure bellow, consists of two identical generation groups (synchronous machine SG1 and SG2) and electric line L and it is characterized by the following data: Electric Line L:
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Electric Power Systems Exam #4: 29/01/2020 1° Part Exercise 1 The power plant PP, depicted in the figure bellow, consists of two identical generation groups (synchronous machine SG1 and SG2) and electric line L and it is characterized by the following data: Electric Line L: Electric resistance (rL) 10 () Electric reactance (xL) 45 () Synchronous machine SG: Nominal power 800 (kVA) Nominal voltage (line-to-line) 15 (kV) Stator winding connection Triangle Synchronous reactance (xs) 150 () Synchronous resistance (rs) 3 () Maximum turbine mechanical power 750 (kW) Maximum electromotive force (phase) 17.5 (kV) The line-to-line voltage at the external bus of the power plant PP is 𝑉𝑃𝑃 =14.5+0.2∙𝑵 (kV) and the power plant PP exports to the External Grid a total real power of 𝑃𝑃𝑃 =500+25∙𝑵 (kW) with a lagging power factor of cos𝜑𝑃𝑃 =0.92. Moreover, the second generating unit, SG2, is operated such that it produces only the entire reactive power of the plant. For the given operating conditions: 1. determine the real and reactive powers produced by each SG (𝑃𝐺1/𝑄𝐺1 and 𝑃𝐺2/𝑄𝐺2); 2. determine the magnitude of the line-to-line voltage at the terminals of SG1, i.e. 𝑉𝐺1; 3. determine the phasors of the emf of the two SG (𝐸𝐺1̅̅̅̅̅ and 𝐸𝐺2̅̅̅̅̅); 4. draw, in a qualitative manner, the phasor diagrams of both SG; 4. determine the mechanical power of the turbines of each SG; 5. check the capability limits for both SG. In the above data, N is the last number of the student’s Person Code/Codice Persona (e.g. if Person Code is 10381486 then N = 6); Please substitute accordingly. PP tern rid Exercise 2 Consider the following electric network Line xl [p.u.] L1 0.4 L2 0.5 L3.1 0.6 L3.2 0.8 – 0.05∙N Generator Real power output: PG Voltage set- point: VG [p.u] [p.u] G1 1.5 1.04 G2 1.5 1.04…
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