The single-line diagram of a three-phase power system is shown in the below figure. Equipment ratings are given as follows: Synchronous generators: GI 1000 MVA x - X2 - 0.18, Xo -0.07 per unit X - X2 - 0.20, Xo =0.10 per unit X- X, -0.15, Xg- 0.05 per unit 15 kV G2 1000 MVA 15 kV G3 500 MVA 13.8 kV G4 750 MVA 13.8 kV X = 0.30, X2 - 0.40, Xo = 0.10 per unit Transformers: 15 kV A/765 kV Y X- 0.10 per unit X - 0.10 per unit X - 0.12 per unit X - 0.11 per unit TI 1000 MVA T2 1000 MVA 15 kV A/765 kV Y T3 500 MVA 15 kV Y/765 kV Y T4 750 MVA 15 kV Y/765 kV Y 3 T, Line 1-3 Line 1-2 Line 2-3 Transmission lines: 1-2 765 kV X = 50 2, Xo -150 N 1-3 765 kV X1 = 40 2, X, - 100 2 2-3 765 kV X = 40 2, X, = 100 2 The inductor connected to Generator 3 neutral has a reactance of 0.05 per unit using generator 3 ratings as a base. Calculate the zero-, positive-, and negative-sequence reactance using a 1000- MVĀ, 765-kV base in the zone of line 1-2. Neglect the A-Y transformer phase shifts.

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2) The power system consists of generators, motors, transformers, and transmission lines. The ratings are as follows: G1: 3-phase generator 25 MVA, 11 KV, X = 20% M1: 3-phase motor M2: 3-phase motor T1:3 single phase transformers T2: 3-phase transformer Line: 15 MVA, 13 KV, X = 25% 7.5 MVA, 13 KV, X = 25% Single phase transformer rating 30 MVA, 6.9/69 KV X = 10% Three phase transformer rating 30 MVA, 13.8/69 KV X = 10% Χ - 50 Ω = Τι G₁ 2. Line Figure 1. 3 T2 Σ M₁ Δι M2 Find the reactance (X) in p.u. units, given the base value of 25 MVA, 11 KV.

A synchronous generator is rated 645 MVA, 24 kV, 0.9 pf lagging. It has a synchronous reactance 1.2 . The generator is feeding full load at 0.9 pf lagging at rated voltage. Calculate: (a) Excitation emf (E,) and power angle 8 (b) Reactive power drawn by the load Carry out calculations in pu form and convert the result to actual values.

In the following power system M ilio YA T₂ L47 YA 5 ΔΥ synchronous generators G₁,G₂ and synchronous motor M all have the same per-unit impedances Xo=0.05, X₁=X₂=0.7 The three transformers T₁, T₂, T3 are identical with X=0.1pu. Finally, the three transmission lines L47, L57, L67 are identical with per-unit impedances X₁=0.2, X₁=X₂=0.1 Pre-fault all voltages are 1 pu. Then the a phase at bus 6 faults to ground (through zero impedance). What is the magnitude of the per-unit fault current? उह 4 7 L 67 L 57 Y

If the load draws a current of 2727 A, in phase, from a generator, which of the following statement is true? O A. The reactive power is flowing from generator to the load and the real power is flowing from the load to the generator. O B. Since the current is in phase with the generator voltage, both the real and reactive power is flowing from the generator to the load. O .Since the current is leading the generator, both the real and reactive power is flowing from the load to the generator. O D. The real power is flowing from generator to the load and the reactive power is flowing from the load to the generator. O E. None of the other choices are correct