Power System Analysis And Design SI Edition 6th Edition By Glover – Test Bank

ECE 476

Examination #1
Tuesday , October 11, 2011

Closed book, closed notes One cheat sheet allowed

Complete

1. ________ / 25
2. ________ / 20
3. ________ / 25
4. ________ / 30________ / 100

1. (25 total points)

A 3, 300-mile, 345-kV line has sequence impedance of z = 0.03 j0.4 /mile and shunt admittance y = j5.0 x 10-6 mho/mile.

(9 pts) a. (9 pts) b.

(7 pts) c.

Compute the street’s characteristic impedance Zc and the propagation constant .

Initially assume that the receiving end of the street is open-circuited and has a line-to-line voltage of 345 kV. Calculate the sending end line-to-line voltage magnitude.

Illustrate the extended line  equivalent circuit for this line, displaying the values of all parameters.

2. (20 total points)

The circuit shown below is a balanced three-phase system with a wye-connected generator producing 1 volt (phase to neutral). Assume that each inductor has an impedance ZL = j10 and each capacitor ZC = -j15. Determine Ia, Icap, and the total three-phase apparent power supplied by the wye-connected voltage source.

3. (25 total points)

A 3-phase, 60Hz, 50km long, fully transposed transmission line is built using Drake conductor. Drake conductor has an outside diameter of 1.108 inches; stranding of 26/7 (Al/St), which yields a GMR for the conductor of 0.0375 feet. Resistance at 60Hz for this conductor is 0.117 /mile. A horizontal tower configuration is used, with a phase spacing of 25 feet (25 feet between left and center phases, 25 feet between center and right, and hence 50 feet between left and right). Bundling is used, with 2 conductors per phase, spaced 1 foot apart. For reference μ0 = 4π x 10-7 H/m and Ɛ0 = 8.854 x 10-12 F/m.

1. a) Find the positive sequence inductance in H/m and inductive reactance in Ω/km.
2. b) Find the capacitance to neutral in F/m and the admittance to neutral in S/km. Neglect the effect of the earth plane.
3. c) Given that the line is 50km, we can make the short line approximation. Draw the short line π equivalent circuit, labeling relevant values.

For reference  = 4 x 10-7 H/m and 0 = 8.854 x 10-12 F/m. There are 1609 meters per mile.

4.

A.

B.

C.

D.

E.

Multiple Choice. Circle the most suitable answer. Ten points, three points each for a total of 30 points.

This Problem Continues on the Next Page

As discussed in class, the most common load model for power flow is

1. Fixed impedance
2. Fixed current
3. Fixed power

We will

1. All loads and sources are Y connected
2. All loads and sources are delta connected
3. There is no mutual inductance between phases
4. A and C
5. B and C

Which statement about phase and line voltages (V) and currents (I) in Wye and Delta connections is correct?

1. Phase I = line I in Wye, and phase V = line V in Delta
2. Phase I = line I in Delta, and phase V = line V in Wye
3. Phase I = line I and phase V = line V in Wye
4. Phase I = line I and phase V = line V in Delta

Using Newton’s approach to solve the equation x^2 – sin(x) – 2 = 0, with an initial guess of x=1 (that is, its value on the zero iteration), select the value that is closest to the value of x after the second iteration:

A. 1.6754 B. 1.7775 C. 1.8073 D. 2.3041 E. 2.3253

The impedance of a 10 MVA, 22/220 kV transformer is 0.2 per unit. What is this impedance in per unit for a power base of 10 MVA, and a voltage base of 11 kV on the low-voltage side of the transformer?

1. 0.05 p .u.
2. 0.1 p  .u.
3. 0.2 p .u.
4. 0.4 p.  u.
5. 0.8 p  .u.

only use per phase analysis when:

6. Transformer open circuit (OC) and short circuit (SC) tests enable us to calculate specific equivalent circuit values. Which parameters are calculated from the OC test and which are from the SC test?
   1. The OC test provides the resistances and the SC test provides the reactances
   2. The OC test provides the sequence impedance and the SC test provides the shunt admittance
   3. The OC test provides the shunt admittance and the SC test provides the sequence impedance
   4. The OC test provides the voltages and the SC test provides currents