EE4161
HomeworkAssignment
DueFeb6
1. Annotated Bibliography for your topic – Due Fri, Feb 7. This should include: a) Four references following IEEE editorial style manua l (cf. pp. 6-18) b) Article titles c) Two articles from technical journ als that are aimed at a broad audience d) Two articles that are addresse d to more specialized audiences e) For each reference, indicate type of journal as described abov e, a one-sentence summary of the topics covered, and a one sentence that describes the main focus of the article. 2. In the power system show n below, all lines are 1000 ohms, purely induct ive. A generator at V1 is supplying 250 kW of rea l power.
Calculate the angles between the voltage busses,
Fig. 1: Grid problem 2
θ 12 , θ 13 , θ 23 , θ 24 , θ 34, and θ 14
3. Continuing Prob. 2, assume that now line 1 is lost. After a transient period, the generator at V1 is again supplying 250 kW of real power, and V 1 and V 2 both return to 34.5 kV. a) Calculate the angle θ 14 . b) Regarding θ 13 and θ 34 , are they equal, or is θ 13 greater than θ 34 , or is θ 34 greater that θ 13 ? c) Which line is now carrying the greatest current, or are they sharing the current equally? 4. Grid stability issues dictate tha t the angle between V1 and V2 should not exceed 15 degrees. (V1 V2 115 kV rms ) =
=
a) What is the maximum real po wer that can be transmitte d between V1 and V2 without exceeding the 15 degree limit? b) To increase the real power that can be transmitted between V1 and V2 , the engineers specify the addition of a second transmission line in parallel with the first. What should the line impedance of the added line be so that 250 MW can be transmitted betwee n V1 and V2 without exceeding the 15 degree limit?
1
EE4161
HomeworkAssignment
DueFeb6
5. You are asked to construct a photovoltaic cell that only uses light over a very narrow wavelength interval, say λ0 ± 0.01 nm. Assume that one phot on can crea te one elect ron, and perfect collection ef ficiency. Use the irradianc e data in the graph below. At λ0 500 nm, how much energy is wasted due to bandgap mismatch ? Assume a Si cell, E g 1.1 eV =
=
1 − 2 −
)
1.2
1 m n 0.8 m 0.6 (W e c n0.4 ia d a rrI 0.2 0 0
500
1000 λ
1500 (nm)
2000
2500
6. Assume that in a Si cell with bandgap of 1.12 eV every photon abov e bandgap creates one electron and that electron is collected. Use the solar spectrum for global tilt. Every excited electron falls down to the bottom of the conduction band before being collected, the energy being given off as heat. a) What is the short ci rcuit current? b) What fraction of the incident energ y is wasted as heat due to the photon ener gy being greater than the bandgap?
2