Visvesvaraya Technological University (VTU) 2006 B.E Electrical and Electronics Engineering 7th SEM / COMPUTER TECHNIQUES IN POWER SYSTEM - Question Paper
Reg. No. 1 1 1 1 1 1 T 1 I I_I
Seventh Semester B.E. Degree Examination, January/February 2006 Electrical & Electronics Engineering Computer Techniques in Power Systems
Time: 3 hrs.) (Max.Marks : 100
Note: Answer any FIVE full questions.
1. (a) Derive the standard expression for Ygus using singular transformation. (6 Marks)
(b) The series Impedances of each line of a 3 bus power system is 0,02+j0,08 pu and half line charging admittance of j0.25 pu, Find the Ygus with ground as reference, using singular transformation and verify the result by the method of inspection.
jpmm(12 Marks)
2. (a) Draw the typical representation of a pair of primitive elements pq and rs with
mutual coupling in the admittance form and derive the performance equation in the standard form i + j = (8 Marks)
(b) Derive an expression for the diagonal element corresponding to the new row and column of Zq when a tree branch Is added to the partial network. (12 Marks)
3. (a) Explain the concept of Bus power In load flow analysis. (5 Marks)
(b) For a 3 bus power system, elements of are given by Yn = 4.5 - j 18, Yi* = -2.5 + 710, Yu = -2 -f j'8, Y22 = 4.5 - j20y y23 = 2 + jlO, >33=4- j 18. Real bus powers are given by 1.6 and - 0.7 and reactive bus powers are 1.6 and - 0.7 at buses 2 and 3 respectively. Bus 1 is the slack bus with Ex = 1.04 +jO. Assuming Initial values of bus voltages at buses 2 and 3 as 1 + j'0, find the value of vottage of bus 3 at the end of first Iteration using Gauss Seidal method and an acceleration factor of 1.6. <15 Marks)
1
4. (a) Given a pair of non linear algebraic equations as a2 6 4-a6 = 6.6anda2 + 62 = 7.69, find the values of a and b at the end of second Iteration using Newton Raphson method and starting values of 1 and 2 for x & y respectively, <12 Marks)
Derive expressions, In the polar form, for the typical diagonal elements of the submatrices of the Jacobtan In the NR method of load fioW analysis, (8 Marks)
(b) 5. (a)
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What Is load frequency control? For a single area case, derive jnecessary equations for generator load modelling and draw the corresponding blbck diagram.
' ! i I I ; ! (12 Marks) -'I I : I' ITwo generators rated 200 MW and 400 MW are operating In parallel. The drop characteristics of their governors are 4% and 5% respectively from no load to full load. Assuming that the generators are operating at 50 Hz at no load, how would a load of 600 MW be shared between them? What will be the system frequency at this load?
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6. (a) For the sysfertj shown In the figure Fig Q6(a), obtain the loss coefficients, /' ..jin -
Ii and In are'ln phase, (10 Marks)
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(b) A power systep consists of two 100 MW units whose Input cost data are given by the equation
Ci = O.ObPf | 20Pj + 800 Rs/Hour C2 = 0.06P22 -f 15P2 + 1000 Rs/Hour
If the total received power Is 150 MW, what wouid be the division of load between the units for the most economic operation? (1 Marks)
7. (a) Explain how the network performance equations used for load flow analysis can
be applied to describe the performance of the network during a transient period.
(10 Marks)
(b) Starting from the pair of equctions representing a swing equation, explain the modified Euler's method of obtaining swing curve. (10 Marks)
8. Write explanatory notes on :
(a) Two area load frequency control
(b) Fast decoupled load flow analysis
(c) Automatic economic load dispaich. (7+7+6 Marks)
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| Earning: Approval pending. |
