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Eighth Semester B.E. Degree Examination, June/July 2014Power System Operation and Gontrol

Time: 3 hrs. Max. Marks:100

Note: Answer any FIVE full questions, selectingatleast TWO questions from euch part.

PART _ Aa. Derive the expression for tie line power and frequency deviation for a two area system.

(10 Marks)b. Explain the objectives and function of AGC in a power system. (05 Marks)c. Two synchronous generators are initially supplying a common load as shown in Fig.Q.1(c)

at IPU frequency (50H2). The rating of unit I is 337MW and has 0.03P.U. droop built intoits governor. Unit 2 is rated at 420MW and has 0.05P.U. droop. Find each units share of a0.lP.U. (75.7MW) increase in the total demand. Also find the new line frequency. (05 Marks)

Fig.Q.1(c)

a. Describe the function of AVR with a neat block diagram. (06 Marks)b. Explain parallel operation of generator with relevant droop characteristic graph with an

infinite bus. (07 Marks)c. Two generators rated 200MW and 400MW are operating in parallel. The droop

characteristics of their governors are 4o/o and 5olo respectively from no load to full load.Assuming that the generators are operating at 50Hz at no load, how would a load of 600MWbe shared between them? What will be the system frequency at this load? Assume freegovernor operation. (07 Marks)

Explain how mathematical model of speed govemor system is developed for autornaticgeneration control (ACG). (10 Marks)What is load frequency control (LFCX Explain with a block diagram the model of a LFC foran isolated power system. Assuming relevant transfer function for each block, arrive at theoverall transfer function (closed loop) to give frequency deviation as output for a loadchange as input. (10 Marks)

4 a. Explain briefly the componentsiequipments of power system that can generate and/or absorbreactive power. (06 Marks)

b. Derive the equations to get the relation between voltage, power and reactive power at anode. (06 Marks)

L of2

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c. In the radial transmission system shown in Fig.Q.4(c), determine the real and reactivepowers to be delivered by the generator G. Neglect the voltage drops in the li1es andtransformers. All P.U values are referred to the voltage bases shown and I0OMVA.Determine also the power factor at which the generator must operate. (08 Marks)

joo\Pt:' 13rru jo'l Pu

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Fig.Q.a(c)

PART _ Ba. Discuss the thermal constraints and the role of spinning reserve in unit commitment

problem. (10 Marks)b. Explain the dynarnic programlning method with a help of flowchart in unit commitrnent.

(10 llarks)

CI

6 a. Discuss the factors affecting power system security.b. Explain the contingency analysis for detection of network problems.c. With the block diagrarn. explain AC power flow security analysis.

(06 Marks)(08 Marks)(06 Marks)

a. Explain the objective and process of power system state estimation (PSSE). (10 Marks)b. Explain how lease square estimation (LSE) method is used in PSSE. (10 Marks)

a. Briefly explain the two state generator models. With the usual notations derive theexpression for availability and unavailability in terms of failure and repair rate. (08 Marks)

b. A power plant has generating units with the data shown table 8(b). Prepare the capacityoutage probability table and indicate the cumulative probabilities.

Unit number Capacitv in MW Failure ratelvear Repair ratelvear1

2

J

100

1s0

250

1.0

0.1

1.1

I94.973.0

(12 Marks)

*****

200MlhJ

2 of 2

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