EE1401 POWER SYSTEMS OPERATION AND CONTROL question papers Anna university April\May2008 question papers Download

B.E/B.Tech DEGREE EXAMINATION April\May2008
Fourth Semester                 
Electrical and Electronics Engineering

EE 1401 --POWER SYSTEMS OPERATION AND CONTROL

(Regulation 2004)
Time: 3 hours                                                    Maximum marks: 100
Answer ALL questions

PART A (10 x 2 =20 marks)

1.What are the advantages of pool operation with respect to LFC?
2. What is base load

3. Why the frequency and voltage to be regulated in a power system

4.Compare the functions of "speed governer" and "speed changer" in a speed govering system of a turbine-generator set

5What are the various functions of excitation system

6.What is the need for a compensator in the AVR loop

7.What is participation factor with respect to economic load dispatch

8.Mention the assumptions made in the formation of loss formula matrix,B

9.What are the major functions that re carried out in an operations control center?

10.What do you understand by security constraints?

PART B (5 x 16 = 80)

11 (a)(i) Explain installed reserve , Spinning reserve, cols reserve and hot reserve(8)

(ii) A power station has to meet folowing demand

Group A : 200kW between 8 A.M and 6 P.M

Group B : 100kW between 8 A.M and 10 A.M

Group C : 100kW between 8 A.M and 10 A.M

Group D : 50kW between 8 A.M and 10 A.M

plot the daily Load curve and determine diversity factor, units generated per day and load factor.
(or)
(b) (i) Discuss about the recent trends in real time control of power systems

(ii)Write short note on load forecasting

(12) (a) Derive the transfer function model and draw the block diagram for a single control area provided with governer system.From the transfer function derive the expression for steady state frequency error for a step load change.
(or)
(b)Two synchrnous machines with the following data are operating in parallel to feed a common load of 300MW.

Machine 1: Governer speed droop : 4% Speed changer set to give 75% rated load at rated speed.

Machine 2: Governer speed droop :3%

Speed changer set to give 50% rated load at ated speed.

The nominal frequency of operation of set is 50Hz.

(i) determine the load taken by each machines to share the loads as in(i) but with a frquency of 50 HZ.

13 (a)draw the circuit diagram for a typical excitation system and derive the transfer function model and draw the block diagram discuss the stability aspects of the AVR.
(or)
(b)A thre e phase overhead line has resistance and reactance of 5 and 20 ohms ,respictivelythe load at the receving end is 30MW ,0.85 power factor lagging at 33kV,Find the voltage at the sending end.What will be th kVAR rating of the compenasating equipment insrted at the rceving end so as to maintain a voltage of 33 kV at each end? Find also the maximum load that can be transmitted.

14.  (a) The fuel-cost functions for thermal plants in $/h are given by

F1=0.000 4P2g1 + 5.3Pg1 +500

F2=0.0006P2g2 +5.5g2 +400

F3=0.0009+ P 2g3+5.8Pg3+200

Where P g1Pg2 and P g3 are in MW

Find the optimal dispatch and the total cost when the total load is 975 MW with following generator limits.

100 MW < = Pg1< = 450 MW

100 MW < = Pg2< = 350 MW

100 MW < = Pg3< = 225MW
(or)
(b) (i) What is unit commitment problem? Discuss the consraints that are to be accounted in unit commitmentproblem

(ii)Explain priority list method of solving unit commitment problem.State merits and limitatations of this method.

15.  (a)(i)What is EMS? What are its major functions in power system operation and control?. (6)

(ii)Draw a block diagram to show the hardware components of a SCADA ystem for a power system and explain the application of SCADA in ,oniotring nd control of poer system.
(or)
b) Draw a state transition diagram of a power system showing different sets of operatingstates clasifieds according to security level.Mark on the diagram and explain the state transitions that may occur due to systemdisturbaces and also the different control actions that can be taken o improve the security level of the system.

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