POWER SYSTEM OPERATION AND CONTROL

EE 1401 – POWER SYSTEM OPERATION AND CONTROL

PART A

UNIT I

1.      What is the objective of power system control?

2.      What is the objective of power system operation and control?

3.      What is load curve?

4.      What is daily, Weekly, Annual load curve?

5.      What is load duration curve?

6.      Define load factor.

7.      Define diversity factor.

8.      Define spinning reserve.

9.      Define Cold reserve.

10.  Define hot reserve.

11.  Define Maximum Demand.

12.  Define demand factor.

13.  What is plant use factor?

14.  Define reserve

15.  Define Plant capacity factor.

16.  What is the necessity of frequency regulation in power systems?

UNIT II

1.      What is the necessity for frequency constancy in a power system? (M/J 2006)

2.      What is the need for frequency regulation? (M/J 2006)

3.      What is the need for voltage regulation in power system? (M/J 2006)

4.      What happens to frequency if the load on the generator increases? (M/J 2006)

5.      What is meant by AFRC? (M/J 2006)

6.      State the difference between P-f and Q-lVl.(N/D 2006)

7.      Define area control error.(M/J 2006)

8.      Give the two control loops of large generators. (A/M 2005)

9.      What is the basic role of ALFC?(N/D 2004)(N/D 2006)

10.  What is meant by control area? (N/D 2004)(N/D 2005)

11.  Specify the disadvantage of ALFC loop.(A/M 2005)

12.  Write the tie line power deviation equation in terms of frequency?(N/D 2005)

13.  List the advantage of multi area operation. (M/J 2007)

14.  Define Control area

15.  Define AGC

UNIT III

1.      List the various components in AVR loop. (N/D 2004)

2.      State whether changes in AVR loop will be reflected in ALFC loop.(N/D 2004)

3. What is meant by stability compensation?(M/J 2007)

4.      Name the methods of voltage control in network

5. Write the need for Stability Compensator.

6.      Draw a simple brushless AVR loop.

7.      Compare SVC and series capacitor.

8. What is SVC?
9. What are the applications of tap changing transformer?
10. What is synchronous condenser?

UNIT IV

1. What is the purpose of economic dispatch?

2.      Write the co- ordination equation taking the effect of losses.

3.      What is meant by unit commitment?

4.      Write the constraints in Unit Commitment.

5.      Write the co- ordination equation without losses.

6.      What is meant by incremental cost curve?

7.      Name the different solution methods for unit commitment.

UNIT V

1.      List the factors that affect power system security.

2.      Denote the hierarchical levels used in EMS.

3.      Name the methods of voltage control in network

4.      List the functions of energy control centre.

5.      What is SCADA?

6.      List the functions of SCADA.

7.      What are the functions of EMS?

8.      Name the different states of a power system.

9.      What is power system security?

10.  Define state estimation in a power system.

PART B

1.      A  generating  station has the following daily load cycle:

Time (hours)	0-6	6-10	10-12	12-16	16-20	20-24
Load(MW)	20	25	30	25	35	20

Draw the Load curve (1)and load duration curve(1) and find

                    i.            Maximum demand(2)

                  ii.            Units generated per day(2)

                iii.            Average Load(2)

                iv.            Load Factor.(2)

2.      Consider an inductive Load of type Z=R+jX

                    i.            By how many percent will the real load drop if the voltage is reduced by 5 percent?(8)

                  ii.            How would a 2 percent drop in frequency affects the real load, if the load is assumed to have a power factor of 0.8.(8)

3.      A Power station has to meet the following demand.

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

            Group B:100kW between 6 A.M and 10 A.M

            Group C:50kW between 6 A.M and 10 A.M

            Group D:100kW between 10 A.M and 6 P.M and  6 P.M and 6 A.M

Plot the daily load cure and load duration curve and determine

(i) diversity factor

(ii) units generated  per day

(iii)  load factor.

1.      Using  a simplified  functional diagram explain the operating features of a speed governing system.(8) (M/J 2006)

2.      Develop a linear mathematical model of a speed governing system.(8) (M/J 2006)

3.      Explain the static and dynamic response of ALFC control loop.(8)(N/D 2004)

4.      Explain the technique involved in load frequency control (LFC)of a single area

      system.(8) (M/J 2006)

5.      Explain the principle , involved in tie line frequency control in case of two area system.

     (M/J 2006)

6.      Develop a linear mathematical model of two area system.(8)(N/D 2004)

7.      Explain the tie line bias control of two area system .(8)(N/D 2004)

8.      Briefly discuss the LFC control of single area systems.(16)(N/D 2005)

9.      Explain the dynamic response of two area system.(8) (N/D 2005)

10.  Develop a linear mathematical model of two area system.(6)

11.  Explain the tie line bias control of two area system.(6)

12.  Describe the expression for Critical gain (4)

13.  A single area controlled system has the following data(8)

            Area capacity =2000MW

            Operating Load=1000MW

            R=2.4Hz/p.u.MW

Find K_I and find the nature of roots for K_I=1.

14.  Determine the primary ALFC loop parameter for a control area having the following

      data :

                     Total rated area capacity, P_r =2000MW

            Normal Operating Load,P_d=1000MW

Inertia constant ,H= 5 sec

            R=2.4Hz/p.u.MW(all area generators)

We shall assume that the load frequency dependency as linear meaning that the old load would increase 1% for 1% frequency increases.

15.  A single area controlled system has the following data(8)

            Area capacity =3000MW

            Operating Load=1500MW

            R=3%

            H=5 sec and frequency=50 Hz

Compute steady state drop in frequency in Hz for a step load changing of 25MW

16.  Two 50 Hz power station are connected by means of an interconnected cable of negligible

impedance so that the station are in parallel. Station A has a full load capacity of 15 MW and uniform speed regulation of 3%, Station B has a capacity of 4MW and a uniform speed regulation of 4%. The load on the bus bar of station A is 10MW and B is 4MW. Calculate the generated output of each station. The power transmitted by the interconnected and the operating frequency .Assume frequency governor action and the speed changer of generator were set to have a frequency of 50 Hz

4.      Develop a mathematical model of an exciter system and brief on its control action. (8)

5.      Explain the static and dynamic performance of AVR loop . (8)

6.      With the neat flow chat explain dynamic programming method in unit commitment.(8)

7.      For a simple  two unit system the loss coefficients are

B₁₁=0.001

B₁₂=-0.0005

B₂₂=0.0024

dC₁/dP₁=0.08P₁+16 Rs/MWhr.

dC₂/dP₂=0.08P₂+12 Rs/MWhr.

Find the generation P1 and P2 for l=50, also compute the transmission loss and total load . (8)

8.     Explain the static VAR compensators(8)

1.      Derive the relation between voltage , power and reactive power at a node.              (8)

2.      Write about the stability compensation of AVR loop .                                     (8)

3.      Develop an iterative algorithm for solving the optimum dispatch equation of an ‘n’ bus power system taking into account the effects of system losses                                 (8)

4.      A generating station has two units A and B. The incremental operating cost of the two

units are as follows

Unit A:l₁=0.1P₁+20 Rs/MWhr.

Unit B:l₂=0.12P₁+16 Rs/MWhr.

Where P1=load on unit A in MW,P2=load on unit B in MW,Calculate the load distribution based on economic loading of two generating stations for load of 180 MW                 (8)

5.      Consider  three units,

C₁=561+7.92P₁+0.00156P₁²

C₂=310+7.85P₂+0.00194P₂²

C₃=780+7.97P₃+0.00482P₃²

Unit            Minimum        Maximum

1                150                  600

2                100                  400

3                50                    200

Find the priority by which the units are committed and de committed in unit commitment problem.                                                                                                                          (8)

1.      a)(i)Develop a mathematical model of an exciter system and brief on its control action. (8)

        (ii)Explain the static and dynamic performance of AVR loop . (8)

      2)(i)Explain the static VAR compensators with a phasor diagram. (8)

         (ii)Discuss the effect of compensation on the maximum power transfer in a transmission lines. (8)

3.(i)Explain the tasks of energy control center and its interaction with individual power plants.(8)

(ii)Explain the different functions that are performed by SCADA systems (8)

(Or)

4)(i)Classify and distinguish between the various operating states of power system (8)

(ii)Explain briefly how the system states are continuously monitored and controlled. (8)