PSD Question Bank

Review Questions: PSD

1. Write the expression for angular speed of the stator mmf in mech rad/sec.
2. Show the variation of mmf along the stator surface with concentrated and distributed winding.
3. Write the expression for fundamentals of mmf per pole with concentrated and distributed winding.
4. Show the stator and rotor mmf waves in a synchronous machine.
5. List the basic equations that are required to describe the electrical part of the SM.
6. List the assumptions made in the modeling of SM.
7. List the different types of winding in a SM.
8. Draw the seven winding model of a 3-phase SM.
9. Show the variation of permeance with rotor position.
10. Write the flux linkage equations for the seven windings of SM.
11. Write the voltage equations of SM.
12. Describe the approach to derive an expression for self inductance of stator winding of SM.
13. What are the different methods of producing changing flux linkages?
14. Give the expression for transformer emf and speed emf.
15. How will you classify the electromagnetic machines using transformer emf and speed emf?
16. What are the assumptions made in mathematical description of SM.
17. What are the  windings considered in the rotor side of the seven winding model of a 3-phase SM.
18. Give the turns ratio between the stator and f-winding before and after transformation from abc to dq0.
19. Give the phasor diagram for the stator voltage equations.
20. Write the complete flux linkage equations in park’s coordinates.
21. What is stator transients?
22. Write the parks direct transformation and inverse transformation matrix.
23. Write the voltage equations after park’s transformation.
24. Define the term β.
25. Derive the expression for stator self inductance and show how it is varied as a function of β.
26. Derive the expression for stator-to-stator mutual inductances.

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Power system protection Question Bank

Review questions

Power system protection

Two marks

1.Describe the essential features of a protective relay with reference to (i) Selectivity (ii) sensitivity (iii) speed (vi) Reliability and dependability.

2.      What do you mean by loss of excitation in the context of generator protection?

3.      What are the situations where there is no need to use directional OC relays and the situations where directional relays must be used.

4.      What are the different types of reactors?  Give short note on each.

5.      Draw the block diagram of numerical protection and explain.

6.      Why primary and back up protection are needed for power system?

7.      Discuss how an amplitude comparator can be converted to a phase comparator and vice versa.

8.      What do you mean by incipient faults and how Buchholz relay is used to protect such a fault.

9.      Sketch the high impedance busbar differential protection for a three-phase busbar?

10.    Write a short note on tap changing transformers.

11.         Why over fluxing is harmful for the transformers?

12.         What are the various faults to which a turbo alternator is likely to be subjected?

13.         What are the situations where DTOC relays are preferred over IDMT relays?

14.         What are the situations were directional relays are needed?

15.         How mho relay is implemented using induction cup structure?

16.         What is the need for carrier aided protection of a transmission line? 

17.         Why does a busbar differential scheme have a tendency to operate for external faults?

18.         What is the need for supervisory relay in busbar differential relay scheme?   

19.         What are the advantages of numerical relays over conventional relays?

20.         Compare the maximum allowable frequency with and without S/H.

21.    Mention the different types of faults involved in power system.

22.    What are the merits and demerits of static relays?

23.    What is Buchholz relay and for what purpose it is used?

24.    What are the possible causes due to which field excitation of an alternator may be lost?

25.    Sketch the high impedance busbar differential protection for a three-phase busbar.

26.    What is the necessity of back up protection in the transmission lines?

27.    Mention the different types of reactors available in power system.

28.    What are the main purposes of a tap-changing transformer?

29.    What are the different types of filters used in digital relays?

30.    What are the most common communication mediums available in power systems?

16 marks

1.Describe the construction and principle of operation of an attracted armature type relays.                                                                                               (8)

 (ii).  In detail explain the primary and back up protection scheme for a radial distribution system and for the maloperation conditions.                    (8)

2.      Explain the phenomenon of inrush.  What are the factors on which the magnitude of inrush current depends?                                        

                                               

3.      What are the various abnormal operating conditions to which a modern turbo alternator is likely to be subjected? Explain each in detail

4.(i).      For a 45 MVA, 11 KV, star-delta transformer, design the percentage differential scheme.  What is the minimum recommended percentage bias?                   (8)

   (ii) Discuss the loss of excitation and loss of prime mover of an alternator.           (8)

5).     Draw the characteristics of directional relay and give the application of a directional relay to a three-phase feeder.

6).    With a neat diagram explain the three stepped distance protection of a transmission line and its trip contact configuration.

7(i).  Explain the trip law for simple impedance relay using the universal torque equation and implementation using balanced beam structure.             (8)

  (ii)  Explain the trip law for reactance relay using the universal torque equation and implementation using induction cup structure.                                     (8)

                                                         

8.      For the radial system shown in Fig. determine the settings of overcurrent relays at locations A, B and C.

      A                       B                         C                             D

  supply         800/1                   500/1            250/1                                                                                                                    

	IL = 180A + 15KW motor Istart = 6 * IR IR = 28A IF = 6000A

 

   I_L = 220A                  I_L = 200A               I_F = 8000A                   I_F = 7000A      

                                     

.

9.      In detail explain the various booster protections of a power system.

                                                         

2..     In detail explain the various capacitor protections of a power system.

10(i).          In detail explain the numerical over-current protection.                      (8)

    (ii).         In detail explain the numerical transformer differential protection.             (8)         

                                                         

11.    Explain the numerical distance protection of transmission line with the help of Mann and Morrison method.        

12.    Describe the construction and principle of operation of an induction type relays and obtain the torque equation.

13.    Explain the various stator and rotor type of faults and its protection of an alternator.

14.    Investigate the differential units, which operate on a-g external and internal fault.

15(i).          Explain the trip law for simple impedance relay using the universal torque equation and implementation using balanced beam structure.             (8)

  (ii)  Explain the trip law for mho relay using the universal torque equation and implementation using induction cup structure.                                               (8)

16.    For the radial system shown in Fig. 8(b) determine the settings for the IDMT OC relays at locations A and B.

  -------------------------------------------------------------------------------------------------------------------

                      Bus A                               Bus B                                Bus C

---------------------------------------------------------------------------------------------------------------------

I_f,min = 3500                               I_f,min = 2000                     I_f,min = 1000

I_f,max = 4000                               I_f,max = 3000                    I_f,max = 1500

---------------------------------------------------------------------------------------------------------------------

Fig 8(b)

                                                           

17.    Explain the various reactor protections available in power system.

                                     

18.    In detail describe the internal and external protection of a shunt capacitor

19.    What are the various abnormal operating conditions observed in the three-phase Induction motor from mechanical side? Also provide the protections schemes for the above. 

                                               

20.    In detail explain the three stepped distance protection of a transmission line and its trip contact configuration.

21          Explain the coupling and trapping of the carrier signals into the desired line section and also explain the internal and external fault protection using carrier-aided directional comparison relaying.

22.        What is the need for high impedance busbar protection when one of the CT is saturated and discuss how minimum internal fault current can be detected by the high impedance busbar differential scheme.

23.         A 132 KV busbar consists of two incoming and four outgoing lines.  The system is solidly earthed and the switchgear capacity is 3500 MVA at 132 KV.  The parameters are: Maximum full-load current in one line = 500 A, R_S = 0.7 W, R_{lead wire} = 2.0 W, Relay load (1A relay is used) = 1.0 W, CT magnetizing current up to 120V = 0.28 mA/V and CT saturation voltage V_knee = >120V.

1.    If the over-current relay in the spill path is set at 1.0 A and the Voltage setting V_set is 100 V, find (a) the maximum ’through fault’ current up to which the scheme will remain stable. (b) whether the answer in part (a) is commensurate with the switchgear capacity. (c) the minimum internal fault current which will be detected by the scheme. (d) the setting for detecting minimum internal fault current by the scheme. (e) the value of the stabilizing resistance.

2.    It is required that a break in the pilot wire from a CT carrying a current of 25 A and more should be detected by the supervisory relay.  Calculate the setting of the supervisory relay?

24).   Describe the Least Error Squared technique applied to numerical protection.

25. Describe the mann and Morrison method applied to numerical distance protection of a transmission line.

25(i).          Describe the essential qualities of protection system.                                 (8)         

      (ii)        Describe the classification of protective relays based on technology.      (8)         

26     Describe the construction and principle of operation of an induction type relays and obtain the torque equation.

27     Explain the phenomenon of inrush.  What are the factors on which the magnitude of inrush current depends?  

28.    Explain the various stator and rotor type of faults and its protection of an alternator.

29.    With a neat diagram explain differential protection of busbars and implementation for an internal and external faults.

30.    In detail explain the three stepped distance protection of a transmission line and its trip contact configuration.

31     Explain the various reactor protections available in power system.

32.    In detail describe the internal and external protection of a shunt capacitor.

33.    Describe the numerical overcurrent protection and transformer differential protection.

34.    Explain the numerical distance protection of transmission line with the help of Mann and Morrison method.

             

                  

                                     

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PS9123: Flexible AC Transmission System Question Bank

PS9123: Flexible AC Transmission System

Unit-1

1.       List the significant loading limits in different types of transmission lines.

2.       Explain load and system compensation.

3.       Explain the need for FACTS controllers.

4.       What is meant by surge impedance loading? Derive characteristics Impedance.

5.       List the different types of FACTS controllers.

6.       Derive from the fundamentals the expressions for the voltage and current at any distance X from the sending end of loss less distributed parameter line.

7.       Consider a 765kV symmetrical lossless transmission line with l=0.98mH/km, c=14.0nF/km, and a line length of 900km.calculate the midpoint voltage at 56% of the surge impedance loading.

8.        Consider a 765kV symmetrical lossless transmission line with l=0.965mH/km, c=11.6nF/km, and a line length of 800km.calculate the MVAR that is required to maintain the midpoint voltage at 1.04 pu when the power flow through the line is in range of 750-850MW.

9.       Consider a 765kV symmetrical lossless transmission line with l=0.965mH/km, c=12.6nF/km, and a line length of 1000km. calculate the voltage at a distance of 550km from the sending end when the power flow through the line is 860MW.

Unit-2

1.       Compare the fixed series and fixed shunt compensation.

2.       Write the advantages of slope in SVC dynamic characteristics.

3.       Show that with the delta connected 3-phase TCR the triplen harmonics will be absent in the line currents.

4.       Explain the need for a reactor in series with a capacitor in the TSC circuit.

5.       Give the susceptance limits (min, max) of SVC with coupling transformer.

6.       Draw the V-I characteristics of mismatched TSC-TCR type of SVC?

7.        Explain the operation of the SVC (FC+TCR) and derive the equations used. Also explain how the         SVC is able to regulate the HVAC bus voltage.    

8.       How transients are eliminated and explain the practical switching strategies of TSC.

9.       Derive the per unit gain model for the power system?

10.   How SVC enhance the steady state power transfer of the power system?

11.   How SVC enhance the damping of small signal oscillations in power system?

12.   Show that with SVC the transient stability margin can be improved by enhancing synchronizing torque. Derive the necessary equations.

13.    What are the applications of SVC?

14.   Explain about IEEE basic models that are available for the SVC to represent in the stability studies?

15.   Show that with SVC the transient stability margin can be implemented by enhancing synchronizing torque. Derive necessary equations?

16.   Draw the functional control block diagram of SVC?

17.   Name the voltage regulators used in SVC

18.   Explain the design procedure of SVC voltage regulator by method of system gain

19.   Define critical clearing angle and critical clearing time? Derive the critical clearing angle and critical clearing time (for critical clearing time refer solution of tutorial problem no.4)

20.   Explain the transient stability of the SMIB system by Equal area criteria?

21.   Show that with SVC the transient stability margin can be implemented by enhancing synchronizing torque. Derive necessary equations?

22.   How SVC modulating the bus voltage. Derive necessary equations?

23.   An SVC is connected to 400kV system has a reactive power range of 500MVAR production to 250MVAR absorption. If the per unit proportional gain of voltage regulator is to be 0.7 determine the short-circuit level of the system. The SVC has slope of 3%.

24.   Derive the expression for the steady state power transfer if there is fixed capacitor connected at the midpoint of the line. Also calculate what will be the maximum power transfer if both end voltages are regulated at 1.0 p.u. X = 0.1 p.u and Bc = 0.25 p.u.

25.   Consider a SMIB system in which the synchronous machine is generating 0.9 p.u. MW and 0.3 p.u. MVAR at a terminal voltage of 1 p.u at angle of 36.  The machine transient reactance is 0.3p.u. and the transmission line reactance is 0.650 p.u. If the damping ratio has to be 0.12 calculate how the mid-point voltage should be modulated by using SVC.

26.   An SVC is connected to 765 kV system has a reactive power range of 550 MVAR production to 250 MVAR absorption. If the per unit proportional gain of voltage regular is to be 0.65 determine the short-circuit level of the system. The SVC has a slope of 3%.

27.   Consider a SMIB system in which the synchronous machine is generating 0.9 p.u. MW and 0.3 p.u. MVAR. The voltage of Infinite bus is 0.995+j0.0 p.u. The machine transient reactance is 0.3p.u. and the transmission line reactance is 0.650 p.u. (a) Calculate what should be the net susceptance of SVC to maintain Vm at 1 p.u. (b) Calculate synchronizing torque co-efficient and with and without SVC at midpoint of the line.(c) Also calculate the critical clearing angle and critical clearing time with and without SVC when a 3-phase end of line fault occurs near to the generator terminals.

Unit-3

1.       Explain various operating modes of TCSC.

2.       What is TSSC? Compare TSSC and TCSC.

3.       Draw V-I and X-I characteristics of single module TCSC and Two modules TCSC.

4.       What will be the size of the jacobian matrix for a 9-bus system which consists of 3 synchronous generators and 6 load buses and a TCSC is placed between bus 7 and bus 8.What are the state variables that have to be calculated from the power flow analysis.

5.       From the fundamental derive the expression for steady state thyristor current when the TCSC is operating in the vernier mode?

6.       Draw V-I and X-I characteristics curves for single modules TCSC and Two module TCSC.

7.       Explain the different modes of operations of TCSC?

8.       Derive the expression for steady state thyristor current in TCSC circuit by drawing necessary waveforms?

9.       Derive the expression for reactance (X_TCSC) in the TCSC circuit?

10.   Explain the constant current control strategies in TCSC applications?

11.   What are the important limits that are considered in the capability characteristics of TCSC?

12.   What are the applications of TCSC?

13.   Consider the SMIB system in which the synchronous machine is generating 0.8 pu MW and 0.25 MVAR. The infinite bus voltage is 1 at angle of 0. The machine transient reactance is 0.32 p.u and the transmission line reactance is 0.65p.u.Calculate the value of net reactance offered by the TCSC and the voltage that has to be injected by the TCSC to enhance the power flow to 1.0 p.u

14.   Explain about modelling of TCSC for power flow analysis.

15.   Explain about modelling of TCSC for stability analysis.

16.   Explain different strategies of TCSC for stability analysis. A) constant current control B) Constant Angle control.

Unit-4

1.       Compare the performance of STATCOM and SVC.

2.       Derive the state space model for a STATCOM connected to the AC system in the synchronously rotating reference frame.

3.       Using equal area criterion show that for the dame rating of SVC and STATCOM connected at the midpoint of SMIB system the transient stability margin will be more with STATCOM than SVC.

4.       Discuss about the operation of SSC and compare the performance of SSSC with that of fixed capacitor compensation.

5.       Discuss about the operation of SSSC and compare the performance of SSC with that of fixed capacitor compensation.

6.       Consider a SMIB system in which the synchronous machine is generating 0.95 MW and 0.35 MVAR at a terminal voltage of 1 p.u at angle of 36. The machine transient reactance is 0.25 p.u and the transmission line reactance is 0.6 p.u. If the damping ration has to be 0.12 calculate how the voltage injected by SSSC has to be modulated.

7.       Consider a transmission line a STATCOM is connected at midpoint of the line. Assume that both end voltages are regulated at 1 p.u, the transmission line reactance is 0.8 p.u. calculate the current that must be injected by STATCOM to maintain the midpoint voltage at 1.01 p.u. When the load at receiving end is varied from 0 to 0.9 p.u.

8.       Consider a symmetrical lossless transmission line whose transmission line reactance is 0.55 p.u and the both end voltages are regulated at 1 p.u when the power flow thro’ the line is 0.85 p.u and the line is series compensated with SSSC.

i)                    If the net voltage magnitude drop across the line is to be 0.2 p.u what should be the voltage injected by SSSC. 

ii)                   ii) Calculate for what value fo voltage there will be negative power flow or reversal of power.

9.       Consider a SMIB system generating 0.8 p.u MW and 0.28 p.u MVAR. The infinite voltage is 1 at 0 and the machine transient reactance is 0.3 p.u, transmission line reactance is 0.57 p.u calculate.

a)      The voltage that has to be injected by SSSC to enhance the power transfer to 0.92 p.u MW

b)      Compute the value of degree of compensation that has to be provided to enhance the power transfer to 0.92 p.u

Unit-5

1.       What is the need for co-ordination of FACTS controllers?

2.       Explain the principle and operation of UPFC.

3.       Give the basic controller design procedure for enhancing the electrical damping of a power system (Page No.401-403).-Refer the  attached ppt

4.       Explain about the effect of electrical coupling and short circuit level on the controller interaction between multiple SVCs that are located in a power system.

5.       Explain the steps that are to be followed for the coordinated tuning of FACTS controllers to maximize the system damping.

6.       Explain the Genetic Algorithm based FACTS controller tuning procedure for the enhancing damping of a power system.

7.       Consider a symmetrical lossless transmission line with transmission lien reactance as 0.6 p.u show that the attainable controllable region of real and reactive power with UPFC is a circle in the P-Q plane. Draw the controllable region for a δ of 30.

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EXTRA HIGH VOLTAGE AC AND DC TRANSMISSION ENGINEERING - QUESTION BANK

EXTRA HIGH VOLTAGE AC AND DC TRANSMISSION ENGINEERING

(FOR VIII SEMESTER EEE)

UNIT – I    TRANSMISSION ENGINEERING

PART A

TWO MARKS QUESTIONS

1. What is principle of transmission?
2. Define power losses?
3. Define power handling capacity?
4. What is power handling capacity of single line circuit?
5. Write the nominal system voltages?
6. Write the maximum operating voltages?
7. Distinguish between nominal system voltages and maximum operating voltages?
8. Define vibration of transmission lines?
9. What are the different types of vibrations in transmission lines?
10. Write the list of equipments in transmission lines?

PART-B

1. Explain the power handling capacity and line losses?
2. Explain the mechanical consideration of transmission lines?
3. Briefly explain about cost of transmission lines and equipment?
4. Explain the principles of transmission?
5. Explain the standard of transmission voltages?

UNIT – II        LINE PARAMETERS

PART A

TWO MARKS QUESTIONS

1.      What is mean by ACSR conductors?

2.      What are the advantages of ACSR conductors?

3.      What is Bundled conductor?

4.      State the advantages of bundled conductors?

5.      Write the expression for the capacitance of a three phase line with unsymmetrical spacing and transposed?

6.      Define resistance of EHV transmission lines and write the equation?

7.      What is the difference between symmetrical and asymmetrical lines?

8.      What is the effect of Earth on Transmission line capacitance?

9.      Define resistance of EHV transmission lines and write the equation?

10.  What is the effect of bundled conductors on transmission inductance?

11.  Distinguish between GMD and GMR?

PART-B

1.         Derive an expression for the inductance per phase for a 3 phase overhead Transmission lines, Conductors are symmetrically placed?

2.         Derive an expression for the inductance per phase for a 3 phase overhead Transmission lines, Conductors are Un-symmetrically placed but the line is completely transposed?

3.         Drive an expression for the capacitance for a 3 phase overhead transmission lines the conductors are symmetrically placed?

4.         Derive an expression for the inductance per phase for a 3 phase overhead Transmission line Un-symmetrically placed but transposed?

5.         Briefly explain about bundled conductors? And why its needed?

UNIT – III     POWER CONTROL

PART A

TWO MARKS QUESTIONS

1.         What is mean by power frequency?

2.         Write the different types of voltage control methods?

3.         What is the need of voltage control in power system?

4.         Define power circle diagram? Why its need?

5.         What is meant by SVC?

6.         Define the term of over voltages?

7.         What for series and shunt compensation provided for?

8.         What is meant by STATCOM?

9.         Give the types of shunt controllers?

10.     Compare STATCOM and SVC?

11.     What is the need of line compensation?

12.     What are the advantages of FACTS controller?  

PART-B

1.      Briefly explain about 

(i)                 Series compensation

(ii)               Shunt compensation

2.     Explain in detail the various types of FACTS controllers?

3.     Briefly explain about SVC (Static Var Compensator)?

4.     Write the advantages of FACTS controllers?

5.     Explain in detail the various types over voltages?

UNIT – IV      EHV AC TRANSMISSION

PART A

TWO MARKS QUESTIONS

1.         What is the need for interconnection of Power systems?

2.         Explain or differentiate primary and secondary transmission?

3.         Explain or differentiate Primary and secondary distribution?

4.         State the advantages of EHV AC transmission?

5.         How the problem of corona is minimized in EHV AC lines?

6.      What are the limitations of increasing the transmission voltage level to very high value?

7.      Define Corona?

8.      What is the corona effect?

9.      What are the problems associated with EHV AC transmission?

10.  On what basis the conductor size is determined for 230kV and EHV AC transmission?

11.  What is one line diagram?

12.  What is the significance of drawing the single line diagram?

13.  What is skin effect? On which factor it depends?

14.  Give the Practical Transmission and Distribution voltage levels in India

15.  Why is electrical power preferable to be transmitted at high voltages? OR State the advantages high   voltage transmission.

16.  What is the highest AC and DC transmission voltage in India?

PART-B

1.      What are the problems involved in EHV AC transmission?

2.      What are the advantages of EHV AC transmission?

3.      What are the limitations of EHV AC transmission?

4.      Explain why EHVAC transmission is preferred? 

5.      What are the needs for preferring EHVAC transmission?

6.      Explain the technical reasons for adopting EHV AC transmission.

UNIT – V   HVDC TRANSMISSION

PART A

TWO MARKS QUESTIONS

1. Give the merits of HVDC systems?
2. List out the different types of HVDC links?
3. What are constituent sections of a power system?
4. What are the components of a power system?
5. Define break even distance in HVDC transmission?
6. Why HVDC lines do not require any compensation?
7. Why DC transmission is economical and preferable over AC transmission?
8. List the application of HVDC transmission?
9. Why is voltage regulation better in case of DC transmission?
10. What are the terminal equipments in HVDC system?
11. What are the main equipments of a DC transmission lines?
12. What is the main limitation of HVDC transmission?

PART-B

1. With the help of neat diagrams, explain the basic principle of HVDC transmission?
2. What are the advantages and disadvantage of HVDC transmission over HVAC transmission?
3. Explain the different types of HVDC links. Explain any one HVDC link available in India with rating?
4. Compare EHVAC and HVDC transmission?
5. Explain in detail any four applications of HVDC transmission?
6. Write short notes on EHVAC and HVDC transmission?
7. Briefly discuss about the terminal equipments of a DC transmission line with a neat diagram?

List out the main components of a HVDC sy

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