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.