10 questions
Q.1. (a) What is meant by power handling capacity of a transmission line? Write the equation for power handling capacity and percentage transfer loss in the line and explain how the higher transmission voltage are important for bulk power transmission. [10]
(b) Describe in brief the surge impedance loading of a transmission line. [6]
Q.1. (a) How can the inductance of a bundled conductor line be calculated? Derive expressions for geometrical mean radii of duplex, triplex and quadruplex arrangement. [8]
(b) A 400 kV, 3 phase bundled conductor line with two sub-conductors per phase has a horizontal configuration with spacing between adjacent phases of 12 m, sub-conductor spacing 45 cm within each phase bundle. The radius of each sub-conductor is 1.6 cm. (i) Find the inductance per phase per km of the line. (ii) Compute the inductance of the line with only one conductor per phase having the same cross sectional area of the conductor of each phase. [8]
Q.2. A three-phase overhead transmission line has per phase resistance and reactance of 6 ohm & 20 ohm respectively. The sending end voltage is 66 kV while the receiving end voltage is maintained at 66 kV by a synchronous phase modifier. Determine the kVAr of modifier when the load at the receiving end is 75MW at power factor 0.8 lagging, also determine the maximum load that can be transmitted. [16]
Q.2. (a) Explain the speed governing characteristics of generating unit and parallel operation of generations. [6]
(b) Two similar 4000 kVA alternators operate in parallel. The governor of first machine is such that frequency drops from 50 Hz on the load to 47.5 Hz on full load. The corresponding drop for the second machine is 50Hz to 48 Hz. How will be a load of 6000 kW be shared by the two machines? What will be the system frequency at this load? [10]
Q.3. (a) Describe FC-TCR scheme with the help of circuit and control characteristic diagram. [8]
(b) Briefly explain the various types of shunt reactors used to limit voltage rise. [8]
Q.3. (a) Explain the various conventional methods of voltage control along with advantages and disadvantages. [8]
(b) What do you mean by reactive power? Give various sources of reactive power. [8]
Q.4. (a) Make a comparative analysis between series & shunt FACTS controllers. [8]
(b) With the help of characteristics curves, explain the operation of TCSC. [8]
Q.4. (a) What are the controllable variables in FACTS? [8]
(b) Explain briefly how voltage control & reactive power control can be achieved using a TCSC-TCR? [8]
Q.5. Explain and draw the basic converters control characteristics for negative current margins. [16]
Q.5. Discuss the techno-economical advantages of HVDC system over AC transmission system. [16]