M.E. DEGREE EXAMINATION, JANUARY 2012.
First semester
Power System Engineering
PS 9223/236207/PS 923 — FLEXIBLE AC TRANSMISSION SYSTEMS
(Common to M.E Power Electronics and Drives, M.E. Electrical Drives and Embedded
Control and M.E. High Voltage Engineering)
(Regulation 2009)
Time: Three hours Maximum: 100 marks
Answer ALL the Questions
PART A—(10 × 2 = 20 marks)
1. What are the conventional methods used for compensation in power systems?
2. What are the factors which limit loading capability?
3. Name the types of harmonics that are present in the o/p of 3 phase bridge converter.
4. Write the advantages of PWM converter?
5. Name the types of converters that are generally used in FACTS devices.
6. What are the objectives of shunt compensation?
7. What is the need for transient free switching of TSG? How it is achieved?
8. Give the objective of NGH-SSR damping scheme.
9. Differentiate clearly between an UPFC and IPFC.
10. What are the drawbacks of continuously controllable tap changer?
PART B—(5 × 16 = 80 marks)
11. (a) (i) Derive the expression for active as well as reactive power flow in a losseless transmission line? Draw necessary phasor diagram. (8)
(ii) By using power angle curve explain how by changing the value of line impedance the maximum amount of active power flow will change? (8)
Or
(b) Write a detailed technical note on the following:
(i) Thermal capability
(ii) Dielectric capability
(iii) Stability limit.
12. (a) (i) How is shunt compensation classified? Explain in detail (8)
(ii) Compare and contrast STATCOM and SVC. (8)
Or
(b) Explain SVC with respect to the following aspects:
(i) Diagram.
(ii) Operation.
(iii) V-I Characteristics.
13. (a) (i) Explain in detail the phenomenon of sub synchronous resonance (SSR) with an example. (8)
(ii) Explain why present transmission system with capacitive series compensation is prone to SSR. (8)
Or
(b) (i) With the help of power angle curve explain how transient stability is improved with the series controllers. (8)
(ii) Draw V-I Characteristics and loss characteristics for TCSC. (8)
14. (a) Explain the construction and working of 3 phase full wave bridge type VSC.
Or
(b) Explain in detail how VSC will act as an inverter or a rectifier in inductive or
15. (a) By means of a block diagram explain the simulation of a generalized IPFC which can be operated as a STATCOM, SSSC, UPFC or IPFC.
Or
(b) Describe the coordination procedure of multiple controllers using Genetic