QUESTION FROM PREVIOUS QUESTION PAPERS

1. 1. Draw the block diagram of load frequency control of a two-area control system
   2. What is area control error? What are the control strategies?
2. 1. What is load frequency control in a two-area power system? Why is it essential to maintain constant frequency in an inter-connected power system?
   2. Two power stations A, B are interconnected by a tie-line and an increase in load of 250 MW on system B causes a power transfer of 150 MW from A to B. When the tie-line is open, the frequency of System A is 50 c/s and that of system B is 49.5 c/s. Determine the value of KA and KB, which are the power frenquency constants of the two generators.
3. Explain the power frequency characteristics of an interconnected power system.

    

4. Derive an expression for steady state change of frequency and tie-line power transfer of a two-area power system.

    

5. Give typical block diagrams for a two-area system interconnected by a tie-line and explain each block. Also deduce relations to determine the frequency of oscillations of tie-line power and static frequency drop.

    

6. Two generators rated 200 MW and 400 MW are operating in parallel. The drop characteristic of thin governors are 4% and 6% respectively from no load to full load. Assuming that the generators are operating at 50Hz, how can a load of 500MW be shared between them.

    

7. Two generators rated 200 MW and 400 MW are operating in parallel. The drop characteristics of their governors are 4% and 5% respectively from no load to full load. The speed changes are so set that the generators operate at 50Hz sharing a load of 600 MW in the ratio of thier ratings. If the load reduces to 400 MW, how will it be shared among the generators and what will the system frequency be?

    

8. Two generators rated 300 MW and 400 MW are operating in parallel. The drop characteristic of thier governors are 4% and 6% respectively from no load to full load. The speed changes of the governors are set so that a load of 400 MW is shared among the generators at 50Hz in the ratio of their ratings. What are the no load frequencies of the generators