VARDHAMAN COLLEGE OF ENGINEERING
(AUTONOMOUS)
B. Tech VI Semester Regular/Supplementary Examinations, May 2018
(Regulations: VCE-R15)
POWER SYSTEM OPERATION AND CONTROL
(Electrical and Electronics Engineering)
Date: 10 May, 2018 FN Time: 3 hours Max Marks: 75
Answer ONE question from each Unit
All Questions Carry Equal Marks
Unit I
1. Write the algorithm for economic load dispatch with losses. 7M
The cost curves of two plants are:
2
C 0.04P 25 P 250 Rs. Hr
1 1 1

2
C 0.05 P 12P 150 Rs. Hr
2 2 1

The loss coefficients for the above system are B11 0.0014/MW, B12 B21 -0.0002/MW
and B22 0.0012/MW. Determine the economical generation scheduling corresponding to
λ 30 Rs/MWHr. Also find the loss.
8M
2. What is meant by penalty factor? What role does it play in economic load dispatch? 8M
The fuel cost for two units are as given below:
IFC 0.5P 20 Rs MW Hr
1 1

IFC 0.75 P 35 Rs MW Hr
2 2

where P
1 and P
2 are in MW
What is the most economic schedule if together they are supplying 250MW? What is the
incremental fuel cost in that case?
7M
Unit II
3. With a neat sketch explain the hydro electric plant model. 7M
Consider the two bus system shown in Fig.1. The incremental production costs at the
two generating station are given by:
dC1/dP1 0.005P1 5 and dC2/dP2 0.004P2 7
The B coefficients are: B11 0.0002, B12 B21 -0.00005; B22 0.0003
Determine the penalty factor at both the buses for the given system and also the
approximate penalty factor. Given 8
Fig.1
8M
Cont…2

4. Derive an expression for short term hydro thermal scheduling considering transmission
losses.
8M
A system consists of two generators with the following characteristics:

2 6
F 7P 0.03 P 70 10
1 1 1


2 6
F 5P 0.05 P 100 10
2 2 2

Where F and P are fuel input in K cal/hr and unit output in MW respectively. The daily
load cycle is given as follows:
Time Load
12 midnight to 6 a.m 50 MW
6 a.m. to 6 p.m 150 MW
6 p.m. to 12 midnight 50 MW
Give the economic schedule for the three periods of the day.
7M
Unit III
5. Obtain the speed governing system model and also derive the transfer function. 7M
The capacities of two generators are 600MW and 800MW and they are operating in
parallel at full load. They have speed governors with a drop of and (from no load
to full load) respectively. How will they share a load of 1000MW? What will be the new
frequency?
8M
6. Draw the block diagram of a turbine model and obtain its transfer function. 8M
A 2 pole, 200MVA synchronous generator has a machine constant H as 7.5MW-ec/MVA.
It is operating at full load and 50Hz, when suddenly a 50MW load is removed. Due to
time lag of the speed governing system, the steam valve starts closing only after
0.4second. Find the new frequency and speed of the generator.
7M
Unit IV
7. Distinguish between load frequency control and economic dispatch 7M
Two control area have the following characteristics
Area1: R1 0.011 p.u, D1 0.85 p.u. base MVA 1000
Area2: R2 0.018 p.u, D2 0.95 p.u., base MVA 1000
A load change of 200 MW occur in area1. Determine the new steady state frequency.
8M
8. Explain the necessity of maintaining frequency constant in power system. 5M
Two power stations A and B operate in parallel. They are inter connected by a short
transmission line. The station capacities are 100 MW and 200 MW respectively. The
generators at A and B have speed regulation and respectively. Calculate the
output of each station and the load on the interconnector if:
i. The load on each station is 125 MW
ii. The loads on respective bus bars are 60 MW and 190 MW and
iii. The load is 150 MW at the station A bus bar only
10M
Unit V
9. Find the capacity of a static VAR compensator to be installed at a bus with voltage
fluctuation. The short circuit capacity 7000 MVA.
5M
Discuss steady state performance of static var compensators.
10M
10. Explain briefly about reactive power compensation in transmission systems. 8M
Explain about load compensation with its objectives. 7M