Download EXP_1 Economic Power System Operation

Power SystemOperation and Control (EET 415)
Laboratory Module
EXPERIMENT 1
ECONOMIC POWER SYSTEM OPERATION
1. OBJECTIVE:
To analyze the economic power flow on the power system by means of MiPower
software
2. EQUIPMENT:
MiPower software
3. INTRODUCTION:
The quantification and minimization of losses is important because it can lead to a more
economic operation of a power system. If we know how the losses occur, we can take
steps to limit the losses. Hence, if more losses can be minimised, the power can be
consumed efficiently. Existing power generation and transmission can be used
effectively without having to build new installations and at the same time save the cost of
losses.
Considering losses associated with resistive material, three things need to be
considered in order to prevent the unnecessary losses;
• either reducing the resistance/impedance,
• or decreasing the current, or
• maximising voltages.
To determine B-loss coefficients, it is necessary to determine the precise loss
mechanisms, which occur in the system. Traditionally, B-loss coefficients have been
applied to transmission line analysis where the losses are predominant by only line loss
determined by I2R. Transformer losses are not significant in such systems. The only
other losses are corona, which will occur only under foul weather conditions. However,in
industrial power systems, the losses are more diverse and thus B-coefficients will be
more complicated to utilize.
Consider a simple three-phase radial transmission line between two points of
generating/source and
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Power SystemOperation and Control (EET 415)
Laboratory Module
receiving/load as illustrated by Figure I.
We can deduce that the line loss is:
where R is the resistance of the line in ohms per phase. The current I can be obtained:
where PG is the generated power (load power and losses)
VG is the magnitude of the generated voltage (line-to-line)
cosφG is the generator power factor
Combining the above two equations, we have
Assuming fixed generator voltage and power factor, we can write the losses as:
where in this case
Losses are thus approximated as a second order function of generation. If a second
power generation is present to supply the load as shown in Figure II, we can express the
transmission losses as a function of the two plant loadings.
Losses can now be expressed by the equation:
Where B is the losses coefficient.
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Power SystemOperation and Control (EET 415)
Laboratory Module
Transmission losses become a major factor to be considered when it is needed to
transmit electric energy over long distances or in the case of relatively low load density
over a vast area. The active power losses may amount to 20 to 30 % of total generation
in some situations.
4. PROCEDURE
Figure 1 shows a 9-bus power system network of an Electric Utility Company. The load
data, voltage magnitude, generation schedule and reactive power limits for regulated
bus are tabulated in Table below. Bus 1, whose voltage is specified as V1 = 1.06 0 is
taken as slack bus. Voltage magnitude and real power generation at Buses 2 and 3 are
1.045pu, 40MW and 1.03 pu and 30MW. Line impedance for the given on 100MVA base.
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Power SystemOperation and Control (EET 415)
Laboratory Module
LINE DATA
LOAD DATA (MW)
Bus
Time
From
Bus i to
Bus j
R
X
No
0<t<8
9<t<18
19<t<24
1–2
0.02
0.06
2
20
20
15
1–3
0.08
0.24
3
10
15
20
2–3
0.06
0.18
4
40
50
60
2–4
0.06
0.18
5
50
55
70
2–5
0.04
0.12
3–4
0.01
0.03
4–5
0.08
0.24
The generator’s operating costs $/h are as follows:
C1 = 500 + 5.3P1 + 0.004P12
C2 = 400 + 5.5P2 + 0.006P22
C7 = 200 + 5.8P3 + 0.009P72
1. Design a power system according to Figure 1 above. Use the element database
as provided in Table given
(18 marks)
2. Run load flow analysis using Fast Decoupled method. Set accuracy for
convergence at 0.01. Also select B Coefficient & Economic Dispatch method
to solve the load flow analysis. Print the results.
3. From the results obtain the optimal generating of each unit, plants incremental
cost, penalty factor and loss Coefficient. Fill in Table 1 in your answer sheet.
4. On the network editor main screen, generate single line diagram with relevant
load flow at 0 <t<8 hour only. Save the diagram and print it.
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Power SystemOperation and Control (EET 415)
Laboratory Module
5. QUESTIONS:
1. From the fuel cost function given above, write a mathematical equation for
incremental fuel cost for all generating units.
(9 marks)
2. From results obtained, sketch the optimal power generated by each unit plant.
Comment the results
(12 marks)
3. Calculate and determined the incremental transmission loss of all units for all time
time sequences. What can be concluded from the obtained penalty factors and
incremental transmission loss.
(9 marks)
4. Calculate the total fuel cost using relevant mathematical represent the above
system and compare it with the results obtained from simulation for 0<t<8 hour.
What can be concluded from the results obtained.
(5 marks)
5. Write the matrix of B coefficient for the above system at 0<t<8 hour. From it,
calculate the total lost for the power system.
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Power SystemOperation and Control (EET 415)
Laboratory Module
ADDITIONAL QUESTIONS
1) Figure 2 shows a three line, two plant systems. The following data is given in the per
unit systems.
V1=V2=V3 = 1 p.u;
R1= 0.0025 pu; R2= 0.02 pu; R3 = 0.03 pu;
PF1=0.85; PF2 = 0.8; PF3 = 0.75;
a) Calculate the loss coefficient B11, B12 and B22 for the above system. (7 marks)
b) Calculate the penalty factors L1 and L2 and the corresponding power loss for the
two plants and the corresponding power loss for an optimum loading of P1 and P2
of 120MW and 100MW respectively. (assume the fuel cost for the two plants are
given by
F1    6.69P  4.7675x103 P 2 $ / h and F2    6.69P  P 2 $ / h
(15 marks)
DISCUSSION AND CONCLUSION
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(10 marks)
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