VFSTR Journal of STEM
Vol. 01, No.02 (2015) 2455-2062
Engineering/Science/Technology
ECE/EEE/CSE/Chemistry
Generation Expansion Planning – A Tutorial Paper
K.Karunanithi, A.Bhuvanesh, S.Kannan
K.Karunanithi, Department of EEE, Kalasalingam University, India, email:
k.karunanithi@klu.ac.in
A.Bhuvanesh, Research scholar, Mepco Schlenk Engineering College, Sivakasi,
India, email: bhuvanesh.ananthan@gmail.com
S.Kannan, Department of EEE, Ramco Institute of Technology, Rajapalayam, India,
email: kannan@ritrjpm.ac.in
*Corresponding Author:
ARTICLE HISTORY
Received 13-10-2015
Revised 26-10-2015
Accepted 06-11-2015
Available online 28-12-2015
GRAPHICAL ABSTRACT
E-mail:
k.karunanithi@klu.ac.in
ABSTRACT
The selection of the best expansion alternative for long
term planning horizon is commonly referred as Generation
Expansion Planning (GEP) problem. It is a highly
constrained, non-linear optimization problem. In this
tutorial paper, steps involved in solving the GEP problem
and the various types of transactions affecting the GEP
results are discussed. This paper will be helpful for those
who wish to do research in GEP. In this paper, two GEP
studies are carried out. In the first study, the GEP problem
is addressed with two expansion candidates (Thermal and
Hydro plants) for a hypothetical test system with different
cases: simple GEP (without any constraints), Transmission
constrained GEP and GEP with Independent Power
Producers (IPP). In the second study, the GEP is analyzed
with three expansion candidates (Thermal, Hydro and
Diesel plants) for the Roy Billinton Test System (RBTS)
with different cases: simple GEP, Transmission constraint
GEP with firm purchase, Transmission constraint GEP with
simultaneous
bilateral
transactions,
Transmission
constraint GEP with multi lateral transaction and
Transmission constraint GEP with all above type of
transactions. The results show that GEP outcomes
(location, cost and capacity to be installed) will be
different if we consider constraints and different type of
transactions.
Keywords – Bilateral Transactions, DC load flow, Firm
power, Generation Expansion Planning, Independent
Power Producers, Multilateral Transactions, RBTS.
© 2014 VFSTR Press. All rights reserved
1. INTRODUCTION
Electric system planning is linked to overall energy
planning primarily through the demand forecast,
Karunanithi. K. et al
XXXX-XXX | http://dx.doi.org/xx.xxx/xxx.xxx.xxx |
which should account for anticipated economic
activity, population growth, and other driving
forces for changes in electricity demand over time
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VFSTR Journal of STEM
Vol. 01, No.02 (2015) 2455-2062
[1]. Generation Expansion Planning (GEP) is the first
crucial step in long-term planning problem, after
the load is properly forecasted for a specified
future period. GEP is, in fact, the problem of
determining when, what and where the generation
plants are required so that the loads are adequately
supplied for a foreseen future while satisfying
technical and economical constraints over a
planning horizon of typically 10-30 years [2, 3].
It is a challenging problem due to its nonlinearity,
large scale, and the discrete nature of the variables
describing unit size and allocation [4]. GEP has a
challenge for numerous reasons: first, there is
uncertainty related with the input data, such as
predictions of demand for electricity, financial and
technical features of developing generating
technologies, construction lead periods, and
governmental rules. A second trouble rises when
considering numerous objectives simultaneously.
These objectives might contain minimization of
overall cost and maximization of the system’s
reliability. Commonly, other costs and features
besides
generation expansion
costs
are
incorporated as constraints in the optimization
problem, that is, most GEP problems have been
modeled as single-objective models, which consider
minimization of the total cost and reliability as one
of the constraints. This problem is a tactical
planning problem for the developing countries.
The demand is estimated to increase in most
cases; an error in selecting the accurate mix of
generating facilities at expected costs could result
in failure to meet the future demand and therefore
the reliability of the system is reduced which in turn
affect the overall economy of the country.
Numerous approaches have been suggested to
solve the GEP problem. Optimization approaches
used to solve GEP include conventional methods
like linear, mixed-integer, non-linear, dynamic
programming; Metaheuristic methods such as
Simulated Annealing, Tabu Search, Evolutionary
Algorithms, Particle Swarm Optimization, etc., [5].
In this paper, GEP problem is solved for a year and
the various steps involved in solving the problem
one presented. Two expansion candidates are
considered for study I and three expansion
candidates are considered for study II. Three
constraints, that is, upper construction limit,
Karunanithi. K. et al
reserve margin and thermal limit of line are
considered in this analysis. This paper analyzes the
effect of various types of transactions on GEP
results. This study is particularly important in
deregulated power system.
The rest of the paper is organized as follows:
Chapter II presents problem formulation, Chapter
III describes test systems used for study I and
study II, Chapter IV gives results and discussion
and Chapter V concludes.
2. PROBLEM FORMULATION
The GEP is a problem of finding a set of optimum
decision vectors over a planning horizon that
reduces the investment and operating costs under
relevant constraints.
2. 1 Cost objective
The cost objective is: Minimize z = aXs + bYt (1)
where
z = Total cost of the system
a = Capacity of thermal plant
X = No. of thermal plants selected for a year
s = Cost of a thermal plant including
investment and operating cost
b = Capacity of Hydro plant
Y = No. of hydro plants selected for a year
t = Cost of a hydro plant including
investment and operating cost
2.2 Constraints
The minimum cost objective function should satisfy
the following constraints.
i) Upper Construction limit
The units to be committed in the expansion plan in
a year should fulfill
0 ≤ X ≤ XX;
0 ≤ Y ≤ YY
(2)
where XX = 6 and YY = 5(Upper construction limits)
ii) Reserve margin
The selected units should satisfy the minimum
reserve margin.
aX + bY + C ≥ D + r.D
(3)
where
C = Existing capacity
D = Demand
r = reserve margin in % of demand in a year
iii) Thermal limit
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VFSTR Journal of STEM
Pj ≤ Limit j
Vol. 01, No.02 (2015) 2455-2062
(4)
where
Pj = Power flow in the line j
Limitj = Thermal limit of line j
III. Test System considered
A) Study I
This test system has total generating capacity of 60
MW with two types of power plants. One is a
thermal plant of capacity 40 MW connected with
bus 1 and other is a hydro plant of capacity 20 MW
connected with bus 2. A peak load 50 MW is
assumed and it is connected in bus 3. Figure 1
shows that the hypothetical test system considered
for analyzing the GEP. Table 1 shows line data and
thermal limit of transmission system. The resistance
of transmission lines is assumed to be zero.
simulator etc., can be used to find the power flow
in the lines. In this paper, DC power flow is
calculated using power world simulator. It is
shown in Figure 2. It has been observed that power
flow in all the three lines are within the thermal
limit of respective lines.
Figure 2 Line flows in the existing case
Two candidate plants both thermal and hydro are
considered for expansion in this analysis. Thermal
plants connected at bus no.1 and hydro plants at
bus no.2. Let us assume that cost/plant, capacity
and number of plants available are as shown in
Table 2. The cost/plant shown is not a realistic value
and is an assumed one.
Sl.
No.
Figure 1 Hypothetical test system
Table 1 Line data for the Hypothetical test system
Sl.
Line
Line Reactance Thermal limit
No.
(Ω)
(MW)
1
Line 1
0.2
55
2
Line 2
0.4
100
3
Line 3
0.25
80
The DC load flow calculation is necessary in order to
check whether the transmission lines are operated
within its thermal limit or not. Different software
packages like ETAP, MI POWER, Power world
Karunanithi. K. et al
1
2
Table 2 List of candidate plants
No. of
Capacity
Plant type
plants
(MW)
available
Thermal
20
6
Hydro plant
10
5
Cost
/plant
(Rs.)
110
50
B) Study II
For this study, Roy Billinton Test System (RBTS) is
considered. It has six buses, nine transmission lines,
total generation capacity of 240 MW and total load
of 185 MW. The RBTS is shown in figure 3. The
details of line data and generator data of RBTS are
given in Appendix. The base case power flow for
this test system is shown in Table 6. It has been
observed that there is no violation of thermal limit
of all lines.
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Vol. 01, No.02 (2015) 2455-2062
thermal plants, two hydro plants and four diesel
plants are assumed to be available for future
expansion and these plants are connected at bus
no.4, bus no.5 and bus no.6 respectively.
Sl.
N
o.
1
2
3
Figure 3 RBTS system
Table 3 RBTS base case power flow
Power flow
Thermal limit
Line No.
(MW)
(MW)
1
58.3
85
2
24.2
71
3
6.5
71
4
7.7
71
5
23.8
71
6
58.3
85
7
24.2
71
8
16.2
71
9
20.0
71
Three candidate plants are considered in this study.
The details of these plants are given in Table 4. Four
Case
No.
Description
Table 4 List of candidate plants
No. of
Locati
Capaci
Plant
plants
on
ty
type
Available/y
(bus
(MW)
ear
no.)
Therm
4
40
4
al
Hydro
10
2
5
Diesel
10
4
6
Cost
/pla
nt
(Rs.)
880
50
650
IV. Results and discussion
A) Study I
In this section, the results of simple GEP,
Transmission constrained GEP and Transmission
constrained GEP with IPP are discussed.
Table 5 shows that summary results of three cases
of study I. It has been observed that for case 1, the
cost is Rs.580/- and total capacity to be added is 110
MW. For case 2, the cost is Rs.600/- with same
additional capacity but different fuel mix ratio and
for case 3, the cost is Rs.600/- with additional
capacity required is 120 MW which is higher than
that of previous cases.
Table 5 Summary of study I
No. of
Type of
Fuel-Mix ratio
plants
plant
(%)
selected
Additional
capacity
added (MW)
Total
capacity
(MW)
Cost
(Rs.)
Thermal
Hydro
3
5
Thermal - 58.8
Hydro - 41.2
110
170
580
GEP with line flow
constraints
Thermal
5
Hydro
1
Thermal - 82.35
Hydro - 17.65
110
170
600
GEP with line flow
constraints and IPP
Thermal
6
Hydro
0
Thermal - 88.88
Hydro - 11.11
120
180
660
1
Simple GEP
2
3
Case 1: Simple GEP
In this case, simple GEP (without any constraints) is
addressed. The load at bus 3 is increased by an
additional amount of 100 MW in next year. After
the increase, the total load is increased to 150 MW.
Karunanithi. K. et al
The reserve capacity is taken as 10% of total load.
Therefore total installed capacity required will be
165 MW including reserve capacity. The additional
capacity to be added in the system will be 105 MW
(existing capacity-60 MW). The cost of each 20 MW
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VFSTR Journal of STEM
Vol. 01, No.02 (2015) 2455-2062
thermal unit is Rs. 110 and each 10 MW hydro unit is
Rs.50.
Table 6 shows the all possible combinations. There
are 42 combinations and among them only fifteen
combinations will satisfy the future demand with
10% reserve margin. If the total capacity of the
Sl. No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
No. of
Thermal
Units
0
0
0
0
0
0
1
1
1
1
1
1
2
2
2
2
2
2
3
3
3
3
3
3
4
4
4
4
4
4
5
5
5
5
5
5
Karunanithi. K. et al
candidate plants is less than 105 MW, are
considered as infeasible solutions and more than
105 MW, are considered as feasible solutions. The
feasible combinations are listed separately in Table
7 in ascending order of total cost.
Table 6 Number of possible combinations
No. of
Capacity of
Capacity of
Total
Hydro
Thermal
Hydro units
Capacity
Units
units (MW)
(MW)
(MW)
0
0
0
0
1
0
10
10
2
0
20
20
3
0
30
30
4
0
40
40
5
0
50
50
0
20
0
20
1
20
10
30
2
20
20
40
3
20
30
50
4
20
40
60
5
20
50
70
0
40
0
40
1
40
10
50
2
40
20
60
3
40
30
70
4
40
40
80
5
40
50
90
0
60
0
60
1
60
10
70
2
60
20
80
3
60
30
90
4
60
40
100
5
60
50
110
0
80
0
80
1
80
10
90
2
80
20
100
3
80
30
110
4
80
40
120
5
80
50
130
0
100
0
100
1
100
10
110
2
100
20
120
3
100
30
130
4
100
40
140
5
100
50
150
Cost
(Rs.)
Feasible/
Infeasible
580
590
640
690
600
650
700
750
800
Infeasible
Infeasible
Infeasible
Infeasible
Infeasible
Infeasible
Infeasible
Infeasible
Infeasible
Infeasible
Infeasible
Infeasible
Infeasible
Infeasible
Infeasible
Infeasible
Infeasible
Infeasible
Infeasible
Infeasible
Infeasible
Infeasible
Infeasible
Feasible
Infeasible
Infeasible
Infeasible
Feasible
Feasible
Feasible
Infeasible
Feasible
Feasible
Feasible
Feasible
Feasible
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38
39
40
41
42
6
6
6
6
6
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Vol. 01, No.02 (2015) 2455-2062
0
1
2
3
4
5
120
120
120
120
120
120
0
10
20
30
40
50
120
130
140
150
160
170
660
710
760
810
860
910
Feasible
Feasible
Feasible
Feasible
Feasible
Feasible
Table 7 Capacity and cost table with ascending order of cost (only feasible solutions)
No. of
No. of
Capacity of
Capacity of
Total
Cost
Sl. No.
Thermal
Hydro
Thermal unit
Hydro unit
Capacity
(Rs.)
Units
Units
(MW)
(MW)
(MW)
1
3
5
60
50
110
580
2
4
3
80
30
110
590
3
5
1
100
10
110
600
4
4
4
80
40
120
640
5
5
2
100
20
120
650
6
6
0
120
0
120
660
7
4
5
80
50
130
690
8
5
3
100
30
130
700
9
6
1
120
10
130
710
10
5
4
100
40
140
750
11
6
2
120
20
140
760
12
5
5
100
50
150
800
13
6
3
120
30
150
810
14
6
4
120
40
160
860
15
6
5
120
50
170
910
From Table 7, we can conclude that the least cost
of Rs. 580 with total capacity of 110 MW having 3
units of 20 MW thermal plants and 5 units of 10 MW
hydro plants satisfy the future load demand and
the reserve margin.
Case 2: GEP with line flow constraints
Karunanithi. K. et al
The same problem stated in case 1 is taken for case
2 also. In addition to the specification of location,
line flow constraints are also considered. Let us
assume that 3 units of thermal, 60 MW connected
at bus 1 and 5 units of hydro, capacity 50 MW
connected in bus 2 (solution obtained in case 1).
Now, once again power flow in the system is
calculated using Power world simulator and line
flows are shown in figure 4 and there will be
violation of thermal limit of line 3 (thermal limit of
this line 3 is 80 MW)
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VFSTR Journal of STEM
Vol. 01, No.02 (2015) 2455-2062
Figure 4 Power flows in the system for case 2
Now next best feasible combination (second merit
order in Table 7) is considered. It has 4 units of 20
MW thermal plants and 3 units of 10 MW hydro
plants. All the 4 thermal plants connected at bus 1
and 3 hydro plants connected at bus 2 as shown in
figure 5. Once again, the DC line flows are
calculated and it can be concluded that again there
will be violation of thermal limit of line 3.
Figure 6 Solution for GEP for third merit order of
feasible combination
Case 3: GEP with line flow constraints with
Independent Power Producers (IPP)
In this case, in addition to line flow constraints, an
IPP is injecting 5 MW power at bus 2 and taking the
same 5 MW power as load at bus 3. Now total load
becomes 155 MW. While analyzing GEP, the first
five merit order list fails to satisfy the constraints.
So, consider the sixth merit order from Table 7. It
has 6 units of thermal plants alone. There is no
hydro plant in this combination. The result of DC
load flow using Power world simulator is shown in
figure 7.
Figure 5 Power flows in the system for second merit
order of feasible combination
Now we consider the third merit order from table
7. It has 5 units of 20 MW thermal plants and one
hydro plant of capacity 10 MW. The result of DC
load flow using Power world simulator is shown in
figure 6. Now there is no thermal limit violation in
all the three lines and satisfy the reserve margin
constraint. For this feasible combination, total cost
of the system increased to Rs.600.
Figure 7 solution of GEP for sixth merit order in the
feasible combination
The sixth merit order in Table 4 satisfies all the
constraints. The solution found for case 3 is 6 units
of 20 MW thermal plants alone (the total capacity
of 120 MW) with a cost of Rs. 660/-.
B. Study II
In this chapter, results of simple GEP, Transmission
constraint GEP with firm purchase, Transmission
constraint GEP with simultaneous bilateral
transactions, Transmission constraint GEP with
multilateral
transaction
and
Transmission
constraint GEP with simultaneous bilateral
transactions, multilateral transaction and firm
purchase are discussed.
Table 8 shows that the summary results of study II.
For simple GEP, the total cost will be Rs. 3570/-. In
this case, four no. of thermal plants and one no. of
hydro plant are selected to meet the future
Karunanithi. K. et al
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VFSTR Journal of STEM
Vol. 01, No.02 (2015) 2455-2062
demand. No diesel plant is selected. The total
capacity added will be 170 MW. For case 2, case 3
the same result can be obtained. For case 4, total
cost will be same but locations are different and for
case 5, total capacity to be added will be same but
total cost is increased to Rs.5290/-.
Table 8 Summary of study II
Case
No.
1
2
3
4
5
Description
Simple GEP
Transmission
constraint GEP with
firm purchase
Transmission
constraint GEP with
simultaneous
bilateral transactions
Transmission
constraint GEP with
multilateral
transactions
Transmission
constraint GEP with
simultaneous
bilateral transactions,
multilateral
transaction and firm
purchase
Thermal
Hydro
Diesel
Thermal
Hydro
Diesel
Thermal
No. of
plants
selecte
d
4
1
0
4
1
0
4
Hydro
1
5
Diesel
Thermal
0
4
3
Hydro
1
5
Diesel
0
-
Thermal
3
4
Hydro
1
5
Diesel
4
6
Type of
plant
Location
of plants
(bus no.)
4
5
4
5
4
Fuel-mix ratio
(%)
Additional
capacity
added
(MW)
Total
capacity
(MW)
Cost
(Rs.)
170
410
3570
170
410
3570
Thermal- 65.85
Hydro - 34.15
Diesel - 0
170
410
3570
Thermal- 65.85
Hydro - 34.15
Diesel - 0
170
410
3570
Thermal - 56.1
Hydro - 34.15
Diesel - 9.76
170
410
5290
Thermal- 65.85
Hydro - 34.15
Diesel - 0
Thermal- 65.85
Hydro - 34.15
Diesel - 0
Case 1: Simple GEP
In this study, it is assumed that load will be doubled in the next year and the reserve capacity is 10% of total peak
load and now additional capacity required will be 167 MW to meet future load with 10% reserve margin.
Seventeen feasible combinations are available which satisfy reserve margin and are listed in Table 9 as
ascending order of cost.
Sl. No.
1
2
3
4
5
6
7
8
Table 9 Capacity with ascending order of cost (only feasible solutions)
No. of
No. of
Additional
No. of Diesel
Total capacity
Thermal
Hydro
capacity
plants
(MW)
plants
plants
(MW)
4
1
0
170
410
4
2
0
180
420
4
0
1
170
410
4
1
1
180
420
4
2
1
190
430
3
2
3
170
410
4
0
2
180
420
4
1
2
190
430
Karunanithi. K. et al
Cost
(Rs.)
3570
3620
4170
4220
4270
4690
4820
4870
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4
3
3
4
4
4
4
4
4
2
1
2
0
1
2
0
1
2
2
4
4
3
3
3
4
4
4
200
170
180
190
200
210
200
210
220
440
410
420
430
440
450
440
450
460
4920
5290
5340
5470
5520
5570
6120
6170
6220
For simple GEP, the total cost is Rs. 3570/- and four no. of thermal plants and one no. of hydro plant are selected
to meet the future demand. The total capacity added will be 170 MW (minimum additional capacity required is
167 MW).
Case 2: Transmission constraint GEP with firm
purchase
The term 'Firm energy (power)' as it applies to the
area of reclamation can be defined as 'Noninterruptible energy and power guaranteed by the
supplier to be available at all times, except for
uncontrollable circumstances'. In this case, a 20
MW firm power is injected at bus no.1 and the same
power will be consumed at bus no.6. In this case,
four no. of thermal plants and one no. of hydro
plant are selected to meet the future demand and
no diesel plant is selected. The power flow in the
lines are shown in figure 8 and it has been observed
that no violation of thermal limit of lines. For
transmission constrained GEP with firm purchase,
the total cost will be Rs. 3570/-. The total capacity
added will be 170 MW.
Case 3: Transmission constraint GEP with
simultaneous bilateral transactions
“Bilateral Transaction” means a transaction for
exchange of energy (MWh) between a specified
buyer and a specified seller, directly or through a
trading licensee from a specified point of injection
to a specified point of withdrawal for a fixed or
varying quantum of power (MW) for any period
during a month. It is a bilateral exchange of power
between a buying and selling entity. The exchange
may be a proposed, scheduled or actual one. In this
case, a 50 MW power is injected at bus no.6 and a
20 MW power is injected at bus no. 4 and same
amount of load is consumed at bus no.3 and bus
no.2 respectively. The power flows in the lines are
shown in figure 9 and all the lines are within their
thermal limits. For this case also same no. of plants
are selected as in case 2. The total cost of the
system is same as case 2.
Figure 8 Power flow in the lines with firm purchase
Figure 9 Power flow in the lines with simultaneous
bilateral transactions
Karunanithi. K. et al
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Vol. 01, No.02 (2015) 2455-2062
Case 4: Transmission constraint GEP with
multilateral transaction
Multilateral transactions are an extension of
bilateral transactions. In a multilateral transaction,
power is injected at different buses and taken out
at some other different buses simultaneously, such
that the sum of all generations is equal to all loads
in the transaction, excluding losses. Transmission
losses may be either supplied by the generators of
the transactions or by the pool utility as per
predefined contract. This trade is arranged by
energy brokers and involves more than two parties.
In this case, a 25 MW and a 20 MW power are
injected at bus no. 3 and bus no.5 respectively. The
load of 10 MW each is taken from bus nos. 2, 4 and
6 and a load of 15 MW is taken from bus no.5
simultaneously.
No
feasible
combinations
mentioned in table 8 are satisfying the line flow
constraint if the locations of candidate plants are
considered as in previous cases. If the location of
thermal plants is changed from bus no.4 to bus
no.3, the first feasible combination in merit order
list satisfies the line flow constraint. The power
flow in the lines with multilateral transaction is
shown in Figure 10. The total capacity added will be
170 MW and total cost will be Rs. 3570/-.
In this case, Transmission constraint GEP with
simultaneous bilateral transactions, multilateral
transaction and firm purchase is considered.
Simultaneous bilateral transactions such as 50 MW
power is injected in bus no. 6 and same amount of
load is connected in bus 3 and 20 MW power is
injected at bus no. 4 and same amount of load is
connected at bus 2 are considered. In addition to
simultaneous bilateral transactions, a multi lateral
transaction is also considered. In bus 3, 25 MW and
in bus 5, 20 MW power is injected and a total load
of 45 MW is taken from bus 2 (10 MW), bus 4 (10
MW), bus 5 (15 MW) and bus 6 (10 MW). In addition
to both transactions, a firm purchase is also
considered. A 20 MW power is injected in bus 1 and
from bus 6, 20 MW load is added.
In this case, feasible combinations from serial No.2
to 9 mentioned in table 9 are not satisfying the
thermal limit constraint and next merit order i.e.,
feasible combination mentioned in serial.No.10
satisfies this constraint also. Three no. of thermal
plants, one no. of hydro plant and four no. of diesel
plants are selected to meet the future demand. The
total capacity added is 170 MW. This is the same as
that of previous cases, but the total cost is
increased to Rs. 5290/- which is higher than all
previous cases. Figure 11 shows Power flow in the
lines for this case.
Figure 10 Power flow in the lines with simultaneous
multilateral transactions
Figure 11 Power flow in the lines with simultaneous
bilateral transactions, multilateral transaction and
firm purchase
V. Conclusion
In this paper, GEP problem is addressed for a
simple hypothetical test system and RBTS test
system with different cases. In study I, three cases,
that is, simple GEP (without any constraints),
Case 5: Transmission constraint GEP with
simultaneous bilateral transactions, multilateral
transaction and firm purchase
Karunanithi. K. et al
10
VFSTR Journal of STEM
Vol. 01, No.02 (2015) 2455-2062
Transmission constrained GEP and GEP with IPP are
analyzed. It has been observed that cost is 580/- for
simple GEP and when transmission constraint is
included, cost is increased by 3.45% and when
transmission constraint with IPP is considered, the
cost is increased by 13.8%.
In study II, five different cases, that is, simple GEP,
transmission constrained GEP with firm purchase,
transmission constrained GEP with simultaneous
bilateral transactions, transmission constrained
GEP with multi lateral transaction and transmission
constrained GEP with all above said transactions
are analyzed. It has been observed that GEP
without any constraint the cost is 3570/-. When firm
purchase and simultaneous bilateral transactions
are considered, the total cost and locations will be
same as that of simple GEP. For transmission
constrained multi lateral transaction, the total cost
is same as previous case but location of thermal
plants have to be changed. When transmission
constrained GEP with simultaneous bilateral
transactions, multi lateral transaction and firm
purchase is considered, the total cost will be
increased by 48.18%. The results show that GEP is
different for different cases i.e., cost, location and
selections of plant are changed. The fuel mix ratio
and reliability constraints are not considered in this
analysis.
Appendix
Roy Billinton Test System Data
Table A1.1: Branch data of RBTS
Line No.
R p.u
X p.u
1,6
2,7
3
4
5
8
0.0342
0.114
0.0456
0.0228
0.0228
0.0228
0.18
0.60
0.48
0.12
0.12
0.12
Karunanithi. K. et al
9
0.0023
0.12
Table A1.2: Generation data of RBTS
Bus no.
No. of units
Rating (MW)
2
1
1
4
2
1
40
10
20
20
5
40
1
2
Table A1.3: Load data of RBTS
Bus No.
1
2
3
4
5
6
Load,
MW
--
20
85
40
20
20
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