International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 4 - September 2015
Nalla Srihari
1
, T.Nireekshana
2
1
PG student, VNRVJIET, Hyderabad, India
2
Assistant professor, VNRVJIET, Hyderabad, India
Abstract-Recent year’s world experienced new technologies in all fields; the same is done in electrical field that is by deregulation. New regulations are determined for generating more power, improvement in service, to achieve reduced cost and introducing competition in electricity field.
By deregulation fair transmission pricing is an important problem. The contribution factors are help to estimate a fair and obvious tariff to consumer. And allocate charges for generating companies and consumers. The contribution factors are finding by using power flow tracing algorithm. Bialek’s upstream looking algorithm is used to calculate contribution factors. both ends of every link) and a number of sources
(generators) and sinks (loads) connected to the nodes. nearly the only requirement for the input data is the
Kirchhoff’s Current Law must be fulfilled for all the nodes in the set of connections.
PROPORTIONAL SHARING
PRINCIPLE:
The most important law used to trace the run of electrical energy will be that of proportional sharing.
This is illustrated in Figure .3.1 where four lines are connected to node i, two each inflows and outflows.
Keywords - Contribution factors, deregulation, upstream looking algorithm
I.
I NTRODUCTION
Deregulation and re-structuring of electric power trade is experience in the bulk part of the world. This tracing technique helps to find the power transmit between individual generators to loads. Tracing process determines the payment to transmission users for transmission usage. Tracing methods is also used for transmission pricing and improving set transmission expenses. The power flow tracing algorithm is a method for tracing the contribution of every user on a transmission system to distribute charges for using the transmission line. Its work is based on the concepts of Kirchhoff’s current law and proportional sharing principle. In deregulated power system using Bialek’s power tracing technique, describes which generators are supplying a exacting load, how much utilize every generator is making of a transmission line and what is each generator’s contribution to the system losses. The method is not incomplete to incremental changes and is valid to together active and reactive power. From the initial of a power flow explanation, first recognize the busses and then locate the set of busses supplied to the matching generators. It is likely to estimate the contribution of all generators to the load and flows by using proportional sharing principle
II.
WORKING PRINCIPLE OF POWER FLOW METHOD
The proposed electricity flow technique is topological in natural world, that is it deals with a common carrying problem of how the flows are spread in a meshed network assumed to be associated and described by a set of n nodes, m aimed at links
(Transmission lines or transformers), 2m flows (at
Fig.1
Proportional Sharing Principle
The total power flow through the node is P i
= 40+60
=100MW of which 40% is supplied by line j – i and
60% by line k – i. as electricity is impossible to tell apart and all of the outflows down the line from node i is dependent just on the voltage gradient with impedance of the transmission line, it may be assumed that each MW leaving the node contains the matching amount of the inflows as the sum nodal flow P i
.Hence the 70MW out flowing in line i – m consists of
70*40/100 =28MW supplied by line j – i and
70*60/100 =42MW supplied by line k- i . Similarly the 30MW out flowing in line i – l consists 30
*40/100= 12MW supplied by line j - i and 30*60/100
=18MW supplied by line k – i.
The proportional sharing principle essentially amounts to assuming that the network node is mixture of inward flows so that it is not possible to tell which particular inflowing electrons goes into which particular outgoing line. This seems to agree with the common sense and with the generally accepted view that electricity is indistinguishable.
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International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 4 - September 2015
III.
ALGORITHM FOR POWER FLOW
TRACING METHOD
The algorithm used for tracing the run of electricity will be at the present derived in two ways. a). The downstream-looking algorithm which looks at the nodal sense of balance of outflows. b). the upstream-looking algorithm will look at the nodal sense of balance of inflows.
. Note that the same is equal to the sum of the load demand, and outflows in lines leaving node i. A line outflow in line i-l from node i can be therefore calculated, using the proportional sharing principle, as
(6)
The upstream-looking algorithm applied to the gross flows determines how the power output from each of the generators would be spread between the loads. The downstream –looking algorithm applied to the net flows determines how the demand of each of the loads would be distributed between individual generators if the transmission losses were removed from line flow [2]. l
(7)
Where
= for all
Similarly, the load demand can be calculated from
as a
) The Upstream-Looking Algorithm
The total flow P i during node I (i.e. the amount of inflows or outflows) may possibly be expressed, when looking at the inflows, as
2 ………n (8)
For i =1,
= for i=1, 2… …..n (1)
This equation shows that the contribution of the k th
generator to the i th
load demand is equal to and can be used to trace where the power of a particular load comes from . Where is the set of nodes supplying directly node i (i.e. power must flow towards node I in the relevant lines), is the line flow into node i in line j-i, and
P
Gi is the generation at node i. As the losses have been eliminated, .
The line flow, can be related to the nodal flow at node j by substituting, , where , to give
(2)
This, on rearrangement, becomes
Or (3)
IV.
CASE STUDY AND RESULTS
It is a loss less system getting from loss allocation method. That is the simplest way of obtaining lossless flows from the lossy ones is by assuming to a line flow is an normal over the transfer and getting end flows and by adding up half of the line loss to the energy flows at every terminal node of that line.
judgment the upstream matrix with three conditions given by equation2 and inverting it then using the this matrix( ) the formulas given in equation 4 and 6 used to find the generator contribution factor, after getting contribution by using equation4 for finding power flow from each bus. And the below tabular form shows the each line flows in network and contribution factors for each line.
Where is the (n x n) upstream distribution matrix, P is the vector of nodal through – flows and is the vector of nodal generations. The (i, j) element of is equal to
CASE STUDY1: STANDARD IEEE5 BUS
SYSTEM
IEEE 5 bus system is considered as test case1 which has 2 generators, 7 transmission lines and 4 loads as shown in figure
(4)
Note that is sparse and non symmetrical. If exists then and its i th
element is
= for i =1, 2 ….n (5)
This equation shows that the contribution of the k th
system generator to i th nodal power is equal to
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International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 4 - September 2015
Lines connecte d between busses
Actual power flows(M
W)
1-2
1-3
2-3
2-4
2-5
3-4
4-5
88.245
40.145
24.525
.
27.725
54.28
18.86
6.315
Contributio n of generator
G1(MW)
Contributio n of generator
G2(MW)
Contribution factor(D)
88.236
40.145
16.86
19.071
37.34
16.62
4.82
0
G1
0.6801
G2
0 0
0
7.648
0.313 0
0.13 0.1912
0
8.644 0.147
16.928 0.2878
2.228 0.1281
1.472 0.0372
0.2161
0.4232
0.0557
0.0368
= =0.6801
Actual power flow in the line by corresponding generator is determined by using equation6
| = 129.74
= 88.236 MW
Similarly all line flows and contribution factors are calculated
And given in table below
TESTCASE2: IEEE30 BUS SYSTEM
IEEE 30 bus system is taken as test case3 which has 6 generators 41 transmission lines and 20 loads are shown in figure. After taking the power flow of 5 bus system the line flows and percentage of line loadings are obtained and tabulated in table.
Fig.2
IEEE Five Bus Test System
By using equation4, upstream matrix is calculated as
[
1
0.6801
0
1
0
0
0.3094
0.1912
0 0.2161
1
0.2916
0 0.4232
0
0
0
0
1
0.1355 1
0
0
0
0
]=
And invert the above matrix,
[ ]
1 0 0 0 0
0.6801
1
0.4394
0.1912
0
1
0
0
0
0
0.3724
0.03275
0.22
1 0
0.3137
0.458
0.0349
0.1355 1
=
Distribution factors for IEEE 5 bus system is calculated by using below formula,
Fig.3 IEEE 30-Buses Test System
After finding this matrix( ) .the formulas given in equation 4 and 6 used to find the generator contribution factor, after getting contribution factor calculate power flow at each bus. And the below tabular form shows the each line flows in transmission network and contribution factors for each line. The contribution factors at each line are tabulated below.
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International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 4 - September 2015
37
38
39
34
35
36
40
41
31
32
33
28
29
30
23
24
25
26
27
18
19
20
21
22
8
9
10
5
6
7
1
2
3
4
14
15
16
17
11
12
13
Line no
From bus
TO
BUS
G1 G2 G3 G4 G5 G6
27
27
29
25
27
27
28
28
24
23
25
22
22
23
18
20
10
10
21
12
12
15
16
15
5
6
6
2
2
4
1
1
2
3
9
12
13
12
6
6
9
29
30
30
26
25
28
8
6
22
24
24
10
21
15
19
19
20
17
10
15
16
14
17
18
7
7
8
5
6
6
2
3
4
4
10
4
12
14
9
10
11
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0.0264
0.0431
0.02499
0
0
0
0
0
0
0.3840
0.6159
0.0835
0.5073
0.0741
0.1095
0.4308
0.0731
0.1117
0.3190
0.0705
0.0403
0
0.0706
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0.00392
0.0109
0
0
0
0
0.00248
0.0014
0
0.0025
0
0
0
0.1312
0.2722
0.2198
0.2293
0.2614
0.1371
0.2198
0.019
0
0
0
0
0
0.1416
0
0
0
0
0
0
0
0
0.1711
0.8232
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0.2542
0.2491
0.01382 0.00782
0
0.2282
0.1495
0.1291
0 0 0.1469 0.08316
0.0618 0.00251 0.00516 0.00219
0.1007 0.00408 0.00835 0.00213
0.0584 0.00236 0.00484 0.00123
0.0881 0.00224 0.00732 0
0
0
0
0
0
0
0
0
0.0142
0.0683
0.4481
0.0831
0.3736
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0.0263
0
0.00556
0.01548
0
0
0
0
0.0035
0.002
0
0.0035
0.03691
1
0.1532
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0.0217
0.0354
0.0205
0
0
0
0
0
0
0
0
0.2175
0
0.1931
0.2853
0.1586
0.1903
0.09181
0.2555
0.0579
0.0331
0
0.058
0
0
0
V.CONCLUSSION:
Bialek’s upstream looking algorithm is works based on proportional sharing principle and kirchoff’s current law. It is used for calculating contribution factors. These contribution factors are used for allocation of charges for each generator to each load .
By test case1 and testcase2 we finding contribution factors for IEEE 5 bus, IEEE 30 bus system and the contribution factors are also used for selection of generators for rescheduling of generators in congestion management.
REFERENCES
[1]. J. Bialek, “ Tracing The Flow Of Electricity ” IEEE proc. Gener.
Transm. Distrib. Vol. 143. no.4. jul 1996, pp.313-320.
[2]. Aswini Kumar, S.C Srivasta, And S.N Singh. “ A Zonal
Congestion Management Using Ac Transmission Congestion
Distribution Factors”. Electric power system reserch, 72(1): 85-93,
November 2004.
[3]. Janusz Bialek university of Durham, England. “Loss allocation
Of Transmission Supplementary Charge To Real And Reactive
Loads”. IEEE transactions on power systems, volume/1, issue/1,
2012.
[4]. Daniel kirsten and Goran Strbac “Tracing Active And Reactive
Power Between Generators And Loads Using Real And Imaginary
Currents” IEEE transactions on power systems, vol.14,
No.4,november 1999.
[5]. B.J. Kirby, J.W. Van Dyke and C.Martinez, A. Rodriguez,
“ Congestion Management Requirements,Methods and Performance
Indices”.
[6]. R.Rajathy and Harish kumar “Power Flow Tracing Based
Congestion Management Using Differential Evaluation In
Deregulated Electricity Market” international journal on electrical engineering and informatics – Volume 4,Number2,july 2012.
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