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269
rule. It was developed by ProfessorBernard Widrow and his graduate student Ted Hoff at
Stanford University in 1960. It is based on the McCulloch–Pitts neuron. It consists of a
weight, a bias and a summation function.The difference between Adaline and the standard
(McCulloch-Pitts) perceptron is that in the learning phase the weights are adjusted
according to the weighted sum of the inputs (the net). In the standard perceptron, the net is
passed to the activation (transfer) function and the function's output is used for adjusting
the weights. The main functional difference with the perceptron training rule is the way the
output of the system is used in the learning rule. The perceptron learning rule uses the
output of the threshold function (either -1 or +1) for learning. The delta-rule uses the net
output without further mapping into output values -1 or +1. The ADALINE network shown
below has one layer of S neurons connected to R inputs through a matrix of weights W.
This network is sometimes called a MADALINE for Many ADALINEs. Note that the figure
on the right defines an S-length output vector a.
The Widrow-Hoff rule can only train single-layer linear networks. This is not much of a
disadvantage, however, as single-layer linear networks are just as capable as multilayer
linear networks. For every multilayer linear network, there is an equivalent single-layer
linear network.
5.1 Single ADALINE
Consider a single ADALINE with two inputs. The following figure shows the diagram for
this network. The weight matrix W in this case has only one row. The network output is:

(
)
(


Input vectors in the upper right gray area lead to an output greater than 0. Input vectors in
the lower left white area lead to an output less than 0. Thus, the ADALINE can be used to
classify objects into two categories.
However, ADALINE can classify objects in this way only when the objects are linearly
separable. Thus, ADALINE has the same limitation as the perceptron.
5.2 Networks with linear activation functions: the delta rule
For a single layer network with an output unit with a linear activation function the output is
simply given by:

1
n
ii
i
ywx
θ
=
=
+
∑
(41)
Such a simple network is able to represent a linear relationship between the value of the
output unit and the value of the input units. By thresholding the output value, a classifier
can be constructed (such as Widrow's Adaline), but here we focus on the linear relationship
and use the network for a function approximation task. In high dimensional input spaces
the network represents a (hyper) plane and it will be clear that also multiple output units
may be defined. Suppose we want to train the network such that a hyper plane is fitted as
well as possible to a set of training samples consisting of input values
p
d

Where the index p ranges over the set of input patterns and
p
E
represents the error on
pattern
p
. The LMS procedure finds the values of all the weights that minimize the error
function by a method called gradient descent. The idea is to make a change in the weight
proportional to the negative of the derivative of the error as measured on the current pattern
with respect to each weight:
A Novel Frequency Tracking Method Based
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271

p
pj
j
E
w
w
γ
∂
Δ=−
∂
(43)
where γ is a constant of proportionality. The derivative is

p
pp

∂
is as follows:

(
)
p
pp
j
E
dE
w
∂
=− −
∂
(46)
Where
ppp
dE
δ
=−
is the difference between the target output and the actual output for
pattern
p
.The delta rule modifies weight appropriately for target and actual outputs of
either polarity and for both continuous and binary input and output units. These
characteristics have opened up a wealth of new applications.
6. Simulation results
Simulation examples include the following three categories. Numerical simulations are
represented in Section 5.1. for two cases, simulation in PSCAD/EMTDC software is
presented in Section 5.2. Lastly, Section 5.3. presents practical measurement of a real fault

⎪
=≤≤
⎨
⎪
⎪
=
⎪
⎩
(47)
After disturbance at 0.3 sec, signals are:

(-10t)
A
(-10t)
V =400sin( t)+40sin(3 t)+400
2
800sin( t- )+60sin(3 t)+800 0.3 t 0.6
3
2
800sin( t+ )+20sin(3 t)
3
xx
Bx x
Cx x
e
Ve
V
ωω
π
ωω

equivalent to two and half cycles, which is fed to all algorithms is magnified in Fig. 6. It can
be seen that CADALINE converges to the real value after first 116 samples, less than three
power cycles, with error of -0.4 %; and reaches a perfect estimation after having more few
samples. Other methods’ estimations are too fare from real value in this snapshoot. DFT,
ADALINE and Kalman respectively need 120, 200 and 360 samples to reach less than one
percent error in estimating the frequency drift. It should be considered that for 2.4-kHz
sampling frequency and power system frequency of 60 Hz, each power cycle includes 40
samples. The complex normalized rotating state vector
1
()
s
An kT with respect to time and in
d-q frame is shown in Fig. 7. It has been seen that for 1-Hz frequency deviation (
1
1f = Hz),
CADALINE has the best convergence response in terms of speed and over/under shoot.
ADALINE method convergence speed is half that in the CADALINE and shows a really
high overshoot. Besides, Kalman approach shows the biggest error. in the first 7 power
system cycles, it converges to 61.7 Hz instead of 61 Hz and its computational burden is
considerably higher than other methods. In this case, presence of a long-lasting decaying DC
offset affects the DFT performance. Consequently, its convergence speed and overshoot are
not as improved as CADALINE. Fig. 4. Tracked frequency (Hz)
A Novel Frequency Tracking Method Based
on Complex Adaptive Linear Neural Network State Vector in Power Systems

273


220sin( t+ )
3
Ax
Bx
Cx
V
V
V
ω
π
ω
π
ω
⎧
⎪
=
⎪
⎪
=
⎨
⎪
⎪
=
⎪
⎩
(49)
where
2
xx
f

f
CADALINE KALMAN ADALINE DFT
70 95 360 202 111
69 97 421 188 114
68 93 358 186 118
67 90 384 187 114
66 95 385 178 114
65 97 305 138 139
64 92 361 211 114
63 93 328 193 116
62 98 430 206 115
61 96 360 231 116
60 92 385 220 112
59 83 234 155 97
58 81 281 181 116
57 88 313 197 117
56 98 216 178 123
55 97 377 192 117
54 96 336 206 122
53 90 331 195 114
52 96 290 190 108
51 96 374 184 120
50 105 405 113 112
Table I Samples needed to estimate with 1 percent error for 50-70 frequency range
The complex normalized rotating state vector (
1
()
s
An kT ) is shown in Fig. 12. The best
transient response and accuracy belongs to ADALINE and CADALINE, but CADALINE

In this case, a practical example is represented. Voltage signal measurements are applied
from the Marvdasht power station in Fars province, Iran. The recorder’s sampling frequency
(
s
f
) is 6.39 kHz and fundamental frequency of power system is 50 Hz. A fault between
pahse-C and groung occurred on 4 March 2006. The fault location was 46.557 km from
Arsanjan substation. Main information on the Marvdasht 230/66 kV station and other
substation supplied by this station is given in Tables II and III, presented in Appendix II.
Fig. 13 shows the performance of CADALINE, ADALINE, Kaman and DFT approaches.
Besides, phase-C voltage and residual voltage are revealed in Fig. 14 (A) and Fig. 14 (B)
respectively. Complex normalized rotating state vector (
1
A
n
) is shown in Fig. 15. Fig. 13. Tracked frequency (Hz), case V.C. Fig. 14. (A): phase-C voltage and (B): residual voltage, case V.C.
A Novel Frequency Tracking Method Based
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279

Fig. 15. Complex normalized rotating state vector (
1
A

Artificial Neural Networks - Industrial and Control Engineering Applications

280
Load active power: 190 [MW]
Load nominal line-to-line voltage: 13.8 [kV]
8.2 Appendix. II
Main information on the Marvdasht 230/66 (kV) station and other substation supplied by
this station is given in Tables II and III.

1-PHASE SHORT
CIRCUIT
CAPACITY (MVA)
3-PHASE SHORT
CIRCUIT
CAPACITY (MVA)
FEEDER
NO. TAG
SUBSTATION
NAME
NO.
1184 1460
-
Marvdasht 230/66
(kV)
1
640 896 602 Marvdasht City 2
423 631 601 Mojtama 3
718 1005 607 Kenare 4
500 751 603 Sahl Abad 5
121 203 604 Dinarloo 6

4.334328 6.280871 8.79147 607 Kenare
4
5.800266 4.373866 6.569546 603 Sahl Abad
5
21.45813 1.058475 1.775789 604 Dinarloo
6
11.43307 2.073212 3.332886 608 Seydan
7
30.04138 0.734809 1.268421 605 Arsanjan
8
Table III Marvdasht substation three-phase and single-phase short circuit capacities and
impedances (
Z )
9. References
J.K. Wu, Frequency tracking techniques of power systems including higher order harmonics
devices, Proceedings of the Fifth IEEE International Caracas Conference, vol. 1, (3–5
Nov. 2004), pp. 298–303.
M. Akke, Frequency estimation by demodulation of two complex signals, IEEE Trans. Power
Del., vol. 12, no. 1, (Jan. 1997), pp. 157–163.
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P.J. Moore, R.D. Carranza and A.T. Johns, Model system tests on a new numeric method of
power system frequency measurement, IEEE Trans. Power Del., vol. 11, no. 2, (Apr.
1996), pp. 696–701.
M.M. Begovic, P.M. Djuric, S. Dunlap and A.G. Phadke, Frequency tracking in power
networks in the presence of harmonics, IEEE Trans. Power Del., vol. 8, no. 2, (April
1993), pp. 480–486.
C.T. Nguyen and K.A. Srinivasan, A new technique for rapid tracking of frequency

S.L. Lu, C.E. Lin and C.L. Huang, Power frequency harmonic measurement using integer
periodic extension method, Elect. Power Syst. Res., vol. 44, no. 2, (1998), pp. 107–
115.
P.J. Moore, R.D. Carranza and A.T. Johns, A new numeric technique for high speed
evaluation of power system frequency, IEE Gen. Trans. Dist. Proc., vol. 141, no. 5
(Sept. 1994), pp. 529–536.
J. Szafran and W. Rebizant, Power system frequency estimation, IEE Gen. Trans. Dist. Proc.,
vol. 145, no. 5, (Sep. 1998), pp. 578–582.
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A.A. Girgis and F.M. Ham, A new FFT-based digital frequency relay for load shedding,
IEEE Trans. Power App. Syst., vol. 101, no. 2, (Feb. 1982), pp. 433–439.
H.C. Lin and C. S. Lee, Enhanced FFT-based parameter algorithm for simultaneous multiple
harmonics analysis, IEE Gen. Trans. Dist. Proc., vol. 148, no. 3, (May 2001), pp. 209–
214.
W.T. Kuang and A.S. Morris, Using short-time Fourier transform and wavelet packet filter
banks for improved frequency measurement in a Doppler robot tracking system,
IEEE Trans. Instrum. Meas., vol. 51, no. 3, (June 2002), pp. 440–444.
V.L. Pham and K. P. Wong, Wavelet-transform-based algorithm for harmonic analysis of
power system waveforms, IEE Gen. Trans. Dist. Proc., vol. 146, no. 3, (May 1999),
pp. 249–254.
V.L. Pham and K.P. Wong, Antidistortion method for wavelet transform filter banks and
nonstationary power system waveform harmonic analysis, IEE Gen. Trans. Dist.
Proc., vol. 148, no. 2, (March 2001), pp. 117–122.
M. Wang and Y. Sun, A practical, precise method for frequency tracking and phasor
estimation, IEEE Trans. Power Del., vol. 19, no. 4, (Oct. 2004), pp. 1547–1552.
D.W.P. Thomas and M.S. Woolfson, Evaluation of a novel frequency tracking method,
Transmission and Distribution Conference, vol. 1, (11–16 April 1999), pp. 248–253.
M.I. Marei, E.F. El-Saadany and M.M.A. Salama, A processing unit for symmetrical

power system such as loss allocation. So, it can be expected that the developed methodology
will further contribute in improving the computation time of transmission usage allocation for
deregulated system.
2. Importance of deregulation
Deregulated power systems unbundles the generation, transmission, distribution and retail
activities, which are traditionally performed by vertically integrated utilities. Consequently
different pricing policies will exist between different companies. With the separate pricing of
generation, transmission and distribution, it is necessary to find the capacity usage of different
transaction happening at the same time so that a fair use-of-transmission-system charge can be
given to individual customer separately. Then the transparency in the operation of
deregulated power systems can be achieved. In addition, the capacity usage is another
application for transmission congestion management. For that reason the power produced by
each generator and consumed by each load through the network should be trace in order to
have acceptable solution in a fair deregulated power system. In Malaysian scenario the future
electricity sector will be highly motivated to be liberalized, i.e. deregulated. Thus the proposed
methodology is expected to contribute significantly to the development of the local
deregulated power system. Promising test results were obtained from the extensive case
studies conducted for several systems. These results shall bring about some differences from
those based on other methods as different view-points and approaches may end up with
different results. This chapter is offering the solution by an alternative method with better
computational time and acceptable accuracy. These findings bring a new perspective on the
Artificial Neural Networks - Industrial and Control Engineering Applications

284
subject of how to improve the conventional real power allocation methods. A technically
sound approach, to determine the real power output of individual generators, is proposed.
This method is based on current operating point computed by the usual laod flow code and
basic equations governing the load flow in the network. The proposed MNE method has also
been extended to reactive power allocation. The simulation results have also shown that of
reactive power supply and reception in a power system is in conformity with a given

Y: is the Y-bus admittance matrix
The nodal admittance matrix of the typical power system is large and sparse, therefore it can
be partitioned in a systematic way. Considering a system in which there are G generator
nodes that participate in selling power and remaining L= n-G nodes as loads, then it is
possible to re-write equation (1) into its matrix form as shown in equation (2): ⎡
⎤⎡ ⎤⎡ ⎤
=
⎢
⎥⎢ ⎥⎢ ⎥
⎣
⎦⎣ ⎦⎣ ⎦
GGGGLG
L
LG LL L
IYYV
IYYV
(2)
Solving for I
G
and I
L
using equation (2), the relationship can be obtained as shown in
equations (3) and (4).
Application of ANN to Real and Reactive Power Allocation Scheme

285


L
of all loads can be expressed as shown in equation (7):

∗
=
L
LL
SVI (7)
where (
∗ ) stands for conjugate,
Substituting equation (6) into equation (7) and solving for
S
L
the relationship as shown in
equation (8) can be found;

() ( )
(
)
*
**
11

−−
=+−
L L LG GG G L LL LG GG GL L
SVYY IVY YYY V
()
(
)

1

−∗∗
=
=Δ
∑
Gi
nG
I
LG GG G
L
i
YY I I
nG : number of generators
Now, in order to decompose the load voltage dependent term further in equation (8), into
components of generator dependent terms, the equation (10) derivations are used. A
possible way to deduce load node voltages as a function of generator bus voltages is to
apply superposition theorem. However, it requires replacing all load bus current injections
into equivalent admittances in the circuit. Using a readily available load flow results, the
equivalent shunt admittance
Y
Lj
of load node j can be calculated using the equation (9):

1
Lj
Lj
Lj Lj
S
Y

1
=
=Δ
∑
Gi
nG
I
L
L
i
VV (11)
It is now, simple mathematical manipulation to obtain required relationship as a function of
generators dependent terms. By substituting equation (11) into equation (8), the
decomposed load real and reactive powers can be expressed as depicted in equation (12):

()
(
)
*
**
1
11

−
==
=Δ+Δ −
∑∑
Gi Gi
nG nG
II

ji
I
L
S
Δ
: current dependent term of generator i to S
Lj

L
V
L
j
i
S
Δ
: voltage dependent term of generator i to S
Lj
All procedures of the computation mentioned above can be demonstrated as a flowchart
illustrated in Figure 1. Vector
S
Lj
is used as a target in the training process of the proposed
ANN.
3. Test conducted on the practical 25-bus equivalent power system of south
Malaysia region
3.1 Application of ANN to real and reactive power allocation method
This section presents test conducted on the practical 25-bus equivalent power system of
south Malaysia region. An ANN can be defined as a data processing system consisting of a
large number of simple, highly interconnected processing elements (artificial neurons) in an
architecture inspired by the structure of the cerebral cortex of the brain (Tsoukalas & Uhrig,

load bus with equation (9)
Obtain the load bus voltages contributed by
all generators with equation (11)

Fig. 1. Flow chart of the proposed real and reactive power allocation method
3.1.1 Structure of the proposed neural network in real and reactive power allocation
method
In this work, 3 fully connected feedforward neural networks under MATLAB platform are
utilized to obtain both real as well as reactive power transfer allocation results for the
practical 25-bus equivalent power system of south Malaysia region as shown in Figure 2.
This system consists of 12 generators located at buses 14 to 25 respectively. They deliver
power to 5 loads, through 37 lines located at buses 1, 2, 4, 5, and 6 respectively. All
discussions on designing of each of these ANN below are for this 25-bus equivalent system.
Each network corresponds to four numbers of generators in the test system and each
consists of two hidden layers and a single output layer. This means that in the first network
is associated with four numbers of generator located at buses 14 to 17. This realization is
adopted for simplicity and to reduce the training time of the neural networks.
Artificial Neural Networks - Industrial and Control Engineering Applications

288
1
2
3
4
5
6
7
8
9
10

2
, Q
4
to Q
6
) for real and reactive power transfer allocation respectively, bus voltage
magnitude (V
1
to V
13
) for both real as well as reactive power, real power (P
line1
to P
line37
) or
reactive power (Q
line1
to Q
line37
) for line flows of real and reactive power transfer allocation
respectively, and the target/output parameter (T) which is real or reactive power transfer
between generators and loads placed at buses 1, 2, 4 to 6. This is considered as 20 outputs for
both real as well as reactive power transfer allocation. Hence the networks have twenty
output neurons. For the neural network 1, the first five neurons represent the contribution
from generator 14 to the loads and the remaining outputs neurons correspond to the other
three generators located at buses 15 to 17 respectively. Tables 1 and 2 summarize the
description of inputs and outputs of the training data for each ANN for real and reactive
power allocation respectively.

Input and Output (layer) Neurons Description (in p.u)

I
6
to I
18
13 Bus voltage magnitude
I
19
to I
55
37 Reactive power for line flows
O
1
to O
20
20 Reactive power transfer between generators and loads
Table 2. Description of inputs and outputs of the training data for each ANN for reactive
power
3.1.2 Training
Neural networks are sensitive to the number of neurons in their hidden layer. Too few
neurons in the hidden layer prevent it from correctly mapping inputs to outputs, while too
many may impede generalization and increasing training time. Therefore number of hidden
neurons is selected through experimentation to find the optimum number of neurons for a
predefined minimum of mean square error in each training process. To take into account the
nonlinear characteristic of input (D) and noting that the target values are either positive or
negative, the suitable transfer function to be used in the hidden layer is a tan-sigmoid
function. Non linear activation functions allow the network to learn nonlinear relationships
between input and output vectors. Levenberg-Marquardt algorithm has been used for
training the network. After the input and target for training data is created, next step is to
divide the data (D and T) up into training, validation and test subsets. In this case 100
samples (60%) of data are used for the training and 34 samples (20%) of each data for

-9
. Note that the mean square error is not much different for both real as well as
reactive power transfer allocation. This indicates that the developed ANN can allocate both
real as well as reactive power transfer between generators and loads with almost similar
accuracy.
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290
0 2 4 6 8 10 12
10
-9
10
-8
10
-7
10
-6
10
-5
10
-4
10
-3
10
-2
10
-1
10
0
10

characteristics with the training set, and it doesn’t appear that any significant overfitting has
occurred. The same network setting parameters is used for training the other 2 networks.
3.1.3 Pre-testing and simulation
After the networks have been trained, next step is to simulate the network. The entire
sample data is used in pre testing. After simulation, the obtained result from the trained
network is evaluated with a linear regression analysis. In real power allocation scheme, the
regression analysis for the trained network that referred to contribution of generator at bus
15 to load at bus 1 is shown in Figure 5.
Application of ANN to Real and Reactive Power Allocation Scheme

291
-0.02 -0.015 -0.01 -0.005
-0.018
-0.016
-0.014
-0.012
-0.01
-0.008
-0.006
-0.004
Target
Output
R = 1
Sample Data Points
Best Linear Fit
Output = Target

Fig. 5. Regression analysis between the network output and
the corresponding target for
real power allocation

Figures 9 to 12.
Artificial Neural Networks - Industrial and Control Engineering Applications

292
20 40 60 80 100 120 140 160
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
Hour
Load Real Power (p.u)
Bus 1
Bus 2
Bus 4
Bus 5
Bus 6

Fig. 7. Real power allocation method daily load curves for different buses
20 40 60 80 100 120 140 160
0
0.2
0.4
0.6

Fig. 9. Selected target patterns of generator at bus 14 of real power allocation scheme within
168 hours
Application of ANN to Real and Reactive Power Allocation Scheme

293
20 40 60 80 100 120 140 160
0
0.05
0.1
0.15
0.2
0.25
Hour
Contributions of generator 22 to loads (p.u)
Bus 1
Bus 2
Bus 4
Bus 5
Bus 6

Fig. 10. Selected target patterns of generator at bus 22 of real power allocation scheme
within 168 hours
20 40 60 80 100 120 140 160
0
0.05
0.1
0.15
0.2
0.25
Hour