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Cuckoo Search Algorithm based Optimal Tuning of
Thyristor Controlled Series Capacitor to Enhance the
Line based Voltage Stability
B. VenkateswaraRao1, G. V. NageshKumar2, B. Sravana Kumar3
and K. Appala Naidu2
1V R Sidharatha Engineering College, Vijayawada, India 2Vignan’s Institute of Information Technology, Visakhapatnam, India
3GITAM University, Visakhapatnam, India
Corresponding author mail ID : gundavarapu_kumar@yahoo.com
Abstract. Voltage stability is the capability of the power system to preserve the
system under stable condition even exposed to small disturbances under normal
or slightly over loaded conditions. Maintaining voltage stability is the one of
the major factor for power system networks. In this paper new line established
voltage stability index entitled fast voltage stability index (FVSI) is proposed
for optimal placement of Thyristor Controlled Series Capacitor (TCSC).
Optimal tuning of TCSC is obtained using Cuckoo Search Algorithm (CSA) to
improve the voltage stability of the power system established on minimization
of the total voltage deviation of the system. The CSA is coded in MATLAB and
the performance is tested on Institute of Electrical and Electronics Engineers
(IEEE) 30 bus test system with voltage deviation minimization as objective
function. TCSC is a series connected device in the Flexible Alternating Current
Transmission System (FACTS) family. It has capable of controlling the power
flow through the line and also improve the line based voltage stability. In this
paper TCSC is merged in CSA based Power Flow to optimize the total voltage
deviation. Results attained by CSA are related to that attained by Genetic
Algorithm (GA) in both without and with TCSC conditions. These results show
that CSA produce better results compared to GA for solving optimal tuning of
TCSC.
Keywords: FACTS device; Cuckoo Search algorithm; optimal tuning; TCSC.
1 Introduction
Voltage instability and collapse have been measured as major hazards to the current
power system networks due to their heavily loaded operation. Due to increasing
usages of inductive loads, losses in the transmission system enhanced and voltage
profile values deviated from prescribed value which also causes to increase the cost of
the real power generation [1]. So for avoiding these problems proper reactive Power
compensation should be done in transmission systems. Reactive power compensation
in transmission systems recovers the stability of the ac system which is achieved by
proper utilization of lines with installing Flexible AC Transmission System (FACTS)
Advanced Science and Technology Letters Vol.147 (SMART DSC-2017), pp.104-109
http://dx.doi.org/10.14257/astl.2017.147.16
ISSN: 2287-1233 ASTL Copyright © 2017 SERSC
devices. Out of the FACTS devices TCSC is one of the best series devices to enhance
the power transferable abilities and stability of the line [2].
In literature, this problem has been revealed in several ways. For example, M.
Saravanan et al. pragmatic the Particle Swam Optimization (PSO) algorithm for
finding size & locality of FACTS devices considering the system load ability [3]. In
KhaiPhuc Nguyen et al [4] apply the cuckoo search algorithm for optimal location of
Static VAR Compensator (SVC) to improve the performance of the power system.
The optimal solution given by Adaptive Differential Evolution algorithm is enhanced
than other evolutionary algorithm methods is explained by K.R.Vadivelu et.al [5].
Another research of optimal power flow using cuckoo search algorithm for
improvement of voltage stability has been explained by M. A. Elhameed [6]. And the
problem of real power generation reallocation is also explained using out dated
optimization methods such as interior point, linear programming, nonlinear
programming [7] & quadratic programming. Disadvantages in these methods are the
struggle to attain the global minimum owing to many local minimums that happen in
these problems. Heuristic optimization outfits have been inspected such as
evolutionary & genetic algorithm, particle swarm optimization, ant colony
optimization, firefly algorithm; gravitational search algorithm & bat search algorithm
[8-11] are used to solve this problem. In this paper Cuckoo searchis scrutinized &
pragmatic to IEEE 30 bus system for voltage deviation optimization and optimal
sizing of TCSC parameters. Results obtained are compared with genetic algorithm,
Cuckoo search gave better results.
This paper use FVSI for insertion the TCSC at a suitable location. Once the place
for installing TCSC is resolute, its optimal fine-tuning is attained using cuckoo search
Algorithm. It is instigated on single objective function in order to acquire the Optimal
Power Flow. The objective function consists of, total voltage magnitude deviations.
Results are figured for cuckoo search Algorithm based Optimal Power Flow without
& with TCSC using MATLAB. Results achieved using the cuckoo search Algorithm
is then compared with Genetic Algorithm (GA).
2 Cuckoo Search Algorithm
Yang & Deb established a population-based optimization algorithm, well-known on
the brood parasitism of selected cuckoo species in nature & named as a Cuckoo
search algorithm. This method pretends the actions of the female Cuckoo bird to lay
her egg into the neighbour’s nest. This method deliberates the probability that the host
bird finds out & abandons the Cuckoo egg. A recent study says that Cuckoo search
algorithm gives better results as compared to other Meta heuristics methods. The
pseudo code of the cuckoo search algorithm is existing in [12].
A random set of solution is generated using
1* ( )
t t
i iLevy yx x
(1)
Equation 1 is the stochastic equation of a random walk, its next step be influenced
by on current location &the evolution probability. α is the step size, the product
Advanced Science and Technology Letters Vol.147 (SMART DSC-2017)
Copyright © 2017 SERSC 105
means entry sensible multiplications. Levny flight offers a random walk &random
step length is pinched from Levy distribution:
)3<λ<1(,t≠Levy λ_
(2)
It is recurring until the maximum number of periods is touched. Initial set of nests
vary from 15 to 40 but n is 20& Pa is 0.25 are suitable values for maximum
optimization complications.
3 Results and Analysis
In order to demonstrate the performance of the Cuckoo Search Algorithm in Optimal
Power Flow with TCSC, IEEE 30 bus system is considered. An OPF program using
Cuckoo Search algorithm for minimization of total voltage deviation is written using
MATLAB without the TCSC, which was further extended with the TCSC. A
MATLAB program is coded for the test system and the results are presented and
analysed. The results obtained with Cuckoo Search Algorithm were compared with
Genetic Algorithm (GA).The input parameters of Cuckoo Search Algorithm for the
test systems are given in Table 1.
Table 1. Input parameters of Cuckoo Search Algorithm
S.No Parameters Quantity
1 Number of nests 20
2 Number of iterations 100
3 Discovery rate of alien eggs/solutions 0.25
In IEEE 30 bus system bus no 1 is taken as a slack bus & bus numbers 2, 5, 8, 11
and 13 are taken as generator buses, continuing are the load buses. This system has 41
interrelated lines. MATLABsoftware is used for simulation & the results are
obtainable and evaluated. The FVSI values for the IEEE 30 bus system without TCSC
are shown in Table 2.
Table 2. Total FVSI value for 30 bus system without TCSC
Severity Rank Line number FVSI value
1 13 0.334
2 5 0.1875
3 6 0.1868
4 15 0.1436
5 2 0.1364
6 14 0.1316
7 36 0.1231
8 3 0.1168
9 12 0.1056
10 9 0.0612
Advanced Science and Technology Letters Vol.147 (SMART DSC-2017)
106 Copyright © 2017 SERSC
From Table 2, it can be seen that the total FVSI value is maximum for line number
13. So in this study TCSC is placed at line number 13 to improve the line based
voltage stability. Table 3 indicates the size/ tuning of the TCSC device.
Table 3. Comparison of total FVSI value and total voltage deviation for 30 bus system without
TCSC and with TCSC placed at line number 13.
Power Flow
Solution
Total FVSI
value for all
lines in p.u
Total Voltage
deviation for
buses in p.u
Size of the
TCSC in p.u
GA-OPF
Without TCSC 2.9823 1.4532 ----
With TCSC 2.086 0.6254 0.2864
CSA-OPF Without TCSC 2.3804 1.3081 ----
With TCSC 1.8275 0.4837 0.2123
From Table 3 it is observed that Cuckoo search algorithm based optimization gives
that, the size of the TCSC is 0.2123 p.u. and placing this TCSC in 13th line Total
FVSI value for all lines is reduced to 1.8275 p.u. from 2.3804 p.u. in without TCSC
condition. It indicates that line based stability has been improved. The size of the
TCSC in Cuckoo search algorithm based optimization is 0.2123 p.u. which is less
when compared to Genetic algorithm based optimization. From this table it has been
observed that Cuckoo search algorithm is superior to Genetic algorithm because of its
global optimization.
Figure 1 shows the convergence characteristics of the voltage deviation using
cuckoo search algorithm without and with TCSC.From Figure 1 it has been observed
that the objective function value that is total voltage deviation is optimized with
1.3081p.u, and it takes nearly 80 iterations to converge.
Fig. 1. Convergence characteristics of voltage deviation with CSA-OPF without TCSC
Figure 2is the convergence characteristics of the voltage deviation using cuckoo
search algorithm with TCSC. From Figure 2 it is observed that after incorporating
TCSC in cuckoo search algorithm reduce the number of iteration to 60 to converge
and the objective function value has been optimized to 0.4837p.u.
Advanced Science and Technology Letters Vol.147 (SMART DSC-2017)
Copyright © 2017 SERSC 107
4 Conclusion
In this paper, fast voltage stability index has been proposed for placement of TCSC
and cuckoo search algorithm has been applied to find the optimal tuning of the TCSC
based on minimization of the total voltage deviation. The results achieved with
cuckoo search algorithm are compared with genetic algorithm. The CSA is totally
overriding and successful for formative optimal tuning of the TCSC device. Affording
to case studies, the Cuckoo search continuously gives the improved solution with the
advanced performance. The results attained for the IEEE 30 bus system, using the
employed method without & with TCSC are compared and interpretations disclose
that the total voltage deviation and fast voltage stability index values are enhanced
with TCSC. The acquired results are helpful, and show that TCSC is the greatest
active devices that can meaningfully improve the stability of power system.
References
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Advanced Science and Technology Letters Vol.147 (SMART DSC-2017)
Copyright © 2017 SERSC 109
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