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.

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Advanced Science and Technology Letters Vol.147 (SMART DSC-2017)

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