A New Method for Optimal Placement of TCSC using ABC ...

Journal of Research in Science, Technology, Engineering and Management (JoRSTEM) ISSN: 2456-0197

© Malla Reddy Engineering College (Autonomous) 73

A New Method for Optimal Placement of TCSC using

ABC Algorithm in Power Systems

Mohammad Rafee Shaik1, Dr. A. Srinivasula Reddy

2

1Asst. Professor, Department of Electrical Engineering, College of Engineering Technology,

Jijiga University, Jijiga, Somali Regional State, Ethiopia

2Principal & Professor, CMR Engineering College, Hyderabad, Telangana State, India.

Abstract— In power systems because of uncertainty of the load curve and transfer of power between

various utilities and loads create block out situations. In these situations the Flexible AC transmission

system (FACTS) controllers play an important role in power system security enhancement. As the capit al

cost of these controllers is high, these controllers must be placed optimally. FACTS devices can regulate

the active and reactive power control as well as adaptive to voltage-magnitude control simultaneously

because of their flexibility and fast control characteristics. Placement of these devices at optimal location

can lead to control in line flow and maintain bus voltages at required level and so improve the voltage

profile, to improve load transfer capability, decreasing the losses in the system and o perate the system

within stable regions. This paper proposes a systematic method for finding optimal location of TCSC to

improve voltage profile of a power system with Artificial Bee Colony (ABC) Algorithm. An OPF

with/without TCSC using ABC algorithm is considered for healthy conditions in simulation and

compared with existing literature. Effectiveness of the proposed method is demonstrated on IEEE 30 -bus

test system.

Keywords— ABC algorithm, FACTS devices, Optimization, TCSC, IEEE 30 bus, Voltage profile

I. INTRO DUCTION

In recent years power demand has increased substantially while the expansion of power generation and

transmission has been limited due to limited resources and environmental restrictions. As a consequence some transmission lines are heavily loaded and system stability becomes a power transfer limiting factor. Flexib le AC

transmission system (FACTS) controllers are mainly used for solving various power system steady state control problems. However recent studies reveal that FACTS controllers could be employed to enhance power system

stability in addition to their main function of power flow control. It is known that the power flow through an AC

transmission line is a function of line impedance, the magnitude and the phase angle between the sending and the receiving end voltages. By proper coordination of FACTS devices in the power system network, both the active and

reactive power flow in the lines can be controlled. FACTS devices improves power transmission capacity, voltage profile, enhancing power system stability [5].FACTS devices include static var compensator (SVC), thyristor

controlled series compensator (TCSC), unified power flow controller (UPFC) etc. Like other FACTS devices, SVC is an expensive device; therefore it is important to find the optimal location and its size in a power system, so that

voltage profile may be improved effectively. In [10], optimal placement of TCSC based on reactive power spot price is discussed.In [14], a method optimal p lacement of TCSC for static and dynamic voltage security enhancement has

been developed. This paper focuses on the placement of TCSC for improving the voltage profile and reducing the

real power losses. TCSC is a series FACTS device which is designed to maintain the voltage profile in a power system conditions. In practical power systems, all buses have different sensitivity to the power system stability,

some buses are more and some are less.

II. TCSC MO DELLING

The model of a transmission line with a TCSC connected between the buses i and j. The change in the lin e flows due to series reactance. The real power injection at buses i and bus j (Pi (com)) and Pj(com)can be expressed as

2

iP ( ) [ cos( ) sin( )]i ij i j ij ij ijcom V G VV G B ijΔ Δ δ Δ δ

(1)



2jj ij i j ij ij ij ijP (com) =V G -VV [ G cos ( )- B sin ( )]

(2)

Similarly, the reactance power injected at bus i and j (Qi (com)) can be expressed as 2

i i ij i j ij ij ij ijQ (com) = -V B -VV [ G sin ( )- B cos ( )] (3)

2

j i ij i j ij ij ij ijQ (com) = -V B -VV [ G sin ( )- B cos ( )] (4)

Where,

csc csc

ij 2 2 2 2

csc

( 2 )G

( )( ( ) )

t ij t ij

ij ij ij ij t

X R X X

R X R X X

(5)

2 2

csc csc

ij 2 2 2 2

csc

( )B

( )( ( ) )

t ij ij t ij

ij ij ij ij t

X R X X X

R X R X X

(6)

III. PROBLEM FO RMULATION

The generation cost function for the real power (P) output of the generators is given as a second order polynomial

function as shown below

CP = α 2P2 + α1P + α 0 [US$/h] (7)

Where P is the output in MW and α0, α1 and α2 are cost coefficients. And the cost function of the reactive power

(Q) output of the generators is given by:

CQ = β 1 Q + β0[US$/h] (8)

As far as the cost of TCSC devices is concerned, only typical cost functions associated with the total investment and

infrastructure costs are considered. Cost function of TCSC is based on the Siemens AG Database which is shown

below.

(9)

The objective function (OF) considered here minimizes the generation cost while taking into consideration the cost

of FACTS devices, i.e.

(10)

CP , CQ and CFACTS are the costs of active and reactive power productions and the cost of allocated FACTS devices,

respectively. The indices n and m are the number of the generators and allocated FACTS devices, respectively.

A. ABC algorithm based optimization method

The TCSC is injected to all lines in 30 bus system and for each line we find power flow and cost of

generation.

The GA algorithm based optimization procedure is then applied to optimally allocate available FACTS

devices. There are two variables per device to be determined, the location and the rating.

A penalty factor is set to prevent the placement of two series connected devices in the same branch. The

penalty factor increases the cost of placing the second device at the same location and discards such

solution from further consideration

IV. ARTIFICIAL BEE COLONY ALGORITHM

In a real bee colony, some tasks are performed by specialized indiv iduals. These specialized bees try to maximize

the nectar amount stored in the hive using efficient self-organization. The Artificial Bee Colony (ABC) algorithm,

proposed by Karaboga [18] in 2005 fo r real-parameter optimization, is a recently introduced optimization algorithm

which simulates the foraging behavior of a bee colony .The minimal model of swarm-intelligent forage selection in

a honey bee colony which the ABC algorithm simulates consists of three kinds of bees: employed bees, onlooker

bees and scout bees. Half of the colony consists of employed bees, and the other half includes onlooker bees.

Employed bees are responsible for exploit ing the nectar sources explored before and giving informat ion to the

wait ing bees (onlooker bees) in the hive about the quality of the food source sites which they are exp loit ing.

Onlooker bees wait in the hive and decide on a food source to explo it based on the information shared by the

employed bees. Scouts either randomly search the environment in order to find a new food source depending on an

internal mot ivation or based on possible external clues .All these units and interactions between them are shown as a

flowchart in Figure 1.

http://www.sciencedirect.com/science/article/pii/S0020025510003336#f0005



Fig..1. Flow chart of Artificial Bee Colony Algorithm

V. RES ULT AND DISCUSS ION

ABC based algorithm for optimal power flow was applied between all the buses in IEEE 30 bus system. This

system comprises of one slack bus, 5 PV buses, 24 PQ buses and 41 lines as shown in fig. 2. After running the

algorithm up to 5 iteration at each bus and then the average generation cost was calculated for each bus. The optimal

location of the device was chosen based on the minimum generation cost i.e. between bus number 10 -21. It is found

that one TCSCs is required to achieve objective of optimization.

After installing TCSC between bus number 10 & 21 in IEEE 30 bus system, the bus voltage (V), act ive power (P),

reactive power (Q) and Bus voltage angle (δ) without TCSC and with TCSC are shown in Table 1 & 2 respectively.

It is observed from Table 1 & 2 that after installing TCSC, the overall voltage profile have been improved

throughout the system. Power transfer capability also has been improved between all the buses. In the following

tables the improvement of voltage profile has shown in table 1 without TCSC and in table 2 with TCSC. Here Table

3 shows cost of generation, savings, Power loss percentage without TCSC and with TCSC. Fig. 3 shows cost of



generation with TCSC graphs with GA. From tables 1 & 2 it is clear that TCSC placing optimally successfully

increased the voltage profile of the system.

Fig.2. IEEE 30 bus system

Table 1: Bus Data without TCSC

Bus no Active Power

(P)

Reactive Power

(Q)

Voltage Magnitude

(|V|)

Angle

(δ)

1 0.8912 1.1541 1.06 0

2 0.5682 -0.6222 1.045 -2.7224

3 -0.0226 -0.0673 1.0253 -2.5936

4 0.0417 -0.6832 1.0167 -4.3402

5 -0.5622 0.1093 1.01 -12.0198

6 0.0312 -0.1785 1.0134 -7.0137

7 -0.1222 -0.1134 1.0042 -10.2313

8 -0.3992 0.3445 1.01 -7.5761

9 -0.0344 -0.1654 1.0532 -11.2273

10 -0.2311 -0.1213 1.0479 -11.2503

11 0.1722 0.2314 1.082 -14.3235

12 -0.3123 -0.2254 1.06 -8.7249

13 0.1298 0.7272 1.071 -7.5378

14 -0.0011 -0.1001 1.0452 -10.5670

15 -0.0195 -0.0742 1.0405 -11.6460

16 0.0294 -0.1006 1.0472 -6.7433

17 0.0100 -0.1432 1.0427 -9.6044

18 0.0085 -0.0711 1.031 -7.7066

19 -0.0301 -0.0849 1.0285 -7.3543

20 -0.0154 -0.0110 1.0326 -7.8190

21 -0.5927 0.5225 1.0355 -14.3763

22 -0.3618 0.7839 1.036 -14.6590

23 -0.5426 0.4076 1.0299 -16.411

24 -0.5686 0.4886 1.0241 -16.6927

25 -0.1115 0.2188 0.9998 -13.1398

26 -0.2156 0.1753 1.0016 -16.6592

27 -0.0056 -0.0504 1.0248 -7.6956

28 0.0530 -0.0577 1.0093 -7.1758

29 0.3041 -0.1448 1.005 -2.8020

30 0.2529 -0.2902 0.9883 -2.4819



Table 2: Bus Data with TCSC

Table 3: Cost of generation using TCSC

Without TCSC With TCSC

Location of TCSC Between buses 10 - 21

Cost of generation ( US $/ hr ) 831.4644 800.9543

Savings in US $/ hr 30.5101

% Ploss 7.34 7.04

Bus no Active Power

(P)

Reactive Power

(Q)

Voltage Magnitude

(|V|)

Angle

(δ)

1 0.9199 1.3674 1.06 0 2 0.5897 -0.6686 1.049 -2.7371

3 -0.0364 -0.0731 1.0267 -4.7133 4 -0.0492 -0.0858 1.0178 -5.6464

5 -0.0578 -0.1785 1.01 -6.4955

6 0.0325 -0.1232 1.0145 -6.4971 7 -0.1535 0.3887 1.0053 -8.0472

8 -0.0593 -0.1949 1.01 -8.5118 9 -0.0086 -0.1668 1.0548 -6.0639

10 -0.3281 0.4491 1.0487 -8.3018 11 0.1747 -0.3347 1.092 -6.0951

12 -0.3716 0.7178 1.062 -9.2411 13 0.1622 -0.1005 1.079 -8.0140

14 -0.0014 -0.0892 1.0465 -10.5737 15 -0.0200 -0.1100 1.0423 -10.5611

16 0.0304 -0.1852 1.0482 -10.9620 17 0.0111 -0.0721 1.0439 -10.8988

18 0.0095 -0.0849 1.042 -11.3504 19 -0.0301 -0.0113 1.029 -10.5818

20 -0.0174 -0.0919 1.0336 -6.9296

21 0.0651 -0.0667 1.036 -11.9044 22 -0.0422 0.0592 1.036 -10.8560

23 -0.0520 -0.0028 1.0349 -10.9620 24 -0.0457 0.0145 1.0251 -10.8988

25 -0.0158 -0.0501 1.0102 -11.3504 26 0.0142 -0.1123 1.0016 -10.1214

27 -0.0067 -0.0374 1.0248 -10.5818 28 0.0354 0.0368 1.0093 -6.9296

29 -0.0367 -0.0367 1.005 -11.9044 30 -0.0982 -0.0982 0.9898 -12.8560



Fig. 3 Cost of generation graphs with TCSC (ABC) to with TCSC (GA)

VI. CONCLUSION

This paper presents a new approach which can be used to optimally locate the least TCSCs as power flow

controllers along system branches in an attempt to enhance both voltage profile and security margin of the system.

IEEE 30-bus test system has been used to evaluate the performance of the proposed approach. Optimally placing

TCSC with optimal cost has been improved the voltage profile and also decreased the cost of generation of power.

This method also decreased the total power losses.

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Cost of generation Comparison with TCSC(ABC) to with TCSC(GA)

Cost of generation without TCSC

Cost of generation with TCSC (ABC)

Cost of generation with TCSC (GA)

http://as.wiley.com/WileyCDA/Section/id-301664.html



[17] Shraddha Udgir, Sarika Varshney and Laxmi Srivastava, “Optimal Placement and Sizing of SVC for Improving Voltage Profile of Power System,” International Journal of Power System Operation and Energy Management , ISSN:2231-4407, Vol. 1, Issue-2, 2011.

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[19] D. Karaboga, “An idea based on honey bee swarm for numerical optimizat ion,technical report -tr06”, Erciyes University, Engineering Faculty, Computer Engineering Department , 2005.

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