International Journal of Scientific & Engineering Research, Volume 4, Issue 11, November-2013 275

ISSN 2229-5518

Enhancement of Active, Reactive power flow

in the Deregulated Powersystem using TCSC

N.SAMBASIVARAO

Associate Professor and Head NRI institute of Technology,agiripalli nsraohodeee@gm ail.com

Dr.J.Amarnath Professor,Department of EEE, JNTU,Hyderabad amarnathjinka@Yahoo.com

Dr.V.Purnachandrarao

Professor,Department of EEE,

DVR & Dr.HS MIC college of Technology

Abstract— In a power systems,power flows from generating center’s to the load centers.In this process many things require investigation,such as flow of Active power(MW ) and Reactive power(MVAR) in transmission lines for different loading conditions. This paper presents a new method to Enhance Active,Reactive Power in a deregulated Powersystem.In deregulated electricity market transmission overloading occurs when there is insufficient transmission capcity to simultaneously accommodate all constraints for a transmission line.The Increased power demand has forced the power system to operate very closer to its stability limits.So Transmission Overloading,Voltage instability and power loss problems are arise in the power system. These are very serious problems which cause damage to the power system.The above mentioned problems are mitigated by incorporating Series Facts device in optimal location by Sensitivity analysis.The Simulation results were successfully tested on modified IEEE 14 bus system using MATLAB-SIMULINK .

Index Terms— Deregulated powersystem, Thyristor Controlled Series Capacitor (TCSC), Enhancement , Overloading, Total VAR Powerloss, Active ,Reactive power flow.

——————————  ——————————

1 INTRODUCTION

In the recent year with the deregulation of the electricity market the traditional concepts and practice of the power sys- tem are changed.As power systems are becoming more com- plex it requires careful design of the new devices for the oper- ation of controlling the power flow in transmission sys- tem,which should be flexible enough to adapt to any momen- tary system conditions.The operation of an ac power transmis- sion line,is generally constrained by limitations of one or more network parameters and operating variables by using FACTS technology such as Thyristor Controlled Series Capacitor (TCSC) Active, Reactive power flow in the power system can be regulated.
Because of the Economic considerations, Instalation of facts Controllers in all the buses or lines is impossible and Unnecessary.There are Several methods for finding the opti- mal location of FACTS devices in a power system.In [1],sencitivity approach is used to find the optimal location for placement of TCSC[6].The reduction of total system reactive Power loss method is one used to find optimal loation for placement of series FACTS device. Power flow index is used to find optimal location of FACTS device mitigation of over- loading.The method firstly put all the busses in the orderby voltage reactive power sensitivity then choose the optimal location and appropriate capability of Thyristor controlled
series capacitor (TCSC).
The issue of transmission overloading is more pronounced in
deregulated and competitive markets and needs a special treatment.In this environment, independent system opera- tor(ISO) has to relieve the overloading,so that the system is maintained in secure state. To Enhance power flow ISO can
use mainly two types of techniques which are as follows: A. Cost free means : using sreies FACTS devices
B. Re-dispatching the generation amounts
Among the above two methods cost free means do have
advantage such as not touching economical matters, So
GENCO and DISCO will not involved. FACTS devic-
es,especially series FACTS devices like TCSC are considered
one such technology that reduced the transmission overload-
ing,powerloss (active,reactive) and allows better utilization of existing grid infrastructure,along with many benfits.

2. Thyristor Controlled Series Capacitor(TCSC)

The basic Thyristor –Controlled Series Capacitor scheme, proposed in 1986 by Vithayathil is shown in figure 1. It con- sists of the series compensating capacitor shunted by a Thy- ristor-controlled Reactor. In a practical TCSC implementation, Several such basic compensators may be connected in series to obtain the desired voltage rating and operating characteristics.

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N.Sambasiva Rao received M. Tech in Electrical Power Engineering and

B.Tech degree in Electrical & Electronics Engineering from JNTU Hydera- bad, India.. He is perusing his Ph.D from JNTU, Hyderabad, India.

International Journal of Scientific & Engineering Research, Volume 4, Issue 11, November-2013 276

ISSN 2229-5518

index is method based on the sensitivity of total system active and reactive power loss with respect to control variable of the FACT device.

Fig 1. Equivalent circuit of TCSC

The power loss sensitivity index with respect to this control variable can be formulated as

aij

= ∂QL

∂X

Loss sensitivity with respect to TCSC

∂Q R 2 − X 2

L = [v2

+ v 2

− 2v v

cos(δ − δ

( 2

2 )2

∂X ij

i j i j

n n  

i j

Rij + X ij

  

Q = ∑

∑ 

 P P

+ Q Q

+ ∈

 Q P

− P Q



L i = 1 j = 1

ij  i j

i j 

ij  j i

j i 

2.1 Transmission line modeling with TCSC

The series impedance of a high voltage transmission line is usually inductive,with only 5 to 10 percentage of resitance

Where a , β , γ and ∈ are loss coefficients computed from the elements of the bus impedance matrix and the bus voltage defined as :

This provides convenient condtion to control the steady state impedance of transmission line by adding both a Thyrister Controlled Series Capacitor(TCSC) and a Thyristor Controlled

a ij

= ViV j

cos(δ i −δ j )

c c c c

Series Reactor

βij

γ ij

sin (δ i −δ j )

Pij Q P ji Q Pic Q P jc Q

Determined from [7] Method.
A General equivalent circuit of TCSC injected in transmis- sion line is shown in fig2.

γ ij =

ViV j

X ij

ViV j

cos(δ i −δ j )

Fig 2. Injection Model of TCSC

∈ij =

X ij

ViV j

cos(δ i −δ j )

3. DEVICE PLACEMENT USING LOSS SENSITIVITY

INDEX METHOD

The objective of the device placement may be reduction in the real power loss of a particular line,reduction in the total sys- tem real power loss,reduction in the total reactive power loss and reduction in the overloading of the system.Loss sensitivity

4. Criteria for Optimal placement for TCSC

The FACTS device should be placed on the most sensitivity bus or line. For the TCSC the location is the line with most positive sesetivity index. The TCSC should be placed on the line having most positive loss sensitivity index.

5.1 Simulation results for modified IEEE 14-bus system. Test results are optained by considering practical IEEE 14 – bus system.OPF soluction is obtained on the system to deter- mine the optimum genatation schedule than satisfied the ob- jective of minimizing the losses from the desire transations and controling of voltage magnitude. Here the sensitive index for TCSC has been calculated for the placement of FACTS de- vice. The FACTS device placement method known as sensi- tivity index has been tested on IEEE 14- bus system.

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With out TCSC

14-bus system has 5 generators and eleven load buses.

Figure3. Shows the single line diagram of IEEE 14-bus

System

5.1 Simulation results on IEEE 14-bus system without

TCSC

Test results are obtained by considering practical IEEE 14-bus system.Real and Reactive Power at each bus shown following graphs for without TCSC.

5.1.1Graphs for without incorporation of TCSC

Figure4.Matlab simulink model for IEEE 14-bus line model

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Above results repragents Real and Reactive power at various
Buses.

Table:1 shows Real and Reactive power magnitudes for without FACTS controller [TCSC] .

Power flow profile of the system for each each bus is present- ed below.

Table:1Real and Reactive Power at each Bus

With out TCSC

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Table:2 Sensitivity index values

From table:2, the line 1-5 has the most positive sensitivity fact or. So this is the best location for placement of Thyristor Con- trolled Switched Capacitor [TCSC] to relieve congestion in the network.By placing the TCSC in the line 1-5, the congestion in the network is relieved.

5.2 TCSC modeling Using Simulink

Figure:5 TCSC model

The complte system has been repragented in terms of Sim- ulink blocks in a single integral model.

5.2 Simulation results on IEEE 14-bus system with TCSC

In this section IEEE 14 –buspractcal system has been presented to numerically demonstrate its performance.It has been used
to show quantitatively, how the TSCS performs.The original network is modified to include the TCSC.This compensates
the line between any of the buses.The TCSC is used to regulate the Active and Reactive power flowing in the line at a prespec- ified value.The MATLAB-SIMULINK model is used to find control settings of TCSC for the prespecified Real and Reactive power flow between any buses and the power flow between the lines are observed the effects of TCSC. The FACTS device placement method known as sensitivity index has been tested on IEEE 14- bus system. After incorparating TCSC the Active and Reactive Power flow can be improved which is shown in Table:3

Figure:6 shows Matlab simulink model for modified IEEE-14 bus line model by incorporating TCSC in the line.

Table:3Real and Reactive Power at each Bus With TCSC

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5.2.1Graphs for witht incorporation of TCSC

JSER ©

http://www.ijser.org

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Above results repragents Real and Reactive power at various
Buses.

Chart1:comprision of Real power flows(MW)

with and without TCSC

Chart2:comprision of Reactive power flows(MW)

with and without TCSC

6 Conclusions:

The contribution of TCSC towards the improvement of Power flow(Active and Reactive) been tested on IEEE 14 bus sys- tem.The FACTS device (TCSC) located at optimal locations is observed to have a better voltage profile and power loss. FACTS devices such as TCSC by controlling the power flow in the network can help to reduce flows in overloaded lines. Be- cause of the considerable costs of FACTS devices, It is im- portant to obtain optimal location for placement of these de- vices. The results presented in this paper show that sensitivity index along with TCSC. So, it can cocluded that after the in- corparation of TCSC the power flow between the lines can be improved.

ACKNOWLEDGEMENTS

We, the authors are very grateful to the Chairman of NRI group of InstitutionsDr. R. Venkat Rao and Principal of NRI Institute of Technology Dr. C. Naga Bhaskar. Without their assistantship the work could not be completed.

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Author Biography

N.Sambasiva Rao received the B.Tech degree in Electrical & Electronics Engi- neering and M. Tech in Electrical Power Engineer- ing from JNTU Hyderabad, India. He has 12 years experience in teaching. He is perusing his Ph.D from JNTU, Hyderabad, India. He published a 8 research papers in various International Journals and

2 research papers in National Conferences. He is the Member of International Association of Engineers (IAENG) and Life member of ISTE.

He is currently working as Associate Professor and Head of the department in Electrical & Electronics Engineering at NRI Institute of Technology, Agiripalli, India. He got “Best Achiever award of Andhra Pradesh “By NCERT, New Del- hi, India. His Areas of interest include Electrical Machines, control Systems and power System Protection