Chapter 3 Optimal Location of Series FACTS Device …shodhganga.inflibnet.ac.in/bitstream/10603/76655/7...Adaptive controller strategies for FACTS controllers in a power system to

Adaptive controller strategies for FACTS controllers in a power system to enhance stability

PET Research centre, PESCE , Mandya 72

Chapter 3

Optimal Location of Series FACTS Device using Loss

Sensitivity Indices

3.1 Introduction

The location and sizing of series FACTS devices constitute a major step in the

application of FACTS devices. This chapter presents the development of methodologies

based on loss sensitivity indices for determining the optimal location of series FACTS

device. Both active and reactive power line losses have been considered in this

development of sensitivity indices. The efficacy of these methods have been tested on

5,9,14 ,30 bus IEEE and 14 Bus part of Indian power network.

3.2 Development of Loss Sensitivity Indices

FACTS sizing and allocation constitutes a milestone problem in power system. In

this regard, various methods of location of FACTS controllers have given below.

Generally, location of FACTS devices in the power system have obtained based

on static and / or dynamic performances. There are several methods for finding optimal

location of FACTS devices in vertically integrated system as well as unbundled power

system. The objective of the series device placement may be reduction in the real power

loss of a particular line, reduction in the total system real power loss, reduction in the

total system reactive power loss and maximum power transfer in the system. Sensitivity

analysis is a widely used terminology to describe the analysis based on the evaluation of

the rate of change of one group of variables in a system with respect to another group.

There are many different ways to perform the analysis depending on the selected

variables and methodologies used to calculate the sensitivities. In this chapter the loss

sensitivity indices have been developed based on active & reactive power losses in each

line with respect to the control variable of the FACTS device of the power network.



Loss sensitivity index is a method based on the sensitivity of total system active

and reactive power loss with respect to control variable of the FACTS devices. In this

research, a method based on the sensitivity of the total system reactive power loss with

respect to the control variable of the TCSC has carried out. Consider TCSC to be placed

between the buses i and j, we consider net line series reactance as a control parameter.

Loss sensitivity indices with respect to real power is bij and with respect to reactive power

is aij. This control parameter of TCSC placed between buses i and j can be written as,

ij

Lij

X

Qa 3.1

ij

Lij

X

Pb 3.2

These factors can computed at a base load flow solution as given below. Consider a

line connected between buses i and j and having a net series impedance of Xij and Qi is

the net reactive power injected in the bus i. The bus sensitivity index with respect to Xij

computed as,

Real part

Pi= 3.3

Pi= 3.4

3.5

3.6

3.7

Imaginary part

3.8

3.9



3.10

3.11

3.12

3.13

3.14

Where PL=Pi+ Pj, i and j are the buses 1 & 2 (Figure 3.1b)

The criteria used in the selection of optimal placement of TCSC is δPL /δXij and δQL

/δXij should have a positive or a value nearer to the origin called sensitivity index.

3.2.1 Thyristor Controlled Series Capacitor (TCSC) Modeling

FACTS devices can be modeled as power injection model. The injection model

describes the FACTS devices as a device that injects a certain amount of active and

reactive power to a node, so that the FACTS device is represented as PQ elements. The

advantage of power injection model is that it does not destroy the symmetrical

characteristic of the admittance matrix and allows efficient and convenient integration of

FACTS devices into existing power system analytical tools.

During steady state operation, TCSC can be considered as an additional reactance

-jxc. The value of xcis adjusted according to control scheme specified. Figure 3.1(a)

shows a model of transmission line with one TCSC which is connected between bus-i and

bus-j. The line flow change is due to series capacitance which is represented as a line

without series capacitance with power injected at the receiving and sending ends of the

line as shown in Figure 3.1(b).

Fig. 3.1(a) TCSC model

Z = r + j xi j i j i j

Bus - jBus - i

jBs h

-jx c

iBs h



Z = r + j xi j i j i j

Bus - jS ic

S j c

Bus - i

Fig. 3.1(b) Injection model of TCSC

The real power injections at bus-i(Pic) and bus-j(pjc) are given by [55]:

Pic=V2i ∆Gij –ViVj[∆Gij cosδij + ∆Bij sinδij] 3.15

Pjc=V2j ∆Gij –ViVj[∆Gij cosδij - ∆Bij sinδij] 3.16

Similarly, the reactive power injections at bus-i (Qic) and bus- j (Qjc) can be expressed as:

Qic= – V2

i ∆Bij –ViVj[∆Gij sinδij - ∆Bij cosδij] 3.17

Qjc= –V2

j ∆Bij + ViVj[∆Gij sinδij + ∆Bij cosδij] 3.18

Where:

2

cij2ij

2ij

2ij

i jcijc

ijxxrxr

)2x(xrxΔG

2

cij2ij

2ij

2ij

ijc

2

ij2ij

xxrxr

xxxrcx

ijΔB

Where ∆Gij and∆Bij are the change in conductance and change in susceptance of the

line i-j.

This model of TCSC is used to properly modify the parameters of transmission

lines with TCSC for optimal location [100].

Static Series Synchronous Compensator (SSSC)

The Static Synchronous Series Compensator (SSSC) is a series connection

FACTS controller dependent on VSC and can be considered as advanced kind of

controlled series compensation, just as a STATCOM is an advanced SVC. A SSSC own

several merits over a TCSC such as

(a) elimination of bulky passive components (capacitors and reactors),



(b) improved technical characteristics,

(c) symmetric capability in both inductive and capacitive operating modes,

(d) the connection availability of an energy source on the DC port to exchange active

power with the AC grid.

A solid-state synchronous voltage source, consisting of a multi-pulse, voltage-

sourced inverter and a DC capacitor, is shown in series with the transmission line in

Figure 3.2.

Fig. 3.2 Schematic diagram for the SSSC.

In general, the active and reactive power exchange is controlled by the phase

displacement of the injected voltage related to the current. For example, when the

injected voltage is in phase with the line current, then only active power is exchanged,

and if it is in quadrature with the line current then only reactive power is exchanged.

The series-connected synchronous voltage source is an extremely powerful tool

for power flow control and, it is able to control both the transmission line impedance and

angle. Its capability to exchange active power with the grid makes it very effective in

enhancing dynamic stability by means of alternately inserting a virtual positive and



negative damping resistance in series with the line by the disturbed generators angular

deceleration and acceleration.

The idea of the solid-state synchronous voltage source for compensation of series

reactive depends on the rule that the characteristic of the impedance with the frequency of

the practically employed series capacitor, which is different than the filter techniques, has

no role in achieving the required line compensation. The goal of the series capacitor is

summarized to generate a suitable voltage at the fundamental AC network frequency in

series with the line to eliminate the voltage drop produced via the inductive impedance of

the line by the fundamental part of the line current. So that the resulting total voltage drop

of the compensated line becomes electrically equivalent to that of a shorter line.

Therefore, if an AC voltage supply with fundamental frequency, which has a quadrature

lagging following to the line current and the magnitude depends on the line current is

flowed in series with the line. A series compensation is equal to the one developed by a

series capacitor during the fundamental frequency is supplied.

The voltage source can be described in mathematical form as follows:

Vn = –jkXI

Vn is the compensating value of the injected voltage, I is the phasor of the line current,

X is the impedance of the series reactive line, and k is the series compensation degree. For

conventional series compensation, k is defined as XC /X, where XC is the impedance of the

series capacitor.

For regular capacitive compensation, the output voltage must lag the line current

by 90 degrees, in order to directly oppose the inductive voltage drop of the line

impedance.

However, the output voltage of the inverter will be opposed by a proper control

method to direct it to be leading the line current with 90 degrees. Then, the inserted

voltage is in phase with the voltage developed by the inductive reactance of line.

Therefore, the series compensation owns the equivalent effect as if the reactive

impedance was raised. This capability can be invested to increase the effectiveness of

power oscillation damping and, with sufficient inverter rating; it can be used for fault



current limitation. Series compensation by a synchronous voltage source that can be

limited to the fundamental frequency is worthy to that provided with series capacitive

compensation in that it cannot produce undesired electrical resonances with the

transmission grid, and for this reason, it cannot cause sub-synchronous resonance.

However, by appropriate control it can damp sub-synchronous oscillations, which may

happen because of present series capacitive compensations by inserting non-fundamental

voltage components with proper magnitudes, phase angles and frequencies, in addition to

the fundamental component, in series with the line.

Due to the stipulated 90-degree phase relationship between the inverter output

voltage and the line current, this, via the series insertion transformer, flows through the

inverter as the load current, the inverter in the solid-state voltage source theoretically

exchanges only reactive power with the AC system. As explained previously, the inverter

can internally generate all the reactive power exchanged and thus can be operated from a

relatively small.

In practice, however, the semiconductor switches of the inverter are not loss-less,

and so the energy saved in the DC capacitor would be balanced through the inverter

internal losses. The typical deviation from 90 degrees is a fraction of a degree. In this

way, the inverter draws a small value of active power from the AC network to balance

the internal losses and save the DC capacitor voltage at the required level. That control

procedure can also be applied to raise or reduce the DC capacitor voltage by making the

inverter voltage lag the line current by an angle smaller or greater than 90 degrees.

Thereby, control the magnitude of the AC output voltage of the inverter and the degree of

series compensation.

3.3 Simulation using MATLAB/SIMULINK

3.3.1 Introduction

The objective of this is to bring about the basic tools needed to use

the SIMULINK package SIMULINK is an extension to MATLAB which uses a icon-driven

interface for the construction of a block diagram representation of a process. A block diagram is

simply a graphical representation of a process (which is composed of an input, the system, and an

output).



Fig.3.3 A very simple block diagram of a process

Typically, the MATLAB m-file ode45 is used to solve sets of linear and nonlinear

ordinary differential equations. One of the reasons why MATLAB is relatively easy to use is that

the `èquation solvers'' are supplied for us, and we access these through a command line interface

(CLI). However, SIMULINK uses a graphical user interface (GUI) for solving process

simulations. Instead of writing MATLAB code, we simply connect the necessary `ìcons''

together to construct the block diagram. The `ìcons'' represent possible inputs to the system, parts

of the systems, or outputs of the system. SIMULINK allows the user to easily simulate systems of

linear and nonlinear ordinary differential equations. A good background in matrix algebra and

lumped parameter systems as well as an understanding of MATLAB is required, and we highly

recommend that the student thoroughly reads and works through this tutorial. Many of the

features of SIMULINK are user-friendly due to the icon-driven interface, yet it is important to

spend some time experimenting with SIMULINK and its many features. Dynamic simulation

packages (such as MATLAB, SIMULINK, etc.) are being used more and more frequently in the

chemical process industries for process simulation and control system design. After completing

this tutorial, the student should be able to ``build'' and simulate block diagram representations of

dynamic systems.

3.3.2 Getting Started in Simulink

Simulink is an icon-driven state of the art dynamic simulation package that allows

the user to specify a block diagram representation of a dynamic process. Assorted

sections of the block diagram are represented by icons which are available via various

"windows" that the user opens (through double clicking on the icon). The block diagram

is composed of icons representing different sections of the process (inputs, state-space

models, transfer functions, outputs, etc.) and connections between the icons (which are

made by "drawing" a line connecting the icons). Once the block diagram is "built", one

has to specify the parameters in the various blocks, for example the gain of a transfer

function. Once these parameters are specified, then the user has to set the integration



method (of the dynamic equations), step size, start and end times of the integration, etc.

in the simulation menu of the block diagram window.

In order to use SIMULINK , one must ``start'' a MATLAB session

Once MATLAB has started up, type simulink (SMALL LETTERS!) at

the MATLAB prompt (>>) followed by a carriage return (press the return key).

A SIMULINK window should appear shortly, with the following icons: Sources, Sinks,

Discrete, Linear, Nonlinear, Connections, and Extras (this window is shown in Figure

4.2). Next, go to the file menu in this window and choose New in order to begin building

the block diagram representation of the system of interest.

Fig.3.4 Simulink block library window.

NOTE: The results are obtained using SIMULINK/MATLAB in the following section.

The results give the bus voltage ,power (P and Q) initiated at the dummy buses placed

near the actual bus. The power flow is calculated by considering the algebraic sum of the

powers at the buses the line is connected to.

3.4 Case studies: The efficacy of algorithms developed based on loss sensitivity

indices have been tested on IEEE 5 , 14, 30 as well as a part of a practical Indian power

network. In order to study the location of TCSC using loss sensitivity active power loss

method, the following systems are considered. The factor bij is calculated for each line

and the line sensitive to active power loss is highlighted. The TCSC is located in those

lines.

3.4.1 Case 1: IEEE 5 bus system

The 5 bus system considered is a IEEE bench mark system consisting of 5 buses,

7 lines , 3 generators. The system data is given in the APPENDIX. The single line

diagram is as shown in figure 3.5.



Fig.3.5 Single line diagram of IEEE 5 bus system

Fig.3.6 Simulink model of 5-Bus System

1

2 3 4

5

6

7

BUS 1 BUS 2

BUS 3 BUS 4

BUS 5



Table 3.1 Line power flow

Line No. Line Power P(MW)

L1 38.75

L2 38.45

L3 16.96

L4 35.58

LL2 47.28

L5 46.37

ll4 11.54

It is seen from the results that the location of FACTS device is in line connected

between nodes 2-5, Hence this is chosen as the proper location for locating TCSC.

Fig.3.7 Simulink model of 5-Bus System with TCSC

Table3.2. Line Losses

Line Nos P(MW)

From T0

1 2 0.3

1 3 0.23

2 3 0.058

3 4 0.13

2 4 0.15

2 5 0.91

4 5 0.11



Fig.3.8. Simulink phasor model of TCSC

Fig.3.9 Simulink internal phasor model of TCSC

Specification of TCSC

Frequency = 50 Hz

Manual alpha (deg) = 78

TCSC capacitance (F) = 21.977e-6

TCSC reactance (H) = 0,043

Average firing delay (s) = 4e-3



Simulink Results

Table3.3. Line active power flow with TCSC

Line No. Line Power P(MW)

L1 39.43

L2 36.16

L3 17.85

L4 33.97

LL2 44.66

L5 45.8

ll4 13.03

Summary of the Result

Comparison of Line Losses with & without TCSC for IEEE-5 bus system is

presented below,

Table3.5. Comparison of without and with TCSC

Line Losses b/w bus 2 and bus 5

WITHOUT TCSC WITH TCSC

0.91 MW 0.86 MW

Table3.4. Line Losses with TCSC

Losses b/w Bus P(MW)

From T0

1 2 0.27

1 3 0.21

2 3 0.053

3 4 0.12

2 4 0.14

2 5 0.86

4 5 0.11



Fig.3.10 Graphical Comparison of Line Losses of 5-Bus System Simulink Model

With and Without TCSC

Result analysis

It is seen from the results that the optimal location of FACTS devices based on

loss sensitivity indices based on active power is in line connected between nodes 2 and 5.

The TCSC is located in the line number 5 connected between buses 2 and 5, the line with

highest loss. The results after locating TCSC is tabulated in table no 3.6 and 3.7. As seen

from the above mentioned tables it is observed that the loss is 0.91 MW before placing

TCSC and it is 0.86 MW after placing the TCSC.

3.4.2 Case 2: IEEE 30-Bus System

In order to study effectiveness of the loss reduction method of locating TCSC a

higher order system is considered. A IEEE 30 bus system is considered. A 30 bus system

consists of 30 buses, 41 lines, 7 generators . and 20 loads. The detailed bus data , line

data, generator data is given in the APPENDIX. The single line diagram is as shown in

Fig 3.11. The SIMULINK model of 30 bus system is as shown in Fig 3.12 without

placing TCSC. Fig 3.12 gives the power flow analysis of this system.

In this proposed method the TCSC is located in branches which are considered to be

sensitive based on losses. That is the losses are calculated based on load flow analysis.

The branch having more loss is identified and the lines surrounding it in a concentric way

are considered and TCSC is located in each and every branch in this concentric and

losses are calculated again. The system considered for proving the credibility of the

method is IEEE 30 bus system.

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1 & 2 1 & 3 2 & 3 3 & 4 2 & 4 2 & 5 4 & 5

po

wer

(M

W)

without TCSC

with TCSC



29

27 28

2630

2423

15 1819

2017

14 16 21

22

13 1012

11 9

6 81

3 4

2 75

25

G6

G1

G2 G3

G4

G5T1T2

T3

T4

Fig 3.11 IEEE 30-bus single line diagram



Fig 3.12 Simulink model of 30-bus system



Simulink Result

Fig 3.13 Simulink output of 30-bus system

In order to find the line flows in each transmission line, there is necessity of

placing 2 additional dummy buses along with the existing buses in each transmission

line. This is done only to find the line flows from one bus to another. This will not change

the performance of the original power system. The new buses are numbered as L2 to L85.

Whereas the original buses are numbered as B1 to B30.



Output of IEEE 30 bus system without TCSC

Table 3.6 Line Losses Table 3.7Line Losses

LINE

INDICATOR

LINE FLOW P

(MW)

LINE

LOSSES

P (MW)

Lines Line Loss

P(MW) From To

L2 – L3 21.5 – 21.41 0.09 L2 L3 0.09

L4 – L5 18.29 – 18.08 0.21 L4 L5 0.21

L6 – L7 7.057 – 7.032 0.025 L6 L7 0.025

L8 – L9 21.79 – 21.48 0.31 L8 L9 0.31

L10 – L11 22.08 – 21.8 0.28 L10 L11 0.28

L12 – L13 0.723 – 0.7227 0.0003 L12 L13 0.0003

L14 – L15 20.23 – 20.02 0.21 L14 L15 0.21

L16 – L17 17.77 – 17.72 0.05 L16 L17 0.05

L18 – L19 16.08 – 16.04 0.04 L18 L19 0.04

L20 – L21 9.759 – 9.759 0 L20 L21 0

L22 – L23 7.499 – 7.499 0 L22 L23 0

L24 – L25 14.1 – 14.07 0.03 L24 L25 0.03

L26 – L27 6.889 – 6.878 0.011 L26 L27 0.011

L28 – L29 19.72 – 19.72 0 L28 L29 0

L30 – L31 0.868 – 0.8673 0.007 L30 L31 0.0007

L32 – L33 19.72 – 19.72 0 L32 L33 0

L34 – L35 3.375 – 3.367 0.008 L34 L35 0.008

L36 – L37 2.217 – 2.21 0.007 L36 L37 0.007

L38 – L39 8.796 – 8.709 0.087 L38 L39 0.087

L40 – L41 7.611 – 7.586 0.025 L40 L41 0.025

L42 – L43 9.958 – 9.958 0 L42 L43 0

L44 – L45 1.218 – 1.207 0.011 L44 L45 0.011

L46 – L47 10.32 – 10.22 0.1 L46 L47 0.1

L48 – L49 3.579 – 3.554 0.025 L48 L49 0.025

L50 – L51 3.232 – 3.232 0 L50 L51 0

L52 – L53 10.34 – 10.3 0.04 L52 L53 0.04

L54 – L55 3.298 – 3.252 0.046 L54 L55 0.046

L56 – L57 4.278 – 4.251 0.027 L56 L57 0.027

L58 – L59 1.897 – 1.879 0.018 L58 L59 0.018

L60 – L61 0.4163 –0.4132 0.0031 L60 L61 0.0031

L62 – L63 1.772 – 1.46 0.312 L62 L63 0.312

L64 –L65 6.788 – 6.769 0.019 L64 L65 0.019

L66 – L67 3.324 – 3.322 0.002 L66 L67 0.002

L68 – L69 5.532 – 5.467 0.065 L68 L69 0.065

L70 – L71 0.9183 – 0.9103 0.008 L70 L71 0.008

L72 – L73 2.977 – 2.957 0.02 L72 L73 0.02

L74 – L75 2.976 – 2.939 0.037 L74 L75 0.037

L76 – L77 6 – 5.953 0.047 L76 L77 0.047

L78 – L79 6.01 – 6.01 0 L78 L79 0

L80 – L81 3.98e-3 – 7.79e-5 0.0039 L80 L81 0.0039

L82 – L83 5.79e-3 – 498.1e-6 0.00529 L82 L83 0.00529

L84 –L85 7.79e-5 – 498.1e-6 0.00042 L84 L85 0.00042



From the above table it is found that the losses are more in line number 31 between

buses 22 and 24. TCSC is placed in all the lines surrounding this line and after placing it

losses are calculated. It is found that the losses will be minimum when TCSC is placed in

line number 35 between buses 25 and 27. Output with TCSC.

IEEE 30-bus with TCSC

Fig 3.14 Simulink model of 30-bus system with TCSC



Results

Fig 3.15 Simulink output of 30-bus system with TCSC



Table 3.8 Line losses

Line Indicator Line Flow P (MW) Line Losses P (MW)

L2 – L3 19.85 – 19.77 0.08

L4 – L5 16.7 – 16.53 0.17

L6 – L7 6.825 – 6.802 0.023

L8 – L9 19.93 – 19.67 0.26

L10 – L11 20.64 – 20.4 0.24

L12 – L13 0.8254- 0.8246 0.0008

L14 – L15 18.57 – 18.4 0.17

L16 – L17 16.13 – 16.09 0.04

L18 – L19 14.84 – 14.81 0.03

L20 – L21 7.921 – 7.921 0

L22 – L23 6.302 – 6.302 0

L24 – L25 14.59 – 14.56 0.03

L26 – L27 4.843 – 4.838 0.005

L28 – L29 17.78 – 17.78 0

L30 – L31 1.605 – 1.604 0.001

L32 – L33 17.08 – 17.08 0

L34 – L35 0.3517 – 0.3515 0.0002

L36 – L37 0.2271 – 0.2269 0.0002

L38 – L39 9.055 – 8.965 0.09

L40 – L41 8.432 – 8.401 0.031

L42 – L43 9.161 – 9.161 0

L44 – L45 1.015 – 1.006 0.009

L46 – L47 8.376 – 8.315 0.061

L48 – L49 2.945 – 2.927 0.018

L50 – L51 2.917 – 2.917 0

L52 – L53 9.573 – 9.545 0.028

L54 – L55 2.692 – 2.661 0.031

L56 – L57 4.269 – 4.242 0.027

L58 – L59 0.7269 – 0.7237 0.0032

L60 – L61 0.2586 – 0.2569 0.0017

L62 – L63 1.398 – 1.352 0.046

L64 –L65 7.007 – 6.987 0.02

L66 – L67 0.3073 – 0.3072 0.0001

L68 – L69 0.5341 – 0.5325 0.0016

L70 – L71 3.631 – 3.612 0.019

L72 – L73 1.169– 3.142 0,023

L74 – L75 0.04388 – 0.04387 0.00001

L76 – L77 3.222 – 3.209 0.013

L78 – L79 3.233 – 3.233 0

L80 – L81 4.11e-3 – 8.05e-5 0.004

L82 – L83 5.99e-3 – 514.7e-6 0.0054

L84 –L85 8.05e-5 – 514.7e-6 0.00043



Comparison of Line losses of 30-bus system with & without TCSC

Fig.3.16 Comparison of Line losses of 30-bus system with & without TCSC

It can be found by placing TCSC between the busses 25 and 27 in line no.35 the

line losses is reduced from 0.047 MW to 0.013 MW, Hence loss is reduced by 2.61%

Fig 3.17 Variation of Line Losses for different Capacitance values

Capacitance 1=21.977µF

Capacitance 2=11.977µF

Capacitance 3=6977µF

0

0.5

1

1.5

2

2.5

3

Line Losses

Capacitance1

Capacitance 2

Capacitance 3

without TCSC

WithFACTS

device



3.4.3 Case 3: IEEE 30 Bus system with SSSC

Fig 3.18 Simulink model of 30-bus system with SSSC

Fig 3.19 Phasor model of SSSC



Simulink Result

Fig.3.20 Simulink output of 30-bus system with SSSC



Fig.3.21 Comparison of Line power in 30 bus system b/w TCSC and SSSC

- SSSC Power Flow -TCSC Power Flow

It can be found by placing TCSC and SSSC between the busses 25 and 27 in line

no.35 the Line power flow is enhanced from 236.474 MW to 404.513 MW, Hence power

transmission capability has increased by 41.541%.

SUMMARY

Table 3.9 Comparison of Power transmission capability

with and without FACTS device

LINE

NUMBER

POWER FLOW (MW)

WITHOUT

FACTS

WITH FACTS

WITH

TCSC

WITH

SSSC

13 3.26 13.27 13.16

23 1.475 2.39 10.28

24 3.114 4.955 22.22

25 4.686 7.526 33.31

29 2.596e-14 4..095e-12 0.01374

30 1.686e-13 6.402e-13 0.02856

0

10

20

30

40

50

60

BU

SES

bu

s2

bu

s4

bu

s6

bu

s8

bu

s10

bu

s12

bu

s14

bu

s16

bu

s18

bu

s20

bu

s22

bu

s24

bu

s26

bu

s28

bu

s30

Comparision of Linepower in 30 bus system between TCSC and SSSC

P(M

W)



1-------Bus Power (MW) without FACTS device

2-------Bus Power (MW) with TCSC

3-------Bus Power (MW) with SSSC

Fig 3.22 Comparison of Power transmission capability with and without FACTS

device

This section aims at locating the TCSC and SSSC and comparing the performance

of the two series FACTS devices. TCSC and SSSC is modeled using

MATLAB/SIMULINK and results obtained are encouraging. Power system is the most

complicated man made system. The problem associated with it also is very complicated.

The power system of today needs to be made more flexible in terms of its transmission

capability. The erection of new lines is cumbersome and is not economically feasible.

The alternate method would be to enhance the transmission capability of the existing

transmission lines. This can be achieved by using FACTS device.

As seen from the results of

I) Implementation of TCSC in a IEEE 30-bus system :

The loss reduction is around 2.61% which is considerable value

II) Implementation of SSSC in a IEEE 30-bus system :

The power transmission capability has increased by 41.541% which is

considerable value for an actual system.

3

2

1



3.4.4 Case 4: 14 Bus Actual System.

1 Basthipura 14 HN Pura

2 Thubinakere 3 KR pet 13 CR patna

4 Kushalnagar

5 Hootgally 6 Vajmangala 11 Tk.halli 12 Kanaka pura

9 Madhunalli

8 Ch Nagar 10 Kanlyampetta

7 Kadakola

89.75 KM

39.6 KM 58.2 KM 46.8 KM

76 KM

27.4 KM

19.7 KM 56.6 KM45 KM

102..9 KM44.8 KM 40 KM

33.7 KM

27.4 KM

P =

Q =

P =

Q =P =

Q =

P =

Q =

P =

Q =P =

Q =P =

Q =

P =

Q =

P =

Q =P =

Q =P =

Q =P =

Q =

Fig 3.23 Real 220KV Bastipura System.



Table 3.10 Abbreviations

Bus no. Bus Name Abbreviations

1 slack Bastipura

2 tbk Thubinakere

3 krp KR pet

4 ksh Kushalnagar

5 htg Hootagally

6 vaj Vajmangala

7 kad Kadkola

8 Ch CH nagar

9 Tnp Madhunalli

10 kzk Kanlyampetta

11 tkh TK Halli

12 Knk Kanakapura

13 Crp CH patna

14 G-pura HN pura

Fig 3.24 Simulink model of 14-bus actual system without TCSC



Fig 3.25 Simulink model of 14-bus actual system with TCSC



Simulink Result

Table 3.11 Transmission line losses

without TCSC

Table 3.12 Transmission line losses

With TCSC

Line losses Line losses

1-2 0 1-2 0.001

1-4 0 1-4 0

1-4 0 1-4 0

1-5 0 1-5 0

1-5 0 1-5 0

1-7 0.42 1-7 0.11

1-7 0.42 1-7 0.11

1-14 0 1-14 0

3-13 0 3-13 0

5-6 0.02 5-6 0.01

5-7 0.002 5-7 0.001

6-11 0.03 6-11 0.01

7-8 0.19 7-8 0.03

7-8 0.19 7-8 0.06

8-9 0.03 8-9 0.06

8-9 0.03 8-9 0.03

10-7 0.0001 10-7 0.0001

11-9 0.02 11-9 0.03

11-9 0.02 11-9 0.03

11-12 0.17 11-12 0.18

Total losses 1.5421 Total losses 0.6621

Result Analysis

Comparison of Line Losses with & without TCSC for 14-bus actual system

is presented below,

Table 3.13 Comparison of Line loss without and with TCSC

Line Losses b/w bus 6 and bus 11

WITHOUT TCSC WITH TCSC

0.03MW 0.01MW



x-axis -Lines Y-axis- losses

Fig 3.26Graphical Comparison of Line Losses of 14-Bus System Simulink Model

With and Without TCSC

It is observed that line flows are reduced in the maximum congested lines.

However, no significant effect is observed in the minimum congested line. The above

method if applied for all the lines, involves a lot of computation.

3.5 Location based on reactive power loss sensitivity method

3.5.1 Case 1: IEEE 9 bus system

Fig.3.27 Single line diagram of IEEE 9 bus system

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

1,1

4

3,1

3

5,6

6,1

1 1…

1,2

1,4

1,4

1,5

1,5

1,7

1,7

5,7

10,7

8,9

8,9

7,8

11,9

11,9

7,8

without TCSC

with TCSC



COMPONENTS OF IEEE 9 BUS SYSTEM

Generators-3 nos

Load-3 nos

Bus-9 nos

Transformer-3 nos

Table 3.14 Sensitivity Method performance index Bus

no

From

Bus

To

Bus

rij xij B/2 vi vj dij (rij)2 (xij)2 (vi)2 (vj)2 cos(dij) aij

1 1 4 0 0.0576 0.088 1.04 0.9742 -67.48 0 0.00331 1.0816 0.9491 -0.0642 -651.7847

2 4 5 0.017 0.092 0.079 0.9742 1.004 -72.825 0.0003 0.00846 0.9491 1.0080 -0.8428 -380.8859

3 5 6 0.039 0.17 0.153 1.004 1.0391 -80.024 0.0015 0.0289 1.0080 1.0797 -0.0865 -67.3366

4 3 6 0 0.0586 0.179 1.0428 1.0391 85.913 0 0.00343 1.0874 1.0797 -0.4625 -947.3615

5 6 7 0.0119 0.1008 0.0745 1.0397 1.0268 115.9542 0.0001 0.01016 1.0810 1.0543 -0.9597 -408.0726

6 7 8 0.0085 0.072 0.1045 1.0268 1.01872 102.6712 0.0001 0.00518 1.0543 1.0378 -0.5392 -605.3772

7 8 2 0 0.0625 0 1.01872 1.022 -61.7409 0 0.0039 1.0378 1.0445 0.4616 -276.8588

8 8 9 0.032 0.161 0 1.01872 0.97458 101.2048 0.0010 0.0259 1.0378 0.9498 0.7814 -15.3311

9 9 4 0.01 0.085 0 0.97458 0.9742 105.724 0.0001 0.0072 0.9498 0.9491 0.4624 -320.4880

Table 3.15 Before placement of TCSC

Bus no Voltage (v) Impedance (z) Real Power (p) Reactive Power (q)

1 1.04 j0.0576 -3.9488 1.6358

2 1.022 0.017+j0.092 0.9686 0.0865

3 1.0428 0.039+j0.17 0.0774 0.0660

4 0.9742 j0.0586 -0.4537 0.3811

5 1.004 0.0119+j0.1008 2.9841 0.1769

6 1.0391 0.0085+j0.072 1.3564 0.1089

Table 3.16 After placement of TCSC in line 3

Bus no Voltage (V) Impedance (Z) Real Power (P) Reactive Power (Q)

1 1.04 j0.0576 -3.8801 0.966

2 1 0.017+j0.092 1.0317 0.0293

3 1.108 0.039+j0.034 0.1628 0.0518

4 0.984 j0.0586 -0.5469 0.3581

5 1 0.0119+j0.1008 2.7671 0.7029

6 1.014 0.0085+j0.072 1.3958 0.0782

7 0.9967 j0.0625 -0.5191 0.0605

8 0.9979 0.032+j0.161 -0.1453 0.0474

9 0.9857 0.01+j0.085 -0.0001 -0.0009



Table 3.18 After placement of TCSC in line 8

Bus no Voltage (V) Impedance (Z) Real Power (P) Reactive Power(Q)

1 1.04 j0.0576 -4.1094 1.3650

2 1.07 0.017+j0.092 1.0749 0.0492

3 1.06 0.039+j0.17 0.2098 0.0107

4 0.9908 j0.0586 -0.5000 0.3220

5 1.0254 0.0119+j0.1008 3.0285 0.1313

6 1.059 0.0085+j0.072 1.4375 0.0563

7 1.06 j0.0625 -0.4702 0.0552

8 1.069 0.032+j0.0322 -0.3700 0.5538

9 1.0148 0.01+j0.085 -0.0002 0.0002

Table 3.17 After placement of TCSC in Line 7

Bus no Voltage (V) Impedance (Z) Real Power (P) Reactive Power(Q)

1 1.04 j0.0576 -3.8801 0.966

2 1 0.017+j0.092 1.0317 0.0293

3 1.108 0.039+j0.034 0.1628 0.0518

4 0.984 j0.0586 -0.5469 0.3581

5 1 0.0119+j0.1008 2.7671 0.7029

6 1.014 0.0085+j0.072 1.3958 0.0782

7 0.9967 j0.0625 -0.5191 0.0605

8 0.9979 0.032+j0.161 -0.1453 0.0474

9 0.9857 0.01+j0.085 -0.0001 -0.0009



3.5.2 Case 2: IEEE 14 bus System

Location of TCSC Found by the Loss Sensitivity reactive power indices

TABLE 3.19 Reactive Power Loss Sensitivity Index for each Line

Branch Line aij

1 1-2 -130.00

2 1-5 -71.69

3 2-3 -39.76

4 2-4 -36.68

5 2-5 -106.68

6 3-4 -87.94

7 4-5 -1195.74

8 4-7 -97.16

9 4-9 -5.30

10 5-6 -1.89

11 6-11 -3.01

12 6-12 -5.90

13 6-13 -24.24

14 7-8 5.83

15 7-9 -200.17

16 9-10 1.13

17 9-14 -10.03

18 10 -11 -0.03

19 12-13 -0.05

20 13-14 -2.69

The most positive lines are highlighted. It can be observed from the above table

that TCSC can be placed either in line 9-10 or 7-8 which are most sensitive lines.



Table 3.20 Result for Optimal Location of TCSC

Line Xold Xtcsc

added

Xeff=

Xold-

Xtcsc

Line losses Power in

MW Power in Mvar

MW Mvar

1-2 0.0592 0 0.0592 5.010 3.543 157.449 -66.751

1-5 0.2230 0 0.2230 2.732 0.583 74.491 -10.594

2-3 0.1980 0 0.1980 2.365 0.438 74.961 0.969

2-4 0.1763 0 0.1763 1.789 -1.855 57.153 10.074

2-5 0.1739 0 0.1739 0.812 -5.115 39.906 -0.661

3-4 0.1710 0 0.1710 0.516 -1.332 -21.578 17.186

4-5 0.0421 0 0.0421 0.469 1.480 -59.993 12.044

4-7 0.2019 0 0.2019 0 1.624 28.564 5.149

4-9 0.5562 0 0.5562 0 2.184 16.923 13.2

5-6 0.2520 0 0.2520 0 4..318 42.793 2.254

6-11 0.1989 0 0.1989 0.051 0.106 6.368 4.074

6-12 0.2558 0 0.2558 0.076 0.159 7.737 2.6

6-13 0.1303 0 0.1303 0.224 0.441 17.486 7.536

7-8 0.1762 0 0.1762 0 0.166 0 -10.028

7-9 0.7100 0 0.7100 0 1.030 28.555 13.55

9-10 0.0845 -0.031 0.0539 0.016 0.027 6.202 3.689

9-14 0.2704 0 0.2704 0.130 0.276 9..766 3.260

10-11 0.1921 0 0.1921 0.010 0.023 -2.807 -2.142

12-13 0.2209 0 0.2209 0.007 0.006 1.560 0.840

13-14 0.3480 0 0.3480 0.054 0.111 5.315 2.131



3.5.3 Case 3: 14 Bus Actual System

Table 3.21 Sensitivity method

Bus

no

From

Bus

To

Bus

rij xij vi vj dij cos(dij) aij

1 1 2 0.0066 0.033 1.05 1.0598 -88.67 0.7613 -277.2081

2 1 5 0.0005 0.0026 1.05 1.05 -93.89 0.9366 10111.7361

3 1 7 0.0071 0.0355 1.05 1.06 -92.36 -0.3117 -2115.4733

4 1 4 0.0126 0.0628 1.05 1.23 -90.79 -0.9504 -1303.738

5 1 14 0.0149 0.0741 1.05 1.06 -95.98 -0.1607 -425.9896

6 2 3 0.0052 0.026 1.05 1.05 79.137 -0.8269 -5653.0583

7 3 13 0.0078 0.0387 1.05 1.04 80.242 0.131 -1120.4584

8 5 6 0.0033 0.0163 1.05 1.05 -88.678 0.7561 -1202.1102

10 6 11 0.0094 0.0468 1.05 1.06 -88.737 0.0220 -901.533

11 7 8 0.0037 0.0188 1.06 1.06 -88.82 0.0205 -5593.778

12 7 10 0.0171 0.085 1.06 1.07 -90.585 -0.0102 -283.001

13 8 9 0.0033 0.0168 1.06 1.06 78.6 0.1976 -5748.223

14 9 11 0.0028 0.0141 1.06 1.06 -81.476 0.1482 -3.35251

11 12 0.0055 0.0273 1.0628 1.07 -88.419 0.0275 -2644.4504

Table 3.22 After placing TCSC in line 1-2 Table 3.23 After placing TCSC in line 7-10

BUS NO VOLTAGE (V) BUS NO VOLTAGE (V)

1 0.9767 1 0.9766

2 1.008 2 09551

3 0.996 3 0.947

4 0.9721 4 0.972

5 0.9734 5 0.9737

6 0.9633 6 0.9666

7 0.9579 7 0.9628

8 0.9564 8 0.9599

9 0.9557 9 0.9581

10 0.9201 10 0.9299

11 0.947 11 0.942

12 0.9355 12 0.9305

13 0.9887 13 0.9367

14 0.943 14 0.9429



3.6 Locating TCSC by changing the degree of compensation (K)

Table 3.24 Before Placement of TCSC in line 1-4

Line Aij Line flow Line losses

MVA Total power losses

MW MVAR MW MVAR MW MVAR

1-4 -353.5 16.12 74.55 0.768 -7.25 76.277 39.903 57.274

Table 3.25 After Placement of TCSC in line 1-4

Line K Aij Line flow Line losses



1-4

0.1 -298.29 13.41 67.74 0.639 -7.578 69.05 39.77 56.95

0.2 -254.64 11.33 61.96 0.54 -7.85 62.98 39.67 56.67

0.3 -219.66 9.694 57.00 0.462 -8.089 57.81 39.59 56.43

0.4 -191.66 8.38 48.94 0.399 -8.29 53.36 39.53 56.23

0.5 -167.93 7.324 82.68 0.349 -8.473 49.48 39.48 56.05

-0.1 -424.43 19.72 92.50 0.930 -6.86 85.0 40.075 57.66

-0.2 -516.63 24.65 104.55 1.174 -6.39 95.73 40.30 58.12

-0.3 -637.60 31.63 119.50 1.506 -5.82 109.231 40.642 58.70

-0.4 -795.58 41.90 1.996 1.996 -5.11 126.64 41.13 59.41

-0.5 -992.40 57.78 138.19 2.750 -4.22 149.79 41.867 60.30





6-11 -48.64 0.00 -3.930 0.00 -7.860 3.930 39.903 57.274







6-11

0.1 -41.04 0.00 -3.93 0.00 -7.860 3.930 39.903 57.274

0.2 -35.04 0.00 -3.93 0.00 -7.860 3.930 39.903 57.274

0.3 -30.22 0.00 -3.93 0.00 -7.860 3.930 39.903 57.274

0.4 -26.32 0.00 -3.93 0.00 -7.860 3.930 39.903 57.274

0.5 -23.11 0.00 -3.93 0.00 -7.860 3.930 39.903 57.274

-0.1 -58.40 0.00 -3.93 0.00 -7.860 3.930 39.903 57.274

-0.2 -71.081 0.00 -3.93 0.00 -7.860 3.930 39.903 57.274

-0.3 -87.71 0.00 -3.93 0.00 -7.860 3.930 39.903 57.274

-0.4 -109.42 0.00 -3.93 0.00 -7.860 3.930 39.903 57.274

-0.5 -136.45 0.00 -3.93 0.00 -7.860 3.930 39.903 57.274





7-10 -93.22 0.00 -7.14 0.00 -14.28 7.140 39.903 57.274





7-10

0.1 -78.66 0.00 -7.14 0.00 -14.28 7.140 39.903 57.274

0.2 -67.158 0.00 -7.14 0.00 -14.28 7.140 39.903 57.274

0.3 -57.93 0.00 -7.14 0.00 -14.28 7.140 39.903 57.274

0.4 -50.44 0.00 -7.14 0.00 -14.28 7.140 39.903 57.274

0.5 -44.29 0.00 -7.14 0.00 -14.28 7.140 39.903 57.274

-0.1 -111.89 0.00 -7.14 0.00 -14.28 7.140 39.903 57.274

-0.2 -136.47 0.00 -7.14 0.00 -14.28 7.140 39.903 57.274

-0.3 -168.01 0.00 -7.14 0.00 -14.28 7.140 39.903 57.274

-0.4 -209.54 0.00 -7.14 0.00 -14.28 7.140 39.903 57.274

-0.5 -261.18 0.00 -7.14 0.00 -14.28 7.140 39.903 57.274





8-9 571.12 0.00 -5.470 0.00 -10.94 5.470 39.903 57.274







8-9

0.1 485.27 0.00 -5.470 0.00 -10.94 5.470 39.903 57.274

0.2 410.75 0.00 -5.470 0.00 -10.94 5.470 39.903 57.274

0.3 354.14 0.00 -5.470 0.00 -10.94 5.470 39.903 57.274

0.4 308.23 0.00 -5.470 0.00 -10.94 5.470 39.903 57.274

0.5 270.54 0.00 -5.470 0.00 -10.94 5.470 39.903 57.274

-0.1 684.44 0.00 -5.470 0.00 -10.94 5.470 39.903 57.274

-0.2 836.90 0.00 -5.470 0.00 -10.94 5.470 39.903 57.274

-0.3 1035.27 0.00 -5.470 0.00 -10.94 5.470 39.903 57.274

-0.4 1296.38 0.00 -5.470 0.00 -10.94 5.470 39.903 57.274

-0.5 1626.66 0.00 -5.470 0.00 -10.94 5.470 39.903 57.274

3.7 Conclusion

This chapter presents the development of hybrid method using both active and

reactive power loss sensitivity factors to decide on the optimal location of FACTS

controllers in transmission line for given loading conditions and for given network. The

methods developed have been simulated using MATLAB/SIULINK and the results

obtained are promising. The systems considered include IEEE 5 bus, 9 Bus , 14 Bus, 30

Bus and 14 bus actual system. The results are found to be in the right direction. In these

methods even though the location of FACTS devices is identified the optimal degree of

compensation necessary has to be determined by conducting repeated load flow studies

by varying the degree of compensation. This limitation can be overcome by application

of AI techniques which is discussed in the next chapter. The cost analysis has also been

carried out in this chapter.

Documents

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