Model B.Tech Project Documentation

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CHAPTER 1

INTRODUCTION

1.1.INTRODUCTION

The inherent power system restricts the power transaction which leads

to under utilization of the existing transmission resources traditionally, fixed

or mechanically switched shunt and series capacitors, reactors and

synchronous generators were being used to solve much of the problems.

However, there are restrictions as to the use of these conventional devices.

Desired performance was not being able to achieve effectively. Wear and tear

in the mechanical components and slow response were the heart of the

problems. There was a greater need for the alternative technology made of

the solid devices with fast response characteristics.

The need was further fueled by worldwide restructuring of electric

utilities , increasing environmental and efficiency regulations and difficulty

in getting permit and right of way for the construction of overhead

transmission lines .This together with the invention of Thyristor Switch(semi conductor device), opened the door for the development of power

electronic devices known as FACTS controllers. The path from historical

Thyristor based FACTS controller to modern state of the art voltage source

converter based FACTS controllers was made possible due to rapid advance

in high power semiconductor devices

Flexible AC Transmission System (FACTS) controllers have been in use

in utilities around the world since 1970’s when the first utility

demonstration of first formality of FACTS named as SVC was accomplished.

The series devices like Thyristor Controlled Series Capacitor (TCSC) belong

to second generation of FACTS devices. The main idea behind this program

is to increase controllability and optimize the utilization of the existing power

system capacities by replacing mechanical controllers by reliable and high-

speed power electronic devices.

Power electronic devices, which are used for power flow control, are

categorized under the generic name of Flexible AC Transmission Systems

(FACTS). There are three major facets of FACTS. They are shunt

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compensation, series compensation and phase angle regulation. This report

describes the theory and modeling technique of Flexible Alternating

Transmission Systems (FACTS) device, namely Thyristor Controlled Series

Capacitor (TCSC) using simulation package.

1.2.AIM

The main aim of TCSC device is to control the active power

transmitted, line current and TCR parameters. TCSC consists of a capacitor

in parallel with a Thyristor Controlled Reactor (TCR). An actual TCSC system

usually comprises a cascaded combination of many TCSC modules together

with a fixed-series capacitor. TCSC vary the electrical length of thetransmission line which enables it to be used to provide fast active power

flow regulation. It also increases the stability margin of the system and has

proved very effective in damping Sub Synchronous Resonance (SSR) and

power oscillations.

1.3.METHODOLOGY

In this project we need to study different types of FACTS controllers.

We are using MATLAB SIMULINK model in this project. We are simulating

first without connecting TCSC into the transmission line and then by

connecting TCSC into the transmission line. We are observing the

waveforms in both cases and from that the performance of TCSC is

observed.

1.4.SIGNIFICANCE OF THE WORK

Generally in now a days power flow control in a transmission line is

the major problem. Therefore it can be done more efficiently by connecting

TCSC into the transmission line. Actually TCSC is a device which is the

parallel combination of capacitor and inductor with TCR, so that it can be

applied to any transmission line. This project has its main application in

controlling active and reactive power in any transmission line.

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1.5.ORGANIZATION OF THE PROJECT

Chapter 2 –Literature review related to the topic of the work.

Chapter 3 –Overview, Types & Benefits of Flexible AC Transmission

Systems (FACTS)

Chapter 4 –Describes about introduction to FC and TCSC – Fixed

Capacitance, Series Compensation, Shunt Compensation and

technical advantages of TCSC.

Chapter 5 –Describes about Main Project – Introduction, Analysis of

TCSC on Power Flow control in Power System, Reactive Power, Power Transfer Capability.

Chapter 6 –Describes about Results and Discussions.

Chapter 7 –Describes about Scope of Future.

Chapter 8 – Appendix.

1.6.CONCLUSION

One of the more intriguing and potentially most versatile classes of

FACTS device is the Thyristor Controlled Series Compensation (TCSC). TCSC

as a dynamic system, besides its capability in increasing power transfer in

transmission lines, can be used to enhance different power system issues.

TCSC's different advantages can be classified as steady-state and transient

ones. During a fault, TCSC can enhance power quality by limiting thecurrent and help to keep the voltage as high as possible. The application of

TCSC to enhance one of the important power quality issues is stability

margin.

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CHAPTER 2

LITERATURE REVIEW

2.1.INTRODUCTION

For many years the use of power electronic equipment in power

transmission systems was restricted to High Voltage Direct Current (HVDC).

But in the 1970’s the Static VAR Compensator (SVC) was introduced as a

means to provide reactive power support and voltage control in the network.

It found widespread application in transmission systems as well as in large

industrial plants. The fast development of high-power semiconductors

during the period 1980s brought forward rugged thyristors capable of

handling high voltages and heavy short circuit currents. As a result, intense

research efforts were initiated in by introducing power electronics to control

voltage, phase and current in many places with the overall objective to

improve the AC transmission technology in such systems. The well-known

FACTS program was launched by EPRI in USA around 1990. Many new

concepts were proposed, among them the Thyristor Controlled Series

Capacitor (TCSC). The first proposed use of TCSC was related to power flow

control, but it was soon realized that the device is also a very effective

means for providing damping of electromechanical power oscillations. A

third possible application of TCSC emerged from the insight that it can

provide series compensation without causing the same risk for Sub-

Synchronous Resonance (SSR) as a fixed series capacitor.

In the TCSC concept the thyristor valve is connected directly in series

with the transmission line and accordingly it becomes fully exposed to all

over voltages occurring in the system. Thus the main circuit, including the

cooling system, requires full insulation relative ground level, which meansthat it shall withstand impulse tests with voltage amplitudes well exceeding

1000 kV. This was a challenge as earlier power electronic apparatus had

always been connected to the high voltage circuit through their own

dedicated transformers. However, the challenge also brings about an

opportunity, because eliminating the need for an interfacing transformer,

which would represent substantial cost and losses, makes the TCSC an

economically attractive device with low losses. The TCSC is a member of the

FACTS family, which consists of a number of power electronic based

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apparatus developed to improve the controllability of the AC transmission s

nystem.

• Thyristor Controlled Phase Angle Regulator (TCPAR), a transformer based

phase shifter with thyristor control

• Unified Power Flow Controller (UPFC), a back-back VSC configured as a

phase shifter between a shunt transformer and a series boost transformer

• Static Synchronous Series Compensator (SSSC), a VSC based device

injecting voltage via a boost transformer

The TCSC has the advantage of being directly implemented in the

main circuit. No interfacing transformer is used, which brings about a big

cost-advantage in high-voltage applications. Also losses are minimized when

the interfacing equipment is not needed. Comparing studies also have

shown that the contribution to damping using a TCSC is as good as or

better than TCPAR or UPFC of similar rating.

2.2.CONTROL MODES

TCSC operates in different modes depending on when the thyristors

for the inductive branch are triggered. The modes of operation are as listed:

A. Mode – I. Thyristor Switched Reactor Mode:-

The thyristor is gated for 180°. The susceptance of the reactor is

greater than capacitor. Most of the line current passes through reactor and

thyristor valves. For protection of capacitor against overvoltage, this mode is

used.

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Fig.2.1 Bypassed

B. Mode – II. Waiting Mode:-

No current pass through valves and gate pulses are blocked. The

reactance of TCSC and fixed capacitor is similar. That’s why this mode is

awaited mostly.

Fig.2.2 Thyristor blocked

C. Mode – III. Vernier Mode

Here the thyristor valves are operated by two gate pulses in the two

region i.e. capacitive vernier region (αmin < α < 90°) and inductive vernier

region α is reduce to 180°.

Fig.2.3 - 6 Vernier operations

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Because of TCSC allowing different operating modes depending on

system requirements, TCSC is desired for several reasons. In addition to all

of the benefits of FSC, TCSC allows for increased compensation simply by

using a different mode of operation, as well as limitation of line current in

the event of a fault. A benefit of using TCSC is the damping of sub

synchronous resonance caused by torsional oscillations and inter-area

oscillations. The ability to dampen these oscillations is due to the control

system controlling the compensator. This results in the ability to transfer

more power, and the possibility of connecting the power systems of several

areas over long distances.

2.3.LIST OF REFERENCE PAPERS

1. Implementing TCSC Device in Kalpakam Khammam Line for Power Flow

Enhancement-G.V.T.Prudhvira,Raghu,S.Meikandasivam and D.Vijayakumar

2. Applications of FACTS Controllers-BindeshwarSingh,Abhiruchi Srivastava

and Manisha.

3. Proposed Terms and Definitions for Flexible AC Transmission System

(FACTS) - R.Adapa, M.H.Baker, L.Bohmann K.Clark, K. Habashi, L.Gyugyi,

J.Lemay, A.S.Mehraban, A.K.Myers, J.Reeve, F.Sener, D.R.Torgerson,

R.R.Wood

4. Impact of Series FACTS Devices (GCSC, TCSC and TCSR) on Distance

Protection Setting Zones in 400 kV Transmission Line - Mohamed Zellagui

and Abdelaziz Chaghi

5. A Study of TCSC Controller Design for Power System Stability

Improvement - Alberto D. Del Rosso, Member, IEEE, Claudio A. Canizares,

Senior Member, IEEE, and Victor M. Dona

6. Behavioral Study of TCSC Device – A MATLAB/Simulink Implementation -

S. Meikandasivam, Rajesh Kumar Nema, Shailendra Kumar Jain

7. Using of the Thyristor Controlled Series Capacitor in Electric Power

System

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8. Voltage Profile Improvement Using FACTS Devices: A Comparison between

SVC, TCSC and TCPST - M.Arun Bhaskar, C.Subramani, M.Jagdeesh

Kumar, Dr.S.S.Dash

9. Impacts of Facts Technology-A State of Art Review - Abhishek Gandhar,Balwinder Singh, Rintu Khanna

10. Optimal Location of SVC, TCSC and UPFC Devices for Voltage Stability

Improvement and Reduction of Power Loss using Genetic Algorithm -

S.K.Dheebika, R.Kalaivani

11. Dynamic Analysis of the Impact of TCSC on Distance Relay Operation -

S.Jamali and H.Imani

12. Allocation of TCSC Devices to Optimize Total Transmission Capacity in aCompetitive Power Market - Wang Feng, G.B.Shrestha

13. Voltage Profile Improvement Using TCSC for IEEE-6 Bus System Using

Trial And Error Method - Ketan Sakhaparia, Dr.Chirag.K.Vibhakar

14. Thysristor-Based FACTS Controllers for Electrical Transmission Systems

- R.Mohan Mathur, Rajiv K.Varma

15. Thysristor-Based FACTS Controllers for Electrical Transmission Systems

- R.Mohan Mathur, Rajiv K.Varma

16. Study of Thyristor Controlled Series Capacitor (TCSC) as a useful FACTS

Device - MD. Nasimul Islam Maruf, A.S.M.Mohsin, MD.Asaduzzaman Shoeb,

MD.Kafiul Islam, MD.Mokarrom Hossain

17. Simulation and Analysis for Real and Reactive Power Control with Series

Type FACTS Controller - Vatsal J. Patel, C.B.Bhatt

18. Modelling, Simulation and Performance Analysis of FACTS Controller in

Transmission line - Dipti Mohanty, Aziz Ahamad, M. A. Khan

19. Voltage Stability Enhancement And Loss Minimization By Optimally

Placed TCSC - Dipesh A. Patel, Snehal V. Malvi, Prabhat Kumar

20. Behavior of TCSC in transmission line using MATLAB/Simulation -

Anita Kanwar, Rachit Saxena

21. Analysis of Impacts of PSS Controllers and TCSC FACTS Devices at

Dynamic Stability of a Multimachine System Power - E. L. Miotto and M. R.Covacic, Member, IEEE

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22. Optimal Allocation of TCSC Devices Using Genetic Algorithms -

A.Y.Abdelaziz,M.A.El-Sharkawy,M.A.Attia

23. Newton-Raphson TCSC Model for Power Flow Solution with Different

Types of Load Models - Abdel-Moamen M.A., IEEE Member

24. Thyristor Controlled Series Compensation: A State of the Art Approach

for Optimization of Transmission over Power Links - R.Grunbaum, Jacques

Pernot

25. Comparison of FACTS Devices for Power System Stability Enhancement -

D.Murali, Dr.M.Rajaram, N.Reka

26. Comparative Study on the Effectiveness of TCSC and UPFC Facts

Controllers - N.Ashok kumar, M.Rathinakumar, M.Yogesh, J.Dinesh

27. Static Voltage Stability Margin Enhancement Using SVC and TCSC -

Mohammed Amroune, Hadi Sebaa, Tarek Bouktir

28. TCSC for Protection of Transmission Line - P.S.Chaudhari, P. P.Kulkarni,

R.M.Holmukhe, Mrs.P.A.Kulkarni

29. Voltage Stability Improvement in Power Systems using FACTS

Controllers: State of the Art Review - Sandeep Gupta, Prof.R.K.Tripathi,

Member, IEEE and Rishabh Dev Shukla

30. Selection of TCSC Parameters: Capacitor and Inductor -

S.Meikandasivam, Rajesh Kumar Nema, and Shailendra Kumar Jain

31. Power Flow Analysis Incorporating Firing Angle Model Based TCSC -

S.Sreejith, Student member , IEEE, Sishaj P Simon , M P Selvan

32. Series Capacitors for Increased Power Transmission Capability of a 500

kV Grid Intertie - Rolf Gruenbaum, Senior Member, IEEE, Jon Rasmussen,

Member,IEEE,ChunLi

2.4.CONCLUSION

TCSC as a dynamic system, besides its capability in increasing power

transfer in transmission lines, can be used to enhance different power

system issues. TCSC's different advantages can be classified as steady-state

and transient ones. During a fault, TCSC can enhance power quality by

limiting the current and help to keep the voltage as high as possible. The

9



application of TCSC to enhance one of the important power quality issues,

stability margin.

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CHAPTER 3

OVERVIEW, TYPES & BENEFITS OF FLEXIBLE AC

TRANSMISSION SYSTEMS (FACTS)

3.1.INTRODUCTION

Flexible AC Transmission Systems (FACTS) are the name given to the

application of power electronics devices to control the power flows and other

quantities in power systems.

FACTS: AC transmission systems incorporating the power electronic-

based and other static controllers to enhance controllability and increase

power transfer capability. FACTS Controllers: A power electronic based

system & other static equipment that provide control of one or more AC

transmission parameters.

FACTS devices enhance the capability of transmission lines. These

controllers are fast and increase the stability operating limits of

transmission systems. When these controllers are properly tuned these

devices provide control of power system through appropriate compensation

of network parameters, such as line series impedance , line shunt

admittance , current, voltage, real and reactive power. They help the

operation of the power system closer to its thermal limit. The FACTS

technology encompasses a combination of various controllers, each of which

can be applied individually or in co-ordination with other devices to control

the interrelated parameters of the system.

We need transmission interconnections because, apart from delivery,the purpose of the transmission network is to pool plants and load centres

in order to minimize the total power generation capacity and fuel cost.

Transmission interconnections enable taking advantage of diversity of loads,

availability of sources, and fuel price in order to supply electricity to the

loads at minimum cost with a required reliability. In general, if a power

delivery system was made up of radial lines from individual local generators

without being part of a grid system, many more generation resources would

be needed to serve the load with the same reliability and the cost ofelectricity would be much higher. With that perspective, transmission is

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often an alternative to a new generation resource. Less transmission

capability means that more generation resources would be required

regardless of whether the system is made up of large or small power plants.

In fact small distributed generation becomes more economically viableif there is a backbone of a transmission grid. One cannot be really sure

about what the optimum balance is between generation and transmission

unless the system planners use advanced methods of analysis which

integrate transmission planning into an integrated value–based

transmission/generation planning scenario. The cost of transmission lines

and losses, as well as difficulties encountered in building new transmission

lines, would often limit the available transmission capacity.

3.2.OPPORTUNITIES FOR FACTS

The most interesting for transmission planners is that FACTS

technology opens up new opportunities for controlling power and enhancing

the usable capacity of present, as well as new and upgraded. The possibility

that current through a line can be controlled at a reasonable cost enables a

large potential of increasing the capacity of existing lines with larger

conductors, and use of one of the FACTS Controllers to enable

corresponding power to flow through such lines under normal and

contingency conditions.

These opportunities arise through the ability of FACTS Controllers to

control the interrelated parameters that govern the operation of

transmission systems including series impedance, shunt impedance,

current, voltage, phase angle, and the damping of oscillations at various

frequencies below the rated frequency. These constraints cannot beovercome, while maintaining the required system reliability, by mechanical

means without lowering the useable transmission capacity. By providing

added flexibility, FACTS Controllers can enable a line to carry power closer

to its thermal rating. Mechanical switching needs to be supplemented by

rapid-response power electronics. It must be emphasized that FACTS is an

enabling technology, and not a one-on-one substitute for mechanical

switches.

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The FACTS technology is not a single high-power Controller, but

rather a collection of Controllers, which can be applied individually or in

coordination with others to control one or more of the interrelated system

parameters mentioned above. A well-chosen FACTS Controller can overcome

the specific limitations of a designated transmission line or a corridor.

Because all FACTS Controllers represent applications of the same basic

technology, their production can eventually take advantage of technologies of

scale. Just as the transistor is the basic element for a whole variety of

microelectronic chips and circuits, the thyristor or high-power transistor is

the basic element for a variety of high-power electronic Controllers.

FACTS technology also lends itself to extending usable transmission

limits in a step-by-step manner with incremental investment as and whenrequired. A planner could foresee a progressive scenario of mechanical

switching means and enabling FACTS Controllers such that the

transmission lines will involve a combination of mechanical and FACTS

Controllers to achieve the objective in an appropriate, staged investment

scenario.

It is also worth pointing out that, in the implementation of FACTS

technology, we are dealing with a base technology, proven through HVDC

and high-power industrial drives. Nevertheless, as power semiconductor

devices continue to improve, particularly the devices with turn-off capability,

and as FACTS Controller concepts advance, the cost of FACTS Controllers

will continue to decrease. Large-scale use of FACTS technology is an assured

scenario.

3.3. RELATIVE IMPORTANCE OF CONTROLLABLE

PARAMETERS

• Control of the line impedance X (e.g., TCSC) can provide a powerful means

of current control.

• Injecting a voltage in series with the line, and perpendicular to the current

flow, can increase or decrease the magnitude of current flow. Since the

current flow lags the driving voltage by 900, this means injection of reactive

power in series, (e.g., with static synchronous series compensation) can

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provide a powerful means of controlling the line current, and hence the

active power when the angle is not large.

• Injecting voltage in series with the line and with any phase angle with

respect to the driving voltage can control the magnitude and the phase ofthe line current. This means that injecting a voltage phasor with variable

phase angle can provide a powerful means of precisely controlling the active

and reactive power flow.

• Because the per unit line impedance is usually a small fraction of the line

voltage, the MVA rating of a series Controller will often be a small fraction of

the throughput line MVA.

• When the angle is not large, which is often the case, control of X or the

angle substantially provides the control of active power.

• Control of angle (with a Phase Angle Regulator, for example), which in turn

controls the driving voltage, provides a powerful means of controlling the

current flow and hence active power flow when the angle is not large.

• Combination of the line impedance control with a series Controller and

voltage regulation with a shunt controller can also provide a cost effective

means to control both the active and reactive power flow between the two

systems.

3.4.ELEMENTARY KNOWLEDGE TO UNDERSTAD FACTS

In an ideal AC power system the voltage and frequency at every supply

point would be constant and free from harmonics, and the power factor

would be unity. In particular these parameters would be independent of the

size and characteristics of consumers' loads. In three-phase systems, the

phase currents and voltages must also be balanced. The stability of the

system against oscillations and faults must also be assured.

The maintenance of constant frequency requires an exact balance

between the overall power supplied by generators and the overall power

absorbed by loads, irrespective of the voltage. However, the voltage plays an

important role in maintaining the stability of power transmission, as we

shall see. Voltage levels are very sensitive to the flow of reactive power and

therefore the control of reactive power is important. This is the subject of

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reactive compensation. Where the focus is on individual loads, we speak of

load compensation.

Load compensation is the management of reactive power to improve

the quality of supply at a particular load or group of loads. Compensatingequipment such as power-factor correction equipment is usually installed on

or near to the consumer's premises. In load compensation there are three

main objectives:

1. power-factor correction

2. Improvement of voltage regulation

3. Load balancing.

Power-factor correction and load balancing are desirable even when

the supply voltage is stiff ': that is, even when there is no requirement to

improve the voltage regulation. Ideally the reactive power requirements of a

load should be provided locally, rather than drawing the reactive component

of current from a remote power station. Most industrial loads have lagging

power factors; that is, they absorb reactive power. The load current therefore

tends to be larger than is required to supply the real power alone. Only the

real power is ultimately useful in energy conversion and the excess load

current represents a waste to the consumer, who has to pay not only for the

excess cable capacity to carry it, but also for the excess Joule loss in the

supply cables. When load power factors are low, generators and distribution

networks cannot be used at full efficiency or full capacity, and the control of

voltage throughout the network can become more difficult. Supply tariffs to

industrial customers usually penalize low power-factor loads, encouraging

the use of power-factor correction equipment.

The most obvious way to improve voltage regulation would be tostrengthen' the power system by increasing the size and number of

generating units and by making the network more densely interconnected.

This approach is costly and severely constrained by environmental planning

factors. It also raises the fault level and the required switch gear ratings. It

is better to size the transmission and distribution system according to the

maximum demand for real power and basic security of supply, and to

manage the reactive power by means of compensators and other equipment

which can be deployed more flexibly than generating units, withoutincreasing the fault level. Similar considerations apply in load balancing.

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Most AC power systems are three- phase, and are designed for

balanced operation. Unbalanced operation gives rise to components of

current in the wrong phase-sequence (i.e. negative- and zero-sequence

components). Such components can have undesirable effects, including

additional losses in motors and generating units, oscillating torque in AC

machines, increased ripple in rectifiers, malfunction of several types of

equipment, saturation of transformers, and excessive triple harmonics and

neutral currents.

The harmonic content in the voltage supply waveform is another

important measure in the quality of supply. Harmonics above the

fundamental power frequency are usually eliminated by filters. Nevertheless,

harmonic problems often arise together with compensation problems andsome types of compensator even generate harmonics which must be

suppressed internally or filtered.

The ideal compensator would

(a) Supply the exact reactive power requirement of the load;

(b) Present a constant-voltage characteristic at its terminals; and

(c) Be capable of operating independently in the three phases.

An example of a load with extremely rapid variation is an electric arc

furnace, where the reactive power requirement varies even within one cycle

and, for a short time at the beginning of the melt, it is erratic and

unbalanced. In this case a dynamic compensator is required, such as a TCR

or a saturated-reactor compensator, to provide sufficiently rapid dynamic

response. Loads that require compensation include arc furnaces, induction

furnaces, arc welders, induction welders, steel rolling mills, mine winders,

large motors (particularly those which start and stop frequently), excavators,

chip mills, and several others. Non-linear loads such a s rectifiers also

generate harmonics and may require harmonic filters, most commonly for

the 5th and 7th but sometimes for higher orders as well.

The power-factor and the voltage regulation can both be improved if

some of the drives in a plant are synchronous motors instead of induction

motors, because the synchronous motor can be controlled to supply (or

absorb) an adjustable amount of reactive power and therefore it can be used

16



as a compensator. Voltage dips caused by motor starts can also be avoided

by using a soft starter', that is, a phase-controlled thyristor switch in series

with the motor, which gradually ramps the motor voltage from a reduced

level instead of connecting suddenly at full voltage.

3.5.TYPES OF FACTS CONTROLLERS

In general, FACTS controllers can be divided into four categories:

• Series controllers.

• Shunt controllers.

• Combined series-series controllers.

• Combined series-shunt controllers.

3.5.1. SERIES CONTROLLERS

The series controller could be variable impedance, such as capacitor,

reactor, etc., or power electronics based variable source of main frequency,sub synchronous and harmonic frequencies to serve the desired need. In

principle, all series controllers inject voltage in series with the line. Even

variable impedance multiplied by the current flow through it, represents an

injected series voltage in the line. As long as the voltage is in phase

quadrature with the line current, the series controller only supplies (or)

consumes variable reactive power.

Series Controller could be a variable impedance such as capacitor,

reactor, etc or power electronics based variable source of main frequency,sub-synchronous or harmonic frequencies (or a combination).All series

controller inject voltage in series with line. If voltage is in phase quadrature

with the line current, it only supplies or absorbs the variable reactive power.

17



Fig.3.1 Series Controller

3.5.2. SHUNT CONTROLLERS

As in the case of series controllers, the shunt controllers may be

variable impedance, Variable source, or a combination of these. In principle,

all shunt controllers inject current into the system at the point of

connection. Even variable shunt impedance connected to the line voltage

causes a variable current flow and hence represents injection of current into

the line. As long as the injected current is in phase quadrature with the line

voltage, the shunt controller only supplies or consumes variable reactive

power.

Shunt Controller could be variable impedance, variable source or a

combination of these. All shunt controllers inject current into the system at

the point of connection. If injected current is in quadrature with the line

voltage, it only supplies or absorbs the variable reactive power.

Fig.3.2 Shunt Controller

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3.5.3. COMBINED SERIES-SERIES CONTROLLERS

This could be a combination of separate series controllers, which arecontrolled in a coordinated manner, is a multilane transmission system or it

could be a united controller in which series controllers provide independent

series reactive compensation for each line but also transfer real power

among the line via the power link. The real power transfer capability of the

unified series – series controller, referred to as interline power flow

controller, makes it possible to balance both the real and reactive power flow

in the lines and there by maximize the utilization of the transmission

system. Note that the term “Unified” here means that the dc terminals of allcontroller converters are all connected together for real power transfer.

3.5.4. COMBINED SERIES-SHUNT CONTROLLERS

This could be a combination of separate shunt and series controllers,

which are controlled in a coordinated manner, or a Unified Power Flow

Controller with series and shunt elements. In principle, combined shunt

and series controllers inject current into the system with the shunt part of

the controller and voltage in series in the line with the series part of the

controller. However, when the shunt and series controllers are unified, there

can be a real power exchange between the series and shunt controllers via

the power link.

Fig.3.3 Combined Series and Shunt Controller

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3.6.BENIFITS FROM FACTS TECHNOLOGY

FACTS Controllers enable the transmission owners to obtain, one or more of

the following benefits:

• Control of power flow as ordered. The use of control of the power flow may

be to follow a contract, meet the utilities’ own needs, ensure optimum power

flow, ride through emergency conditions, or a combination thereof.

• Increase the system security through raising the transient stability limit,

limiting short-circuits currents and overloads, managing cascading black

outstand damping electromechanical oscillations of power systems and

machines.

• Provide secure tie line connections to neighbouring utilities and regions

thereby decreasing over all generation reserve requirements on both sides.

• Provide greater flexibility in sitting new generation.

• Upgrade of lines.

• Reduce reactive power flows, thus allowing the lines to carry more active

power.

• Increase the loading capability of lines to their thermal capabilities,

including short term and seasonal. This can be accomplished by overcoming

other limitations, and sharing of power among lines according to their

capability. It is also important to note that thermal capability of a line varies

by a very large margin based on the environmental conditions and loading

history.

• Reduce loop flow.

Increase utilization of lowest cost generation. One of the principal reasons

for Transmission interconnection is to utilize lowest cost generation.

3.7.CONCLUSION

In this chapter, we are seen that basic types of FACTS controllers. We also

known that Series Compensation can control only if injected voltage is inquadrature with transmission line current but TCSC can control if injected

20



voltage is in any angle with line current. We studied about Overview of

FACTS devices, importance of FACTS devices and benefits of FACTS devices.

We conclude that FACTS devices are more efficient to control power flow and

to increase the transmission line capability in any transmission lines.

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CHAPTER 4

INTRODUCTION TO FC AND TCSC

4.1.INTRODUTION TO FC (FIXED CAPACITOR)

As power demand increases in many parts of the world, power

transmission needs to be developed, as well. The building of more power

lines may not be the best way, however, as transmission lines cost a lot of

money, take considerable time to construct, and are subject to severe

environmental constraints. With series compensation, the power

transmission capability of existing, long lines can be increased considerably.

Likewise, in green-field projects, the number of parallel lines can be kept to

a minimum by using series compensation from the outset. This can be

utilized to benefit when large amounts of power need to be transmitted over

long distances to consumer areas.

There is an example of employing a series capacitor in a Canadian

utility, Hydro One. Hydro One is the largest electricity transmission and

distribution company in the province of Ontario, Canada. The Companyowns and operates substantially all of Ontario’s electricity transmission

system, accounting for approximately 96.6% of Ontario’s transmission

capacity.

4.2.BASIC MECHANISMS OF FC

Series compensation of AC transmission systems has been utilized for

many years with excellent results in a number of countries all over the

world. The usefulness of the concept can be illustrated by means of well-

known expressions relating to angular and voltage stability of power

transmission systems Fig. 4.1

22



Fig.4.1 Series

Compensated Power Transmission Corridor

4.2.1. ANGULAR STABILITY IMPROVEMENT:

With regard to angular stability improvement, series compensation is

highly efficient. By means of series compensation, the overall reactance

between the line ends is reduced. The power transfer across a line can be

approximated by the following expression:

(4.1)

Where

P = active power transfer

V1 and V2 = end voltages of the transmission circuit

XL= line reactance

XC = reactance of the series capacitor

δ = angular separation between the line ends

From (4.1) it is evident that the flow of active power can be increased

by decreasing the effective series reactance of the line. In other words, if areactance of opposite sign (i.e. a capacitive reactance) is introduced in the

denominator, a corresponding increase in power transmission is enabled

without having to increase the angular separation of the end voltages, i.e.

with the angular stability of the link unimpeded. Similarly it is demonstrated

that by introducing a capacitive reactance in the denominator of (4.1), it is

possible to achieve a decrease of the angular separation with power

transmission capability unaffected, i.e. an increase of the angular stability of

the link.

23



An alternative way of expressing the impact of series compensation is

by means of an increase of synchronizing torque, equal to the slope of the

power vs angle separation relationship given by (4.1).

The influencing of transmission reactance by means of seriescompensation also opens up for optimizing of load sharing between parallel

circuits, thereby bringing about an increase in overall power transmission

capacity again.

4.2.2. VOLTAGE STABILITY IMPROVEMENT:

The voltage of a transmission circuit depends of the flow of active

power (P) as well as of reactive power (Q):

V = f (P, Q) (4.2)

The explicit relationships between the quantities are not simple.

Closer analysis reveals, however, that the reactive power contribution from a

capacitive element in series with the line acts to improve the reactive power

balance of the circuit, and thereby to bring about a stabilization of the

transmission voltage. It can further be shown that this reactive power

contribution is instantaneous and of a self-regulatory nature, i.e. it

increases when the line load increases, and vice versa. It consequently

contributes to voltage stability in a truly dynamic fashion. This makes series

compensation a highly effective means for maintaining or even increasing

voltage stability in a heavily loaded transmission circuit. And likewise, it

allows additional power transmission over the circuit without upsetting

voltage stability.

4.2.3. DEGREE OF COMPENSATION:

With the reactance of the capacitive element, i.e. the series capacitor

equal to XC and the inductive reactance of the line equal to XL, we can

introduce a measure of the degree of series compensation, k:

k = XC / XL (4.3)

In power transmission applications, the degree of compensation is

usually chosen within the range 0.3 ≤ k ≤ 0.7. Substituting XC by k, we get

24



(4.4)

This links power transmission capacity improvement of the intertie

directly to the degree of compensation of the series capacitors.

4.3.INTODUCTION TO TCSC (THYRISTOR CONTROLLED

SERIED COMPENSATION)

In the TCSC concept the thyristor valve is connected directly in series

with the transmission line and accordingly it becomes fully exposed to all

over voltages occurring in the system. Thus the main circuit, including the

cooling system, requires full insulation relative ground level, which means

that it shall withstand impulse tests with voltage amplitudes well exceeding

1000 kV. This was a challenge as earlier power electronic apparatus had

always been connected to the high voltage circuit through their own

dedicated transformers. However, the challenge also brings about an

opportunity, because eliminating the need for an interfacing transformer,

which would represent substantial cost and losses, makes the TCSC an

economically attractive device with low losses. The TCSC is a member of the

FACTS family, which consists of a number of power electronic based

apparatus developed to improve the controllability of the AC transmission

system. Beside the since long established members, like SVC and HVDC,

TCSC seems to be one of the first new FACTS devices to find commercial

applications. In the subclass of devices that insert voltage in series with the

line the TCSC is competing with the

• Thyristor Controlled Phase Angle Regulator (TCPAR), a transformer

based phase shifter with thyristor control.

• Unified Power Flow Controller (UPFC), a back-back VSC configured as

a phase shifter between a shunt transformer and a series boost transformer.

• Static Synchronous Series Compensator (SSSC), a VSC based device

injecting voltage via a boost transformer.

The TCSC has the advantage of being directly implemented in themain circuit. No interfacing transformer is used, which brings about a big

25



cost-advantage in high-voltage applications. Also losses are minimized when

the interfacing equipment is not needed.

Comparing studies also have shown that the contribution to damping

using a TCSC is as good as or better than TCPAR or UPFC of similar rating.

In the TCSC, on the other hand each thyristor is fired with phase

angle control once per cycle. A bigger inductance is required; typically its

reactance at network frequency is 5-20 % of the capacitor bank reactance

4.3.1. TOPOLOGY, PARAMETERS, NOTATION:

In our analysis we shall first look at the waveforms in steady state

operation. In this study we consider the simple main circuit according to

figure. The reference directions of currents and capacitor voltage have been

indicated in figure these references are used throughout this thesis. The

thyristor carrying conducting current in the positive direction is marked

with an ‘F’, for FORWARD direction. It can only be triggered when positive

capacitor voltage exists. Correspondingly the ‘R’ thyristor, the REVERSE

thyristor, conducts current in the negative direction and can only be

triggered, when the capacitor voltage is negative.

Fig.4.2. TCSC Main Circuit

The capacitance of the bank in each phase is C and the inductance in

the thyristor branch is L. These two branches together form an LC circuit

with the resonance frequencyɷ0

26



If a transmission line is compensated to a degree less than 100 %, an

electrical resonance occurs at a subsynchronous frequency, where the

magnitude of the capacitive reactance equals the total inductive reactance of

the transmission line and the connected sources. The existence of the

electrical resonance constitutes one of the prerequisites for establishing

“Subsynchronous resonance”, SSR, in a power system. (SSR is an

interaction between the electrical resonance in the transmission system and

the mechanical torsional resonance in the turbine-generator shaft string in

a thermal power station connected to the transmission system).

4.4. CONCLUSION

In this chapter, we are seen that basic methods of FC and TCSC

controllers and also observed that TCSC is more efficient to control the

power flow in transmission line over the other FACTS devices.

27



CHAPTER 5

MAIN PROJECT

The TCSC concept is that it uses an extremely simple main circuit. The capacitor is inserted directly in series with the transmission line and

the thyristor controlled inductor is mounted directly in parallel with the

capacitor. Thus no interfacing equipment like e.g. high voltage transformers

is required. This makes TCSC much more economic than some other

competing FACTS technologies. Thus it makes TCSC simple and easy to

understand the operation.

5.1.INTRODUCTION

The electricity is an everyday, as it were an essential part of our life

and need to get electricity to the consumer in reliable and specified quality.

Transmission of electricity in the interconnected, cooperating electricity

systems is steadily increasing due to increasing growth in consumption and

electricity generation. While occur to excessive burden of transmission

equipment, which leads ultimately to a disruption in electricity end user. In

addition, there are other unforeseen disturbances and situations of power

system operation. Technical development, which is essential for electrical

power engineering, brings in this area new trends and solutions to various

problems in power system. In recent years in the world are getting to the fore

so called FACTS devices.

In modern semiconductor components control equipment, which have

many potential uses, the issue of options for using these facilities to improve

the performance and operation of power systems is therefore a hot topic.Significant device from the group FACTS is a TCSC, which finds application

in solving many problems in the power system. Its properties can increase

the power lines transmission capacity and power flow control. It also

provides a wide range of other uses to ensure effective, trouble-free and

economical operation of power systems. Behaviours simulation of these

devices is very important before the real deployment of these devices to the

power system. Various computing and simulation programs, which help in

understanding the activities and setting appropriate parameters of these

28



devices, have found its application to modelling and simulating these

devices.

5.2.TCSC

TCSC - Thyristor Controlled Series Capacitor compensator consisting

of the series compensating capacitor, where it is parallel connected

thyristors controlled reactor (TCR), and it is one of FACTS devices which are

mainly used to control active power flow in power system and increase the

transmission power lines capacity. TCSC is involved in a series to line (in

terminal) and allows changing impedance of the transmission path and thus

affecting the power flows. Control is fast, efficient and increased between the

transmitted powers. Basic scheme of TCSC device is shown in the follows

figure 5.1.

Fig.5.1. Basic TCSC Circuit

Change of impedance of TCSC is achieved by changing the thyristor

controlled inductive reactance of inductors connected in parallel to the

capacitor. The magnitude of inductive reactance is determined by angle

switching thyristors, which can also be controlled continuously flowing

amplitude of current reactor from the maximum value to zero. Angle

switching thyristors can change inductive reactance controlled choke from a

minimum value theoretically to infinity. Magnitude of inductance this

compensator is given by:

(5.1)

29



The compensator TCSC

mounted on Figure 5.2 is a type of

series FACTS compensators. It consists of a capacitance (C) connected inparallel with an inductance (L) controlled by a valve mounted in anti-parallel

conventional thyristors (T1 and T2) and controlled by an angle of extinction

(α) varied between 90° and 180°.

Fig.5.2. TCSC Operation

Reactive power (VARs) is required to maintain the voltage to deliver

active power through transmission lines. When there is not enough reactive

power, the voltage sags down and it is not possible to push the power

demanded by loads through the lines. Many devices contribute to systems

reactive power and voltage profile. Example: Capacitors supply reactive

power, inductors absorb reactive power.

Voltage stability is required for the perfect functioning of the system;

compensating devices are required for the compensation purposes.

5.3.ANALYSIS OF THE TCSC FROM THE VIEWPOINT OFPOWER FLOW CONTROL IN POWER SYSTEM

TCSC compensator is not a power source, but it can change the

impedance of the transmission path, in which it is installed; affect the power

flow in networks. The following assumptions can be adopted to simplify the

analysis:

- Since the active resistance of transmission lines is small due to their

inductive reactance, in the following description it is not consider (R = 0).

30



- For simplification, at loaded lines in our transmission system we can

ignore the cross admittance (B = 0).

Active power transmitted by line between nodes 1 and 2 is directly

proportional to the voltages U1 and U2 also difference between load angles,and inversely proportional to the resultant reactance (impedance) of line

Xline:

(5.2)

From equation (2) is seen that is possible influence the power flow of

power lines by change the resulting reactance (impedance) transmission

path. If TCSC is located in terminal, the transmitted power can be

determined by the following equation:

(5.3)

Where:

- U is voltage change in node 2 caused by a reactance change of line.

- X is reactance change of the transmission path, which is decisive for

effectiveness of the power flow control in networks by TCSC device.

- ∆δ is the angle of transmission change (load angle) caused by a change

reactance of the transmission path.

5.4.REACTIVE POWER

5.4.1. SIGNIFICANCE OF RACTIVE POWER:

Many devices contribute to reactive power compensation and voltage

profile. A transmission line, due to its physical characteristics, supplies

reactive power under light loading and consumes it under heavy loading

conditions. Power system voltages are controlled through the supply and

consumption of reactive power. In general terms, decreasing reactive power

31



margin causes voltage fall, while increasing reactive power margin causes

voltage rise. A voltage collapse occurs when the system is trying to serve

much more load than the voltage can support.

To maintain efficient transmission and distribution, it is necessary toimprove the reactive power balance in a system by controlling the

production, absorption, and flow of reactive power at all levels in the system.

Fig.5.3. Power Triangle

5.4.2. DEPENDANCY OF VOLTAGE ON REACTIVE POWER

VARIATION:

The Reactive power in a power system has a great deal of impact on

the voltage that is prevailing in the system. By compensating the reactivepower the voltage profile in the whole power system can be greatly improved

which finally leads to the figure represents the general phasor diagram

showing active power (P) reactive power (Q) where as S represents the

apparent power. Reactive power does not transfer energy, so it is represented

as the imaginary axis of the vector diagram. Real power moves energy, so it

is the real axis. The overall improvement of the efficiency and also the power

factor of the power system. For a simple radial Transmission line the relation

between receiving end bus voltage is given by, V2 = V1*Q X / V1.In order to

keep the receiving end voltage V2 fixed for a particular sending end voltage

V1, the drop (Q X / V1) must remain constant.

Voltage variations are mostly dependent on reactive power variations.

So, to keep the receiving end voltage constant for constant sending end

voltage any deviation of Q must be adjusted locally or by remote control.

Hence reactive power control is required to maintain the voltage within the

acceptable limits.

32



5.5.PRINCIPLE CHARACTERISTICS OF TCSC OPERATION

Fig.5.4. Block diagram for TCSC

Fig.5.5. Control Circuit for TCSC

33



The TCSC block diagram is shown in Fig.5.4 to which the thyristors

gating pulse are to be given, which is given by the Power Circuit. The power

circuit for controlling thyrisors in TCSC is a control circuit as shown in

Fig.5.5. Power is calculated from instantaneous voltage and current signal

with PQ conversion block. The line power flow is computed from themeasured local voltage and current signals the calculated power signal is

converted into a per-unit quantity and filtered, then fed to the summing

junction of the power controller. The reference signal, Pref, denotes the

desired level of real-power flow in the TCSC compensated line, and

combination is fed to PI regulator. From there, susceptance signal is

converted to firing angle. And angle is converted to time. That time fed as

delay to pulse generator.

5.6.OPERATION OF TCSC

The basic operation of TCSC can be easily explained from circuit

analysis. It consists of a series compensating capacitor shunted by a

Thyristor controlled reactor (TCR). TCR is a variable inductive reactor XL

(figure 5.6) controlled by firing angle α. Here variation of XL with respect to α

is given by

(5.4)

Fig.5.6. Equivalent circuit for TCR

For the range of 0 to 90 of α, XL (α) start vary from actual reactance XL

to infinity. This controlled reactor is connected across the series capacitor,

so that the variable capacitive reactance (figure 5.7) is possible across the

TCSC to modify the transmission line impedance. Effective TCSC reactance

X TCSC with respect to alpha (α) is

34



Fig.5.7. Equivalent circuit of TCSC

5.7.TEST SYSTEM AND COMPENSATION

Series compensator is designed for 50 % of line reactance

compensation. Among 50%, 30 % is considered for fixed compensation and

remaining 20 % is for TCSC device. Respective data are given in Table 5.7.1.

& 5.7.2.

TECHNICAL DATA(Test System)

35



Distance 364 km

System Voltage 400 kV

Line Resistance [RI RO] [0.0308 0.2118] Ω/km

Line Inductance [Ll LO] [0.9337 4. 1264] mH/km

Line Capacitance [Cl CO] [6.032 3.67] nF/km

Power transfer 350 MW

Table.5.1

TECHNICAL DATA

(TCSC deviee)

Compensation degree

30 % (FSC)

20% - 20% (TCSC)

FC 9.9373*10-5 F

TCSC

1.4906*10-4 F

0.01179 H

Table.5.2

5.8.CONCLUSIONIn this chapter, we are seen that basic methods of analysis of the

TCSC the viewpoint of power flow control in power system, principle

characteristics of TCSC operation, reactive power control, operation of TCSC

and the method of series compensation in transmission line.

36



CHAPTER 6

RESULTS AND DISCUSSIONS

6.1.WITHOUT COMPENSATION

Fig.6.1.Circuit connection of Transmission Line without compensation

The above figure 6.1 shows the basic circuit connection of 3-phase

transmission line without compensation. In this no compensation the Load1 is at 100% load and Circuit Breaker 2 enables Load 2 at 0.2ms to get

110% load and Circuit Breaker 1 enables Load 3 at 0.6ms to get 120% load.

So, here the variation of outputs at load side for VR, IR and PLfor 100

% Load to 110% Load are as follows:

VR (KV) Vs T (ms)

37



IR (A) Vs T (ms)

PL (MW) Vs T (ms)

38



The variation of outputs at load side for VR, IR and PLfor 110 % Load

to 120 % are as follows:

VR (KV) Vs T (ms)

39



IR (A)Vs T (ms)

PL (M

W) Vs T (ms)

40



As there is no compensation there is a drastic difference of Voltage

(VR), Current (IR) and Power (PR) on the receiving end at load.

6.2.FC COMPENSATION

Fig.6.2. Circuit connection of Transmission Line with FC

compensation


transmission line with Fixed Capacitance (FC) compensation of 9.9373e-5 F.

In this FC compensation the Load 1 is at 100% load and Circuit Breaker 2

enables Load 2 at 0.2ms to get 110% load and Circuit Breaker 1 enables

Load 3 at 0.6ms to get 120% load.


% Load to 110% are as follows:

VR (KV) Vs T (ms)

41



IR (A)Vs T (ms)

PL

(MW)

Vs T (ms)

42





VR (KV) Vs T (ms)

43



IR (A)Vs T (ms)

PL (MW) Vs T (ms)

44



We have that the power transfer across a line can be approximated by

the following expression:

(6.1)

Where

P = active power transfer

U1 and U2 = end voltages of the transmission circuit

XL = line reactance

XC = reactance of the series capacitor

δ = angular separation between the line ends

Hence from the above equation 6.1 we can see that if XC changes the

power also changes which in turn changes the voltage and current.

So, as there is FC compensation there is only a less difference of

Voltage (VR), Current (IR) and Power (PR) on the receiving end at load on

comparing with no compensation in previous section.

45



6.3.FC + TCSC COMPENSATION

Fig.6.3. Circuit connection of Transmission Line with FC +TCSC

compensation


transmission line with Fixed Capacitance (FC) and Thyristor Controlled

Sereies Capacitor (TCSC) compensation of 9.9373e-5 F of FC and TCSC

capacitance & inductance of 1.4906e-4 F, 0.01179 H. In this FC + TCSC

compensation the Load 1 is at 100% load and Circuit Breaker 2 enablesLoad 2 at 0.2ms to get 110% load and Circuit Breaker 1 enables Load 3 at

0.6ms to get 120% load.


% Load to 110% are as follows:

VR (KV) Vs T (ms)

46



IR (A)Vs T (ms)

PL (MW) Vs T (ms)



VR (KV) Vs T (ms)

47



IR (A)

Vs T

(ms)

48



PL (MW) Vs T (ms)

We can see that TCSC consists of a series compensating capacitor shunted

by a Thyristor controlled reactor (TCR). TCR is a variable inductive reactor

XL (figure 6.4) controlled by firing angle α. Here variation of XL with respect

to α is given by

(6.2)

49



Fig.6.4. Equivalent circuit for TCR

For the range of 0 to 90 of α, XL (α) start vary from actual reactance XL

to infinity. This controlled reactor is connected across the series capacitor,

so that the variable capacitive reactance (figure 5.7) is possible across the

TCSC to modify the transmission line impedance. Effective TCSC reactance

X TCSC with respect to alpha (α) is

50



Fig.6.5. Equivalent circuit of TCSC

So, as there is FC + TCSC compensation there is a very high

improvement in the flow of Voltage (VR), Current (IR) and Power (PR) on the

receiving end at load on comparing with FC compensation alone in previoussection

6.4. COMPARISON TABLE FOR NO COMPENSATION, FC, FC

+TCSC

Load

Receiving

end Voltage VR (KV)

Receiving

end CurrentIR (A)

Receiving

end PowerPL (MW)

No

Compensatio

n

100 % 3 650 2.92

110 % 2 1000 2.98

120 % 1.9 1010 2.88

FC

Compensatio

n

100 % 3 650 3.09

110 % 2.2 900 3.35

120 % 2.2 910 3.36

FC + TCSC

Compensatio

100 % 3 650 3.1

110 % 2.95 700 3.27

51



n

120 % 2.95 700 3.27

Table 6.1. Comparison Table for No Compensation, FC, FC + TCSC

Compensation

6.5.CONCLUSION

In this chapter we are seen all the three types of simulinks i.e.

No Compensation, FC (Fixed Capacitance) Compensation, FC + TCSC

Compensation. Also all the block parameters of simulinks and more over the

resultant waveforms parameters at load side. And also the comparison table

for comparing all the values of these three simulinks.

52



CHAPTER 7

SCOPE OF FUTURE AND CONCLUSION

7.1.FUTURE SCOPE

• This system can not only be applied for 2 bus system but also multi

bus system.

• The dynamics of the system, as a whole, when subjected to large

disturbances, has to be studied and analyzed for voltage stability of

the system.

• The system investigated has been limited up to a three-phase power

system. It would be desirable to extend the proposed approach for

larger and more realistic systems.

• In this project voltage constrained transfer capability is computed the

future work could implement the other constraints like power

oscillations and sub-synchronous resonance considerations.

• The complex neural network approach is implemented for location of

TCSC as these devices are already in operation. This approach can be

extended to other FACTS devices also as they can shift the attitude

from ‘preventive’ approach requiring large standbys for emergency

purpose to a ‘corrective’ approach by creating instant corrections with

fewer versatile, controllable and manageable devices.

• The present work can be extended for damping of torsional

oscillations.

• The application of complex valued neural network approach is

implemented for contingency analysis using the offline data for

training purpose. This method can be extended for online application

of realistic power system.

•

For larger power system having thousands of variables, input featureselection for the neural network plays an important role. As the size of

the system increases the number of neurons increases there by

increasing the training time. A method of mutual information between

the input and output variables is to be investigated.

• In this research voltage constrained transfer capability is computed

the future work could implement the other constraints like thermal

and economic considerations.

• A well coordinated power system planning, control and operation is

required for the future electric utilities as they will find themselves inan increasingly competitive environment. There is an urgent need for

53



the development of methods, procedures and software tools to deal

with various contingencies, wide range of operating conditions. This

would help in further research on accurate transfer capability

computations.

• This project work can be extended to power system with generalized TCSC, UPFC and Interline Power Flow Controller (IPFC).

• This project work can be extended for STATCOM and SSSC with

energy storage such as battery Energy Storage System (BESS) and

Superconducting Magnetic Storage (SMSS) for enhancing power

system stability.

• Stability issues for a distribution network with different types of

distributed generation sources and FACTS devices could be examined

and FACTS-based controllers could be designed for improving the

stability in presence of different types of distributed generations.

• Different strategies could be tested and implemented in an attempt to

achieve a less time consuming process and gain better understanding

of heuristic optimization techniques applicability to various power

system phenomena.

• The dynamics of the system, as a whole, when subjected to large

disturbances, has to be studied and analyzed for voltage stability of

the system.

• New approach can be formulated to determine the voltage stability

index under multiple contingency conditions.

•

• FACTS devices are more effective in voltage stability enhancement.

The effect of various FACTS devices for voltage stability enhancement

can be analyzed and compared.

• Various optimization techniques like PSO and DE can be adopted for

the optimal location and optimal setting of FACTS devices for voltage

stability enhancement and their effectiveness can becompared.

•

Neuro-Fuzzy technique can be applied for voltage stability assessmentand its enhancement.

7.2.CONCLUSION

In this chapter we are see the future scope of TCSC. The completion of

project opens the avenues for work in many other related areas. The one of

54



the area is effect of TCSC on line outage in order to relieve congestion can be

studied. In this way the TCSC can be applied to various fields.

55



CHAPTER 8

APPENDIX

8.1. WITHOUT COMPENSATION

Fig.8.1. Matlab Simulink for No Compensation

8.2.WITH FC COMPENSATION

56



Fig.8.7. Matlab Simulink for FC Compensation

Fig.8.8. Fixed Capacitance Block Parameters

8.3.WITH FC & TCSC COMPENSATION

57



Fig.8.9. Matlab Simulink for FC + TCSC Compensation

Fig.8.10. Internal Simulnk Connection of TCSC Block

Fig.8.11. Control Ciruit for TCSC

8.4.CONCLUSION

Documents

Model B.Tech Project Documentation