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8/18/2019 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
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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
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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.
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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
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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
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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.
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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
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(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
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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
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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.
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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
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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)
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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).
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- 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
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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.
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5.5.PRINCIPLE CHARACTERISTICS OF TCSC OPERATION
Fig.5.4. Block diagram for TCSC
Fig.5.5. Control Circuit for TCSC
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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
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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)
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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.
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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)
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IR (A) Vs T (ms)
PL (MW) Vs T (ms)
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The variation of outputs at load side for VR, IR and PLfor 110 % Load
to 120 % are as follows:
VR (KV) Vs T (ms)
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IR (A)Vs T (ms)
PL (M
W) Vs T (ms)
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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
The above figure 6.2 shows the basic circuit connection of 3-phase
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.
So, here the variation of outputs at load side for VR, IR and PLfor 100
% Load to 110% are as follows:
VR (KV) Vs T (ms)
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IR (A)Vs T (ms)
PL
(MW)
Vs T (ms)
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The variation of outputs at load side for VR, IR and PLfor 110 % Load
to 120 % are as follows:
VR (KV) Vs T (ms)
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IR (A)Vs T (ms)
PL (MW) Vs T (ms)
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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.
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6.3.FC + TCSC COMPENSATION
Fig.6.3. Circuit connection of Transmission Line with FC +TCSC
compensation
The above figure 6.3 shows the basic circuit connection of 3-phase
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.
So, here the variation of outputs at load side for VR, IR and PLfor 100
% Load to 110% are as follows:
VR (KV) Vs T (ms)
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IR (A)Vs T (ms)
PL (MW) Vs T (ms)
The variation of outputs at load side for VR, IR and PLfor 110 % Load
to 120 % are as follows:
VR (KV) Vs T (ms)
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IR (A)
Vs T
(ms)
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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)
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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
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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
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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.
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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
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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
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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.
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CHAPTER 8
APPENDIX
8.1. WITHOUT COMPENSATION
Fig.8.1. Matlab Simulink for No Compensation
8.2.WITH FC COMPENSATION
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Fig.8.7. Matlab Simulink for FC Compensation
Fig.8.8. Fixed Capacitance Block Parameters
8.3.WITH FC & TCSC COMPENSATION
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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