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Advanced FACTS Devices and Applications: Performance, Power Quality and Cost Considerations


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Title: Advanced FACTS Devices and Applications: Performance, Power Quality and Cost Considerations

Lecture 3 Advanced FACTS Devices and
Applications Performance, Power Quality and Cost
Paulo F. Ribeiro, BSEE, MBA, PHD, PE CALVIN
COLLEGE Engineering Department Grand Rapids, MI
49546 http// PR
  • The Concept
  • History / Background - Origin of FACTS,
    Opportunities, Trends
  • System Architectures and Limitations
  • Power Flow Control on AC Systems
  • Application Studies and Implementation
  • Basic Switching Devices
  • Conditioners SVC, STATCOM, TCSC, UPFC, SMES
  • Specification, Cost Considerations and
    Technology Trends
  • Impact of FACTS in interconnected networks
  • Market Assessment, Deregulation and Predictions

The Concept
The Concept and Challenges
A transmission system can carry power up to its
thermal loading limits. But in practice the
system has the following constraints -Transmissi
on stability limits -Voltage limits -Loop
flows Transmission stability limits limits of
transmittable power with which a transmission
system can ride through major faults in the
system with its power transmission capability
intact. Voltage limits limits of power
transmission where the system voltage can be kept
within permitted deviations from nominal. Loop
flows can be a problem as they are governed by
the laws of nature which may not be coincident
with the contracted path. This means that power
which is to be sent from point A to point B
in a grid will not necessarily take the shortest,
direct route, but will go uncontrolled and fan
out to take unwanted paths available in the grid.
The Concept
FACTS devices FACTS are designed to remove such
constraints and to meet planners, investors and
operators goals without their having to
undertake major system additions. This offers
ways of attaining an increase of power
transmission capacity at optimum conditions, i.e.
at maximum availability, minimum transmission
losses, and minimum environmental impact. Plus,
of course, at minimum investment cost and time
expenditure. The term FACTS covers several
power electronics based systems used for AC power
transmission. Given the nature of power
electronics equipment, FACTS solutions will be
particularly justifiable in applications
requiring one or more of the following
qualities -Rapid dynamic response -Ability for
frequent variations in output -Smoothly
adjustable output. Important applications in
power transmission involving FACTS and Power
Quality devices SVC (Static Var Compensators),
Fixed as well as Thyristor-Controlled Series
Capacitors (TCSC) and Statcom. Still others are
PST (Phase-shifting Transformers), IPC
(Interphase Power Controllers), UPFC (Universal
Power Flow Controllers), and DVR (Dynamic Voltage
History, Concepts, Background, and Issues
Origin of FACTS -Oil Embargo of 1974 and
1979 -Environmental Movement -Magnetic Field
Concerns -Permit to build new transmission
lines -HVDC and SVCs -EPRI FACTS Initiative
(1988) -Increase AC Power Transfer (GE and DOE
Papers) -The Need for Power semiconductors Why
we need transmission interconnection -Pool power
plants and load centers to minimize generation
cost -Important in a deregulated
environment Opportunities for FACTS Increase
power transfer capacity SVC (Nebraska GE 1974,
Minnesota Westinghouse 1975, Brazil Siemens
1985) TCSC, UPFC AEP 1999 Trends -Generation is
not being built -Power sales/purchases are being
System Architectures and Limitations
System Architecture Radial, interconnected
areas, complex network Power Flow in an AC
System Power Flow in Parallel and Meshed
Paths Transmission Limitations Steady-State
(angular stability, thermal limits, voltage
limits) Stability Issues (transient, dynamic,
voltage and SSR) System Issues (Post contingency
conditions, loop flows, short-circuit
levels) Power Flow and Dynamic Stability
Considerations Controllable Parameters Basic
FACTS Devices - Impact of Energy Storage
Power Flow Control on AC Systems
Power Flow in Parallel Paths Power Flow in a
Meshed Systems What limits the loading
capability? Power Flow and Dynamic Considerations
Power Flow Control on AC Systems
Relative Importance of Controllable
Parameters Control of X can provide current
control When angle is large X can provide power
control Injecting voltage in series and
perpendicular to the current flow, can increase
or decrease
FACTS Applications and Implementations
Transmission Transfer Capacity Enhancement
Steady State Issues Voltage Limits Thermal
Limits Angular Stability Limits Loop Flows
Dynamic Issues Transient Stability Damping Power
Swings Post-Contingency Voltage Control Voltage
Stability Subsynchronous Res.
Traditional Solutions
Breaking Resistors Load Shedding
Advanced Solutions

FACTS Energy Storage
Fixed Compensation
Transmission Link
Enhanced Power Transfer and Stability
Line Reconfiguration
Better Protection
FACTS Devices
Increased Inertia
FACTS Devices Shunt Connected Static VAR
Compensator (SVC) Static Synchronous Compensator
(STATCOM) Static Synchronous Generator -
SSG Battery Energy Storage System
(BESS) Superconducting Magnetic Energy Storage
(SMES) Combined Series and Series-Shunt
Connected Static Synchronous Series Controllers
(SSSC) Thyristor Controlled Phase-Shifting
Transformer or Phase Angle Regulator
(PAR) Interline Power Flow Controller
(IPFC) Thyristor Controlled Series Capacitor
(TCSC) Unified Power Flow Controller
(UPFC) Relative Importance of Different Types of
Controllers Shunt, Shunt-Series
Energy Storage
Energy Storage
Power Electronics - Semiconductor Devices
Diodes Transistors IGBT Thyristors SCR, GTO, MTO,
Devices Diode (pn Junction) Silicon Controlled
Rectifier (SCR) Gate Turn-Off Thyristor (GTO)
GE MOS Turn-Off Thyristor (MTO) SPCO Emitter
Turn-Off Thyristor (ETO) Virginia Tech Integrated
Gate-Commutated Thyristor (IGCT) Mitsubishi,
ABB MOS-Controlled Thyristor (MCT) Victor
Temple Insulated Gate Bipolar Transistor (IGBT)
Power Electronics - Semiconductor Devices
Principal Characteristics Voltage and
Current Losses and Speed of Switching Speed of
Switching Switching Losses Gate-driver power and
energy requirements Parameter Trade-off Power
requirements for the gate di/dt and dv/dt
capability turn-on and turn-off
time Uniformity Quality of silicon wafers
IGBT has pushed out the conventional GTO as IGBTs
ratings go up. IGBTs - Low-switching losses, fast
switching, current-limiting capability GTOs -
large gate-drive requirements, slow-switching,
high-switching losses IGBTs (higher forward
voltage drop)
Power Electronics - Semiconductor Devices
Decision-Making Matrix
AC Transmission Fundamentals (Series Compensation)
E2 / ?2
E1 / ?1
Changes in X will increase or decrease real power
flow for a fixed angle or change angle for a
fixed power flow. Alternatively, the reactive
power flow will change with the change of X.
Adjustments on the bus voltage have little impact
on the real power flow.
P1 E1 . E2 . sin (?) / (X - Xc)
Vseff Vs Vc
Real Power Angle Curve
Xeff X - Xc
Power Transfer
Phase Angle
AC Transmission Fundamentals (Voltage-Series and
Shunt Comp.)
E2 / ?2
E1 / ?1
Integrated voltage series injection and bus
voltage regulation (unified) will directly
increase or decrease real and reactive power flow.
AC Transmission Fundamentals (Stability Margin)
Improvement of Transient Stability With FACTS
Compensation Equal Area Criteria
?1 - prior to fault
A1 Acceleration Energy A2 Deceleration Energy
?2 - fault cleared
?3 - equal area
Therefore, FACTS compensation can increase power
transfer without reducing the stability margin
?3 gt?crit - loss of synchronism
Voltage Source Vs. Current Source Converters
Voltage Source Converters
Voltage Source Converters
Basic 6-Pulse, 2-level, Voltage-Source Converter
Voltage Source Converters
2, 3, 5-level, VSC Waveforms
Voltage Source Converters
Output voltage control of a two-level VSC
FACTS Technology - Possible Benefits
  • Control of power flow as ordered. Increase the
    loading capability of lines to their thermal
    capabilities, including short term and seasonal.
  • Increase the system security through raising
    the transient stability limit, limiting
    short-circuit currents and overloads, managing
    cascading blackouts and damping
    electromechanical oscillations of power systems
    and machines.
  • Provide secure tie lines connections to
    neighboring utilities and regions thereby
    decreasing overall generation reserve
    requirements on both sides.
  • Provide greater flexibility in siting new
  • Reduce reactive power flows, thus allowing the
    lines to carry more active power.
  • Reduce loop flows.
  • Increase utilization of lowest cost generation.

FACTS and HVDC Complimentary Solutions
HVDC Independent frequency and control Lower line
costs Power control, voltage control, stability
FACTS Power control, voltage control, stability
Installed Costs (millions of dollars) Throughput
MW HVDC 2 Terminals FACTS 2000 MW 40-50
M 5-10 M 500 MW 75-100M 10-20M 1000
MW 120-170M 20-30M 2000 MW 200-300M
30-50M ()Hingorani/Gyugyi
FACTS and HVDC Complimentary Solutions
HVDC Projects Applications Submarine
cable Long distance overhead transmission
Underground Transmission Connecting AC systems
of different or incompatible frequencies
  • Large market potential for FACTS is within the ac
    system on a value-added basis, where
  • The existing steady-state phase angle between
    bus nodes is reasonable
  • The cost of a FACTS device solution is lower
    than HVDC or other alternatives
  • The required FACTS controller capacity is less
    than 100 of the transmission throughput rating

FACTS Attributes for Different Controllers
FACTS Implementation - STATCOM
E2 / ?2
E1 / ?1
Regulating Bus Voltage Can Affect Power Flow
Indirectly / Dynamically
P1 E1 (E2 . sin (?))/X
FACTS Implementation - TCSC
E2 / ?2
E1 / ?1

Line Impedance Compensation Can Control Power
Flow Continuously
P1 E1 (E2 . sin (?)) / Xeff
Xeff X- Xc
The alternative solutions need to be distributed
often series compensation has to be installed in
several places along a line but many of the other
alternatives would put both voltage support and
power flow control in the same location. This may
not be useful. For instance, if voltage support
were needed at the midpoint of a line, an IPFC
would not be very useful at that spot. TCSC for
damping oscillations ...
FACTS Implementation - SSSC
E2 / ?2
E1 / ?1
P1 E1 (E2 . sin (?)) / Xeff
Xeff X - Vinj/I
FACTS Implementation - UPFC
E2 / ?2
E1 / ?1
Regulating Bus Voltage and Injecting Voltage In
Series With the Line Can Control Power Flow
P1 E1 (E2 . sin (?)) / Xeff
Xeff X - Vinj / I
Q1 E1(E2 - E2 . cos (?)) / X
FACTS Implementation - UPFC
FACTS Implementation - STATCOM Energy Storage
E2 / ?2
E1 / ?1
Regulating Bus Voltage Plus Energy Storage Can
Affect Power Flow Directly / Dynamically
Plus Energy Storage
FACTS Implementation - SSSC Energy Storage
E2 / ?2
E1 / ?1
Voltage Injection in Series Plus Energy
Storage Can Affect Power Flow Directly /
Dynamically and sustain operation under fault
Plus Energy Storage
FACTS Implementation - UPFC Energy Storage
E2 / ?2
E1 / ?1
Regulating Bus Voltage Injected Voltage
Energy Storage Can Control Power Flow
Continuously, and Support Operation Under Severe
Fault Conditions (enhanced performance)
Plus Energy Storage
FACTS Implementation - UPFC Energy Storage
FACTS Implementation - UPFC Energy Storage
FACTS Implementation - TCSC STACOM Energy

Regulating Bus Voltage Energy Storage Line
Impedance Compensation Can Control Power Flow
Continuously, and Support Operation Under Severe
Fault Conditions (enhanced performance)
FACTS Implementation - IPFC
E3 / ?3
E1 / ?1
E2 / ?2
P12 E1 (E2 . sin (?1- ?2)) / X
P13 E1 (E2 . sin (?1- ?3)) / X
FACTS Implementation - IPFC
Enhanced Power Transfer and Stability Technologie
s Perspective
Increased Power Transfer
FACTS Energy Storage
The Role of Energy Storage real power
compensation can increase operating control and
reduce capital costs
STATCOM Reactive Power Only Operates in the
vertical axis only
MVA Reduction
P - Active Power Q - Reactive Power
The Combination or Real and Reactive Power will
typically reduce the Rating of the Power
Electronics front end interface. Real Power takes
care of power oscillation, whereas reactive power
controls voltage.
STATCOM SMES Real and Reactive Power Operates
anywhere within the PQ Plane / Circle (4-Quadrant)
FACTS Energy Storage - Location Sensitivity
Enhanced Power Transfer and Stability Location
and Configuration Type Sensitivity
FACTS For Optimizing Grid Investments FACTS
Devices Can Delay Transmission Lines
Construction By considering series compensation
from the very beginning, power transmission
between regions can be planned with a minimum of
transmission circuits, thus minimizing costs as
well as environmental impact from the start. The
Way to Proceed Planners, investors and
financiers should issue functional specifications
for the transmission system to qualified
contractors, as opposed to the practice of
issuing technical specifications, which are often
inflexible, and many times include older
technologies and techniques) while inviting bids
for a transmission system. Functional
specifications could lay down the power capacity,
distance, availability and reliability requirement
s and last but not least, the environmental
conditions. Manufacturers should be allowed to
bid either a FACTS solution or a solution
involving the building of (a) new line(s) and/or
generation and the best option chosen.
Specifications (Functional rather than
Technical ) Transformer Connections Higher-Pulse
Operation Higher-Level Operation PWM
Converter Pay Attention to Interface Issues and
Controls Converter Increase Pulse Number Higher
Level Double the Number of Phase-Legs and Connect
them in Parallel Connect Converter Groups in
Parallel Use A Combination of several options
listed to achieve required rating and performance
Cost Considerations
Cost Considerations
Cost structure The cost of a FACTS installation
depends on many factors, such as power rating,
type of device, system voltage, system
requirements, environmental conditions,
regulatory requirements etc. On top of this, the
variety of options available for optimum design
renders it impossible to give a cost figure for a
FACTS installation. It is strongly recommended
that contact is taken with a manufacturer in
order to get a first idea of costs
and alternatives. The manufacturers should be
able to give a budgetary price based on a brief
description of the transmission system along with
the problem(s) needing to be solved and the
improvement(s) needing to be attained. () Joint
World Bank / ABB Power Systems Paper Improving
the efficiency and quality of AC transmission
Technology Cost Trends
Concerns About FACTS Cost Losses Reliability
Economics of Power Electronics Sometimes a mix
of conventional and FACTS systems has the lowest
cost Losses will increase with higher loading and
FACTS equipment more lossy than conventional
ones Reliability and security issues - when
system loaded beyond the limits of
experience Demonstration projects required
Stig Nilsons paper
Operation and Maintenance Operation of FACTS in
power systems is coordinated with operation of
other items in the same system, for smooth and
optimum function of the system. This is achieved
in a natural way through the Central Power System
Control, with which the FACTS device(s) is (are)
communicating via system SCADA. This means that
each FACTS device in the system can be operated
from a central control point in the grid, where
the operator will have skilled human resources
available for the task. The FACTS device itself
is normally unmanned, and there is normally no
need for local presence in conjunction with FACTS
operation, although the device itself may be
located far out in the grid. Maintenance is
usually done in conjunction with regular system
maintenance, i.e. normally once a year. It will
require a planned standstill of typically a
couple of days. Tasks normally to be done are
cleaning of structures and porcelains, exchanging
of mechanical seals in pump motors, checking
through of capacitors, checking of control and
protective settings, and similar. It can normally
be done by a crew of 2-3 people with engineers
skill. Joint World Bank / ABB Power Systems
Paper Improving the efficiency and quality of AC
transmission systems
Impact of FACTS in interconnected networks The
benefits of power system interconnection are well
established. It enables the participating parties
to share the benefits of large power systems,
such as optimization of power generation,
utilization of differences in load profiles and
pooling of reserve capacity. From this follows
not only technical and economical benefits, but
also environmental, when for example surplus of
clean hydro resources from one region can help to
replace polluting fossil-fuelled generation in
another. For interconnections to serve their
purpose, however, available transmission links
must be powerful enough to safely transmit the
amounts of power intended. If this is not the
case, from a purely technical point of view it
can always be remedied by building additional
lines in parallel with the existing, or by
uprating the existing system(s) to a higher
voltage. This, however, is expensive,
time-consuming, and calls for elaborate
procedures for gaining the necessary permits.
Also, in many cases, environmental
considerations, popular opinion or other
impediments will render the building of new lines
as well as uprating to ultrahigh system voltages
impossible in practice. This is where FACTS comes
in. Examples of successful implementation of
FACTS for power system interconnection can be
found among others between the Nordic Countries,
and between Canada and the United States. In such
cases, FACTS helps to enable mutually beneficial
trade of electric energy between the
countries. Other regions in the world where FACTS
is emerging as a means for AC bulk power
interchange between regions can be found in South
Asia as well as in Africa and Latin America. In
fact, AC power corridors equipped with SVC and/or
SC transmitting bulk power over distances of more
than 1.000 km are a reality today. Joint World
Bank / ABB Power Systems Paper Improving the
efficiency and quality of AC transmission systems
Power Quality Issues 1 Background 2 The Need
For An Integrated Perspective of PQ 3
Harmonics 4 Imbalance 5 Voltage
Fluctuations 6 Voltage Sags 7 Standards,
Limits, Diagnostics, and Recommendations Flexibili
ty, Compatibility, Probabilistic Nature,
Alternative Indices 8 Combined effects 9
Power Quality Economics 10 Measurement
Protocols 11 Probabilistic Approach 12
Modeling Simulation 13 Advanced Techniques
(Wavelet, Fuzzy Logic, Neural Net, Genetic
Algorithms) 14 Power Quality Programs
Compatibility The Key Approach
Relative Trespass Level (RTL)
Uk - measured or calculated harmonic
voltage Uref - harmonic voltage limit (standard
or particular equipment) k - harmonic order
Harmonic Distortion Diagnostic Index Applying
Fuzzy Logic Comparisons Alternative Approach
How To Interpret This?
How To Interpret This?
(No Transcript)
  • Future systems can be expected to operate at
    higher stress levels
  • FACTS could provide means to control and
    alleviate stress
  • Reliability of the existing systems minimize
    risks (but not risk-free)
  • Interaction between FACTS devices needs to be
  • Existing Projects - Met Expectations
  • More Demonstrations Needed
  • RD needed on avoiding security problems (with
    and w/o FACTS)
  • Energy storage can significantly enhance FACTS
    controllers performance

Conclusions A Balanced and Cautious
Application The acceptance of the new tools and
technologies will take time, due to the
computational requirements and educational
barriers. The flexibility and adaptability of
these new techniques indicate that they will
become part of the tools for solving power
quality problems in this increasingly complex
electrical environment. The implementation and
use of these advanced techniques needs to be done
with much care and sensitivity. They should not
replace the engineering understanding of the
electromagnetic nature of the problems that need
to be solved.
Questions and Open Discussions