No Slide TitleAdvanced FACTS Devices and Applications: Performance,
Power Quality and Cost Considerations
Paulo F. Ribeiro, BSEE, MBA, PHD, PE
CALVIN COLLEGE
Engineering Department
System Architectures and Limitations
Application Studies and Implementation
Market Assessment, Deregulation and Predictions
P. Ribeiro
June, 2002
The Concept
P. Ribeiro
June, 2002
A transmission system can carry power up to its thermal loading
limits. But in practice the system has the following
constraints:
-Transmission 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 and Challenges
P. Ribeiro
June, 2002
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
-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 Restorers).
The Concept
P. Ribeiro
June, 2002
Origin of FACTS
-Environmental Movement
-HVDC and SVCs
-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
SVC (Nebraska GE 1974, Minnesota Westinghouse 1975, Brazil Siemens
1985)
TCSC, UPFC AEP 1999
-Power sales/purchases are being
Power Flow in an AC System
Power Flow in Parallel and Meshed Paths
Transmission Limitations
System Issues (Post contingency conditions, loop flows,
short-circuit levels)
Power Flow and Dynamic Stability Considerations
Controllable Parameters
System Architectures and Limitations
Power Flow in Parallel Paths
Power Flow in a Meshed Systems
What limits the loading capability?
Power Flow and Dynamic Considerations
Radial
Parallel
Meshed
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
50% Series Compensation
Line Reconfiguration
Fixed Compensation
Phase Angle Regulator (PAR)
Relative Importance of Different Types of Controllers
Shunt, Shunt-Series
Energy Storage
Energy Storage
P. Ribeiro
June, 2002
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
P. Ribeiro
June, 2002
Speed of Switching
Parameter Trade-off
di/dt and dv/dt capability
turn-on and turn-off time
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)
P. Ribeiro
June, 2002
Real Power Angle Curve
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.
Vx
I
Vxo
Vs
I
Vs
P. Ribeiro
June, 2002
Integrated voltage series injection and bus voltage regulation
(unified) will directly increase or decrease real and reactive
power flow.
AC Transmission Fundamentals (Voltage-Series and Shunt Comp.)
E1
E2
I
Improvement of Transient Stability With FACTS Compensation
Equal Area Criteria
A1 = Acceleration Energy
A2 = Deceleration Energy
power transfer without reducing the stability margin
AC Transmission Fundamentals (Stability Margin)
1
2
3
crit
A1
A2
Amargin
Q / V
P. Ribeiro
June, 2002
CSC
AdvDis
VSC
Adv
Dis
Limited by DC Reactor
Losses
Higher
Independent of Energy Storage
Voltage Source Converters
Voltage Source Converters
Voltage Source Converters
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 generation.
Reduce reactive power flows, thus allowing the lines to carry more
active power.
Reduce loop flows.
P. Ribeiro
June, 2002
HVDC
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
FACTS and HVDC: Complimentary Solutions
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
HVDC Projects: Applications
P. Ribeiro
June, 2002
FACTS Controller
Control Attributes
Voltage control, VAR compensation, damping oscillations, voltage
stability
Static Synchronous Compensator (STATCOM with storage, BESS, SMES,
large dc capacitor)
Voltage control, VAR compensation, damping oscillations, transient
and dynamic stability, voltage stability, AGC
Static VAR Compensator (SVC, TCR, TCS, TRS
Voltage control, VAR compensation, damping oscillations, transient
and dynamic stability, voltage stability
Thyristor-Controlled Braking Resistor (TCBR)
Static Synchronous Series Compensator (SSSC without storage)
Current control, damping oscillations, transient and dynamic
stability, voltage stability, fault current limiting
Static Synchronous Series Compensator (SSSC with storage)
Current control, damping oscillations, transient and dynamic
stability, voltage stability
Thrystor-Controlled Series Capacitor (TCSC, TSSC)
Current control, damping oscillations, transient and dynamic
stability, voltage stability, fault current limiting
Thyristor-Controlled Series Reactor (TCSR, TSSR)
Current control, damping oscillations, transient and dynamic
stability, voltage stability, fault current limiting
Thyristor-Controlled Phase-Shifting Transformer (TCPST or
TCPR)
Active power control, damping oscillations, transient and dynamic
stability, voltage stability
Unified Power Flow Controller (UPFC)
Active and reactive power control, voltage control, VAR
compensation, damping oscillations, transient and dynamic
stability, voltage stability, fault current limiting
Thyristor-Controlled Voltage Limiter (TCVL)
Thyristor-Controlled Voltage Regulator (TCVR)
Interline Power Flow Controller (IPFC)
Reactive power control, voltage control, damping oscillations,
transient and dynamic stability, voltage stability
P. Ribeiro
June, 2002
E1 / 1
E2 / 2
FACTS Implementation - STATCOM
E1 / 1
E2 / 2
P&Q
X
FACTS Implementation - TCSC
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 ...
P. Ribeiro
June, 2002
Xeff = X - Vinj/I
P&Q
Regulating Bus Voltage and Injecting Voltage In Series With the
Line
Can Control Power Flow
Xeff = X - Vinj / I
P. Ribeiro
June, 2002
E1 / 1
E2 / 2
P. Ribeiro
June, 2002
Plus Energy Storage
Can Affect Power Flow Directly / Dynamically
and sustain operation under fault conditions
P. Ribeiro
June, 2002
Regulating Bus Voltage + Injected Voltage + Energy Storage
Can Control Power Flow Continuously, and Support Operation Under
Severe Fault Conditions (enhanced performance)
FACTS Implementation - UPFC + Energy Storage
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June, 2002
Shunt Inverter
Series Inverter
SMES Chopper and Coil
SMES Chopper and Coil - Overvoltage Protection
UPFC Grounding
Regulating Bus Voltage + Energy Storage + Line Impedance
Compensation
Can Control Power Flow Continuously, and Support Operation Under
Severe Fault Conditions (enhanced performance)
FACTS Implementation - TCSC + STACOM + Energy Storage
P. Ribeiro
June, 2002
E1 / 1
E3 / 3
E2 / 2
P. Ribeiro
June, 2002
Technologies’ Perspective
STATCOM + SMES
P
Q
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.
The Role of Energy Storage: real power compensation can increase
operating control and reduce capital costs
P - Active Power
Q - Reactive Power
SMES Power (MW)
Additional Power Transfer(MW)
Closer to generation
System Frequency
System Frequency
System Frequency
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
requirements; 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.
P. Ribeiro
June, 2002
Converter
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
P. Ribeiro
June, 2002
Cost Considerations
Competitive
$8-$12 kVAR
Voltage support and stability
Power flow control, Voltage support and Stability
$12-$16 kVAR
Competitive
Power flow control, Voltage support and stability
$25-$50 kVAR
Limited competition
Limited competition
STATCOM w/SMES
Compensates for inductive and/or capacitive var-load plus energy
storage for active power
Limited
Power flow control, Voltage support, and Stability
$150-$200 kW
Sole source
Power flow control Voltage support and Stability,
$250-$350 kW
SVC and TCSC functions plus voltage regulator, phase angle
controller and energy storage
Sole source
Shaded area indicates technologies that are either permanently
connected or switched on or off with mechanical switches. (i.e.
these are not continuously controllable)
P. Ribeiro
June, 2002
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.
Improving the efficiency and quality of AC transmission
systems
Chart2
Hardware
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
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 engineer´s skill.
Joint World Bank / ABB Power Systems Paper
Improving the efficiency and quality of AC transmission
systems
P. Ribeiro
June, 2002
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
P. Ribeiro
June, 2002
3 – Harmonics
4 – Imbalance
8 – Combined effects
14 – Power Quality Programs
Uref - harmonic voltage limit (standard or particular
equipment)
k - harmonic order
Alternative Approach
SMES
Batteries
FACTS
SMES
Conclusions
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 studied
Existing Projects - Met Expectations
More Demonstrations Needed
R&D needed on avoiding security problems (with and w/o
FACTS)
Energy storage can significantly enhance FACTS controllers
performance
P. Ribeiro
June, 2002
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.
P. Ribeiro
June, 2002
Competitive
Limited
phase angle control
voltage regulator, phase angle
controller and energy storage
Shaded area indicates technologies that are either permanently
connected or switched on or off with mechanical switches. (i.e.
these are
not continuously controllable)
stability
large dc capacitor)
and dynamic stability, voltage stability, AGC
Static VAR Compensator (SVC, TCR,
TCS, TRS
and dynamic stability, voltage stability
Thyristor-Controlled Braking Resistor
Static Synchronous Series Compensator
voltage stability, fault current limiting
Static Synchronous Series Compensator
voltage stability
voltage stability, fault current limiting
Thyristor-Controlled Series Reactor
voltage stability, fault current limiting
Thyristor-Controlled Phase-Shifting
stability, voltage stability
Active and reactive power control, voltage control, VAR
compensation, damping oscillations, transient and dynamic
stability,
voltage stability, fault current limiting
Thyristor-Controlled Voltage Limiter
Thyristor-Controlled Voltage Regulator
transient and dynamic stability, voltage stability
Interline Power Flow Controller (IPFC)
Reactive power control, voltage control, damping
oscillations,
transient and dynamic stability, voltage stability
P
tg
P
V
V
P
X
X
P
Current
Losses
Higher
Current
Losses
Higher