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8/8/2019 Mini Curso FACTS 2001F
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1P. Ribeiro August, 2001
Mini-Curso
Paulo F. Ribeiro, BSEE, MBA, PHD, PE
CALVIN COLLEGE
Engineering Department
Grand Rapids, MI 49546
PowerTra
nsfer
Phase Angle
From EPRI
An Overview on FACTS Controllers
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2P. Ribeiro August, 2001
Outline
• Introduction - 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• Systems Studies
• AC Transmission Fundamentals
• Voltage Source vs. Current Source
• Voltage Sources
• Static Var Compensator (SVC), STATCOM, TCSC, UPFC, SMES
• System Studies (by EMTP, ATP, Saber, EDSA, EMTDC)
• Systems Integration, Specification, Cost Considerations and Technology Trends• Operation and Maintenance
• Impact of FACTS in interconnected networks
• Market Assessment, Deregulation and Predictions
• Conclusions - Final Words
• Questions and Open Discussions
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3P. Ribeiro August, 2001
The reason, therefore, that some intuitive minds are not mathematical is that they
cannot at all turn their attention to the principles of mathematics. But the reason
that mathematicians are not intuitive is that they do not see what is before them,
and that, accustomed to the exact and plain principles of mathematics, and not
reasoning till they have well inspected and arranged their principles, they are
lost in matters of intuition where the principles do not allow of such arrangement.
They are scarcely seen; they are felt rather than seen; there is the greatest
difficulty in making them felt by those who do not of themselves perceive them.These principles are so fine and so numerous that a very delicate and very clear
sense is needed to perceive them, and to judge rightly and justly when they are
perceived, without for the most part being able to demonstrate them in order as in
mathematics, because the principles are not known to us in the same way, and
because it would be an endless matter to undertake it. We must see the matter at
once, at one glance, and not by a process of reasoning, at least to a certain
degree.
1660 PENSEES by Blaise Pascal
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4P. Ribeiro August, 2001
P tg P V
V
P X
X
P •
∆
+•
∆
+•
∆
−=∆ φ
φ The Concept
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5P. Ribeiro August, 2001
A transmission system can carry power up to its thermal loading limits. But inpractice the system has the following constraints:
-Transmission stability limits-Voltage limits-Loop flows
Transmission stability limits: limits of transmittable power with which a transmissionsystem can ride through major faults in the system with its power transmissioncapability intact.
Voltage limits: limits of power transmission where the system voltage can be keptwithin permitted deviations from nominal. Voltage is governed by reactive power (Q).
Q in its turn depends of the physical length of the transmission circuit as well as fromthe flow of active power. The longer the line and/or the heavier the flow of activepower, the stronger will be the flow of reactive power, as a consequence of which thevoltage will drop, until, at some critical level, the voltage collapses altogether.
Loop flows can be a problem as they are governed by the laws of nature which maynot 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, directroute, but will go uncontrolled and fan out to take unwanted paths available in the
The Concept
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6P. Ribeiro August, 2001
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 Restorers).
The Concept
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7P. Ribeiro August, 2001
Introduction: 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 FACTSIncrease 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
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8P. Ribeiro August, 2001
System Architecture
Radial, interconnected areas, complex network
Power Flow in an AC System
Power Flow in Parallel and Meshed Paths
Transmission LimitationsSteady-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
System Architectures and Limitations
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9P. Ribeiro August, 2001
The relative importance of transmission interconnection
Interconnections in a European type system are not very important because the system is built by
providing generation close to the loads and therefore, transmission is mainly for emergency
conditions.
In the US,very large power plants far from the load centers were built to bring "coal or water by
wire". Large plants provided the best solution - economy of scale. Also, seasonal power exchanges
have been used to the economic advantage of the consumers.
Newer generation technologies favor smaller plants which can be located close to the loads and
therefore, reduces the need for transmission. Also, if distributed generation takes off, then generationwill be much closer to the loads which would lessen the need for transmission even further.
However, for major market players, once the plant is built, the transmission system is the only way to
bring power to the consumer that is willing to pay the most for the power. That is, without
transmission, we will not get a well functioning competitive market for power.
System Architectures and Limitations
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10P. Ribeiro August, 2001
Power Flow Control on AC Systems
Radial
Parallel
Meshed
Power Flow in Parallel Paths
Power Flow in a Meshed Systems
What limits the loading capability?
Power Flow and Dynamic Considerations
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11P. Ribeiro August, 2001
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
50% Series Compensation
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12P. Ribeiro August, 2001
Transmission Transfer Capacity Enhancement
Advanced Solutions
Transmission
Link
Enhanced
Power Transfer
and Stability
Line
Reconfiguration
Fixed
Compensation
FACTS
Energy Storage
Better
Protection
Increased
Inertia
Breaking
Resistors LoadShedding
FACTS
Devices
Traditional Solutions
SVC
STATCOM
TCSC, SSSC
UPFC
Steady State
Issues
Voltage Limits
Thermal LimitsAngular Stability Limits
Loop Flows
Dynamic
Issues
Transient StabilityDamping Power Swings
Post-Contingency
Voltage Control
Voltage Stability
Subsynchronous Res.
FACTS Applications and Implementations
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13P. Ribeiro August, 2001
FACTS Devices
Shunt ConnectedStatic 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-Serie Energy Storage
Energy Storage
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14P. Ribeiro August, 2001
DevicesDiode (pn Junction)
Silicon Controlled Rectifier (SCR)
Gate Turn-Off Thyristor (GTO) GEMOS 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
DiodesTransistors
IGBT
Thyristors
SCR, GTO, MTO, ETO, GCT, IGCT, MCT
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15P. Ribeiro August, 2001
Power Electronics - Semiconductor DevicesPrincipal 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
UniformityQuality 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)
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16P. Ribeiro August, 2001
VSI CSI
Natural Forced
Synchronous PWM
Hard Soft
Two-Level Multi-Level
SCR GTO IGBT MCT MTO
System
CommutationApproach
SwitchingTechnology
TransitionApproach
CircuitTopology
DeviceType
Power Electronics - Semiconductor DevicesDecision-Making Matrix
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17P. Ribeiro August, 2001
Planing Studies
Evaluate the technical and economic benefits of a range of FACTS alternative solutions which
may allow enhancement of power transfer across weak transmission links. Part I of thiseffort should concentrate on preliminary feasibility studies to assess the technical merits of alternative solutions to correct real and reactive power transfer ratings, system voltageprofiles, operational effects on the network, equipment configurations, etc.
A - Load flow studies will be performed to establish steady-state ratings, and identify theappropriate locations for connection of alternative compensation devices. Load flow studieswill be used to address the following:
•System Criteria (maximum steady-state power transfers, short-term operating limits, etc.)•Controller Enhancements (controller types, ratings, sensitivities, etc.)•Controller Losses (based on operating points and duration)•System Losses (system losses base on controller operating point and duration)•Overvoltsages ((steady-state and short-term voltage insulation requirements)•Compare technical and economic benefits of alternatives•Identify interconnection points•Identify critical system contingencies•Establish power transfer capability of the transmission system•Confirm that reliability criteria can be met•Identify the cost of capital of equipment and losses•Identify steady-state and dynamic characteristics of FACTS controllers
Stability Studies
IEEE
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18P. Ribeiro August, 2001
Power Transfer Enhancement Studies
Study Category
Study Type Planning Performance Design OperationalLOAD FLOW
System
Controller
Overvoltages &
Short-Circuit
Establish existing and future network benchmarks for
power flows, bus voltages, and phase-angles
Identify network control variables, evaluate FACTScontroller configurations, enhancements, and establish preliminary controller steady-state ratings andlocations
Establish steady-state and short-term overvoltagerequirements for network and controllers
Determine final power flow conditions and
system performance criteria.
Determine final steady-state ratings, controlvariables, controller configurations, andlocation
Determine final controller fault levels andmitigation criteria.
Verify detailed design studies
Establish controller equipment hardwareratings and software requirements
Establish FACTS controller equipmentovervoltage ratings.
Confirm network loadflow conditions are
within benchmark limits
Confirm FACTS controller effectiveness toenhance network steady-state performance
Setup instrumentation and obtainmeasurements during staged fault tests andevaluate on-line faults.
DYMANIC
Damping
Voltage
Stability
Interaction
Control
Strategies
Fault Duties
Overvoltages
Frequency
Establish effectiveness of alternatives to dampnetwork power oscillations
Establish preliminary criteria
Establish preliminary criteria
Establish preliminary criteria
xxx
Evaluate symmetric and unsymmetric fault duties for system and controller, including mitigation measures
xxx
Determine final performance criteria andcontrol variables
Finalize performance criteria
Finalize performance criteria
Finalize performance criteria
Establish performance criteria
Establish performance criteria
Establish network performance criteria
Verify performance
Verify performance
Verify performance
Verify performance
Verify performance
Verify performance
Verify performance
Confirm performance
Confirm performance
Confirm performance
Confirm performance
Setup instrumentation and obtainmeasurements during staged fault tests andevaluate on-line system faults
Confirm performance
Confirm performance
TRANSIENT
Short-Circuit
Post-Transient
Voltage
Instability
System SSR
Controller SSR
xxx
xxx
xxx
Identify system sensitivity issues
xxx
Establish criteria
Establish criteria
Establish criteria
Evaluate mitigation measures
Establish criteria for interaction with system
Verify performance
Verify performance
Verify performance
Verify performance
Verify system SSR models and demonstratedamping or mitigation performance
Confirm performance
Confirm performance
Confirm performance
Confirm performance
Instrument and confirm system sensitivitywhile monitoring and testing SSR damping/mitigation performance
System Studies
IEEE
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19P. Ribeiro August, 2001
System Studies
System data and
configuration
Outagesand load
transfer
Load Flow(P,Q, V, θ )
Transient
Stability
(P,Q, V, θ , time)
Dynamic
Stability
(P,Q, V, θ , ω ,
time)
Generator
data
Voltage
Reg. Data
(AVR)
Governor data
Relay
data
Systemoperat.
limits
Induction
motor data
Fault
data
Systemchanges
Load
Shedding
Identify
Transmission
Systems - Provide
System data and
Configuration
Outages
and load
transfer
Perform Load
Flow
(P,Q, V, θ )
System
operat.
limits
Identify and Size
Transfer Enhancement
Solutions Devices
Perform
Economic
Analysis
IEEE
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20P. Ribeiro August, 2001
Power Transfer Enhancement Studies (Cont’d)
Study Category
Study Type Planning Performance Design OperationalHARMONICS
System
Controller
Interaction
Controller
Performance
xxx
xxx
xxx
Analyze system sensitivity and establish
criteria
Analyze and identify potential system
interactions and establish performance criteria
Establish harmonic current, voltage, and
communication system harmonic criteria
xxx
Perform design studies and offsite tests to
verify controller can meet established
criteria
Perform design studies and calculations to
establish equipment performance
requirements.
Instrumentation and testing to confirm system
harmonics are within established, limits
without FACTS controller
Monitor potential system interactions to
confirm performance of FACTS controller
causes no interactions
Instrumentation and testing to confirm FACTS
controller performance levels
CR&I
Control
Relaying
Instrumentation
xxx
xxx
xxx
Establish criteria
Establish criteria
Establish criteria
Verify performance
Verify performance
Verify performance
Confirm performance
Confirm performance
Confirm performance
RELIABILITY/
AVAILABILITY Assess impact of FACTS controller configurations on
system criteria including cooling systems
Finalize reliability/availability criteria for
FACTS controller
Calculate expected FACTS controller
reliability/availability performance
Measure reliability/availability performance of
FACTS controller
COST FACTORS
System
Controller
Losses
Benefits
Risks
Assess impact of system transmission network and
substation facilities
Preliminary impact assessment
Analysis of controller and system losses
Preliminary impact assessment
Preliminary impact assessment
Determine impact of control, relaying, and
instrumentation requirements
Final Assessment
xxx
Final Assessment
Final Assessment
Evaluate impact that alternatives have on
system and develop cost factors
Establish preliminary cost estimates for
various controller configurations
Determine network electrical losses and
establish value for each configuration being
investigated.
Summarize technical and economic benefits
for alternatives being investigated
Summarize technical and economic risks
for each alternative
xxx
xxx
Establish operational losses algorithm
xxx
xxx
System Studies
IEEE
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21P. Ribeiro August, 2001
E2 / δ 2
X
E1 / δ 1
I
P&Q
E1
E2
E1 . sin (δ )
E2 . cos(δ )
(E1 - E2 . cos(δ )E2 . sin(δ )
I
(E2 - E1 . cos(δ )Iq1 = (E1 - E2 . cos(δ ) / X
E1 . Cos (δ )
Ip1 = E2 sin(δ ) / X
E1 - E2P1 = E1 . Ip1
AC Transmission Fundamentals
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22P. Ribeiro August, 2001
Active component of the current flow at E1
Ip1 = (E2 . sin (δ )) / X
Reactive component of the current flow at E1
Iq1 = (E1 - E2 . cos (δ ))/X
Active Power at the E1 end
P1 = E1 (E2 . sin (δ ))/X
Reactive Power at the E1 end
Q1 = E1(E1 - E2 . cos (δ )) / X
AC Transmission Fundamentals
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23P. Ribeiro August, 2001
E2 / δ 2
P1 = E1 (E2 . sin (δ ))/X
I
X
E1
E2
E1 - E2
Regulating end bus voltage mostly change reactive power - Compensating at an intermediate
point between buses can significantly impact power flow
E1 / δ 1 I P&Q
Q / VP1 = k1.E1 (E2 . sin (δ /k2))/X
AC Transmission Fundamentals (Voltage - Shunt Control)
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24P. Ribeiro August, 2001
E1
E2
I
X
E1 - E2
Injected Voltage
Injecting Voltage in series with the line mostly change real power
E1 /δ
1
E2 / δ 2
IP&Q
Vinj
P1 = E1 . E2 . sin (δ ) / (X - Vinj / I)
AC Transmission Fundamentals (Voltage-Series Injection)
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25P. Ribeiro August, 2001
X
E1 /δ
1
E2 / δ 2
I P&Q
0 0.5 1 1.5 2 2.5 3 3.50
1
22
0
P1 x delta, V1,( )
3.140 delta
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
Xeff = X - Xc
Vx
Vr
Vc
Vseff = Vs + Vc
Vr
Vc
Vseff
P1 = E1 . E2 . sin (δ ) / (X - Xc)
Vs
Phase Angle
PowerTran
sfer
AC Transmission Fundamentals (Series Compensation)
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26P. Ribeiro August, 2001
X
E1 / δ 1 E2 / δ 2
I
P&Q
P
E1
E2
I
E1 - E2
Injected Voltage
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.)
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27P. Ribeiro August, 2001
δ 1 - prior to fault
δ 2 - fault cleared
δ 3 - equal area
δ 3 >δ crit - loss of synchronism
Improvement of Transient Stability With FACTS Compensation
Equal Area Criteria
δ 1 δ 2 δ 3 δ crit
A1
A2
Amargin
Maximum
PowerTransfer
Phase Angle
no compensation
with VAR compensation (ideal midpoint)
A1 = Acceleration Energy
A2 = Deceleration Energy
Therefore, FACTS compensation can increase
power transfer without reducing the stability margin
Q / V
AC Transmission Fundamentals (Stability Margin)
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28P. Ribeiro August, 2001
Voltage Source Vs. Current Source Converters
CSC Adv/Dis VSC Adv/Dis
DeviceType Thyristor Self -Commutation
Thyristor Self -Commutation
DeviceCharacteristicSymmetry
Symmetrical Asymmetrical +
Short -CircuitCurrent
Lower + Higher
Rateof Riseof Fault Current
LimitedbyDCR eactor + Fast Rise(Duetocapacitor discharge)
Losses Higher - Lower +
ACCapacitors Required Not Required +
DCCapacitors Not Required + Required
Valves dv/dt Lower
(ACCapacitors)
+ Higher
InterfacewithACSystem
MoreComplex Less Comp lex +
ReactivePower Generation
Depends onCurrentFlowingthroughEnergyStorage
Independent of EnergyStorage
+
Performance
Harmonics ACcapacitors may produceresonancesnear thecharacteristicharmonics – maycauseovervoltages onvalvesan dtransformer.
-
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29P. Ribeiro August, 2001
S y s t e m b u s
C o n v e r t e r S w i t c h i n g D C - A C
C +
V d c
s
S h u n t C o m p e
S y s t e m b u sV
T r a n s f o r m e r l e a k a g e i n d u c t a n c e
T r a n s f o r m e r
o
X
V
I
C o u p l i n g
C +
V d c
s
C o n v e r t e r S w i t c h i n g D C - A C
T r a n s f o r m e r l e a k a g e i n d u c t a n c e
T r a n s f o r m e r C o u p l i n g
S e r i e s C o m p e n s a t i o n
o
X
V
I
V V
Voltage Source Converters
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31P. Ribeiro August, 2001
2, 3, 5-level, VSC Waveforms
v d c
2
v d c
2 +
v d c
2
v d c
2 e o u t
v d c +
N e u t r a l ( m i d - ) p o i n t
d c +
v
e o u t
- v α d c
+ v d c
+ v d c
d c
+ v
N e u t r a l ( m i d - ) p o i n t
+ v d c
d c
+ v
α
1
2
α
e o u t
2 d c v
d c v
Voltage Source Converters
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32P. Ribeiro August, 2001
Voltage-Source Converter Bridges
T h r e e - p h a s e , t w o - l e v e l s i x - p u l s e b r i d g e
S i n g l e -p t w o - l e v e l
C C
v d c
C
v d c
v o a v v o a o b v o c
T h r e e - p h a s e , t h r e e - l e v e l 1 2 - p u l s e b r i d g e
C / 2 C
d c V d c V
C / 2
v v o a o b v o c
Voltage Source Converters
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33P. Ribeiro August, 2001
Output voltage control of a two-level VSC
ω
−
v
o F v (
α
α
o v ( )α
o v ( )
+ * =
+ α
δ = ) V ( + s i n ω t )
V = o F + ( ) s i n ( + )
=
*
v s i n V ω t
ω t
=
=
d c
ω t
v d c
d c i
C C
t ( v + ∆ v ) d c
d c n o m i n a l v
d c v ) ( v -
ω t
v
1 d c i d t
f ( C
d c i
ω t α ( V = v o oδ ) α
0 i o
V v =
Voltage Source Converters
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34P. Ribeiro August, 2001
Output voltage control of a three-level VSC
ω
=
ω
ω
ω
α
= Θ *+ α
τ
o m a x v
α < <
o v
) ( 0 π
d c V
m a x =π 2
3
α o F = , v f (τ = - ) s i n (ω t
s i n
*
v = V ω t
t
c o n s t V d c
t C / 2
)
t
V d c
C / 2
t)
o oτ v = V ( α
V i o
v = 0
Voltage Source Converters
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35P. Ribeiro August, 2001
Multi-pulse VSC with
wave-forming magnetic circuits
M a g n e t i c s t r u c t u r e f o r m u l t i - p u l s e w a v e f o r m s y n t h e s i s
C o n v e r t e r 1 C o n v e r t e r 2
S y s t e m B u s b a r
C o n v e r t e r n
T r a n s f o r m e r
C o u p l i n g
I n t e r f a c e M a g n e t i c s
1 3 8 k V B u s
C o u p l i n g T r a n s f o r m e r
Voltage Source Converters
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36P. Ribeiro
August, 2001
FACTS Technology - Possible Benefits
• Control of power flow as ordered. Increase the loading capability of lines to theirthermal 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.
• Increase utilization of lowest cost generation.
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37P. Ribeiro
August, 2001
FACTS and HVDC: Complimentary Solutions
HVDC
Independent frequency and control
Lower line costs
Power control, voltage control,
stability control
FACTSPower control, voltage control,
stability control
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
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38P. Ribeiro
August, 2001
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
Submarine cable
Long distance overhead transmission
Underground Transmission
Connecting AC systems of different or incompatible frequencies
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39P. Ribeiro
August, 2001
FACTS Attributes for Different Controllers
FACTS Controller Control Attributes
Static Synchronous Compensator (STATCOMwithout storage)
Voltage control, VAR compensation, damping oscillations, voltagestability
Static Synchronous Compensator
(STATCOMwith 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)
Damping oscillations, transient and dynamic stability
Static Synchronous Series Compensator
(SSSC without storage)
Current control, damping oscillations, transient and dynamic stability,
voltage stability, fault current limitingStatic 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)
Transient and dynamic voltage limit
Thyristor-Controlled Voltage Regulator
(TCVR)
Reactive power control, voltage control, damping oscillations,
transient and dynamic stability, voltage stability
Interline Power Flow Controller (IPFC) Reactive power control, voltage control, damping oscillations,
transient and dynamic stability, voltage stability
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40P. Ribeiro
August, 2001
X
Regulating Bus Voltage
Can Affect Power Flow Indirectly / Dynamically
E1 /δ
1
E2 / δ 2
I P&Q
P1 = E1 (E2 . sin (δ ))/X
FACTS Implementation - STATCOM
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41P. Ribeiro
August, 2001
Line Impedance Compensation
Can Control Power Flow Continuously
E1 / δ 1 E2 / δ 2P&Q
P1 = E1 (E2 . sin (δ )) / Xeff
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 ...
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42P. Ribeiro
August, 2001
X
Breaker
Slatt TCSC
TCSC module #1
MOV
TCSC
#2
TCSC
#5
TCSC
#3
TCSC
#6
TCSC
#4
FACTS Implementation - TCSC
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43P. Ribeiro
August, 2001
X X
Damping
Circuit
Damping
Circuit
Breaker
Kayenta TCSC
TCSC 15 to 60 Ω
MOV
Breaker
MOV MOV
40 Ω 55 Ω
FACTS Implementation - TCSC
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44P. Ribeiro
August, 2001
X
E1 / δ 1 E2 / δ 2I
P&Q
FACTS Implementation - SSSC
P1 = E1 (E2 . sin (δ )) / Xeff
Xeff = X - Vinj/I
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45P. Ribeiro August, 2001
X
E1 / δ 1 E2 / δ 2IP&Q
Regulating Bus Voltage and Injecting Voltage
In Series With the Line
Can Control Power Flow
P1 = E1 (E2 . sin (δ )) / Xeff
Xeff = X - Vinj / I
FACTS Implementation - UPFC
Q1 = E1(E2 - E2 . cos (δ )) / X
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46P. Ribeiro August, 2001
Shunt Inverter Series Inverter
Unified Power Flow Controller
Series Transformer
Shunt
Transformer
FACTS Implementation - UPFC
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47P. Ribeiro August, 2001
X
Regulating Bus Voltage Plus Energy Storage
Can Affect Power Flow Directly / Dynamically
E1 / δ 1 E2 / δ 2I
P&Q
Plus Energy Storage
FACTS Implementation - STATCOM + Energy Storage
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48P. Ribeiro August, 2001
X
E1 / δ 1 E2 / δ 2I
P&Q
FACTS Implementation - SSSC + Energy Storage
Plus Energy Storage
Voltage Injection in Series Plus Energy Storage
Can Affect Power Flow Directly / Dynamically
and sustain operation under fault conditions
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50P. Ribeiro August, 2001
Shunt
Inverter
Series
Inverter
Unified Power Flow Controller - SMES Interface
SMES Chopper
and Coil
1000μ
F
1000μ
F
1000μ
F
1000μ
F
FACTS Implementation - UPFC + Energy Storage
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51P. Ribeiro August, 2001
SMES Chopper and Coil - Overvoltage Protection
UPFC
Grounding
MOV
FACTS Implementation - UPFC + Energy Storage
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52P. Ribeiro August, 2001
$
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
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53P. Ribeiro August, 2001
E1 / δ 1 E3 / δ 3
FACTS Implementation - IPFC
P12 = E1 (E2 . sin (δ 1- δ 2)) / X
E2 / δ 2
P13 = E1 (E2 . sin (δ 1- δ 3)) / X
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54
P. Ribeiro August, 2001
Series Inverter #1 Series Inverter #2
Interline Power Flow Controller
Series Transformer, Line 2
Series Transformer, Line 1
FACTS Implementation - IPFC
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55
P. Ribeiro August, 2001
Increased Power
Transfer
Enhanced Power Transfer and Stability:
Technologies’ Perspective
Fast
Real Power Injection
and Absorption
Fast
Reactive Power Injection
and Absorption
Fast
Reactive Power Injection and
Absorption
CompensationDevices
FACTS DevicesEnergy Storage
Electric Grid Electric Grid
P
P Additional
Stability Margin
PTSSC
SSSC
UPFC
SMES
0 0.5 1 1.5 2 2.5 30
0.5
1
1.5
2
PhaseAngle
P o w e r T r a n s f e r
Acceleration
Area
Deceleration
Area
Stability
Margin
STATCOM STATCOM
TSSC
SSSC
UPFC
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P. Ribeiro August, 2001
STATCOM
Reactive Power Only
Operates in the vertical
axis only
STATCOM + SMES
Real and Reactive Power
Operates anywhere within the
PQ Plane / Circle (4-Quadrant)
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 PowerQ - Reactive Power
MVA Reduction
FACTS + Energy Storage
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P. Ribeiro August, 2001
SMES Power (MW)
Additiona l
Power
Transfer(MW)
Closer to generation
Closer to load centers
FACTS + Energy Storage - Location Sensitivity
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P. Ribeiro August, 2001
2 STATCOMs 1 STATCOM + SMES
Voltage and Stability Control Enhanced Voltage and Stability Control
S y s t e m F
r e q u e n c y
( H z )
60.8
59.2
time (sec)time (sec)
(2 x 80 MVA Inverters) ( 80 MVA Inverter + 100Mjs SMES)
S y s t e
m F
r e q u e n c y
( H z )
60.8
59.2 S y s t e
m F
r e q u e n c y
( H z )
60.8
59.2
time (sec)
No Compensation
Enhanced Power Transfer and Stability:
Location and Configuration Type Sensitivity
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P. Ribeiro August, 2001
Specifications
(Functional rather than Technical )
Transformer Connections
Higher-Pulse Operation
Higher-Level Operation
PWM Converter
Pay Attention to Interface Issues and Controls
ConverterIncrease 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
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P. Ribeiro August, 2001
Technology Transmission Line
Transfer Enhancement
Cost Range Operating principle Procurement
AvailabilityReconductor lines Increase thermal capacity $50K to $200K per
mile
Increases thermal limit for line Competitive
Fixed or Switched ShuntReactors
Voltage reduction – LightLoad Management
$8-$12 kVAR Compensates for capacitive var-load
Competitive
Fixed or Switched ShuntCapacitors
Voltage support andstability
$8-$10 kVAR Compensates for inductive var-load
Competitive
Fixed or Switched SeriesCapacitors
Power flow control,Voltage support andStability
$12-$16 kVAR Reduces inductive lineimpedance
Competitive
Static VAR Compensators Voltage support andstability
$20-$45 kVAR Compensates for inductiveand/or capacitive var-load
Competitive
Thyristor Controlled SeriesCompensation (TCSC)
Power flow control,Voltage support and
stability
$25-$50 kVAR Reduces or increases inductiveline impedance
Limitedcompetition
STATCOM Voltage support andstability
$80-$100 kVAR Compensates for inductive andcapacitive var-load
Limitedcompetition
STATCOM w/SMES Voltage support and
stability
$150-$300 kW Compensates for inductive
and/or capacitive var-load plus
energy storage for active power
Limited
Unified Power FlowController (UPFC)
Power flow control,Voltage support, andStability
$150-$200 kW SVC and TCSC functions plus phase angle control
Sole source
Unified Power Flow
Controller (UPFC) w/SMES
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 arenot continuously controllable)
Cost Considerations
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Hardware
Eng & Project Mgmt.
Installation
Civil Works
Commissioning
Insurance
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 firstidea of costs andalternatives. The manufacturers should be able to give a budgetary price based on a brief description of thetransmission system along with the problem(s) needing to be solved and the improvement(s)needing to be
attained.
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Technology & Cost Trends
I
$$$
$
I
additional cost savings possible
$
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Economics of Power Electronics
Sometimes a mix of conventional and FACTS systems has the lowest costLosses 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
Cost of SystemCost of System
100% Power100% PowerElectronicsElectronics
100%100%
ConventionalConventional
Delta-PDelta-P11
Delta-PDelta-P22
Delta-PDelta-P33
Delta-PDelta-P44
Stig Nilson’s paper
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Operation and Maintenance
Operation of FACTS in power systems is coordinated with operation of otheritems 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. Thismeans 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 resourcesavailable for the task. The FACTS device itself is normally unmanned, and thereis 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 andporcelains, exchanging of mechanical seals in pump motors, checking throughof capacitors, checking of control and protective settings, and similar. It cannormally 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
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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, whenfor example surplus of clean hydro resources from one region can help to replace pollutingfossil-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 inparallel 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 thenecessary permits. Also, in many cases, environmental considerations, popular opinion orother impediments will render the building of new lines as well as uprating to ultrahighsystem voltages impossible inpractice. This is where FACTS comes in.
Examples of successful implementation of FACTS for power system interconnection can befound among others between the Nordic Countries, and between Canada and the UnitedStates. In such cases, FACTS helps to enable mutually beneficial trade of electric energybetween the countries.Other regions in the world where FACTS is emerging as a means for AC bulk powerinterchange 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 powerover distances of more than 1.000 km are a reality today.
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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
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Final Words
Power supply industry is undergoing dramatic change as a result of
deregulation and political and economical maneuvers. This new marketenvironment puts demands for flexibility and power quality into focus. Also,trade between companies and countries of electric power is gainingmomentum, to the benefit of all involved. This calls for the right solutionsas far as power transmission facilities between countries as well asbetween regions within countries are concerned.
FACTS Benefits included:-An increase of synchronous stability of the grid;-An increased voltage stability in the grid;-Decreased power wheeling between different power systems;-Improved load sharing between parallel circuits;
-Decreased overall system transmission losses;-Improved power quality in grids.
• The choice of FACTS device is simple and needs to be made the subject of detailed system studies, taking all relevant requirements and prerequisitesof the system into consideration, so as to arrive at the optimum technicaland economical solution. In fact, the best solution may often be lying in acombination of devices.
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From an economical point of view, more power can be transmitted overexisting or new transmission grids with unimpeded availability at aninvestment cost and time expenditure lower, or in cases even far lowerthan it would cost to achieve the same with more extensive grids. Also,in many cases, money can be saved on a decrease of power transmission losses.
From an environmental point of view, FACTS enables the transmission of power over vast distances with less or much less right-of-way impactthan would otherwise be possible. Furthermore, the saving intransmission losses may well bring a corresponding decrease in need forgeneration, with so much less toll on the environment.
All these things help to enable active, useful power to reach out ingrowing quantities to growing populations under safe and favorableconditions all over the world. Also, individual countries´ own border linesno longer constitute any limit to power industry. With FACTS, powertrade to the benefit of many can be established to a growing extent
across borders, by making more efficient use of interconnections
Final Words
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Questions and Open Discussions
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Appendix