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"An Overview on FACTS and Power Quality Issues: Technical Challenges, Research Opportunities and Cost Considerations.". Paulo F. Ribeiro, BSEE, MBA, PHD, PE CALVIN COLLEGE Engineering Department Grand Rapids, MI 49546 http://engr.calvin.edu/PRibeiro_WEBPAGE/ [email protected]. FACTS - PowerPoint PPT Presentation
Citation preview
1P. Ribeiro June, 2002
"An Overview on FACTS and Power Quality Issues:Technical Challenges, Research Opportunities
and Cost Considerations."
Paulo F. Ribeiro, BSEE, MBA, PHD, PE
CALVIN COLLEGEEngineering DepartmentGrand Rapids, MI 49546
http://engr.calvin.edu/PRibeiro_WEBPAGE/[email protected]
10 5 0 5 102
0
2
2P. Ribeiro June, 2002
FACTS
• 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• Impact of FACTS in interconnected networks• Market Assessment, Deregulation and Predictions
3P. Ribeiro June, 2002
Power Quality
Objectives - Motivation - Background
Limitation of Traditional Tools
Advanced Techniques:· Wavelet Theory Making Waves· Expert Systems To Sag or Not to Sag: This is The ?· Fuzzy Logic Not Really a Harmonic Distortion· Neural Networks Remembering Wave Signatures· Genetic Algorithms Evolutionary Distortions· Combining Techniques Power Quality Diagnostic System• Power Electronics Implementing Advanced Power
Concepts
4P. Ribeiro June, 2002
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
5P. Ribeiro June, 2002
Ptg
PV
VP
X
XP
The Concept
6P. 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. Voltage is governed by reactive power (Q). Q in its turn depends of the physical length of the transmission circuit as well as from the flow of active power. The longer the line and/or the heavier the flow of active power, the stronger will be the flow of reactive power, as a consequence of which the voltage 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 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
7P. 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-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
8P. Ribeiro June, 2002
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 capacitySVC (Nebraska GE 1974, Minnesota Westinghouse 1975, Brazil Siemens 1985)TCSC, UPFC AEP 1999
Trends-Generation is not being built-Power sales/purchases are being
9P. Ribeiro June, 2002
System ArchitectureRadial, interconnected areas, complex network
Power Flow in an AC SystemPower 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
10P. Ribeiro June, 2002
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 generation will 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
11P. Ribeiro June, 2002
Power Flow Control on AC Systems
RadialParallel
Meshed
Power Flow in Parallel PathsPower Flow in a Meshed SystemsWhat limits the loading capability?
Power Flow and Dynamic Considerations
12P. Ribeiro June, 2002
Power Flow Control on AC Systems
Relative Importance of Controllable Parameters
Control of X can provide current controlWhen angle is large X can provide power controlInjecting voltage in series and perpendicular to the current flow, can increase or decrease
50% Series Compensation
13P. Ribeiro June, 2002
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 Load
Shedding
FACTS
Devices
Traditional Solutions
SVCSTATCOMTCSC, SSSCUPFC
Steady StateIssues
Voltage LimitsThermal Limits
Angular Stability LimitsLoop Flows
DynamicIssues
Transient StabilityDamping Power Swings
Post-Contingency Voltage ControlVoltage Stability
Subsynchronous Res.
FACTS Applications and Implementations
14P. Ribeiro June, 2002
FACTS DevicesShunt Connected
Static VAR Compensator (SVC)Static Synchronous Compensator (STATCOM)Static Synchronous Generator - SSGBattery Energy Storage System (BESS)Superconducting Magnetic Energy Storage (SMES)
Combined Series and Series-Shunt ConnectedStatic Synchronous Series Controllers (SSSC)Thyristor Controlled Phase-Shifting Transformer orPhase Angle Regulator (PAR)Interline Power Flow Controller (IPFC)Thyristor Controlled Series Capacitor (TCSC)Unified Power Flow Controller (UPFC)
Relative Importance of Different Types of ControllersShunt, Shunt-Serie Energy Storage
Energy Storage
15P. Ribeiro June, 2002
DevicesDiode (pn Junction)Silicon Controlled Rectifier (SCR)Gate Turn-Off Thyristor (GTO) GEMOS Turn-Off Thyristor (MTO) SPCOEmitter Turn-Off Thyristor (ETO) Virginia TechIntegrated Gate-Commutated Thyristor (IGCT) Mitsubishi, ABBMOS-Controlled Thyristor (MCT) Victor TempleInsulated Gate Bipolar Transistor (IGBT)
Power Electronics - Semiconductor Devices
DiodesTransistors
IGBTThyristors
SCR, GTO, MTO, ETO, GCT, IGCT, MCT
16P. Ribeiro June, 2002
Power Electronics - Semiconductor DevicesPrincipal Characteristics
Voltage and CurrentLosses and Speed of Switching
Speed of SwitchingSwitching Losses
Gate-driver power and energy requirements
Parameter Trade-offPower requirements for the gatedi/dt and dv/dt capabilityturn-on and turn-off timeUniformityQuality of silicon wafers
IGBT has pushed out the conventional GTO as IGBTs ratings go up.IGBTs - Low-switching losses, fast switching, current-limiting capabilityGTOs - large gate-drive requirements, slow-switching, high-switching lossesIGBTs (higher forward voltage drop)
17P. Ribeiro June, 2002
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
18P. Ribeiro June, 2002
Planing StudiesEvaluate 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 this effort should concentrate on preliminary feasibility studies to assess the technical merits of alternative solutions to correct real and reactive power transfer ratings, system voltage profiles, operational effects on the network, equipment configurations, etc.
A - Load flow studies will be performed to establish steady-state ratings, and identify the appropriate locations for connection of alternative compensation devices. Load flow studies will 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
19P. Ribeiro June, 2002
System Studies
System data and configuration
Outages and load transfer
Load Flow(P,Q, V, )
Transient Stability
(P,Q, V, , time)
Dynamic Stability
(P,Q, V, , , time)
Generator data
Voltage Reg. Data
(AVR)
Governor data
Relay data
System operat. limits
Induction motor data
Fault data
System changes
Load Shedding
Identify Transmission
Systems - Provide System data and Configuration
Outages and load transfer
Perform Load Flow
(P,Q, V, )
System operat. limits
Identify and Size Transfer
Enhancement Solutions Devices
Perform Economic Analysis
IEEE
20P. Ribeiro June, 2002
E2 / 2
X
E1 / 1 I
P&Q
E1
E2
E1 . sin ()
E2 . cos()
(E1 - E2 . cos()E2 . sin()
I
(E2 - E1 . cos()Iq1 = (E1 - E2 . cos() / X
E1 . Cos ()
Ip1 = E2 sin() / X
E1 - E2P1 = E1 . Ip1
AC Transmission Fundamentals
21P. Ribeiro June, 2002
Active component of the current flow at E1
Ip1 = (E2 . sin ()) / X
Reactive component of the current flow at E1
Iq1 = (E1 - E2 . cos ())/X
Active Power at the E1 end
P1 = E1 (E2 . sin ())/X
Reactive Power at the E1 end
Q1 = E1(E1 - E2 . cos ()) / X
AC Transmission Fundamentals
22P. Ribeiro June, 2002
E2 / 2
P1 = E1 (E2 . sin ())/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 / 1 I
P&Q
Q / VP1 = k1.E1 (E2 . sin (/k2))/X
AC Transmission Fundamentals (Voltage - Shunt Control)
23P. Ribeiro June, 2002
E1
E2
I
X
E1 - E2
Injected Voltage
Injecting Voltage in series with the line mostly change real power
E1 / 1 E2 / 2I
P&Q
Vinj
P1 = E1 . E2 . sin () / (X - Vinj / I)
AC Transmission Fundamentals (Voltage-Series Injection)
24P. Ribeiro June, 2002
X
E1 / 1 E2 / 2I
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
VrVc
Vseff
P1 = E1 . E2 . sin () / (X - Xc)
Vs
Phase Angle
Pow
er T
rans
f er
AC Transmission Fundamentals (Series Compensation)
25P. Ribeiro June, 2002
X
E1 / 1 E2 / 2
IP&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.)
26P. Ribeiro June, 2002
1 - prior to fault
2 - fault cleared
3 - equal area
3 >crit - loss of synchronism
Improvement of Transient Stability With FACTS CompensationEqual Area Criteria
1 2 3 crit
A1
A2
Amargin
Max
imum
Po w
e r T
ran s
f er
Phase Angle
no compensation
with VAR compensation (ideal midpoint)
A1 = Acceleration EnergyA2 = Deceleration Energy
Therefore, FACTS compensation can increase
power transfer without reducing the stability margin
Q / V
AC Transmission Fundamentals (Stability Margin)
27P. Ribeiro June, 2002
Voltage Source Vs. Current Source Converters
CSC Adv/Dis
VSC
Adv/Dis
Device Type
Thyristor Self-Commutation
Thyristor Self-Commutation
Device Characteristic Symmetry
Symmetrical Asymmetrical +
Short-Circuit Current
Lower
+ Higher
Rate of Rise of Fault Current
Limited by DC Reactor + Fast Rise (Due to capacitor discharge)
Losses
Higher - Lower +
AC Capacitors
Required Not Required +
DC Capacitors
Not Required + Required
Valves dv/dt
Lower (AC Capacitors)
+ Higher
Interface with AC System
More Complex Less Complex +
Reactive Power Generation
Depends on Current Flowing through Energy Storage
Independent of Energy Storage
+
Performance
Harmonics
AC capacitors may produce resonances near the characteristic harmonics – may cause overvoltages on valves and transformer.
-
28P. Ribeiro June, 2002
System bus
ConverterSwitching
DC-AC
C+
Vdc
s
Shunt Compensation
System busV
Transformer leakageinductance
Transformer
o
X
V
I
Coupling
C+
Vdc
s
ConverterSwitching
DC-AC
Transformer leakageinductance
TransformerCoupling
Series Compensation
o
X
V
I
VV
Voltage Source Converters
29P. Ribeiro June, 2002
Basic 6-Pulse, 2-level, Voltage-Source Converter
cec
Ta2 a2D Tb2
a
b
e
e
ai a1T
ib
i
a1 b1D T
D Tb2 c2 Dc2
dc2
V
b1 c1D T c1D
dc+Cs
V
dci
dcV
Hypotheticalneutral point
2
Voltage Source Converters
30P. Ribeiro June, 2002
2, 3, 5-level, VSC Waveforms
vdc2
vdc2 +
vdc2
vdc2
eout
vdc+
Neutral(mid-) point
dc+v
eout
- v dc
+ v dc
+vdc
dc+
v
Neutral(mid-) point
+vdc
dc+
v
1
2
eout
2 dcv
dcv
Voltage Source Converters
31P. Ribeiro June, 2002
Voltage-Source Converter Bridges
Three-phase, two-level six-pulse bridge
Single-phase,two-level H-bridge
CC
vdc
C
vdc
voa vvoa obvoc
Three-phase, three-level 12-pulse bridge
C/2C
dcV dcV
C/2
vvoa obvoc
Voltage Source Converters
32P. Ribeiro June, 2002
Output voltage control of a two-level VSC
v
oFv (
ov ( )
ov ( )
*=
=) V(+ sin t)
V=oF ( ) sin(+ )
=
*
v sinV t
t
=
=
dc
t
v dc
dci
CC
t(v+v)dc
dc nominalvdcv)(v-
t
v
1dci dt
f C
dci
t (V=vo o )
0io
Vv=
Voltage Source Converters
33P. Ribeiro June, 2002
Output voltage control of a three-level VSC
=
= *
omaxv
< <
ov
)(
dcV
max = 23
oF= ,v f ( = -) sin(t
sin
*
v=V t
t
const Vdc
tC/2
)
t
Vdc
C/2
t)oo v =V (
Vio
v= 0
Voltage Source Converters
34P. Ribeiro June, 2002
Multi-pulse VSC with wave-forming magnetic circuits
Magnetic structurefor multi-pulse waveform synthesis
Converter 1 Converter 2
System Busbar
Converter n
TransformerCoupling
Interface Magnetics
138kV Bus
CouplingTransformer
Voltage Source Converters
35P. Ribeiro June, 2002
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.
• Increase utilization of lowest cost generation.
36P. Ribeiro June, 2002
FACTS and HVDC: Complimentary SolutionsHVDCIndependent frequency and controlLower line costsPower 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 $ 10-20M1000 MW $120-170M $ 20-30M2000 MW $200-300M $ 30-50M
(*)Hingorani/Gyugyi
37P. Ribeiro June, 2002
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
38P. Ribeiro June, 2002
FACTS Attributes for Different ControllersFACTS Controller Control Attributes
Static Synchronous Compensator(STATCOM without storage)
Voltage control, VAR compensation, damping oscillations, voltagestability
Static Synchronous Compensator(STATCOM with storage, BESS, SMES,large dc capacitor)
Voltage control, VAR compensation, damping oscillations, transientand dynamic stability, voltage stability, AGC
Static VAR Compensator (SVC, TCR,TCS, TRS
Voltage control, VAR compensation, damping oscillations, transientand 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 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-ShiftingTransformer (TCPST or TCPR)
Active power control, damping oscillations, transient and dynamicstability, voltage stability
Unified Power Flow Controller (UPFC) Active and reactive power control, voltage control, VARcompensation, 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
39P. Ribeiro June, 2002
X
Regulating Bus VoltageCan Affect Power Flow Indirectly / Dynamically
E1 / 1 E2 / 2I P&Q
P1 = E1 (E2 . sin ())/X
FACTS Implementation - STATCOM
40P. Ribeiro June, 2002
Line Impedance CompensationCan Control Power Flow Continuously
E1 / 1 E2 / 2P&Q
P1 = E1 (E2 . sin ()) / 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 ...
41P. Ribeiro June, 2002
X
Breaker
Slatt TCSC
TCSC module #1
MOV
TCSC
#2
TCSC
#5
TCSC
#3
TCSC
#6
TCSC
#4
FACTS Implementation - TCSC
42P. Ribeiro June, 2002
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
43P. Ribeiro June, 2002
X
E1 / 1 E2 / 2I
P&Q
FACTS Implementation - SSSC
P1 = E1 (E2 . sin ()) / Xeff
Xeff = X - Vinj/I
44P. Ribeiro June, 2002
X
E1 / 1 E2 / 2I
P&Q
Regulating Bus Voltage and Injecting Voltage In Series With the LineCan Control Power Flow
P1 = E1 (E2 . sin ()) / Xeff
Xeff = X - Vinj / I
FACTS Implementation - UPFC
Q1 = E1(E2 - E2 . cos ()) / X
45P. Ribeiro June, 2002
Shunt Inverter Series Inverter
Unified Power Flow Controller
Series Transformer
Shunt
Transformer
FACTS Implementation - UPFC
46P. Ribeiro June, 2002
X
Regulating Bus Voltage Plus Energy StorageCan Affect Power Flow Directly / Dynamically
E1 / 1 E2 / 2I
P&Q
Plus Energy Storage
FACTS Implementation - STATCOM + Energy Storage
47P. Ribeiro June, 2002
X
E1 / 1 E2 / 2I
P&Q
FACTS Implementation - SSSC + Energy Storage
Plus Energy Storage
Voltage Injection in Series Plus Energy StorageCan Affect Power Flow Directly / Dynamicallyand sustain operation under fault conditions
48P. Ribeiro June, 2002
X
E1 / 1 E2 / 2
IP&Q
Plus Energy Storage
Regulating Bus Voltage + Injected Voltage + Energy StorageCan Control Power Flow Continuously, and Support Operation Under Severe Fault Conditions (enhanced performance)
FACTS Implementation - UPFC + Energy Storage
49P. Ribeiro June, 2002
Shunt Inverter
Series Inverter
Unified Power Flow Controller - SMES Interface
SMES Chopper and Coil
1000μF
1000μF
1000μF
1000μF
FACTS Implementation - UPFC + Energy Storage
50P. Ribeiro June, 2002
SMES Chopper and Coil - Overvoltage Protection
UPFC Grounding
MOV
FACTS Implementation - UPFC + Energy Storage
51P. Ribeiro June, 2002
$
Regulating Bus Voltage + Energy Storage + Line Impedance CompensationCan Control Power Flow Continuously, and Support Operation Under Severe Fault Conditions (enhanced performance)
FACTS Implementation - TCSC + STACOM + Energy Storage
52P. Ribeiro June, 2002
E1 / 1 E3 / 3
FACTS Implementation - IPFC
P12 = E1 (E2 . sin (1- 2)) / X
E2 / 2
P13 = E1 (E2 . sin (1- 3)) / X
53P. Ribeiro June, 2002
Series Inverter #1 Series Inverter #2
Interline Power Flow Controller
Series Transformer, Line 2
Series Transformer, Line 1
FACTS Implementation - IPFC
54P. Ribeiro June, 2002
Increased Power Transfer
Enhanced Power Transfer and Stability:Technologies’ Perspective
FastReal Power Injection
and Absorption
FastReactive Power Injection
and Absorption
FastReactive Power Injection and
Absorption
CompensationDevices
FACTS DevicesEnergy Storage
Electric Grid Electric Grid
P
P AdditionalStability Margin
PTSSCSSSCUPFC
SMES
0 0.5 1 1.5 2 2.5 30
0.5
1
1.5
2
Phase Angle
Pow
er T
ransf
er
AccelerationArea
DecelerationArea
StabilityMargin
STATCOM STATCOM
TSSCSSSCUPFC
55P. Ribeiro June, 2002
STATCOMReactive Power OnlyOperates in the vertical axis only
STATCOM + SMESReal and Reactive PowerOperates anywhere within thePQ 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
56P. Ribeiro June, 2002
SMES Power (MW)
Add
itio
nal P
ower
Tra
nsfe
r(M
W)
Closer to generation
Closer to load centers
FACTS + Energy Storage - Location Sensitivity
57P. Ribeiro June, 2002
2 STATCOMs 1 STATCOM + SMES
Voltage and Stability Control Enhanced Voltage and Stability Control
Syst
em F
requ
ency
(H
z)
60.8
59.2
time (sec) time (sec)
(2 x 80 MVA Inverters) ( 80 MVA Inverter + 100Mjs SMES)
Syst
em F
requ
ency
(H
z)
60.8
59.2
Syst
em F
requ
ency
(H
z)
60.8
59.2
time (sec)
No Compensation
Enhanced Power Transfer and Stability:Location and Configuration Type Sensitivity
58P. Ribeiro June, 2002
FACTS For Optimizing Grid Investments
FACTS Devices Can Delay Transmission Lines ConstructionBy 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 reliabilityrequirements; 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.
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Specifications
(Functional rather than Technical )
Transformer ConnectionsHigher-Pulse OperationHigher-Level OperationPWM ConverterPay Attention to Interface Issues and Controls
ConverterIncrease Pulse NumberHigher LevelDouble the Number of Phase-Legs and Connect them in ParallelConnect Converter Groups in ParallelUse A Combination of several options listed to achieve required rating and performance
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Technology Transmission LineTransfer Enhancement
Cost Range Operating principle ProcurementAvailability
Reconductor lines Increase thermal capacity $50K to $200K permile
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 andstability
$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 andstability
$150-$300 kW Compensates for inductiveand/or capacitive var-load plusenergy storage for active power
Limited
Unified Power FlowController (UPFC)
Power flow control,Voltage support, andStability
$150-$200 kW SVC and TCSC functions plusphase angle control
Sole source
Unified Power FlowController (UPFC) w/SMES
Power flow controlVoltage support andStability,
$250-$350 kW SVC and TCSC functions plusvoltage regulator, phase anglecontroller 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 first idea 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 beattained.
(*) Joint World Bank / ABB Power Systems PaperImproving the efficiency and quality of AC transmission systems
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Technology & Cost Trends
I
$$$
$
I
additional cost savings possible
$
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Concerns About FACTS
CostLosses
Reliability
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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 onesReliability and security issues - when system loaded beyond the limits of experienceDemonstration projects required
Cost of SystemCost of System
100% Power 100% Power Electronics Electronics
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 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 PaperImproving the efficiency and quality of AC transmission systems
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Impact of FACTS in interconnected networksThe 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 inpractice. 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 PaperImproving the efficiency and quality of AC transmission systems
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Power Quality Issues
1 – Background (Power Quality – Trade Mark)2 – The Need For An Integrated Perspective of PQ3 – Harmonics4 – Imbalance5 – Voltage Fluctuations6 – Voltage Sags 7 – Standards, Limits, Diagnostics, and Recommendations
Flexibility, Compatibility, Probabilistic Nature, Alternative Indices8 – Combined effects9 – Power Quality Economics10 – Measurement Protocols11 – Probabilistic Approach12 – Modeling & Simulation13 – Advanced Techniques
(Wavelet, Fuzzy Logic, Neural Net, Genetic Algorithms)14 – Power Quality Programs
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Compatibility: The Key Approach
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kUref
kUrefkUkRTL ,0max
Relative Trespass Level (RTL)
Uk - measured or calculated harmonic voltage
Uref - harmonic voltage limit (standard or particular equipment)
k - harmonic order
2 4 6 8 10 12 140
2
4
6
88
0
RTL k
132 k
0 0.05 0.10
2
4
6
88
0
RTL k
.10 Uk
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Possible Problems
Caution SevereDistortions
DangerousLevels
NormalLevels
A B C D E F G RTL0
1
Norm
alB
elowN
ormal
Over
Heating
Very
Hot
Below
Norm
alab
cd
e
Equ
ipm
ent
Mal
fun c
t io n
Mag
nitu
de $
Ph a
se
Ang
le
Individual Harmonics (Vh)Equipment Malfunction
Fuzzy - Color Code CriteriaNo Problem
Caution
Possible Problems
Imminent Problems
Harmonic Distortion Diagnostic Index Applying Fuzzy Logic Comparisons
Alternative Approach
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HarmonicsDefinition of harmonics
Sources of harmonics
Effects of harmonics
Mitigation methods
Considerations on the extra costs due to harmonic pollution
Measurement results
Voltage fluctuations/FlickerDefinitions
Sources of voltage fluctuations/flicker
Effects of voltage fluctuations/flicker
Mitigation methods
Measurement results
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Voltage DipsDefinition
Sources of voltage dips
Effects of voltage dips
Mitigation methods
Measurement results
Conclusions
UnbalanceDefinition
Sources of unbalance
Effects of unbalance
Mitigation methods
Measurement results
Transient Overvoltages
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How To Interpret This?
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How To Interpret This?
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How To Interpret This?
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Generation Delivery Conversion Processing
CentralStation
T&D AC-ACSupplies
Motion
Environmental Maintainability Availability Safety Efficiency Reliability Performance PricePower Quality
Power System Value Chain
Power Electronics Systems and Components
SMESBatteries
FACTSSMESPQ Parks
UPS Appliances
INPUTS OUTPUTS
Val
ue D
imen
sion
s
Energy Power Communication
Light / Motion
Utility User
The Total Quality Environment
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Benefits of a Power Quality Program
Offer options to customers with PQ concerns
Attract new business to area (regional development)
Facilitate load retention of current customers
Meet changing needs of customer's new technology
Discourage co-generation or self-generation as solutions of PQ Problems
Enhance and public image - as customers hold utility accountable for both PQ and reliability
Add value to service
Serve customers' best interests and save customers money
Support utility mission
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Suggested Topics for Investigation
FACTS
Inclusion of Energy Storage
Topology Combination
Power Quality
Effects of Power Quality on Relaying Equipment
Cost/Benefit Analysis of PQ
Application of Advanced Techniques
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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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ConclusionsPower supply industry is undergoing dramatic change as a result of deregulation and political and economical maneuvers. This new market environment puts demands for flexibility and power quality into focus. Also, trade between companies and countries of electric power is gaining momentum, to the benefit of all involved. This calls for the right solutions as far as power transmission facilities between countries as well as between 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 prerequisites of the system into consideration, so as to arrive at the optimum technical and economical solution. In fact, the best solution may often be lying in a combination of devices.
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From an economical point of view, more power can be transmitted over existing or new transmission grids with unimpeded availability at an investment cost and time expenditure lower, or in cases even far lower than it would cost to achieve the same with more extensive grids. Also, in many cases, money can be saved on a decrease ofpower 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 impact than would otherwise be possible. Furthermore, the saving in transmission losses may well bring a corresponding decrease in need for generation, with so much less toll on the environment.
All these things help to enable active, useful power to reach out in growing quantities to growing populations under safe and favorable conditions all over the world. Also, individual countries´ own border lines no longer constitute any limit to power industry. With FACTS, power trade to the benefit of many can be established to a growing extent across borders, by making more efficient use of interconnections between countries, new as well as existing.
Conclusions
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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.
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Questions and Open Discussions
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Appendix