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

[email protected]

PowerTra

nsfer

Phase Angle

From EPRI

An Overview on FACTS Controllers




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




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




P tg P V

V

P X

X

P •

∆

+•

∆

+•

∆

−=∆ φ

φ The Concept




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




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




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




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




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




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




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




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




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




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




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)




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




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




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



xxx

Evaluate symmetric and unsymmetric fault duties for system and controller, including mitigation measures

xxx

Determine final performance criteria andcontrol variables

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




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




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



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




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




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




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)




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)




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)




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.)




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)




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.

-




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




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 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





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 =





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





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




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.



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



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



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)


voltage stability

Thrystor-Controlled Series Capacitor

(TCSC, TSSC)


voltage stability, fault current limiting

Thyristor-Controlled Series Reactor

(TCSR, TSSR)



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,


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



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



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 ...



42P. Ribeiro

August, 2001

X

Breaker

Slatt TCSC

TCSC module #1

MOV

TCSC

#2

TCSC

#5

TCSC

#3

TCSC

#6

TCSC

#4




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




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




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




Shunt Inverter Series Inverter

Unified Power Flow Controller

Series Transformer

Shunt

Transformer

FACTS Implementation - UPFC




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




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




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




SMES Chopper and Coil - Overvoltage Protection

UPFC

Grounding

MOV

FACTS Implementation - UPFC + Energy Storage




$

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




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



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



55


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

QQ

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



56


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



57


SMES Power (MW)

Additiona l

Power

Transfer(MW)

Closer to generation

Closer to load centers

FACTS + Energy Storage - Location Sensitivity



58


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



60


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



61


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



62


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.



63


Technology & Cost Trends

I

$$$

$

I

additional cost savings possible

$



65


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



66


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



67


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.



68


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



69


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.



70


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



71


Questions and Open Discussions



Appendix

Mini Curso FACTS 2001F

Documents

Transcript of Mini Curso FACTS 2001F