role of facts technology on transmission grid …...hitchhiker’s guide1) to facts technology...

Role of FACTS Technology on Transmission Grid

Reliability

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IEEE San Francisco PESSpring BanquetMay 15, 2003

Hitchhiker’s Guide1) to FACTS Technology describes the role technology plays in increasing reliable power transfers thereby relieving transmission congestion.1) Hitchhiker’s Guide to the Galaxy by Douglas Adams, BBC miniseries

1981 http://www.bbc.co.uk/cult/hitchhikers

FACTS Technology – Need a Guide?

STATCOM

SSSCGPFC

SCR GTO

RTO FERC

LLPWECC

Hitchhiker’s Guide – Table of ContentsTransmission Characteristics

Impact of Deregulation on Transmission – Theory of Indeterminacy

Transmission Provider Response – Marvin the Paranoid Android

Cost of Congestion

Congestion Relief Technologies – Don’t Panic!System AnalysisReconductoringFACTS – Infinite Improbability DriveHVDC – Hyper Space Bypass

Application Examples

Conclusions – Restaurant at the End of the Universe

AC Transmission Network Characteristics

Power flow uncontrolledCircuits may be overloaded or underutilizedReserve capacity required for contingenciesVariable reactive power demandRequires voltage control and dynamic reactive power reserve Often limited to less than thermal by instability or inadequate voltage support Transmission capacity a function of distance and intermediate voltage supportFinite limit to cable lengthSynchronous

Impact of Deregulation on TransmissionTransmission transactions growing Transmission investment decliningResource diversity decliningGenerators access to markets limitedMore regional transmission assessment by non-owners Regulatory power struggleMarket manipulation - e.g. DeathstarTransmission congestion is increasing– attack of the free-ridersEconomic incentives to relieve congestion inadequate

Public oppositionLengthy and uncertain processAsset utilizationWill it be bypassed? Regulatory uncertainty How will market risk be rewarded?Financial viabilityObligation to serve

Barriers to Transmission Investment

Theory of Indeterminacy

Response of the Transmission Provider

Cut costsSell assets Merge, spin off, change nameDiversifyJoin an ISO1), form an RTO2)

Never mind - form a larger RTOIf I build it, will anybody come? Accept regulated rate of return?FTR’s, CRR’sDo I really want to be in this business?Marvin the Paranoid Android

1) Independent System Operator2) Regional Transmission Organization

Cost of Congestion

FERC estimated costs for 16 individual constraints that ranged up to $700M/y (eastern NY) - Electric Transmission Constraint Study

ISO New England estimates the costs of congestion in New England are $125-600M/y - 2001 Regional Transmission Expansion Plan

Cost of congestion on Path 15 > $222M over 16 mo prior to 12/00 - California ISO

Congestion relief – overall net efficiency gain but there are individual winners and losers!

Interregional Congestion

Source: National Transmission Grid Study - DOE May, 2002

Congestion curtails economic dispatchInterregional or localizedCongestion - time is money Raise limits by new lines or by technologySolutions – FACTS1) & HVDC 2)

1) Flexible Alternating Current Transmission Systems2) High Voltage Direct Current

Congestion Relief Technologies – DON’T PANIC!

System Analysis – Limits and Cost of Congestion

Re-conductor – Increases Reactive Power Demand

FACTSDynamic Shunt Compensation – SVC and STATCOMControlled Series Compensation - TCSCPower Flow Control – UPFC and SSSC

HVDCConventional - LCICapacitor Commutated Converter – CCCVSC Based TransmissionGrid Power Flow Controller – GPFC

FACTS Benefits

AC transmission lines generally operate below their thermal capacity

Limitations often due to VoltageStability

FACTS devices raise transfer capability towards thermal limit

Transmission constraints as functions of line lengthSource: Eric Hirst, Edison Electrical Institute

PDCI(N2S) Power Flow Duration Curve When Price Cap is 250 $/MWH in 2004

0 1000 2000 3000 4000 5000 6000 7000 8000

PDCI-3100MWPDCI-1650MWPDCI-1100MW

Cost of Congestion - Case Study Pacific DC Intertie

Comparison of 1033 kcmil 54/7 SSAC 1) and ACSR2)

Increase in line capacity by reconductoring but must supply theadditional reactive power demand – application for FACTS!

Line Re-conductoring

ACSR SSAC % ChangeLine Current Rating (A)Normal Summer (95 ºF)

1300 2190 168%

Line Rating (MVA)Normal Summer (95 ºF) 168%

Maximum Line InductiveReactive Power Demand(excluding Vll2 Bc)

3*(1300)2 Xl 3*(2190)2 Xl 284%

√ 3(1300)Vll √ 3(2190)Vll

1) Steel-Supported Aluminum Conductor2) Aluminum Conductor Steel-Reinforced

Study - New TechnologyFACTS, HVDC, SSAC

Minimal environmental impactMaximize use of existing resourcesAdapted to new electric marketControllableResponsive

Congestion ReliefT

Technology

Thermal Limit

FACTS& HVDC

Voltage

Stability Limit

New Thermal Limit

SVC and STATCOM - Established Technologies

VSC w. BtB, Eagle Pass, TX

19 VSCs installed since 1997

In service today >1500 MVA

>300 MVA in manufacturing

STATCOM - VSC SVC

>160 SVC utility inst. since 1975

In service today > 32 000 MVA

> 500 MVA in manufacturing

+/- 160 Mvar, 420 kV, Sylling, Norway

Infinite Improbability Drive

SVC – AC Control of Reactors & Capacitors

STATCOM – Synthesize AC from DC

Increased Transfer with Voltage Support

Maximum power flow depends on network and voltage supportSteady state voltage via slow devices, e.g., switched capacitors, tap changersDynamic reactive power reserve required for contingencies Dynamic voltage support requires fast action, e.g., generators, SVC1)

or STATCOM2) - all VARS are not the same

1) Static Var Compensator2) Static Compensator (ABB SVC Light)

Increased Transfer with Voltage Support

Top: P-V curve at bus – all lines in service

Middle: P-V curve at bus – post contingency without compensation

Bottom: P-V curve at bus – post contingency with compensation

Normal System Conditions – 2000 MVA Short Circuit

n-1 Contingency – 1500 MVA Short Circuit Level

Improved Post-Contingency Voltage Profile due to Dynamic Reactive

Support by SVC or STATCOM

Yonder there be dragons!

SVC Building Blocks

STATCOM – SVC Light

Power Electronics

SVC - Thyristor ValveControls AC Current – switched (TSC or TCR), phase control (TCR)Anti-parallel thyristors (SCR)Up to 4000 A, ~ 8 kV per single device

SVC Light - IGBT ValvesAC/DC VSC converterInsulated gate bipolar transistorHigh switching frequency for PWMAnti-parallel diodesUp to 1500 A, 2.5 kV per parallel array

Insulated Gate Bipolar Transistor (IGBT)

Same IGBT for all applications

The IGBTNominal current 1300 ARated voltage 2500 VSwitching frequency 1350 HzPresspackDiode

partIGBTpart

TSC/TCR Operation

Pulse Width Modulation

Va - refu

(1)-max(SPWM)u

STATCOM – 3-Level Converter with PWM

Filter Bus Voltage

Voltage at Filterbus, kV. No filter Voltage at Filterbus, kV.

Harmonic Spectrum

Harmonic spectrum in pu of Ud pole voltage

Harmonic order

Current-Voltage Characteristic - STATCOM

SVC curveLimitation due to transformer reactance

Es θ V 0XS

P=P (V/V )0 0mp

Q=Q (V/V )o 0mq

Es θ V 0Xs

P=P (V/V )0 0mp

Q=Q (V/V )0 0mq

ISTATCOMEs θV 0

XSTATCOM

P=P (V/V )0 0mp

Q=Q (V/V )0 0mq

Shunt Compensation – Fixed + Dynamic

Fixed compensation to hold unity voltage at nominal conditions withSsc=10p.u. (Xs=0.1p.u.)SVC and STATCOM MVAR equal to 0.5p.u. @ 1.00p.u. voltage Load equal to 2.3 + j0.8 p.u. Load voltage sensitivity: power mp=1, reactive power mq=2

Voltage Regulation v. System Impedance

Both SVC and STATCOM regulate the voltage up to an Xs of about 0.25p.u.Above this level both compensators hit their limitIf the contingency reduces Xs to 0.33p.u., the voltage is about 1.7% less with the SVC

Overvoltage v. Load RejectionLoad level is increased up to 4.0 p.u. Fixed compensation is increased from 1.1 to 2.5 p.u.Typical SVC can absorb reactive power up to OV of 1.3p.u. until FC are switched off to reach SVC continuous OV rating of 1.1p.u. Typical STATCOM can absorb reactive power up to OV of 1.2p.u. until FC are switched off to reach continuous OV rating of 1.1p.u.

SVC/STATCOM

P=300 MWp.f.=1.0

162 Mvar153 Mvar

230-kV

230-kVSOURCE REC

Transient Voltage Stability – Equivalent System

600 MW load, 50% induction motor, 50% resistive Load supplied by two 113 km 230 kV linesThree-phase permanent fault at midpoint of one lineSVC gain supervised to compensate for weaker systems

Recoveries with Equal Nominal Ratings

SVC – 200 MVAR @ 1.00 p.u. voltageSTATCOM – 200 MVAR @ 1.00 p.u. voltage

Recoveries with Functionally Sized SVC

SVC – 200 MVAR @ 1.00 p.u. voltage rated 260 MVAR dynamic overloadSTATCOM – 200 MVAR @ 1.00 p.u. voltage

Shunt Compensation, building blocks

The building blocks are the base, the arrangement is the solution

SVC Light®

STATCOMContinuous control

Classical switched and phase control

Series Compensation – Improves Voltage Profile

Series Compensation – Improves Stability Margin

Series capacitors – “shorter” lines and improved voltage profileReactive power supply proportional to current squaredPassive – Automatic post contingency reactive support to mitigate voltage dropTurbo available - thyristor control to boost compensation or damp oscillations (TCSC )

Series Compensation – Increases Transfer Capability

Voltage Profile - Uncompensated

Voltage Profile - 50% Compensation

Series compensation can be boosted, oscillation damped and SSR mitigated by thryristor control, e.g. TCSC

Thyristor Controlled Series Compensation

SSR Mitigation by means of CSC

Increased Line Loading - Clothes Line Analogy

Elevation = voltage profileAmount of laundry = transmission loadingKeep clothes off ground = stability criterionDistance above ground stability marginMain supports (brown) = on-line generators Props = intermediate reactive power compensation, e.g. SVC, STATCOM, SC

Increased Loading with Support - Remedial FACTS

Improved Post-Contingency Voltage Profile due to Dynamic Reactive Support by SVC, STATCOM, SC

Static Synchronous Series Compensator

Unified Power Flow Controller - UPFC

DC Transmission Characteristics

345 kV AC400 MW

500 kV DC3000 MW

Controllable - power injected where neededBypass congested circuits – no inadvertent flowHigher power, fewer lines, no intermediate S/S neededTwo circuits on less expensive lineNo stability distance limitationReactive power demand limited to terminalsNarrower ROWLower lossesNo limit to underground cable lengthAsynchronous

Hyper-space bypass

DC Transmission TechnologiesHVDC Classic for the Long Heavy Haul

HVDC Light for the Intermediate Haul

Power controlTerminal reactive power demand by shunt bank switchingBulk power transmissionMinimum system short circuit capacity > twice rated power (or > rated power with series compensation)

Real and Reactive Power controlDynamic voltage regulationUnderground transmissionReplace local inefficient generationModular and expandableBlack start capabilityNo short circuit restriction

The HVDC Classic Converter Station

Converter station Transmissionline or cable

Converter

Smoothingreactor

DC filter

Telecommunication

Controlsystem

AC filtersShunt

capacitorsor otherreactive

equipment

AC bus

Power Ratings: 500 - 3000 MW

Reactive Power Supply

The CCC* Converter Station*Capacitor-commutated converter station

TransmissionLine, Cable or Back-Back

Converter

Controlsystem

Contune AC filters

AC bus

Smoothingreactor

DC filter

Telecommunication~~

Commutation capacitors

Weaker SystemsBack-to-Back 100 - 550 MW

HVDC Light Station

Converter station

Transmission Cable

Voltage Source(d) Converter - VSC

AC filters

AC bus

Controlsystem

PhaseReactor

DC Capacitor

IGBT Valves

Dry DC Capacitor

Strong or Weak SystemsDynamic Voltage ControlUnderground TransmissionUp to ±150kV, 330MW

Infinite Improbability Drive

VSC Operating Characteristics

FACTSApplication Examples

Increased Interchange with FACTSForbes Static Var Compensator

Increases interchange capacityInnovative dynamic overload-150 / 110 MVAR continuous range- 450 / 400 MVAR dynamic overload2 x 300 MVAR 500 kV MSCReduces LLP and OOS TrippingSingle 500 kV line possible due to HVDC controllability

TCSC case - North/South Interconnection, Brazil

Brazil

North-SouthInterconnection5 SCs + 1 TCSC

Location Rating Voltage

Maraba 348 Mvar SC 500 kVMiracena 161 Mvar SC 500 kVColinas 2x161 Mvar SC 500 kVImperatriz 161 Mvar SC 500 kV

107 Mvar TCSC 500 kV

Power Oscillation Damping using TCSC

0 10 20 30 40 50 60 70 800

time (sec)

No TCSC POD active

0 10 20 30 40 50 60 70 800

time (sec)

North TCSC POD active

0 10 20 30 40 50 60 70 800

time (sec)

Both TCSC PODs active

No TCSC POD active North TCSC POD active

Both TCSC PODs active

Eagle Pass, BtB Light® Project sponsored by EPRI

ApplicationVoltage SupportPower Transfer (BtB)

AlternativesClassic HVDC B-t-B combined with SVC

ChallengesShort delivery timeSmall site

SolutionBtB Light®, +/- 2x36 MVA

Foot print +/- 2x36 MVA: 90 x 120 ft

SVC Light® STATCOM for Industry, AvestaPolarit

ApplicationFlicker mitigation (EAF Steel)

AlternativesNew linesConventional SVC

ChallengesShort delivery time ( 14 month)Flicker reduction > 3 timesHigh avaliabilitySmall site (15 X 20 m)

SolutionSVC Light® : 0/+164 Mvar

SVC Light® STATCOM for Industry

Recordings with & without SVC Light®, AvestaPolarit Stainless Steel, Finland

1 3 : 0 3 1 3 : 2 3 1 3 : 4 3 1 4 : 0 3 1 4 : 2 3 1 4 : 4 3 1 5 : 0 3 1 5 : 2 3 1 5 : 4 3 1 6 : 0 3 1 6 : 2 30

4 06 0

1 2 01 4 01 6 0

E A F M W & M va r , N e t w o rk M v a r

E A F M WE A F M va rN e t w o r k M v a r

1 3 : 0 3 1 3 : 2 3 1 3 : 4 3 1 4 : 0 3 1 4 : 2 3 1 4 : 4 3 1 5 : 0 3 1 5 : 2 3 1 5 : 4 3 1 6 : 0 3 1 6 : 2 30 . 9

0 . 9 20 . 9 40 . 9 60 . 9 8

11 . 0 21 . 0 41 . 0 61 . 0 8

F l i c k e r s t a r t i n g 2 0 0 3 - 0 1 - 2 1 1 3 : 0 3 : 0 0

3 3 k V b u s v o lt a g e

M e a s u r e dC o m p u t e d

Recordings made during operation of EAF w and w/o SVC Light®First EAF batch w/o SVC Light® (13:03-14:25)Second EAF batch w SVC Light® (14:43-16:10)Reduced flicker guaranteed to >3.0 – actual > 4.0

w/o SVC Light w SVC Light

ProblemOld inefficient power plant in residential areaEnvironmental concernsRMR generation needed for voltage supportSmall, congested siteAudible noise

Solution±100 MVAR STATCOM (SVC Light)3 x 32 MVAR switched capacitor banksCompact designVariable rating “modular” solution

BenefitsAllows retirement of old generating stationImproves local environmentMaintains reliable transmission service

Holly STATCOM – SVC Light

PG&E Newark SVCApplication

High load growth, increasing importVintage synchronous condensers used for voltage/ VAr Control

AlternativesReplace synchronous condensersNew generation/ transmissionFACTS: STATCOM or SVC

ChallengesShort implementation timeHigh reliability requirementSmall footprint required, high seismic

SolutionFixed 225 MVAr Shunt Caps, 230 kVDyn. -100/+ 200 MVAr SVC FACTS, 230 kV with 10% capacitive overload

ProblemInadequate interconnection capacity to LI High location marginal pricing on LILocalized capacity shortages at peakHigh Load growthPlant siting difficultiesAll “roads” go through NYC

Solution330MW, ±150kV HVDC Light Submarine Cable from New Haven, CT to Shoreham, NYInterconnects NEISO and NYISOMerchant TransmissionExpandable Solution

BenefitsImproves system reliabilityRelieves congestion - more economic dispatchProvides for emergency transfer, reserve sharing

Cross Sound Cable – HVDC Light

Step Response Test

No Change in Reactive Power Demand or AC Voltage

ProblemInadequate E-W transfer capacityHigh differential energy costsLocalized capacity shortagesRelatively weak ac networksTight Schedule – 19 months

Solution2x100MW modular Back-to-Back TieOptimized aggressive scheduleCapacitor Commutated ConvertersExpandable Solution

BenefitsSolves problem with minimal ac system additionsRelieves congestion - more economic dispatchProvides for emergency transfer, reserve sharing

Basin Electric Rapid City Tie – HVDC CCC

ProblemUnreliable, aging, obsolete equipmentEnvironmentally unfriendly Hg-Arc ValvesExpensive O&M, contaminationSeismic vulnerability

SolutionReplace vintage equipment with 3100MW, ±500kV bipole housed in 1/3 the spaceElimination of Hg-Arc Valves & auxiliariesReuse existing filtering and switchgear Replace control & protection system

BenefitsDramatic reduction in area, complexity and O&MMeets current seismic requirementsMore reliable & dependable power transfer

Sylmar Replacement – HVDC Classic

Existing Sylmar West 2000MW - circa ’69,’84

Sylmar East with Replacement Converters

1100MW circa ’89 -> 3100MW

Better Asset Utilization Through Technology

ABB HVDC

Markettoday

Environment Environment

TechnologyControllability

HVAC with RPC / FACTS

Future market

Conventional HVAC

DC & AC

Adequate incentives

Fast track permiting

Regional planning

Multiple solutions

Restaurant at the End of the Universe . . . MenuFACTS

(Flexible AC Transmission System)HVDC

(High Voltage Direct Current)Static Var CompensatorAvoid voltage collapse(Biggie size available, extra value-meal)

SVC Light, a.k.a. STATCOMFor flicker mitigation, dynamic voltage control(Recommended for the light eater, “yuppie fare”)

Series CapacitorTry this to carry heavier loads over longer distances!

Thyristor Controlled Series CapacitorDamps infinite improbability drive oscillations

HVDC ClassicHyper-space bypass for the long, heavy haul(Man-size portions, multi-terminal available)

HVDC Light, a.k.a. VSC TransmissionA favorite on the edge of the galaxy(For smaller appetites, stealthy and healthy)

Capacitor Commutated ConverterAdded zest for the traditional favorite(Portions for 2, strengthen your back-to-back relationship)

DRINKSPan-Galactic Garble BlasterA real knock-out punch! (Warning – the 2nd one will kill you.)

Pulse-Width ModulatorOnly served with SVC Light & HVDC Light(Shaken – not stirred, Marvin’s favorite refreshment!)

FACTS(Flexible AC Transmission System)

HVDC(High Voltage Direct Current)

Static Var CompensatorAvoid voltage collapse(Biggie size available, extra value-meal)