1cmc2016
Solar Storms: Risks to Electric Power Systems
Chathan M. Cooke MIT, RLE, Laboratory for Electromagnetic and Electronics Systems, High Voltage Laboratory, Cambridge, MA, USA
Tuesday, March 15, 2016 Swiss RE Centre for Global Dialogue, Ruschlikon/Zurich
Expert Hearing on Solar Storms, Electric Power Systems
3d
2cmc2016
Discussion Topics Outline
• Power System Limits: Self-Preservation Conflict - Simultaneity vulnerability
• Solar Storms: - Coupling to Earth - Coupling to Power Systems - Solar Variations
• Models: Features, Uncertainties
• Apparatus: Heating, Harmonics • Key Limits/Actions Today: Models, Impact Calculations
3cmc2016
‘Bad’ Things Do Happen !!!
How to be Prepared ?
DesertWellsNevadaVia:UniversityLibrariesUniversityofNevadaNevadaMagazine2016
4cmc2016
Core Concepts for GMD Power System Risks
1. Inherent Collapse due to Self – Preservation A)Wide-arearecoveryprocess,Black-starts
2. Abnormal Injected Perturbation Energy
3. Inadequate Models
4. Unknown / Variable Parameters
5. Unknown Solar Event Size/Extent
5cmc2016
Power System: Two Major Conflicting Requirements:
1. Protect itself from Self-Destruction
2. Always supply electric power to customers
In the end ‘1’ takes Priority: (Temporary Collapse vs ‘Permanent’ Damage)
(Example:ThesuddenSIMULTANEOUSoutageof‘3ormore’largesourceswillbringmostpowersystemstocollapse.)
6cmc2016
The biggest risk from Large GMD Events is Tipping Point; ‘Simultaneity’
1. The system designed to tolerate ‘local’ failure
2. The system cannot tolerate many ‘source’ failures over a wide area region
example:
(Ice Storm of 1998 on HydroQuebec grid)
7cmc2016
Simultaneity – Warm & Cold
hXp://alaingazon.ca/Meteo/verglas.html
BetweenJanuary5and10,1998,Québecexperiencedexcep_onallyharshweathercondi_onsasthreesuccessivestormsle`upto110mmoficeoverthesouthoftheprovince.Thoughrobustandwell-maintained,theHydro-Québecgridsufferedunprecedenteddamage.
cold
warm meet
8cmc2016
Self-Preservation First !!!
hXps://en.wikipedia.org/wiki/Hydro-Quebec’s_electricity_transmission_system
a) Thousandsofpoles,towersandkilometersoflinesfell.
b) Inarea100by250kilometres,some116transmissionlineswereoutofcommission,includingseveralmajor735kVpowerlinesandtheQuebec–NewEnglandHVDC±450kVline.
c) Attheheightoftheblackout,some1.5millionhomesandcustomers,housingthreetomorethanfourmillionpeople,wereinthedark.
d) Blackoutsinsomeareaslastedfor33days,and90%ofthoseaffectedbytheblackouthadnopowerformorethansevendays.
e) Eventually,the$1billionlevelwasmet–andhandilyexceeded–andforcloseto15years,theGreatIceStormof1998remainedasthecostliestinsurednaturalcatastropheinCanadianhistory.
hXps://merelmarc.wordpress.com/2014/02/12/la-crise-du-verglas-de-1998/
hXp://www.iclr.org/icestorm98insurance.html
9cmc2016
Lessons Learned ?? “Ifthe1998stormhappenednow,howwouldthepowersystemrespond?”1)Restora_on_meswouldbemuchshorter.
Reinforcedthegrid,suchascrea_ngloops,strengtheningfacili_esandpruningtrees,reducesthenumberofcustomersaffectedandtheextentofdamage.Repaireffortswouldthusbemorelocalizedandtakeless_me.
hXp://news.hydroquebec.com/en/news/116/ice-storm-1998-15-years-later/
2)Certain---construc_onstandardsandmethods---helptomakethepowersystemmorerobust.
MajorresearchanddevelopmenteffortstobeXerunderstandeventsandtostrengthenfacili_esbeganimmediatelya`ertheicestormandcon_nuetoday.TestlineshavebeenbuiltatHydro-Québec’sresearchins_tute,IREQ,inordertoreplicateicingcondi_ons,andtotestandvalidatespecificdesignsandparameters.
10cmc2016
Causes for Extended Duration Outages
1. Destroyed essential elements (long-time repair)
A. Energytransportelements(ex.Transformers,T-lines,compensators)B. Measurementandcontrolelements(ex.CTs,VTs,VARcontrol,PMU)
2. Damaged essential elements, which then fail later.
3. Loss of system control communications
A. SCADA,intranet,satellites(ex.GPS_me-stamp)
4. Lack of raw materials/energy/transportation
11cmc2016
Solar Storms – Premonitions ?
1970:Albertson,Baelen
[Calculated]E-fieldshavesufficientmagnitudetocausedisturbancesonpowersystems,andareinagreementwithpreviouslyrecordedvalues.---regionswithlowconduc_vityaremoresuscep_bletomagne_cstormdisturbances.
[|Eo|3.4V/km,at500nT,for1-60min]
1972:Albertson,etal
Theimportanceoflocalizedinternalhea_nginpowertransformersdueto[GIC]ispresented.[GICof5-100ampereandmore,forminutes]
1973:Albertson,Thorson
K-8StormofAugust1972:Geomagne_cstormsproducequasi-dccurrentsin60Hzelectricpowersystems.Thesespuriousdccurrentscausedundesirableequipmentandsystemopera_ngeffects.---load-flowstudiesmadewithGICpresentinlargeinterconnectedpowersystemsinNorthAmerica
1981:Albertson,etal
THEN:1989HydroquebecGICBlackout
12cmc2016
Power System GMD Event Response
Lessons:the1989Hydro-QuebecGMDevent:
‘DC’ Induced Harmonics (via Transformer Magnetic Saturation)
1. Voltageregula_ngSVCsmalfunc_on->tripmajorTLines2. Lossofmajorgenera_on->frequencycollapse3. Unabletoshedloadfastenough->furtherfrequencycollapse4. Self-protec_onshutdown->lackofadequatea`erfailure
strategies
13cmc2016
The 2nd Biggest Risk from large GMDs on Grids is the Abnormal Unknown
Injected Energy
1. Abnormal Energy enters Grid via highly non-standard paths A. ‘DC’GroundRiseNOTencounteredexceptwithGMDs,NOdesignexperience
2. Added abnormal energy causes unknown (unexpected) consequences [harmonics, heating]
A.Howmuch,howlong,where?
14cmc2016
The 3nd Biggest Risk from large GMDs is ‘Inadequate Models’
1. Simulation Circuit Models
A) Couplingfrommagne_cfieldtoinducedearthvoltages
B) InducedearthvoltagesthatcauseGICs§ Source‘In-Earth’,not‘on-lines’
C)GICeffects‘spread’intonetworkandload-flow
2. Transformer thermal models with ‘DC’ 3. Unexpected System Response
circuit example: NERC (2014) vs Albertson (1981)
15cmc2016
Inadequate Models enhance Risk from large GMD caused Power Apparatus Damage
1. Transformer over-heating with ‘DC’ A)Hea_ngofWindingsB) Hea_ngofancillarypartsC) Roleofharmonicsfrequencyvsstrayfluxloca_onand
magnitudeD) Howto‘harden’transformerdesignfromGMDsE) Add‘fastdetectandprotect’controloftransformers
2. VAR stabilizers 3. Measurement/control devices
16cmc2016
GIC Model: Actual Structure
Albertson1981,Wait1952
EarthisNOTanEquipoten_al
17cmc2016
GIC Model: Actual Structure
Lindahl2003
EarthisNOTanEquipoten_al
18cmc2016
GIC Model: Actual Structure
Albertson1981
DifferentEarthSurfacePoten_alsatEveryEarthContact
19cmc2016
GIC Model: ‘NERC’ Circuit Conflict
[ApparentlyUsedBy:World-Power,andPSS®E;Boteler,Overbye,PirjolaandSiemens]
SOURCESNOTINEARTH
20cmc2016
GIC Model: ‘NERC’ Circuit Conflict
‘In-Line’equivalentcircuitemployedbyPSS@Esimulator[Siemens2014]
21cmc2016
GIC Model: ‘NERC’ Circuit Conflict
EquivalentCircuitforin-lineandin-earthvoltagesourcemodel[boteler]
22cmc2016
The 4th biggest risk is from uncertain parameters and values
1. Induced earth surface voltages that cause GICs A) Effec_veearthresistanceB) WhereGICstravelinsystem
2. Transformer losses with harmonics
23cmc2016
Uncertain Earth Resistivity
€
Ey(ω ) = −Z(ω )
µBx(ω )
EarthSurfacePoten_alDirectlychangedbyearthvolumeresis_vity:
[refnato2005]
24cmc2016
Transformer Heating Models
nerc-std-GICthermStep5A
[nercTPL-007-1.2014]
25cmc2016
Transformer Heating Models
nerc-std-xfrmrGICtherms-Fig12
[nercTPL-007-1.2014]
26cmc2016
Transformer Heating Models
girgis2013_GIC-hotSpot
27cmc2016
Transformer Heating Measurements
picher1997_GICthermRise-370MVA_HQ-ABB
28cmc2016
5th Risk Factor: Unknown ‘expected size’ of GMD event to tolerate
1. Solar event size (magnitude/physical extent) • Verylargeevent:<1ppmofsolardailyenergy• Sta_s_csconsistentformany‘observables’
2. Many ‘metrics’ for statistics • CMEmass,energy• EarthsurfaceB-fields,DST(equator),local• EarthsurfaceE-fields• Physicalextentoffieldperturba_ons
29cmc2016
Solar Event Stats
|E| (V/km)
# of 10 secper 100 yrs
108
106
104
102
100
10-3 10-2 10-1 100 101 102
blue = |E| (V/km) NERCgreen = |E| (V/km) pulkkinen hydroQbrown = |E| (V/km) pulkkinen BCgrape = Dst (nT) pulkkinen
105
|Dst| (nT)
# of 1 hour eventsper 100 yrs
103
101
100
103
# Eventsper 14 yrs
102
101
100
red = CME (mass) vourlidasred (dashed) = CME (mass) LASCO vourlidas
1015
CME mass (g)1016 1017 1018
101 102 103
SOLAR EVENT STATISITICS
cmc20161030
CME energy (erg)1031 1032 1033
10-1
10-2
10-3
10-4
spring = CME (energy) vourlidasProbability
100X
104
102
<1 ppmdaily solar
energy
30cmc2016
Very Large Solar Events "It'slikelythattheCarringtoneventwasalsoassociatedwithmul_pleerup_ons,andthismayturnouttobeakeyrequirementforextremeevents,"notesRiley."Infact,itseemsthatextremeeventsmayrequireanidealcombina_onofanumberofkeyfeaturestoproducethe'perfectsolarstorm.'"
IntheirDec.2013paper,Bakeretal.es_matedDstfortheJuly2012storm."IfthatCMEhadhitEarth,theresul_nggeomagne_cstormwouldhaveregisteredaDstof-1200,comparabletotheCarringtonEventandtwiceasbadastheMarch1989Quebecblackout."
31cmc2016
The Start of Troubles
32cmc2016
Power System GMD Effects 1) Addedhea_ngduetoeddycurrenteffects
inmetallicpartswithinatransformerexposedtohighharmoniccontentmagne_cfields.
2) Addedhea_ngwithintransformerwindingsduetothelargeaddedharmoniccurrents.
3) Addedhea_ngwithintransformerwindingsduetoeddycurrentlossesinthewindingconductorsandnearbymetalvolumes.
4) Theharmonicsproducedwithinatransformerpropagateintothepowersystemandcauseunplannedresponseofmeasurementapparatus
5) Theharmonicsproducedwithinatransformerpropagateintothepowersystemandcauseunexpectedreactanceandsystemstabilityissues.
Hea_ng:highlysensi_ve
toamountanddura_onOfGICcurrents,EasilyexceedsStandardLevels
Unknownsensi_vityToamountanddura_on
OfGICcurrents
33cmc2016
Power Systems
twokeypathsforGMDeventstodisturbanelectricpowersystem
(1)istointroduceaddedabnormalenergyviaextendedpowerlines
(2)istodisturbcommunica_onssothepowersystemisinsomesense‘blinded’andlacksinforma_onneededfornormalopera_on.
34cmc2016
Insufficient Clarity of Response-1
• Ambiguous basic electro-magnetic model for coupling GMD energy into the grid,
• Unsubstantiated equivalent circuit models employed by utilities for calculations of the perturbation energy flow into the grid,
• Uncertainty for earth resistivity and how much it changes with weather and climate, especially over the long term,
35cmc2016
Insufficient Clarity of Response-2
• Restrictive assumptions about calculated transformer response to coupled GMD energy and lack of experimental test data,
• Unknown criteria, models and testing for the impact of large GMD induced harmonic content,
• Unknown criteria for and coordination of the impact of numerous simultaneous local outages over a broad area including recovery schemes and adequacy of ‘black-start’ contingencies.
36cmc2016
Insufficient Clarity of Response-3
• Uncertain models and criteria to evaluate and access the impact of communications loss, especially with the expected greater reliance on centralized automated electronic controls.
• Uncertain preparedness models to deal with large-scale simultaneous outages.
37cmc2016
Areas of Uncertainty of Risk
• A validated agreed physical model for GMD energy coupling into the electric grid.
• A validated agreed equivalent circuit to enable accurate calculations of GMD induced energy and currents in the electric power system.
• A better understanding of earth resistivity effects, especially with regard to spatial variations and long-term global weather variations.
• Full or near full-size tests for GMD current effects in loaded transformers, heating and harmonics production.
• Validated modeling for wide area full system tolerance to total system harmonics production.
38cmc2016
Solar Storm Questions
(1)DoescompliancewithFERCdirec_ve“779”adequatelyinsurethatthedefinedBaselineeventwillactuallybetoleratedbycompliantpowersystems,and
(2)Whatdamage/riskcanbeexpectedforGMDeventsofevengreaterlevelsabovethedefinedBaselineevent?ThisBaselineeventisconsideredan‘extreme’eventbyitsauthors.
39cmc2016
What To-Do ‘Next’ to Reduce Risk
1. Develop Quantified ‘Severity’ Scale – Reliableearlywarningforecas_ngwithwellquan_fiedscaleofseverityof
approachingGMDeventsprovidednear-real-_metou_lityoperators,perhapsalogarithmicscalelikeearth-quakeRichter-Scale.
2. Measure true ‘ground-rise’, Earth-Surface Potentials – Over50kmby50kmminimumareagrid(2or3loca_ons)– Atleast5yearobserva_onsminimum
3. Validate simulation models, design practice – Confirmaccurateposi_onforGICcircuitsources,impedances– Improve,validatetransformerhea_ngmodels– Improve,validatetransformerdesign/specifica_onguidesforGIC– Improve,validateharmonic/stabilityeffectsonsystemduetoGIC
4. Model very-wide region system impact – Minimum½con_nent-widesimultaneoussolar-stormimpact– Quan_fyimpactofwide-areacommunica_onsloss– Includelocalsystemcollapseandrecovery
5. Evaluate long-term parameter changes – Climate-changeeffects(extremesensi_vityofresis_vity)
40cmc2016
Earthquake Quantification Example
41cmc2016
Thank You
and thanks to the internet for so many images, etc.
