1 ieee psrcc wg 24 -modification of commercial fault ...€¦ · type-3 wind generator model...

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IEEEPSRCCWG24- ModificationofCommercialFaultCalculationPrograms

forWindTurbineGeneratorsNeedfortheWG

Dr.SukumarBrahma,ClemsonUniversityWGChair

sbrahma@clemson.edu

Scope2

1. TosurveyWTGmanufacturerstodeterminewhatparameterstheycouldprovidethatcouldbeusedbysteadystateshortcircuitprogramdevelopersinvarioustimeframes.

2. Usetheresultofthissurveytoprepareareportthatcanbeusedbysteadystateprogramdeveloperstorefinetheirmodels.

Motivation• TypeIIIandTypeIVwindturbinegenerators(WTGs)connectthroughinverters.

• Highlynonlinearresponseofinverterstofaults.• Conventionalphasordomainshortcircuitanalysisassumes– Linearresponseofsources(TheveninEquivalent)– Loadcurrentsnegligiblecomparedtofaultcurrents.

• Theseassumptionsarenolongervalid.• Invertercontrolsareproprietary– hampersemtpmodelingaswell.

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FaultResponse- I4

Gear Box DFIG

C

RSC GSC

Ps,Qs

Pr,Qr

Ecap

Crow bar

Wind Turbine

Coupling Inductor

Controls

Grid

AC/DC DC/AC

• TypeIIIWindTurbineGenerators(WTGs)canhavethemostcomplexbehavior–– oldermodelscrowbarforclose-infaultstoprotecttheconverter

circuit– behaviorsimilartoinductiongenerators.– current-controlledmodefordistantfaults.– canswitchfromonemodetoanotherduringfault.– newermodelscanavoidcrowbaraltogether.

FaultResponse- II5

• TypeIVWTGsandPVconnecttothesystemthroughinverters– responsedeterminedsolelybyinverter.– typicalfeatures– currentcontrolled,purelypositivesequence

current.– lowvoltageridethroughcanbeimplemented– changeinpower

factorduringfault.– completelynonlinearresponse- voltagecontrolledcurrent

source.

Wind Turbine

PMSG

Controls

Ps, QsGrid

MSC GSC

PV

FaultResponse– FullConverter6

• Timeforcontroltotakeoverisdifferentfordifferentmodels.• Noticepurelypositivesequencecurrentwithmagnitudecomparableto

loadcurrent.

Model – 1 (Clemson)

Model - 2 (PSRCC C17 WG report)

A-G Fault3-ph Fault

ShortCircuitBehavior- Example7

• 8– bus4.16kVbalanceddistributionsystem– 3-phfaultatbus3.• Inverter-connectedPVwithLVRTatbuses1,5,6.• Duringfaultpowerfactoranglesatthesebusesareapproximately57,54,and

41degreesleading (generatingkVar).• Conventionally,forsynchronousgenerators,ΔVi

(1)/ΔIi (1) equalsthesourceimpedanceofthegeneratoratbusi,whichhasalargereactiveangle.Inthiscasetheangleis1330.Clearlylinearitydoesnothold.

• TotalfaultcurrentangleusingVPF-3/Zbus(3,3) isverydifferent(almost1800)fromtheobservedcurrent-angle.Anglesofvoltagescalculatedusingthiscurrentinjectionarealsowidelydifferentthanmeasuredvalues.

1

8

2 3

5

4

6

7

Fault

WGRecommendation8

1. PSRCCWG24hasconsultedwithallstake-holders(utilities,softwaredevelopers,EPRI,consultants)andcomeupwiththefollowingdatarequirementsfrommanufacturersfordifferenttime-frames:

2. EPRIhasalsocontributedfieldtestedgenericmodelsthatcanbeusedinsteadoftables– caution– thesedonotmimicalldesigns.

• Invertersareungrounded– donotcontributezero-sequencecurrents.

Timeframe1,2,3(unit-secondsorcycles) FaultType:Positivesequence

voltage(asspecifiedinitem3)(pu)

Positivesequencecurrent(pu)

Positivesequencecurrentanglewithrespectto

positivesequencevoltage(deg)

1.00.90.80.70.60.50.40.30.20.1

Timeframe1,2,3(unit-secondsorcycles) FaultType:Negativesequence

voltage(asspecifiedinitem3)(pu)

Negativesequencecurrent(pu)

Negativesequencecurrentanglewithrespectto

negativesequencevoltage(deg)

1.00.90.80.70.60.50.40.30.20.1

Implementation9

1. Findfaultcurrentatbusi asVPF-i /Zbus(i,i) – thiswillnotmatchtheactualfaultcurrentbecauseofnonlinearfaultresponsefromrenewables.

2. Adjustcurrentsfromrenewablesbasedonthecalculatedterminalvoltages– usetablesprovided,oruseagenericmodelforthisstep.

3. Adjusttotalfaultcurrentbasedonadjustedcurrentinjectionsfromrenewablesandrecalculatevoltages.

4. Repeatsteps2and3untilthesuccessivevoltagesarecloseenough.

EvangelosFarantatos,Ph.D.Sr.ProjectManager

TransmissionOperations&PlanningR&DGroupEPRI

Panel“Modelingofconverter-interfacedrenewablesourcesforshortcircuitstudies”2019IEEEPESGeneralMeeting

Atlanta,GAAugust5,2019

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GenericShort-CircuitModelsofWindTurbine&PhotovoltaicSolarGeneration

Motivation,Challenges&Needs• Continuouslyincreasingpenetrationlevelofinverterbasedresources(IBR),predominantlyrenewables(TypeIII,TypeIVWTGs&PVs)

• Complexfaultresponse• Differssignificantlyfromsynchronousgeneratorshort-circuitcurrent(SCC)

• Accurateshort-circuitmodelsforprotectionstudies• Performanceoflegacyprotectionschemes(distanceprotectionetc.)

InverterBasedResources

Gearbox

Grid

Step downtransformer

Windturbine

iPMSG

Stator-Side Converter

Grid-Side Converter

ig

IL , PLType III WTG

Slip ringsGearbox

GridStator power

Rotor -Side Converter

Grid-Side Converter

Rotor power

Transformer

Windturbine

Crowbar

Chopper

Type IV WTG

Solar PV

InverterBasedResourcesFaultResponseCharacteristicsSynchronous Generator

Type IV WTG

• SCC magnitude close to nominal load current (typically 1.1-1.5 pu)

• Initial transient (typical duration 0.5-1.5 cycles) –uncontrolled response – controller “reaction time”

• Fault current can be capacitive, inductive or resistive• Typically low negative sequence current contribution• No zero sequence current

InverterBasedResourcesShort-CircuitModeling

Synchronous generator classical short circuit model (voltage source behind an impedance) is not applicable

•EPRI Project 173.09 “Impact of Renewables on System Protection” • IEEE PSRC WG C24 “Modification of Commercial Fault Calculation Programs for Wind Turbine Generators”

EPRIWind/PVPhasorDomainShort-CircuitModel

•Voltage controlled current source• Iterative solution (nonlinear behavior)

• considers the impact of controls on the short circuit response• respects inverter current limits

InverterGenericControlModeOptionsFunction ControlMode Performance/Description

Reactivepower/voltagecontrolduringride-through

Constantpowerfactor Allowsforinverterinjection/absorptionof

reactivepowerbasedonadesiredpowerfactor

ConstantQ Allowsforinverterfixeddesiredvalueofreactive

powerinjection/absorptionVControl Allowsforinvertercontrolof

voltagetodesiredvalueDynamicreactivecurrentcontrolbasedonreference

curve(FRT)

Allowsforreactivecurrentinjectionbasedona

referencecurve(e.g.gridcode)

FRT Curve

CurrentLimiter- PQPriority

Assume:Active Power: 1 p.u.Post fault voltage: 0.7 puControl mode: FRT withslope 2Q priorityIlimit=1.1 pu

Example:Desired Currents:Iactive= 1/0.7=1.43 p.uIreactive=2(1-0.7) = 0.6 p.uItotal=1.55 pu (exceedslimit)

Upon current limiter:Iactive= 0.92 (reduced tosatisfy limit)Ireactive= 0.6 p.uItotal= 1.1 pu

IterativeSolution

DemonstratingResultsType IV WTG - LLG fault (AB) - BUS 1

Type III WTG - LL fault (AB) - BUS 4

•Here, Type IV WTG/Solar model assumeszero negative sequence currentcontribution

•Type III WTG has negative sequencecurrent contribution due to the DFIG statorconnection to the grid

NegativeSequenceControl

ControlMode:DynamicReactiveCurrentInjection(k=2),QPriority

Coupled Decoupled Germancode(k=2)

WTGvariable

EMTP-RVSolution

PhasorDomainSolution

EMTP-RVSolution

PhasorDomainSolution

EMTP-RVSolution

PhasorDomainSolution

Vpos0.710(23.9)

0.710(24.1) 0.719(13.8) 0.720(13.6) 0.720(6.9) 0.720(6.9)

Ipos1.135(-10.7)

1.135(-10.4) 0.898(-30.4) 0.893(-30.9) 0.743(-50.4)

0.743(-50.5)

Vneg0.336(-120.1)

0.337(-117.4) 0.281(-132.9)

0.281(-133.5) 0.213(-118.1)

0.213(-118.0)

Ineg0.063(97.2)

0.030(152.6) 0.296(26.8) 0.305(27.7) 0.407(-28.1)

0.407(-28.0)

1.Coupled: Elimination of negative sequence current injection2.Decoupled: Mitigation of second harmonic oscillation by

injection of negative sequence current3.German Grid Code: Negative sequence current injection

proportional to variation in negative sequence voltage

22.5 MVA Solar Plant: I2 & V2

VDE-AR-N 4120

ModelValidation– 3Approaches1. Generic EMT Models 2. Manufacturer EMT Models

3. Fault Records

Type-IIIWTGWindParkConnectedtoa230-kVSubstation

+VwZ1

230kVRMSLL /_0

PI

+

Line_LATIGO_3BUTTESWP_DFIG1

DFIG AVM110.022MVA230kVQ-control

LFLF1

Slack: 230kVRMSLL/_0Vsine_z:VwZ1

+ Relay_Wind

+ Relay_Transmission

6604_LATIGO

V1:1.00/_-0.00V2:0.00/_102.09V0:0.00/_45.00Va:1.00/_0.00Vb:1.00/_-120.00Vc:1.00/_120.00

11847_THREE_BUTTES

V1:1.00/_0.2V2:0.00/_-89.8V0:0.00/_-89.8Va:1.00/_0.2Vb:1.00/_-119.8Vc:1.00/_120.2

Variable

POI- pu

EMTP-RV PhasorModel

0.825(-39.7) 0.810(-56.4)0.509(1.5) 0.509(0.6)

0.858(105.8) 0.862(98.4)

0.488(0.4) 0.486(0.1)

I +

V +

I -

V -

Phasor Model

EMTP Model

• Windfarmwith66x1.5MWtype-IIIwindturbinegenerators

• B-CphasetophasefaultonthetielinetothePOIsubstation

IEEEPSRC&VendorEngagement

•Goal: Vendor engagement and implementation of the models in commercial platforms (CAPE, ASPEN OneLiner, CYME, Powerfactory, etc).

•Contribution to IEEE PSRC WG C24 “Modification of Commercial Fault Calculation Programs for Wind Turbine Generators”

Timeframe1(secondsorcycles) FaultType:Positivesequencevoltage(asspecified

initem3)(pu)

Positivesequencecurrent(pu)

Positivesequencecurrentanglewithrespectto

positivesequencevoltage(deg)

0.90.70.50.30.1

Contact: efarantatos@epri.com

Q&A

• EPRI project is conducted in collaboration with Polytechnique Montreal (Prof. Ilhan Kocar, Prof. Jean Mahseredjian, Dr. Aboutaleb Haddadi, Dr. Thomas Kauffmann)

References

Acknowledgements

1. T. Kauffmann, U. Karaagac, I. Kocar, S. Jensen, E. Farantatos, A. Haddadi, and J. Mahseredjian, “Short-circuit model for Type-IV wind turbine generators with decoupled sequence control”, IEEE Transactions on Power Delivery (Early access), DOI: 10.1109/TPWRD.2019.2908686, Apr. 2019

2. T. Kauffmann, U. Karaagac, I. Kocar, S. Jensen, J. Mahseredjian, and E. Farantatos “An accurate Type III wind turbine generator short circuit model for protection applications”, IEEE Transactions on Power Delivery, vol. 32. No. 6, Dec 2017

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Implementation of Converter-Interfaced Generator ModelType-3 Wind Generator Model in Short Circuit Programs

Presented bySherman Chan ASPEN

Converter Interfaced Generator Model

• For solar plants• For Type-4 wind plants• For other generating plants that has a

converter as the interface

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Converter Interfaced Generator Model

• Perfect current source with infinite internal impedance.

• Injects no zero- or negative-sequence fault current now. Negative-sequence current will be added in a future update.

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Converter Interfaced Generator Model

• Within the voltage deadband, the generator maintains constant power.

• The deadband width is adjustable.

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Converter Interfaced Generator Model

• Outside the deadband, control options are:1. Constant power2. Fault-ride-through (FRT) control method3. Constant voltage (by setting the FRT slope to

the impedance of the network as seen from the generator).

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Converter Interfaced Generator Model

• All the control options are subject to a current limit, usually 1.1 or 1.2 pu.

• User can set a lower current limit when the terminal voltage is low.

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Converter Interfaced Generator Dialog Box

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Converter Interfaced Generator Simulation

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Type-3 Wind Generator Model

• Based on EPRI’s phasor-domain model.• Injects positive- and negative-sequence fault

currents, but no zero-sequence current.

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Type-3 Wind Generator Model

The user must decide to simulate:1. The controlled mode, or2. The crowbarred state

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Type-3 Wind Generator Model

The fault current in the controlled mode is usually limited to 1.1 or 1.2 pu.The fault current in the crowbarred state is usually around 5 pu, plus dc offset.

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Type-3 Wind Generator Model Dialog Boxes

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Type-3 Wind Generator Model Simulation

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Voltage Controlled Current Source

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Wasdesignedtosimulatevoltagesourceconverters.

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Short Circuit Models for Wind and PV Generation in CAPE

Presented at 2019 IEEE PES GM Panel Session“Modeling of converter-interfaced renewable sources for

short circuit studies,” August 5, 2019

Donald MacGregorSiemens Industry, Inc.

Ann Arbor, MIdonald.macgregor@siemens.com

ObjectiveCalculate current contributions from wind and solar generators during external faults. Use a steady-state phasor model. Use manufacturer’s data where possible.

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AG 2019

Three-Phase Fault

Solar Generator

EPRI Test Network

Outline • CAPE Algorithms for Type III, Type IV, and

Voltage-Controlled Current Source• Special Cases• Reporting Options

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CAPE Algorithms for Type III, Type IV, and Voltage-Controlled

Current Source

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Synchronous Generator• A synchronous generator has an internal EMF proportional

to prefault load, or 1.0 pu for a classical flat voltage profile.• After a fault or disturbance, the shunt impedance

immediately decreases from steady-state to subtransient; the EMF is unchanged.

• Fault current Ifault= (Prefault voltage)/ (Thevenin equivalent impedance) at fault bus

• In a linear network, change of Vbus is proportional to Ifault .

Inverter-Based Generator

Type III: Doubly Fed Induction Generator

Diagram provided by Electric Power ResearchInstitute, Palo Alto, CA

Inverter-BasedGenerator Type III

Doubly-Fed Induction Generator treated as synchronous withchosen impedance, for currents up to a fixed limit (e.g. 0.5 pu)Magnitudes of other phase currents kept in proportion to first to reach limit; phase angles heldconstant; zero sequence removed

Type III with CrowbarRotor circuit is shorted for overcurrentsMachine becomes an induction generator, with constant EMF behind the given impedance The current limit is set at 999 perunit Optional for all or selected generators

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Type IV Generator with Full-Power Conversion

Diagram and data provided by Electric Power ResearchInstitute, Palo Alto, CA, and by Southern Company, Atlanta, GA.

Type IV Model from LV to MV 12

VLV, ILV

Diagram and data provided by Electric Power ResearchInstitute, Palo Alto, CA, and by Southern Company, Atlanta, GA.

Inverter-Based Generator Type IV13

TYPE IV Power Converter• Start iteration (k) • P = Prefault real power • Desired current Îd = P / |Vd

(k-1)|• Derive quadrature current Îq from the controls

(chosen from Q, PF, V, Fault-Ride-Through)• Limit the d-q (Direct & Quadrature) currents

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TYPE IV Power Converter• Transform Id + j Iq to positive sequence phasor

Ip = (Id + j Iq ) exp j [ arg (Vp (k-1)) ]

• Inject current into faulted network and compute three-phase voltage (Va, Vb, Vc) for iteration (k)

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Type IV Limits of |I|, Id, and Iq• Î = √(Id

2 + Iq2)

• With P control priority, reduce Id with constant Iq, then reduce Î, and finally reduce Iq.

• With Q control priority, reduce Iq with constant Id, then reduce Î, and finally reduce Id.

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Remote-Fault Option• Power penetration into network depends on local load • Without the loads, the computed short-circuit current is

too high at remote buses• Remove generators having Vpu in the dead-band:

VMIN_REMOTE < Vpu < VMAX_REMOTE (e.g. 0.95 < Vpu < 1.1)

• Or remove the dead-band with VMAX_REMOTE = -999 and keep all generators

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Eliminate Neg. & Zero Sequences

| Ia' | | Ia | | Ib' | = A * W * A-1 * | Ib | | Ic' | | Ic |

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Eliminate Neg. & Zero sequences| 0 0 0 | 0seq

W = | 0 1 0 | +seq| 0 0 0 | -seq

| 1 1 1 | A = | 1 a2 a |

| 1 a a2 | a = 1.0 @ 120 deg

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Available DataKey parameters: machine MVA and bus voltageTypes III & IV limits fixed in perunitIdlim = 1.0 Iqlim = 1.0 |I| = 1.1 puTransformer and filter impedances in perunitType IV control mode and priority

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TYPE VCCS: Voltage Controlled Current Source

TYPE VCCS: Voltage Controlled Current Source

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Current and Power Factor are tabulated functions of bus voltage.Different tables apply at specified times.Positive-sequence only.Values are supplied by manufacturer.

Special Cases

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Desired Power Factor not Compatible with Controls

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• Current angle arg(I/V) has a range with no solution. • To help borderline cases to converge, smooth the

differences between iterations using interpolation.• After 20 iterations, inject current at the Iq limit, lagging

the voltage by 90ο. This is the “Iq Injection” state.• After 20 more iterations, remove the generator.

Type IV Generator Isolated by Open Breakers

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No convergence after 40 steps

Generator Islanded by FaultCompute postfault +seq apparent impedance as Zp = Vp/Ip

If Zp is constant in the first three iterations, the generator is islandedby the fault. Replace arg(Vp) by arg(Vprefault)

when converting (d,q) currents to positive sequence

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Reporting Options

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Reports• Reports show which generators operate and

their current sources: • One-Line Diagram Branch currents and voltages

• Report_IBG Details for single generator

• Report_Active_IBGs List of operating IBGs

• Report_All_IBGs List all IBGs: local and remote

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Report Single GeneratorGenerator status: Switched to limited-Iq injection; Iter 11 Convergence Report THREE_PHASE at 3 Loop Iter bus CCT VP_MV .... P,Q MVA 2 1 8 1 0.26 @ 20.9 17.40 9.17 2 2 8 1 0.37 @ -0.7 18.72 21.93 2 3 8 1 0.42 @ -14.8 14.75 29.47 2 4 8 1 0.44 @ -24.3 10.36 32.92 2 5 8 1 0.44 @ -30.7 6.89 34.29 2 6 8 1 0.44 @ -35.1 4.41 34.74 2 7 8 1 0.44 @ -38.0 2.71 34.81 2 8 8 1 0.44 @ -40.0 1.56 34.76 2 9 8 1 0.44 @ -41.3 0.78 34.67 2 10 8 1 0.44 @ -42.2 0.26 34.59 2 11 8 1 0.44 @ -42.2 0.26 34.59

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Report Active IBGsSummary of controlled generation

Bus Shunt # P,Q MVA Status1 24580 1 1.16, 81.67 Iq injection at current limit2 9634 1 0.00, 0.00 Remote fault3 8869 1 1.13, 80.91 Iq injection at current limit4 8464 1 0.00, 0.00 Remote fault...81 11700 1 0.00, 0.00 Remote fault82 11701 1 0.00, 0.00 Remote fault85 7235 1 0.00, 22.50 Radial line (islanded)86 11728 1 34.99, 14.37 Converged normally...

113 11775 1 0.00, 83.22 Iq injection at current limit114 11779 1 100.87, 41.55 Converged normally

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Summary• EPRI has provided algorithms for fault contributions

from wind and solar generators. • In CAPE, Type III (DFIG) uses a fixed current limit.• Type IV (full-power converter) follows EPRI algorithm.• CAPE has detailed reports for each generator or

summary reports for a large network (e.g. 100 or more wind or solar generators).

Summary• With limited data, user supplies desired real power

and control type.

• Default per-unit parameters give current limits.

• Type VCCS (voltage-controlled current source) uses tables of I-V characteristics.

Discussion

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34

MohammadDadash Zadeh,Ph.D.,SMIEEE,PEETAP,Irvine,CA,USA

ShortCircuitModelsforWindandPVGenerationinETAP

1

Content• ConverterModelforShortCircuitStudies• HigherLevelCurrentLimiter• FaultRightThroughControl• ConverterControlModes• ANSIvsIEC• User-definedModel• Negative-sequenceCurrentInjection

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ConverterModelforShortCircuitStudies• InverterandWTGType4• f()isnonlinear• f()dependsonconvertercontrolsettingsandlimits

• Iterativesolutionvstime-domain• Steady-statevsdynamic

3

I1=f(V1,V1Prefault,PPrefault)

I2=0

I0=0

ConverterModelforShortCircuitStudies

• InverterandWTGType3

4

I1=f(V1,V1Prefault,PPrefault)

I2=0

I0=0

Z2

Z0

Crowbarnotactivated Crowbarisactivated

SimilartoTypes1&2

ANSI:Crowbarresistanceisadded

IEC:SpecialCalculation

HigherLevelCurrentLimits5

FaultRightThroughControl6

𝐼" = 𝐼"$%"×'()*+,-./0

'(

ConverterControlModes• ReactiveCurrentSupport:Iq ismetfirstandthenId• ActiveCurrentSupport:Id ismetfirstandthenIq• User-DefinedPF:– Id iscalculatedfirst.– Iq iscalculatedbasedontheuser-definedPF.– Id andIq arescaledproportionallytomeetthelimits.

7

ANSIvsIEC8

User-DefinedModel• Genericmodelmaynotmeetspecificconverterresponse

• Time-domainsimulationusing– WECCmodel– User-definedmodel

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Negative-sequenceCurrentInjection10

I1=f(V1,V1Prefault,PPrefault)

I0=0

I2=f(V2)

Question?

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