Western Electricity Coordinating CouncilRenewable Energy Modeling Task Force

Wind and Solar Modeling Update

Contact: Abraham Ellisaellis@sandia.gov

Salt Lake City, UTMarch 21, 2012

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.

WECC REMTF Charter• The Renewable Energy Modeling Task Force shall

– Develop and validate generic, non-proprietary, positive-sequence power flow and dynamic simulation models for solar (and wind) generation for use in bulk system studies

– Implement models in commercial simulation software– Issue guidelines, model documentation– Coordinate with stakeholders

• REMTF reports to the WECC Modeling & Validation Work Group (MVWG)– Responsible for maintaining dynamic modeling in the

Western Region, per NERC MOD standards

SOLAR MODELS

Copper Mountain 48 MW PV plant in Nevada (Picture: inhabitat.com)

Solar (PV) Models Under Development

• REMTF working on three models for PV plants– PV Plants (full-featured and simple models)– Distributed PV

Model Purpose Status

PV1X Large-scale PV plats Specification complete

PVD1 Stand-alone model for plant or aggregated distributed PV Specification nearly complete

CMPLDWg CMPLDW with DG for distributed PV

Version 3Options for PF representation

under discussion

Large PV Plant ModelingIn power flow, PV modeled explicitly as generator

Should include feeder or collector system equivalent per WECC guide

In dynamics, use stand-alone PVD1 model or PV1X model

PVD1 (stand alone) PV1XOR

PV1X Model Structure– Identical structure as WT4 model

PV1X P/Q and Plant Control

Q Priority (pqflag =0): ipmax = min[VDL2,(imaxtd2-iqcmd2)1/2], ipmin = 0 iqmax = min[VDL1,imaxtd], iqmin = -iqmaxP Priority (pqflag =1): ipmax = min[VDL2,imaxtd], ipmin = 0 iqmax = min[VDL1,(imaxtd2-ipcmd2)1/2], iqmin = -iqmax

PLANT LEVEL V/Q CONTROL

LOCAL V/Q CONTROL

LOCAL P CONTROL

1

0

vreg

vref

Freeze state if vreg_f < vfrz

ibranch Xc

11 + svtr

-

qbranch1

1 + sqtr

qref-

vqemax

vqemin

kpvq + kivq s

vqmax

vqmin

1 + s tft1 + s tfv

qext

vreg_f

ref_flag

÷

ipmax & dipdtmaxipcmd

vterm_f

11 + stpord

pmax & dpdtmax

pmin & dpdtmin

0 & dipdtmin

0.01

femin

femax 1

0

pflag

pgen

pref

11 + sptr

pgen_f

ddn

dup

0

0fref

f-

fdb1,fdb2

- kpd + kid s

pmax

pmin

VDL1

VDL2

pfaref

×

taniqcmd

1

0

1

0

vmin

1

0

iqmin

iqmax

qflagvflag

qmin

qmaxpf_flag

vterm

qext

pgen_f

vterm_f1

1 + strv÷

0.01

qgen

-kpq + kiq

s

vmax

vminFreeze state if voltage_dip = 1

vref1

vmax

kpv + kiv s

iqmax

iqminFreeze state if voltage_dip = 1

11 + stiq Freeze state if

voltage_dip = 1

021

iqh1

iql1

kqvvdb1,vdb2

vref0

vterm_f-

voltage_dip = 1 when (vterm <vdip) or (vterm >vup)

LVRT State Transition Switch

iqinj

LVRT State Transition Switch0: iqinj = 01: iqinj = per Position 12: iqinj = iqfrz

0

1

dip=1

(dip=1)&(thld>0)

(dip=0)&(t>thld)

(dip=0)&(t>thld)

2

qbranch_f

(1) Separate model for plant control, including power-frequency droop(2) Simplify as indicated (items are WGT4-specific)

1

Generator/Converter

ipcmd

iqcmd-1

1 + stg

11 + stg

LVPL & rrpwr

igen

11 + stlvl

LVPLvterm

zerox brkpt

lvpl1

LVPL

V

0

1

iq

ip

vterm

iq ×

÷

volim

-khv

0

0

vterm ≤ volim vterm > volim

HIGH VOLTAGE CLAMP LOGIC

iolim

V

lvpnt0 lvpnt1

gain

V

1

0

vterm ×

ip

ejπ/2

vterm

LOW VOLTAGE ACTIVE CURRENT

MANAGEMENT

LOW VOLTAGE POWER LOGIC

lvplsw

iqrmax (rate limit active when qgen(0-) > 0)

iqrmin (rate limit active when qgen(0-) < 0)

Simplify as indicated (item is WGT4-specific)

PVD1 Model

÷

vterm

N

D×

÷

pref

0

ipmax

iqmin

iqmax

0.01

N

D

×

vt0 vt1 vt2 vt3

1

0

v0 v1

dqdvqmx

qmnqref

vrflag

fterm

ft0 ft1 ft2 ft3

1

0

frflag

ireal

iimag

igen = ireal +j iimag

-11 + stiq

11 + stip

Q Priority (pqflag =0)iqmax = ialimiqmin = -ialiimipmax = (ialim2-iqcmd2)1/2

P Priority (pqflag =1)ipmax = ialimiqmax = (ialim2-ipcmd2)1/2

iqmin = -iqmax

ipcmd

iqcmd

PVD1

v(igreg)

(1) Change input to vterm + (iterm)(xcomp)(2) Insert summation, + qref(3) Insert summation, + p_var

3

1 2

Distributed PV GenerationIn power flow, residential/commercial PV would be load-netted or represented explicitly (several options possible)

In dynamics, represent with CMPLDWg model

CMPLDWg = CMPLDW + DG

• Simple version of PVD1

PV Portion of CMPLDWg

Simplified version of PVD1: No p_var, no volt/var control, no P/Q priority

CMPLDWg PSLF DYD Filecmpldw 11 "LOAD-CMP" 230.00 "CM" : #9 mva=200. /cmpldw 11 "LOAD-CMP" 230.00 "CM" : #9 mva=200. /

"Bss" 0.15 "Rfdr" 0.030 "Xfdr" 0.040 "Fb" 0.1 /"Bss" 0.15 "Rfdr" 0.030 "Xfdr" 0.040 "Fb" 0.1 /

"Xxf" 0.08 "TfixHS" 1.00 "TfixLS" 1.01 "LTC" 0 "Tmin" 0.9 "Tmax" 1.1 "step" 0.00625 /"Xxf" 0.08 "TfixHS" 1.00 "TfixLS" 1.01 "LTC" 0 "Tmin" 0.9 "Tmax" 1.1 "step" 0.00625 /

"Vmin" 1.025 "Vmax" 1.04 "Tdel" 30. "Ttap" 5. "Rcomp" 0 "Xcomp" 0 /"Vmin" 1.025 "Vmax" 1.04 "Tdel" 30. "Ttap" 5. "Rcomp" 0 "Xcomp" 0 /

"Fma" 0.15 "Fmb" 0.3 "Fmc" 0.15 "Fmd" 0. "Fel" 0.1 /"Fma" 0.15 "Fmb" 0.3 "Fmc" 0.15 "Fmd" 0. "Fel" 0.1 /

"Pfe" 0.9 "Vd1" 0.8 "Vd2" 0.7 "frel" 0.5 /"Pfe" 0.9 "Vd1" 0.8 "Vd2" 0.7 "frel" 0.5 /

"Pfs" 0.95 "P1e" 2. "P1c" 0.33 "P2e" 1 "P2c" 0.67 "Pfreq" 1 /"Pfs" 0.95 "P1e" 2. "P1c" 0.33 "P2e" 1 "P2c" 0.67 "Pfreq" 1 /

"Q1e" 2. "Q1c" 0.33 "Q2e" 1 "Q2c" 0.67 "Qfreq" -1 /"Q1e" 2. "Q1c" 0.33 "Q2e" 1 "Q2c" 0.67 "Qfreq" -1 /

"MtpA" 3 "MtpB" 1 "MtpC" 3 "MtpD" 0 /"MtpA" 3 "MtpB" 1 "MtpC" 3 "MtpD" 0 /

"LfmA" 0.85 "RsA" 0.02 "LsA" 3.6 "LpA" 0.18 "LppA" 0.18 /"LfmA" 0.85 "RsA" 0.02 "LsA" 3.6 "LpA" 0.18 "LppA" 0.18 /

"TpoA" 0.16 "TppoA" 0.02 "HA" 0.3 "etrqA" 0 /"TpoA" 0.16 "TppoA" 0.02 "HA" 0.3 "etrqA" 0 /

"Vtr1A" 0.7 "Ttr1A" 5.0 "Ftr1A" 0.5 "Vrc1A" 1.1 "Trc1A" 55. /"Vtr1A" 0.7 "Ttr1A" 5.0 "Ftr1A" 0.5 "Vrc1A" 1.1 "Trc1A" 55. /

"Vtr2A" 0.8 "Ttr2A" 6.0. "Ftr2A" 0.2 "Vrc2A" 1.2 "Trc2A" 66. / "Vtr2A" 0.8 "Ttr2A" 6.0. "Ftr2A" 0.2 "Vrc2A" 1.2 "Trc2A" 66. /

"LfmB" 1.0 "CompPF" 0.97 /"LfmB" 1.0 "CompPF" 0.97 /

"Vstall" 0.6 "Rstall" 0.124 "Xstall" 0.114 "Tstall" 0.033 "Frst" 0.5 "Vrst" 0.60 "Trst" 0.4 / "Vstall" 0.6 "Rstall" 0.124 "Xstall" 0.114 "Tstall" 0.033 "Frst" 0.5 "Vrst" 0.60 "Trst" 0.4 /

"fuvr" 0.0 "vtr1" 0. "ttr1" 0.2 "vtr2" 0. "ttr2" 5. /"fuvr" 0.0 "vtr1" 0. "ttr1" 0.2 "vtr2" 0. "ttr2" 5. /

"Vc1off" 0.5 "Vc2off" 0.4 "Vc1on" 0.6 "Vc2on" 0.5 /"Vc1off" 0.5 "Vc2off" 0.4 "Vc1on" 0.6 "Vc2on" 0.5 /

"Tth" 20 "Th1t" 0.7 "Th2t" 1.3 "Tv" 0.05 /"Tth" 20 "Th1t" 0.7 "Th2t" 1.3 "Tv" 0.05 /

"LfmC" 0.85 "RsC" 0.02 "LsC" 3.6 "LpC" 0.18 "LppC" 0.15 /"LfmC" 0.85 "RsC" 0.02 "LsC" 3.6 "LpC" 0.18 "LppC" 0.15 /

"TpoC" 0.16 "TppoC" 0.02 "HC" 0.3 "etrqC" 2 /"TpoC" 0.16 "TppoC" 0.02 "HC" 0.3 "etrqC" 2 /

"Vtr1A" 0.7 "Ttr1A" 5.0 "Ftr1A" 0.5 "Vrc1A" 1.1 "Trc1A" 55. / "Vtr1A" 0.7 "Ttr1A" 5.0 "Ftr1A" 0.5 "Vrc1A" 1.1 "Trc1A" 55. /

"Vtr2A" 0.8 "Ttr2A" 6.0. "Ftr2A" 0.2 "Vrc2A" 1.2 "Trc2A" 66. "Vtr2A" 0.8 "Ttr2A" 6.0. "Ftr2A" 0.2 "Vrc2A" 1.2 "Trc2A" 66.

““DGtypeDGtype”” 1.0 1.0 ““PdgflagPdgflag”” 1.0 1.0 ““Fdg_PdgFdg_Pdg”” 0.2 0.2 ““PFdgPFdg”” 1.0 1.0 ““ialimialim”” 1.1 / 1.1 /

““vt0vt0”” 0.7 0.7 ““vt1vt1”” 0.8 0.8 ““vt2vt2”” 1.1 1.1 ““vt3vt3”” 1.2 1.2 ““vrflagvrflag”” 0.5 / 0.5 /

““ft0ft0”” 0.7 0.7 ““ft1ft1”” 0.8 0.8 ““ft2ft2”” 1.1 1.1 ““ft3ft3”” 1.2 1.2 ““frflagfrflag”” 0.0 / 0.0 /

Specification of DG FractionA1. In dynamic file only, as a fraction of load

– Best alternative short termA2. In dynamic file only, as an absolute MW valueB. In power flow, as a negative load associated with existing

load through special ID– Could be confusing to users

C. In power flow load record – Would require changes to power flow programs– Best solution long term

• CMPLDWg prototype to support A1 and A2• Consult with MVWG and SRWG on C (future)

Summary for Solar Models• PV1X/PVD1 and CMPLDWg

– Specifications working documents– Prototype for testing/validation under development– Collecting lab/field data for model validation effort

WIND MODELS

WT1/WT2 Pitch Control Model

REMTF consensus: need to re-design

WT1/WT2 Pitch Control Model• Proposed new implementation

– PI Control, Rate Limiter, Lag filter– Voltage Dip Flag

• Set based on voltage; reset based on voltage and generator speed

• Action Items: test/validate against manufacturer models; update draft REMTF specification

Source: R. Zavadil

WT1/WT2 Pitch Control Model• Good results compared to two major Type 1 WTG

vendor-specific PSCAD models

P-I block: Gain=1, Time Constant=0.1sLag Filter: Gain=2, Time Constant=3 sRate Limiter: Up(pitch back)=1.5, Dn(restore)=0.5

P-I block: Gain=1, Time Constant=0.001sLag Filter: Gain=1, Time Constant=0.01 sRate Limiter: Up(pitch back)=0.5, Dn(restore)=0.5

Source: ZavadilSource: Zavadil

WT1/WT2 Pitch Control Model• Good validation against MWT1000A manufacturer model

0 1 2 3 4 5 6 7 8 9 10

0

100

200

Act

ive

pow

er [

pu]

0 1 2 3 4 5 6 7 8 9 10-100

0

100

200

Rea

ctiv

e po

wer

[pu

]

0 1 2 3 4 5 6 7 8 9 100

0.5

1

1.5

WT

G t

erm

inal

vol

tage

[pu

]

Time [s]

Detail

Generic

Detail

Generic

Detail

Generic

WT1/WT2 Pitch Control Model• Partial success with validation against V82-AGO

0 1 2 3 4 5 6 7 8 9 10-7

-6.5

-6

-5.5

-5

-4.5

-4

Pitch

0 1 2 3 4 5 6 7 8 9 10-2

-1.8

-1.6

-1.4

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

Pitch

50% output80% voltage dip

0 1 2 3 4 5 6 7 8 9 10-6

-5.8

-5.6

-5.4

-5.2

-5

-4.8

-4.6

-4.4

-4.2

-4

Pitch

0 1 2 3 4 5 6 7 8 9 10-2

-1.8

-1.6

-1.4

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

Pitch

50% output40% voltage dip

100 % output80% voltage dip

100% output40% voltage dip

Proposed model structure would not capture this behavior

WT1/WT2 Pitch Control Model• Acceleration control comes into play for severe

disturbances and Pgen = Prated

0 1 2 3 4 5 6 7 8 9 10-7

-6.5

-6

-5.5

-5

-4.5

-4

Pitch

ev

Pitch

Speed

Torque

• Do we need to change anything? No– Manufacturer: WT2 model is fine as is

WT2 Rotor Resistance Model

New WT4 Model• Approved by REMTF with minor modifications

WT4 Generator/Converter

WT4 P/Q Control

WT4 Drive Train

WT4 Plant Control• Need to add active power control

– High frequency droop

WT4 Validation

• Good results for multiple manufacturers– Differences in controls approach drove model options

Siemens Vestas ABB

Source: Pourbeik

New WT3 Model• Identical to WT4 model, except for pitch and torque control

New WT3 Model• Initial validation with two vendors – good news

Source: Pourbeik

ABB Vestas

Summary for Wind

• Summary for Phase 2 WTG models– WT1: Redesigned pitch control, investigating ways

to emulate acceleration control for V82-AGO– WT2: Use redesigned pitch; otherwise OK as is– WT3: Progress– WT4: Specs approved, with addition of P/f droop

• Next Steps– Complete official specifications by June– Present for MVWG approval in November

Other REMTF Items to Address

• Default Data for Existing WTG Models– Typical machine data

• Testing Procedures for Non-Synchronous Generators

• Data Preparation manual– Language around DG?

Discussion About Plant-Level Model Validation

Why So Much Detail in EU Models• Driven by Grid Codes! • For example, Latest Proposed ENTSO-E Grid Code, Article 32:

Common Provisions on Compliance Simulations, Parts (3) & (4):3. The Power Generating Facility Owner shall provide simulation results relevant

to each and any individual Generating Unit within the Power Generating Facility in a report form in order to demonstrate the fulfillment of the requirements of this Network Code. The Power Generating Facility Owner shall produce and provide a validated simulation model for a Generating Unit. […]

4. The Relevant Network Operator shall have the right to check the compliance of a Generating Unit with the requirements of this Network Code by carrying out its own compliance simulations based on the provided simulation reports, simulation models and compliance test measurements.

– Reference: https://www.entsoe.eu/resources/network-codes/requirements-for-generators/

Models for Interconnection Studies• Requirements are vague in comparison

– Applicable requirements: NERC FAC/TPL and FERC LGIP/SGIP – IVGTF Task Force 1.1 recommended changes to MOD

standards and also recommended that FAC-001 be reviewed and expanded to clearly cover modeling requirements for generator interconnection study process

– NERC Standard FAC-002-013 requires evidence that assessments included steady-state, short circuit and dynamics studies as necessary to confirm compliance with NERC Standard TPL-001-0

NERC IGVTF Task 1.3 Report

Reference: IVGTF Task 1.3 Report, Section 6: Models for Facility Connection, Page 91

NERC IGVTF Task 1.3 Recommendations• Specific recommendations to FAC-001-0 shown in red:

R2 The Transmission Owner’s facility connection requirements shall address, but are not limited to, the following items:

[…]

[Add] R2.1.17 Generation facility modeling data, including appropriate power flow, short circuit and dynamic models, and verification requirements. [add appendix to clarify]

NERC IGVTF Task 1.3 Report• Proposed Appendix to FAC-001-0 about models:

Preliminary or approximate power flow and dynamic models may be adequate for the preliminary assessment of interconnection impacts, or to represent existing and proposed projects that are not in the immediate electrical vicinity of the Facility being studied. However, detailed dynamic (and possibly transient) models for the specific equipment may be needed for the System Impact Study and Facilities Study, to represent the Facility and other equipment in the electrical vicinity. Generic non-proprietary publicly available models are more appropriate for the NERC model building process covered by existing MOD standards, although validated generic models with specifically tuned parameters may be adequate for interconnection studies. The models for interconnection studies must be acceptable to the TO in terms of simulation platform, usability, documentation & performance.

IVGTF 1.3 Proposed Modeling Grid Code• Preliminary model data may be used for the initial feasibility study of a variable

generator interconnection project• The best model available shall be used for the final SIS or FS. These models can be user

written and require non-disclosure agreements• The detailed dynamic model must be accurate over the frequency range of 0.1 to 5 Hz.

Time constants in the model should not be less than 5 ms• Detailed dynamic models must be validated against a physical or type test.• Verification of detailed model performance should be confirmed during

commissioning to the extent possible. The following tests shall be performed:– Primary/secondary voltage control– Low voltage and high voltage ride through– Power factor/reactive power capability– Power ramping and power curtailment

• Verification of the non-propriety model accuracy may be performed by simulation tests compared with the detailed model performance.

• At the end of the commissioning tests, the Generator Owner shall provide a verified detailed model and a non-proprietary model, ideally in IEEE, IEC or other approved format, for ongoing regional studies such as TPL-001.