MVWG Report to MS

May 13, 2019

Song Wang

MVWG Chair

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Recent Meetings

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MVWG Activities Overview

• MVWG Charter and Dynamic Model List

• Load Modeling

• Renewable Energy Modeling

• Generator Modeling, Testing, and Model Validation

• HVDC Modeling

• Upcoming Meetings

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MVWG Charter and Dynamic Model List

• Modify MVWG Charter by adding • “Maintain and update the WECC Approved

Dynamic Models Library as directed by the MS”

• Unapproved models are in WECC base caseMODEL Recommended replacement model Notes

ccbt1 (TGOV1) Steam plant boiler/turbine governor model

ewtgfc REEC_A 2nd gen renewable model

exac6a AC6A (ESAC6A) 1992 IEEE AC6A

exoel OEL2C OEL for GE EX2100

exwtg1 WT2E1 2nd gen renewable model

exwtge REEC_A 2nd gen renewable model

gast ggov1

genwri WT2G1 Wound rotor induction generator model

gewtg REGC_A 2nd gen renewable model

ifmon No conversion required

lsdt3 LVSHBL Definite time under voltage load shedding relay

lsdt3a LVSHBL

pfqrg TBD, not converted initially Reactive power regulator/power factor angle

scmov SCGAP2 (Jay) SC MOV bypass

sexs SEXS - already being converted - approved?

stcon CSTATT

svcwsc CSVGN6

vscdc No conversion required

wndtge 2nd gen renewable model

wndtrb 2nd gen renewable model

texs ST6B Transformer Excitation

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Load Modeling

• Climate zone based composite load model

• Composite load with DER model

• Others

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Climate Zone Based Composite Load Model

• Climate zone based composite load model provides much more effective management

• Today “CMPLDW” data file has about 5,600 records:

• Most data records are repeated

• Very difficult to make changes

• More than 8 MB size data file

• Climate zone based composite load model has only 60 records

• Easy manageable, easy to make data changes to run sensitivities

• Less than 200KB size data

• PSLF automatically expends 60 records to 5,600 records when reading the data

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Benchmarking

• Compare:• Bus level “CMPLDW” model

• Climate zone based “_CMPLDW” model

• Expectations – identical results in two cases

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Benchmarking Results

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Next Step

• Software Developers:• Include CLZONE-type field in powerflow data

• Be able to read and interpret model records defined using CLZONE

• Proposed Phased Approach:• Develop a plan to start using climate zone based records

for PSLF, PW and TSAT users starting 2020 study program• Strengthen MOD-032 requirement to update and populate

CLZONE field in powerflow base cases

• Update tools for creating climate zone based records

• Continue providing data and tools for PSS®E users to produce their own bus based records

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Composite Load with DER

• DER as a part of composite load model sensitivity studies in large system

• Composite load with DER model benchmarking among software platforms in small system

• Interim approval of using composite load with DER model

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Large System Simulation

• 2020 Summer Peak case with high renewable generation was used in the study

• Composite load model phase II

• DER are part of composite load model

• Default parameters as recommended by EPRI

• Studies include three-phase faults• Fault near a feeder with large reverse flow

• Fault near a feeder with negligible load and large DER

• Fault near a feeder with low load and low DER

• Delayed clearing on 500kV bus

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Large System Simulation Conclusions

• The DER model works with wide range of conditions: reverse flow, low DER or low load

• Study results are sensitive to the DER parameters

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Small System Benchmarking

• Two bus system, four type of testing with different model parameter combinations

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Small System Benchmarking Conclusions

• Frequency output at the bus needs more looking into

• Initialization of the motor model components needs more looking into

• Large inconsistency when motors of the model stall and reconnect/trip

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Small System Benchmarking Conclusions

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Interim approval

• MVWG continue work with software vendors by biweekly meetings

• MVWG will have a conference meeting in June review this model again. Goal to final approval

• By consensus, the MVWG approved the Distributed Energy Resource data to be collected in the power flow

• The MVWG approved the composite load with DER model will be used as an interim solution

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Load Modeling Others…

• Developing a next generation load model data tool – it will be a excel-based tool, which can produce load model records in Bus, Zone, Area and LoadType formats

• DOE is developing end-use load composition data sets for the Eastern Interconnection and ECORT. We asked DOE to update data for Western Interconnection as well• Details was discussed on May 7 at PacifiCorp’s

office with load modeling experts

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Renewable Energy Modeling

• REEC_B model retirement

• Convert REEC_B model to REEC_A model in the WECC master dynamic file

• WECC documents update plan

• Updates on new features for the renewable energy system generic models

• Wind power plant modeling

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REEC_B Model Retirement

• Model development background

• Difference between REEC_B and REEC_A

• Retire REEC_B

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Background

• Originally approved in 2014 to 2015 that REEC_A for wind, REEC_B for solar, and REEC_C for energy storage

• In 2018, MVWG modified the approval of REEC models to• REEC_A for wind, and solar PV if using

momentary cessation

• REEC_B for solar PV not using momentary cessation

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Difference between REEC_B and REEC_A

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Retirement

• The distinction between REEC_B and REEC_A for solar PV inverters may be neglected or cause confusion

• REEC_B model, simplified from REEC_A, does not have much benefit or additional modeling capability from REEC_A

• MVWG approved the retirement of REEC_B model in April 2019

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Convert REEC_B to REEC_A

• Draft WECC white paper to provide guideline of converting REEC_B to REEC_A model in WECC master dynamic file

• Next step to develop a tool to convert REEC_B to REEC_A model

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Methodology

• Will write a WECC white paper. It will provide guideline on model conversion based on different model structure• Parameters for Kqv reactive current injection arm

• thld and SW

• Parameters for VDL blocks• (vq1,iq1),(vq2,iq2) and (vp1,ip1),(vp2,ip2)

• Other parameters for REEC_A model• thld2, vref1, pflag

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Test Results (Benchmark)

• Abnormal operating condition (terminal voltage outside of voltage set points)

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Test Results (Benchmark)

• Normal operating condition (terminal voltage inside of voltage set points)

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Conversion Conclusion

• Conversion from REEC_B to REEC_A could be done systematically without losing any model accuracy or introducing any modeling errors.

• It is recommended to convert all REEC_B models in the WECC master dynamic file to REEC_A

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WECC White Papers Update Plan

• Documents to be updated

• WECC PV Plant Power Flow Modeling Guide

• WECC Solar Plant Dynamic Modeling Guidelines

• Central Station PV Plant Model Validation Guideline

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Updates of RES model adds-on

• Prioritization of the implementation of the proposed new modules into 2nd generation renewable models• REGC_B

• WGO and REEC_D

• REPC_C

• WTGP_B

• WTGT_B

• REGC_C

• WTGQ_B

• IBFFR

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Wind Power Plant Modeling

• NW Utilities held a regional workshops in November 2017• In process of updating all models to “as-built”

status

• Working with wind plant operators on updating powerflow data

• Engaged WTG OEMs and industry experts in dynamic model data

• Use SCADA ramp and PMU disturbance data for model validation

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Wind Model Data Status

• Type 3 and 4• Dynamic models for Siemens type 4, GE type 3 and 4,

Repower type 3 produce credible results. Consistent with actual plant performance observed with PMU data

• Type 2• Dynamic models for type2 plants can be unstable in

weak systems - This is consistent with observed historic performance, but may cause issues in large scale simulations

• Type 2 pitch controller model W2P produces a fictitious frequency response

• Type 2 models failed flat initialization at 20% load – big issue for real-time transient stability studies

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Generator & Power Plant Modeling

• GENQSC/GENSEC model

• CCOMP4 model

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GENQSC/GENSEC Model

• Two types of generator model• GENROU/GENSAL

• GENTPF/GENTPJ

• Current status of model application in North America• WECC mandated the GENTPJ model to replace

GENROU/GENSAL model for stability studies in 2011

• NERC approved the GENTPJ model in 2016 for replacing GENROU/GENSAL in the whole North America reign

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Existing Methods of Modeling Generator Rotor

Field Current Saturation

• Conventionally considered rotor field current saturation only affected by magnetic saturation (GENROU/GENSAL)

• GENTPJ model use modified saturation functions to account for the increased field current in loaded operating conditions

• Potier reactance is well known to match the field measurements better, but not practical in use of stability studies

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Proposed Methods of Modeling Generator Rotor

Field Current Saturation

• Modifications made on the standard 2nd order equivalent circuit in IEEE Std 1110

• A factor was proposed to compensate the additional rotor field winding leakage flux when generator loaded

• In order to use constant generator model parameters for simulation, a separate MMF source is considered to cause the extra rotor field winding leakage flux

• That separate MMF is formed by part of the total rotor field winding current

D-axis Generator Equivalent Circuit

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Portion of the rotor field current is considered to be only related the increased field winding leakage flux while keeping the self- and mutual-inductance terms constant

Magnetic Saturation

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GENQSC Dynamic Model

• Magnetic saturation effect considered on both stator and rotor windings

• Rotor field winding current compensated based on stator d-axis current load, independent from magnetic saturation

• Steady-state and Dynamic performance accuracy improvement proven from field measurement data

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Testing Result

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Summary of Proposed Generator Model

• Derived from IEEE standard second-order generator equivalent circuit with saturation and compensation

• Considers magnetic saturation on both generator rotor and stator inductance terms

• Rotor compensation factor obtained from zero power-factor load characteristics

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GENQSC Model Development Status

• Model specification request for comments (RFC) sent out to industry experts

• The developed GENQSC model is coded in MATLAB

• Beta version of GENQSC model is implementing to commercial software for testing

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Cross Current Compensation Model

• CCOMP model

• CCOMP4 model

• Next step

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CCOMP Model

• CCOMP Model• CCOMP model approved by 2014 and is in the

WECC basecase

• CCOMP issues• Use complex current feedback into the current

compensation model

• In reality, the actual equipment use reactive current feedback

• CCOMP not allow for more than two units in the current compensation model

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CCOMP4 Model

• CCOMP4 model• CCOMP4 model approved by 2015 but is NOT in

the WECC basecase

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Next Step

• WECC staff will encourage people to use CCOMP4 and converting existing CCOMP to CCOMP4

• MVWG will seeking to retire CCOMP model in next meeting

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HVDC Model

• The WECC HVDC TF is working on developing simple planning models for both powerflow and dynamic time-domain simulation in positive sequence software tools for HVDC point-to-point transmission

• Models are being developed for both conventional line commutated converter (LCC) HVDC and voltage converter(VSC) technology

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HVDC Model Status

• LCC-HVDC model• The powerflow models for conventional HVDC

have always existed in the commercial tools

• In 2017, one simple LCC-HVDC dynamic model (chvdc2) was approved and now has been implemented and tested in the four major North American commercial tools

• VSC-HVDC model• The definition of the VSC powerflow model was

completed in the past several years and has been implemented by the four major commercial tools

• The VSC dynamic model is under development

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Upcoming Meeting

• June conference meeting – date TBD

• August 14–16, 2019 Salt Lake City, UT

• November 20–22, 2019 Salt Lake City, UT

Contact:

Song Wang

Song.Wang@pacificorp.com

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