MVWG Report to MS May 13, 2019 Song Wang MVWG Chair
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MVWG Report to MS
May 13, 2019
Song Wang
MVWG Chair
2
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
4
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
34
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
35
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
40
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
43
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
45
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
46
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
47
Upcoming Meeting
• June conference meeting – date TBD
• August 14–16, 2019 Salt Lake City, UT
• November 20–22, 2019 Salt Lake City, UT
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