Presentation on theme: "WECC Modeling and Validation Work Group"— Presentation transcript:
1 WECC Modeling and Validation Work Group Report to TSSAugust 2007Dmitry KosterevBonneville Power AdministrationTransmission Planning
2 MVWG Workload Load Modeling Generating Unit Model Validation Wind Farm ModelingModeling of Power Electronics DevicesStatic VAR SystemsHVDC SystemsDisturbance Analysis and System Performance ValidationWECC Modeling and Validation Work Group
4 Load Modeling Load Model Structure Load Model Data System Studies: Composite load model in production programExplicit load representationLoad Model DataSystem Studies:Sensitivity, Validation, System PerformanceNew Research ItemsLoad models for post-transient voltage stabilitySimulation of single-phase loads under un-balanced disturbances
5 Load Model Structure Today Proposed M Static M M M M Static 20% 115-kV ComponentsProposedMTransformerFeederEquivalentM115-kV230-kVMMStatic
6 Load Model StructureLMTF developed EPCL routines for explicit load representation in PSLF programWECC developed load model specificationsWECC Composite Load Model is implemented in GE PSLF 16.1 (no single-phase motor model or partial load tripping by UVLS / UFLS ).LMTF tested model performance:Simple test systemWECC-wide representationSingle-Phase Motor Model is under developmentSingle-phase motor model will be in PSLF 17.? :part of composite load modelas a stand-alone model
7 Single-Phase Motor Models SCE, BPA, APS/EPRI tested a large number of residential single-phase air-conditioner motorsThere is a difference between equipment-level and grid-level modelsCEC funded development of a mathematical model for single-phase motors – Bernie Lesieutre (LBNL) is the leadJohn Undrill developed a “motorc” model in PSLF based on machine physical principlesJohn Undrill and Bernie Lesieutre are reconciling the amount of detail that should go into grid-level PSLF model
8 Single-Phase Motor Models Single-phase motor model will include:Compressor motor model“motorc” is the preferred choicePerformance model (static)Thermal protection modelUnder-Voltage relay model (SCE solution)Control and contactor model
9 Load Model Data Load model data records include: Distribution equivalent model dataFractions of total load assigned to each load model componentModel data for load model components (e.g. motor inertia, driven load, electrical data, etc)
10 Load Component Model Data Models and model data for various electrical end-usesequipment testingSingle-phase air-conditionersLights, ElectronicsLarge FansLarge PumpsVariable-Frequency DrivesResidential Appliancesmanufacturer’s data analysisModel and data aggregation:separate end-uses that exhibit different behavioraggregate model data for end-uses within the same groupMap electric end-users to model components
11 Load Component Model Fractions The most challenging part of model dataHigh level of uncertainty and variabilityShown to have significant impact on study resultsShort-term objective:Get reasonable region-wide estimates for heavy summer loadsUnderstand sensitivitiesContact WECC Load and Resource GroupPNNL work under CEC Contract
12 Load Component Model Fractions SubstationTime, Date, TempCOMRESC1C2C5R1……kWkWkWkWLarge OfficeGroceryRetailResidential
15 Load Model Validation Studies Challenges of load model validation:Load composition is constantly changingLarge disturbances may not occur during loading conditions of interestMost disturbances are not large enough to extrapolate the load behavior for most planned for disturbancesLack of dynamic measurementsValidate the load behavior in principle rather than curve-fitting a particular disturbance event
17 Load Model Studies Simulations done by Robert Tucker, SCE Explicit load representation“Performance” model for 1phase A/C unitsSimulations done by Robert Tucker, SCE
18 Load Model Studies 3-hase fault Hassayampa – Palo Verde Normal clearingExplicit load representationBPA “Performance” A/C modelBaseline simulation20% of a/c tripped by UV relay30% of a/c tripped by UV relay60% of a/c tripped by UV relay
19 Load Model for Post-Transient Studies How good is our present assumption of constant load P and Q ?How is reactive margin affected with assumptions of voltage sensitivity of loads?Work in Progress
20 Non-Symmetric Simulations Present transient stability programs:designed to study angular stability of synchronous generatorsassume symmetric loads and generatorsOne-line system representationassume balanced post-fault systemThere is a growing need to study dynamic voltage stability events:Such events are greatly influenced by load behaviorCan be initiated by non-symmetric faults, with non-symmetry in post-fault conditions (e.g. single-phase air-conditioners are stalling in the faulted phase initially)Existing simulation methods may not capture the severity of non-symmetric disturbancesWork in Progress, request CEC to fund research
21 Something to Think About Criteria100%75%Reality30 seconds
23 Generating Unit Modeling Generating Unit Model Validation StandardModel Validation Using Disturbance RecordingsGenerator Saturation ModelsUSBR Governor Model
24 Generating Unit Model Validation WECC will continue operating under the existing Policy, approved in July 2006WECC will not pursue development of a regional StandardWECC will make sure that its expertise and 10+ years of experience are represented in the development of the national standard:Donald Davies, Shawn Patterson, Les Pereira, John Undrill, Abe Ellis, Baj Agrawal and Dmitry Kosterev
25 Generating Unit Model Validation BPA developed an EPCL program for model validation using disturbance measurements at generating facility POIThe tool is being tested and manuals are developed
26 Generator Saturation Modeling Long-known deficient area of synchronous machine dynamic modelingPresent assumptions are believed to be more conservative from angular stability standpointPresent assumptions produce much more optimistic reactive power for a given field current when machine is over-excited at full loadJohn Undrill, BPA, USBR collected test data from a number:Open circuit magnetization curveV-curve at no-load, partial load, full loadCurrent interruption tests
28 Generator Saturation Modeling Both parabolic and exponential saturation models are OK, with exponential having a slightly better fitMost model validation tests (current interruption) are not affected by saturation modeling
29 Generator Saturation Modeling Explanation from John Undrill:The 'standard' models (gensal, gentpf, genrou) all assume that saturation is a function of an internal flux linkage. These models assume that the effect of saturation on the voltages induced throughout the generator are the same when stator current is at normal operational values as at zero real power output.The “gentpj” model recognizes that the leakage flux components induced in the stator teeth by high stator currents can increase the reluctance of the magnetic circuit significantly above the level seen on open circuit.That the reluctance of the magnetic circuit is affected by leakage flux effects of stator current has long been recognized in generator design practice but has been ignored in the generator models used in grid-level simulations.
30 Generator Saturation Modeling Recommendation from John Undrill:The use of the GENSAL model in the PSLF and PSS/E programs should be discontinued. References to the GENSAL model should be replaced by references to the GENTPF with the new saturation model.The model saturation is implemented within the present GENTPF model.Saturation parameter “Kis” is added at the end of GENTPF data record. Typical Kis = 0.08 to 0.15 and can be estimated from reactive limit tests.The GENTPF with new saturation model is available in PSLF 17.0
31 Generator Saturation Modeling Palo Verde reactive power on June 14, 2004ActualGentpfGenrouGentpj (modified Gentpf)
32 Wind Farm ModelingAbe Ellis, PNM Juan Sanchez-Gasca, GE Bill Price, GE Yuri Kazachkov, Siemens PTI Eduard Muljadi, NREL
33 Wind Farm Powerflow Model Equivalent WTGMain transformerEquivalent pad-mounted transformerPOIEquivalent feederPlant-level reactive compensation.Could be static and/or dynamicTurbine-level power factor correction shunt capacitor, if anyCollector stationWind power plant capacity = 100 MWSubstation transformer: RTX = 0.0, XTX = 0.10 to 0.12 puCollector system (34.5 kV): Ze = ( j 0.025) p.u. with Be = 0.01 p.u.Pad mount transformer: Zte = (0.0 + j 0.05) p.u.NREL has a tool for equivalencing collector system
34 Dynamic Model Specifications WTG modeling detailEffects of grid disturbances, not wind disturbances.P, Q, V response, not internal details.Simplified aerodynamic model (no Cp curves)One-mass or two-mass mechanical modelSeparate models for shunt compensation and protectionLVRT trip levels, not internal details.InitializationP and Q from power flowIf P = rated, initialize at specified wind speed > rated
35 Proposed Standard Models Four basic topologies based on grid interfaceType 1 – conventional induction generatorType 2 – wound rotor induction generator with variable rotor resistanceType 3 – doubly-fed induction generator (APPROVED)Type 4 – full converter interfaceType 1Type 2Type 3Type 4PlantFeedersacdcgeneratortotodcacfull power
36 PSLF WTG Dynamic Models Under developmentNew modelsUndergoing verification tests (PSLF vs. EMTP)Under development
38 Power Electronic Devices What happened to NERC MOD-028 “Models and Data for Transmission Power Electronic Control Devices” ? – chopped outWECC SVC Modeling Task Force is developing powerflow and dynamic models of Static VAR Systems.WECC MVWG developed HVDC Modeling Requirements in The requirements are currently being reviewed and updated.
39 Static VAR Systems: Powerflow Models Represent the device as a shunt for SVCs and as a current injection in STATCOMsModel droop in power flows (post-transient ?)Modeling coordinated shunt switching and ULTCs in power flowsModel slow-susceptance regulatorDead band representationModel reactive power controlHigh-side or low-side of coupling transformer representationSeamless transition of sav case from power flow to dynamics
40 Static VAR Systems: Dynamic Models Voltage cutout (under / over voltage performance)Integrated fast-switched capacitor banksCoordinated control with local and remote capacitor banks, shunt reactors, and LTCsHigh-side or low-side of coupling transformer representationDefault set of parameters for different types of SVC and STATCOMTCR based SVS, STATCOM based SVS or TSC/TSR based SVSControl modes ( Main voltage regulator, Slow-susceptance, Deadband control, Non-linear droop, MSC coordinated switching, Hysteresis )
41 Static VAR Systems Survey Was sent out in MayReceived information on 12 SVCs by June 30, 2007Donald Davis has compiled the list and a summary has been provided to the SVC TF membersSVC TF will be contacting some Companies individually as the responses have not been received from themSVC TF will be updating the information and a summary report will be preparedSome Information in the survey is being treated as confidential information and the survey as such is not being released for general use.
42 Static VAR Systems - Comments Prioritize efforts to focus on what is critical for grid simulationsAvoid excessive and unnecessary control detailCapture essential controls affecting system performanceDevelop SVC monitoring requirementsDevelop SVC model validation requirements and guidelines
43 PDCI Model – Siemens PTI Siemens PTI implemented PDCI model in PSS™ELoad Flow:In PSS™E load flow, each pole of the PDCI is represented as a 3-terminal HVDC.Because of the difference between multi-terminal HVDC data records in PSS™E and PSLF, PDCI power flow data had to be manually inserted from PSLF to PSS™E.Different data for north to south versus south to north flows on the PDCI must be used. Dynamics:When developing the latest PSS™E dynamic simulation model for the present PDCI arrangement the PSLF epcl (pseudo code) programs have been used, along with the original ABB block diagrams.Two PSS™E dynamic simulation models have been developed: PDCINS for the PDCI power flow from North to South and PDCISN for the opposite direction of the power flow.The data sets for both PSS™E dynamic simulation models for PDCI are exactly the same as for the PSLF model.
44 PDCI Model ValidationPSS™E models were tested and successfully validated against results of testing the respective PSLF models.Model Validation against reality:SCE, LADWP are installing monitors to monitor voltages, frequency, real and reactive power at the Sylmar terminalBPA already has monitors at CeliloModel validation tests are plannedFeasibility of model validation against disturbances is studied by PNNL
46 West-Wide System Model MVWG supports development of West-Wide System ModelAccurate powerflow snapshot of system conditions prior to a disturbance is necessary for model validation studiesBPA is mapping state estimator solution from July heat-wave onto WECC base caseNeed to make sure that State Estimator solution is sufficiently good for voltage and transient stability studies
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