2009-08 - Load Model Overview

8/9/2019 2009-08 - Load Model Overview

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Load Modeling in WECCLoad Modeling in WECC

August 2009August 2009

Dmitry Kosterev

BPA

360-619-6836

[email protected]


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History Of Load Modeling in WECCHistory Of Load Modeling in WECC

1990s Constant current real, constant impedancereactive models connected to a transmission bus

1990s IEEE Task Force recommends dynamic load

modeling, however the recommendation does not gettraction in the industry

1996 BPA model validation study for August 10 1996

outage: Need for motor load modeling to represent oscillations and

voltage decline

2000 2001 WECC Interim Load Model: 20% of load is represented with induction motors

Tuned to match inter-area oscillations for August 10 1996 and

August 4, 2000 oscillation events Address critical operational issues for COI


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o

o

o o o o

o

o

o o o o

Simulations

instantaneous voltage recovery

This is what we thought would happen using interim load model

Motivation for Better Load ModelingMotivation for Better Load Modeling

30 seconds


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0.60

0.65

0.70

0.75

0.80

0.85

0.90

0.95

1.00

1.05

1.10

0 5 10 15 20 25 30

Seconds

Voltage

(pu

)

and this is what actually happened

Reality

30-second voltage recovery, 12 seconds below 80%

Motivation for Better Load ModelingMotivation for Better Load Modeling

30 seconds

100%

75%


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History Of Load Modeling in WECCHistory Of Load Modeling in WECC

Late 1980s Southern California Edison observed eventsof delayed voltage recovery attributed to stalling of

residential air-conditioners

1994 Florida Power published an IEEE paper on thesimilar experiences of delayed voltage recovery following

transmission faults

1997 SCE model validation study of Lugo event:

Need to represent a distribution equivalent

Need to have special models for air-conditioning load

2004-2005 Increased number of observed events of

delayed voltage recovery in Southern California, greaterneed to develop models to assess dynamic voltage stability


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WECC LMTF ApproachWECC LMTF Approach

WECC LMTF was formed in 2002

Component-based approach Understand load behavior over the wide range

of disturbances

Bottom-up model development

Top-down model validation


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WECC Composite Load ModelWECC Composite Load Model

2004-2005 Load Model prototype is developed and

extensively tested

Sequence of EPCL programs

2006 composite load model specifications are developed

2007 GE implemented version 0 of composite load modelin PSLF

2006-2008 residential AC testing and modeling research

is complete, models are developed, tested and validated 2008 LD1PAC model is approved

2009 composite load model development is completed in

PSLF program


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WECC LMTF Approval ProcessWECC LMTF Approval Process

Load Model Structure Approval

TOscan use composite load model data

Provide Guidance to Users on Composite LoadModel Data Sets

Generic data sets for load composition and load component data

Model Approval for WECC-wide planning andoperational studies

Composite load model to replace interim model in WECC planning andoperational studies

Review the need for WECC disturbance performance standard

Develop database management tools


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Load Model StructureLoad Model Structure


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CompositeComposite Load Model StructureLoad Model Structure

Electronic

M

M

M

115-kV

230-kV

Static

M

UVLS

UFLS


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Event Validation Studies with LD1PAC ModelEvent Validation Studies with LD1PAC Model


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Load Model DataLoad Model Data


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WECCWECCCompositeComposite Load ModelLoad Model

Electronic

M

Load Model

Composition

Data

M

M

115-kV

230-kV

Static

Load Component

Model

Data

Distribution Equivalent Data

UVLS and UFLS Data

M


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Load Model DataLoad Model Data

Load model data records include:

Distribution equivalent model data

PG&E developed methodology, proven to work, feel very confident Model data for load model components (e.g. motor inertia,

driven load, electrical data, etc)

Getting test data, develop better understanding of end-usecharacteristics

Motor protection and control remains least known

Fractions of total load assigned to each load model

component Finally we are getting reasonable estimates

UFLS and UVLS data

External to the model


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Modeling EndModeling End--Use ComponentsUse Components

Models and model data for various electrical end-uses

For Smaller End-Uses:

One test is worth a thousand of expert opinions

Single-phase air-conditioners

Lights, Electronics

Large Fans

Large Pumps

Variable-Frequency Drives

Residential Appliances

For Large End-Uses: manufacturers data analysis

IEEE Literature review

Model Aggregation Studies


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LBNL Electricity Use In California StudyLBNL Electricity Use In California Study

0

1

2

3

4

5

6

7

8

Res. - AirConditioning

Com'l. - AirConditioning

Com'l. -InteriorLighting

Com'l. - Other Res. -Miscellaneous

Res. -Refrigerator

Com'l. -Ventilation

Res. -Cooking

Res. - Dryer Com'l. -Refrigeration

0

5

10

15

20

25

30

35

Peak Demand

Annual Consumption

Source: CEC Demand Analysis Office

Peak Demand (GW) Consumption (TWh

Residential ACResidential AC

Commercial ACCommercial AC

LightingLighting


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< 1%4%< 1%5%

6%

26%

< 1%

9% 4%< 1%

11%

33%

< 1%

CoolingCooling

VentilationVentilation

RefrigerationRefrigeration

LightingLighting

CEC California Commercial EndCEC California Commercial End--Use SurveyUse Survey

Summer Peak LoadSummer Peak Load


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Component Model FractionsComponent Model Fractions

The most challenging part of model data

Sources of data:

California Energy Commission: 2006 Commercial End-Use Survey

LBNL Reports on Electricity Use in California

PNNL DOE2 building simulations and BPA ELCAP

PG&E methodology and tools for deriving bus-specific load

composition from billing data

BPA recorded / purchased building data

Rules of Association to map end users onto models


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LBNL: California Summer Peak Day LoadLBNL: California Summer Peak Day Load

0

10

20

30

40

50

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Residual ("Other" Area)

Res. - Air Conditioning

Com'l. - Air Conditioning

Com'l. - Interior Lighting

Res. - Miscellaneous

Com'l. - Other

Res. - Refrigerator

Com'l. - Ventilation

Res. - Cooking

Res. - Clothes Dryer

Com'l. - Refrigeration

Remainder of Buildings

sectorIndustrial Sector

Agriculture & OtherSector

Time of Day (hour starting)

System Peak

Demand (GW)

Source: LBNL: Electricity Use in California: Past Trends and Present Usage Patterns


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Component Model FractionsComponent Model Fractions

WECC LMTF will provide regional defaults

winter, summer, and shoulder seasons

6:00, 9:00, 15:00, 18:00 hours

Multiple climate zones in WECC

Composition for residential, commercial and mixed load types Please review and provide your comments when LMTF data

becomes available (WECC posting is expected in middle of June2009)

Utilities can over-ride the defaults with bus-specificinformation (recommended)


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WECC TPL StandardsWECC TPL Standards

Existing WECC transient voltage dip criteria was developed underpresumption that load does not experience a structural change duringa disturbance (mostly constant current active and constantimpedance reactive components were used for load representation)

WECC voltage dip criteria was developed as a proxy for low voltagesat which load loss may occur

Transient voltage dip criteria is used only by WECC (not in NERCTPL Standards)

WECC transient

voltage dip criteria

(developed underassumption of constant

current load model)


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WECC TPL StandardsWECC TPL Standards

Transmission faults are likely to results in a wide-spread stalling of air-conditioners, when a stalled motor becomes a locked-rotor shortcircuit for several seconds until it is disconnected by a thermal relay

Actual system performance (and that captured by the new loadsmodel) may not be able to meet the WECC voltage dip criteria

See next slide

Actual system

performance (and that

simulated with a newcomposite load model)

may not meet WECC

transient voltage dip

criteria Time

Bus Voltage


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Palo VerdePalo VerdeDevers Fault Simulations and ActualDevers Fault Simulations and Actual

2009-08 - Load Model Overview

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