Resource Data Needed For Dynamic Simulations

And the problems created by incorrect or incomplete data

Importance of Accurate Modeling

Source: BPA Presentation to NERC Planning Committee, Dec. 7, 2010

Importance of Accurate Modeling

Source: Transmission Research Colloquium Sacramento, CA September 11, 2008

Importance of Acc Modeling

Source: Transmission Research Colloquium Sacramento, CA September 11, 2008

Generator Modeling in Dynamics

• Stability Studies are interested in calculating the response of machines connected to the system in three time frames following an event:– Sub-transient – a few cycles– Transient – a few cycles to several seconds– Steady State

Generator Modeling in Dynamics

• Pmax, Pmin, Qmax, Qmin • MVA BASE and Zsource• Unsaturated Sub-transient Reactance• Dynamic Models and Parameters• Transformer (GSU) Data• Collection System Data• Under/Over Voltage set points• Under/Over Frequency set points

Resource Asset Registration Form

Generator Data In PSSE

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• Pmax, Pmin, Qmax, Qmin, Mbase, Rsource and Xsource values in PSSE

MVA Base• Transmission line parameters MVABASE = 100 MVA

• Transformers and Machines may use– MVA Rating– Arbitrary

• Per Unit Values need to be Accompanied by their MVABASE and kVBASE Base values

Generator Model in PSSE

Generator Model in PSSEThe magnitude and phase of the source current are determinedat any instant as a function of the instantaneous values of generator state variables (i.e., rotor circuit flux linkages, shaft speed, and rotor angle).

Dynamic Impact of increased QMAX and MBASE values

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• Larger QMAX and MBASE values suggest more dynamic reactive compensation from a generator is available for system voltage recovery contribution.

• Study results will be overly optimistic and will mask system dynamic voltage issues.

• MBASE values are a source of reference for calculation many generator dynamic model parameters

• Unit inertia (H constant) =

• Generator impedances

• Exciter and Governor limits

MBASE

rpmWR 922 10***231.0

Dynamic Impact of increased QMAX and MBASE values

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CenterPoint Energy System dynamic bus voltages after a large disturbanceActual QMAX and MBASE data Larger QMAX and MBASE data from current RARF

Results in 3824 MW of Under Voltage Load Shedding

Results in 0 MW of Under Voltage Load Shedding

Generator Dynamic VAR output example

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Resource Asset Registration Form

What is Saturation• Saturation is the state reached when an increase in applied external

magnetizing field H cannot increase the magnetization of the material further, so the total magnetic field B levels off.

• The flux linkages in a synchronous machine are primarily through air and are not significantly affected by saturation.

• Generator models recognize that the extent of the saturation effect depends upon both rotor (field) and stator currents.

• Accordingly, the models derive the effective saturated parameters of the machine at each instant by internal calculation from the specified (constant) unsaturated values of machine reactances and the instantaneous internal flux level.

• The user should enter unsaturated values of all machine reactances in setting up Dynamics data for simulation, and must enter an appropriate set of open-circuit magnetization curve data for each machine.

What is Saturation• Straight line is the “air-

gap line” used to determine the field voltage/current.

• Curved line is an indication of the degree of saturation.

• Equations here can be used to provide data

• Saturation Factors needed in Model data

Typical Models for a Conventional Generator

Gov.

Gov.

Exciter

GenGov.

Sample Model Data Sheets

Sample Model Data Sheets

Sample Model Data Sheets

Generator Data

ERCOT ConfidentialOne Line DiagramEmbed a PDF or CAD One Line Diagram below:

ERCOT ConfidentialStability Study Model (if applicable)Embed a PDF (zip) (

Additional Data Needed- • User Models need application notes for models;• data sheets• dyr files

Protection Tabs Undervoltage and Overvoltage

Protection Tabs Under-frequency and Over-frequency

Additional Information

Maintaining Data Critical • Upgrades– Exciters– Turbine– Stabilizer additions– Reactive devices (Caps, Reactors, D-Vars, SVCs)

• New – Preliminary to Commissioning

• Generator tests should provide the data needed to update the appropriate data sheets.

• Some Resource Owners are providing detailed engineering reports containing the model parameters and test data used to establish the parameters.