RARF Frequently Asked Questions from Resource Entities Ed Geer RARF Workshop III 8/29/2013

RARF Frequently Asked Questions from Resource Entities

Ed Geer RARF Workshop III8/29/2013

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• Q: What is our Point of Interconnection – Substation Code? A: Generally, the substation where Resource Entity equipment

connects to TSP equipment.

• Q: What are the acceptable ranges for Governor Droop Setting and Dead-band?

A: Governor Droop Setting >= 0.02 and <= 0.05 Governor Dead-band <= 0.036

• Q: What do we enter for Governor Droop Setting and Dead-band if our resource is exempted from providing governor

response, or is a WGR currently in PRR833 ADR? A: Enter Governor Droop Setting of 5% (entered as 0.05) and

Governor Dead-Band of 1 Hz.

Questions about Data Items – UNIT Info tab

RARF Workshop III8/29/2013 3

• Q: What needs to be entered on the Reactive Capability tab? A: The actual gross leading and lagging reactive capability of the

resource, specified at four MW output levels covering the full range of operation.

• Q: Should substation capacitors, reactors or other reactive devices be reflected in the Reactive Capability tab?

A: No; substation capacitors, reactors or other reactive devices are modeled separately and are NOT included in the Reactive

Capability tab. Enter the substation capacitors, reactors on the Capacitor and Reactor Data tab and dynamic reactive

devices on the Static_Var_Compensator Data tab.

• Q: Where can we find more information about Resource Reactive Capability and Reactive Testing?

A: Refer to the presentation posted with the June 14, 2013 Reactive Testing Workshop.

Questions about Data Items – Reactive Capability tab


• Q: What is needed for Positive Sequence Reactance? A: Synchronous Reactance – Xdi (unsaturated) and Xdv (saturated)

• Q: What sites need Collector System one-lines and collector system data? A: Currently only the Wind RARF has tabs for submitting

Collector System one-lines and Collector system data. Future RARF form updates will add forms and tabs for Solar and Battery/Storage resources.

• Q: What is meant by “Zero Sequence Grounding Resistance For An Impedance Grounded Generator In P.u. (100 MVA Base)”

A: The grounding of the generator through a resistor or reactance

Questions about Data Items – Planning tab


• Q: Do we need to change the RARF to reflect that we have a 3 -winding transformer?

A: Case 1: No, if you have a buried tertiary or no connections to the tertiary winding, only enter Zero Sequence Data - Winding Connection Code =5. (Transformer Test Report must be submitted with RARF)

Case 2: Yes, if you have a modeled generator, device or load connected to the tertiary or additional secondary winding (Transformer Test Report submitted with RARF)

• Q: Do we need to complete the Transformer Tap Settings tab for each transformer

A: Yes, we need the high side and low side taps, if they exist. You would have one row on the spreadsheet for high side and one row for low side taps. For more information about transformer taps as modeled by ERCOT, please refer to the Key Documents posted for the August 9, 2011 Transmission Model Workshop.

• Q: What is meant by “Zero Sequence Grounding Resistance For An Impedance Grounded Transformer In P.u. (100 MVA Base)”

A: The grounding of the transformer – if solidly grounded wye, then enter 0.0 for Grounding Resistance and Reactance. If ungrounded wye, enter 99999.0 for Grounding Resistance and Reactance. If wye grounded through a resistance or reactance, enter those values in per unit on 100 MVA base.

Questions about Data Items – Transformer Data tab


• Q: Can we use the positive sequence reactance for the transformer for the zero sequence reactance?

A: Generally, the zero sequence reactance will be less than the positive sequence reactance, for example for core form

transformers (Transformer Test Report submitted with RARF).



• Q: What are valid codes for the Zero Sequence Data - Winding Connection Code?

A: Taken from Jay Teixeira’s October 29, 2012 RARF Workshop II presentation Item #6.


Transformer Connection Codes

2 Winding Transformers (in order of voltage highest first)1 Wye - Wye Bank Both Neutrals Grounded2 Wye - Delta Bank Grounded Y3 Delta - Wye Bank Grounded Wye

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Delta - Delta Bank Wye - Delta Bank Ungrounded WyeDelta - Wye Bank Ungrounded WyeWye - Wye Bank Either Wye Ungrounded

5 Three Winding only


• Q: What is Planning Rate C for a line?

A: The conductor 2 hour rating. Per Protocols: Conductor/Transformer 2-Hour RatingThe two-hour MVA rating of the conductor or transformer only, excluding substation terminal equipment in series with a conductor or transformer, at the applicable ambient temperature. The conductor or transformer can operate at this rating for two hours without violation of National Electrical Safety Code (NESC) clearances or equipment failure.

Questions about Data Items – Line Data tab


• Q: Why do we need to submit all the embedded files (Dynamic Data, site one-lines, collector system one-lines) and attached files (Transformer Reports) every time we submit a RARF update?

A: The files must be embedded or attached with each submittal because we don’t have an incremental update system – ALL

RARF data is submitted on each RARF update. Each RARF submittal must be a complete stand-alone package (zip file with all forms and associated files).

Questions about RARF Submission

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Additional Questions?