TSPs,

Last Friday in our Face to Face meeting we discussed an approach to reconcile TSP/RE interfaces. It was requested that I write up these steps as a suggested approach to addressing interface questions. The steps are pasted below.

Suggested Approach:

1.       List generator buses within associated generator area. For instance CNP area is 4, associated generator area is 904.

2.       Group that list into substations and create SLDs to confirm model connections with TSP buses.

3.       Review location of transformers associated with these generator buses using imagery tools such as google maps or MapInfo as a first pass to determine if transformers are collocated with TSPs stations (shares the same ground grid).

4.       If it is unclear if a transformer shares a ground grid with the TSP station after using imagery tools, drawings can be used to determine whether it shares a ground grid connection (through ground leads or shield wire).

5.       If the transformers are not collocated (do not share the same ground grid) then the associated generator buses should be in a generator station. Then determine if extra buses are needed to separate the generator station from the TSP station. If extra buses are needed, create idevs to add buses to the case so that the transformer has all winding buses in the same station. Provide those idevs to ERCOT with the template submission.

6.       If the transformers are collocated then the TSP can add the generator buses to their substation tab in the submission template so that ERCOT knows those generator buses are not supposed to be in a separate GIC model station.

This is the suggested approach we discussed last week. Any approach that helps improve the model and determines correct location of all the buses is acceptable. If you have any questions, please feel free to contact me. We can share other approaches to reconciling interfaces at our next Face to Face meeting. Also please consider the examples shown in the presentation given by Oncor at our last meeting.

Thank you to everyone for your continued hard work on the GIC model.

Best Regards,

Omar A. Urquidez, PhD, P.E.
Chairman Planning Geomagnetic Disturbance Task Force

CenterPoint Energy
Office: (713) 207-2344
Cell: (617) 504-8704
Email: [log in to unmask]<mailto:[log in to unmask]>

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