Path Rating Catalog 2013 - Western Electricity Coordinating Council

Revised January 2013
19. Bridger West (Pre Gateway)
Accepted Rating
Existing Rating
Other
Location:
Definition:
Transfer Limit:
Critical
Disturbance
that limits the
transfer
capability:
When:
System
Conditions:
Study Criteria:
Border between Southeast Idaho and Southwest Wyoming
Sum of the flows on the following lines:
Line
Jim Bridger-Three Mile Knoll 345 kV
Jim Bridger-Populus 345 kV #1
Jim Bridger-Populus 345 kV #2
Metered End
Jim Bridger
Jim Bridger
Jim Bridger
East to West: 2400 MW
West to East: 600 MW (“Other rating”: Rating established following NERC
MOD-029-1a_R2.2 requirement)
The 30 minute thermal rating of the Bridger- Three Mile Knoll 345 kV lime
limits transfer for the single most critical outage which is the loss of the Jim
Bridger-Populus #1 or #2 345 kV line. Transient voltage and frequency dips
are the limiting conditions for N-2 outages of the Jim Bridger 345 kV system
(with RAS C&D disabled).
The 2400 MW rating was established in 2011. The studies were conducted
jointly by Idaho Power Company and PacifiCorp.
The Bridger West transfer rating is determined with simultaneous heavy
transfers on series and parallel paths consistent with heavy transfers of eastern
thermal resources to the west during light load. The Bridger West 2400 MW
rating with Path C at 1600 MW (N-S) and Montana- Idaho at 337 MW (N-S);
and with Path C at 1250 MW (S-N), Montana-Idaho at 256 MW (S-N), TOT
4A at 600 MW and West of Borah at 2557 MW. Due to the interaction with
the Path C (Northbound), a nomogram between Path C (Northbound) and
Bridger West has been established. (See figure 1)
Initial Conditions:
• Per unit bus voltages within PacifiCorp and IPCO systems between
0.95 p.u. and 1.05 p.u.
• All line and transformer loadings maintained within allowable
continuous ratings.
• Synchronous condensers at Kinport, Goshen, and American Falls
operating in the middle of their boost-buck range. One of two of the
Jim Bridger 200 MVAR shunt capacitor bank in service to achieve
transfer level.
Transient: WECC/NERC Reliability Criteria for Transmission System
Planning.
Post Transient: For single contingencies (N-1), a 250 MVAR reactive margin
will be maintained from the point of voltage instability (nose of the QV curve)
at the critical bus for an outage of the critical line with successful operation of
remedial action scheme. For double contingencies (N-2), a 200 MVAR
reactive margin will be maintained at the critical bus.
PART VI Item 1-52