Path Rating Catalog 2013 - Western Electricity Coordinating Council

20. Path C (Pre Gateway)
Revised January 2013
Accepted Rating
Existing Rating
Other
Location:
Definition:
Transfer Limit:
Critical
Disturbance
that limits the
transfer
capability:
Northern Utah/Southern Idaho
Sum of the flows on the following transmission lines:
Line
Malad-American Falls* 138 kV
Ben Lomond-Populus* #1 345 kV
Ben Lomond-Populus* #2 345 kV
Terminal-Populus * 345 kV
Treasureton-SunBeam-Brady* 345 kV
FishCreek-Goshen* 161 kV
Threemile Knoll 138/345 * kV transformer
Threemile Knoll 138*/115 kV transformer (Future)
North to South: 1600 MW (nominal)
South to North: 1250 MW (nominal)
Operating limits are based on System Operating Limit (SOL) studies.
Southbound: Post disturbance voltages on Path 18 limit southbound capacity
to 1600 MW following an N-2 Path 19 outage which causes two Bridger units
to trip due to Bridger RAS operation.
Northbound: Post disturbance flows following N-1 or N-2 outages on the
remaining line west of Populus limit the Northbound capacity to 1250 MW or
less based on a simultaneous nomogram (Figure 1) with Bridger West. Up to
two Bridger units may trip due to Bridger RAS operation to reduce Populus
west flow.
When: Phase 3 status granted November 20, 2008
System
Conditions:
Study Criteria:
Remedial
Actions
Required:
Formal
Operating
Procedure:
Northbound capacity is determined under light load conditions when thermal
resources in Utah are being transferred to the NW, and Southbound capacity
is determined under heavy summer loading conditions. Due to the interaction
with the Bridger West Path, a nomogram between Path C (Northbound) and
Bridger West has been established. (See Figure 1)
• Steady state pre disturbance voltages between .95 p.u. and 1.05 p.u.
• Post-disturbance voltages between .90 p.u. and 1.10 p.u.
• Post-disturbance line loadings less than “emergency ratings.”
• First-swing transient voltage dips not to exceed .80 p.u.
Bridger RAS operation may trip up to two units as discussed above.
Yes
Allocation:
100% PacifiCorp
PART VI Item 1-56