Path Rating Catalog 2013 - Western Electricity Coordinating Council

66. COI
Revised January 2013
Accepted Rating
Existing Rating
Other
Location: Between Oregon and northern California
Definition: Line Owner Metered End
Transfer Limit:
Critical
Disturbance
that limits the
transfer
capability:
When:
System
Conditions:
Study Criteria:
Malin to Round Mt. 500 kV
Joint
Malin
(2 lines) (Pacific AC Intertie)
(north end)
Captain Jack-Olinda 500 kV line (COTP) Joint Captain Jack
(north end)
4800 MW North to South
3675 MW South to North
With north to south transfers, the critical outage is the loss of two Palo Verde
units or the DC Bipole outage. The critical outage for the California portion
of the COI when transfers are north to south is the south of Table Mt. 500 kV
outage (Table Mt. To Tesla and Table Mt. To Vaca-Dixon) that could
potentially cause thermal overloads on the underlying system.
With south to north transfers, the critical outages are (1) single line outage of
the Captain Jack-Meridian 500 kV line or the PDCI, (2) a double line outage
of the Malin-Round Mt. 500 kV lines, and (3) a double line outage of the
Ashe-Marion and Buckley-Marion 500 kV lines (this latter outage is limiting
with high west-side loads in Oregon). Most of these critical outages were
limiting due to voltage stability margin.
The 4800 MW north to south rating was established in 1986 through the
WECC Annual Progress Report Procedure. Update reports have been
submitted each year since 1992.
The 3675 MW south to north limit was established in November 1992.
Six cases were studied (Heavy Summer; Heavy Spring; Light Winter; PG&E
importing; PG&E exporting; BPA spring).
• The PDCI is 3100 MW (n-s) in the N-S cases, 2000 MW (n-s) in the
PG&E import case and 2000 MW (s-n) in the S-N cases.
• Northern California hydro is at 60% of generating capacity in the
BPA spring case and 90% in other cases.
• Cases were developed showing both 1 and 2 units on line at Diablo
for the Spring and Summer. The light winter case had 2 units on line
as does the PG&E import case. The PG&E export case has 1 Diablo
unit on line.
All facilities loaded within normal ratings under normal system conditions.
All facilities loaded within emergency ratings under outage conditions.
The system meets the WECC voltage stability criteria recommended by TSS.
Fully meets WECC reliability criteria in effect at time rating was established.
The study’s results meet the reliability criteria of all utilities in the Northwest
and northern California.
PART VI Item 1-174