Path Rating Catalog 2013 - Western Electricity Coordinating Council

Revised January 2013
75. Hemingway – Summer Lake
Accepted Rating
Existing Rating
Other
Location:
Definition:
Transfer Limit:
Critical
Disturbance
that limits the
transfer
capability:
When:
Southwest Idaho and eastern Oregon
Hemingway-Summer Lake 500 kV metered at the Hemingway 500 kV.
Note: The path is also within Path 14 Idaho-Northwest.
East to West: 1500 MW
West to East: 550 MW
East to West: Thermal overload on the Walla Walla 230 kV series capacitor
following the loss of the Hemmingway – Summer Lake 500 kV line.
West to East: The thermal overload of the Lolo-Oxbow 230 kV line is the
limiting condition for an outage of the Hemingway-Summer Lake 500 kV
line. The path is also limited by a reactive margin in the northwest for a
double Palo Verde unit outage.
The east to west rating is limited by thermal ratings of Midpoint 345/500 kV
transformer and series capacitor in the line. It was established along with the
2400 MW east to west rating of Idaho to Northwest path in August, 1989 with
the publication of Idaho Power Company to Pacific Northwest Intertie
Capacity Study. The WECC Notification Procedures for Changes in Facility
Rating and/or Operating Procedures was followed.
The east to west rating was conducted jointly by:
Bonneville Power Administration (BPA)
Idaho Power Company (IPCO)
PacifiCorp (PAC)
Avista Corp. (AVA)
The 550 west to east rating is based on path studies completed in 2009. Phase
3 status was granted on July 22, 2009
Midpoint-Summer Lake was redefined to Hemingway-Summer Lake in 2010
due to addition of the Hemingway 500/230 kV substation.
PART VI Item 1-189