Path Rating Catalog 2013 - Western Electricity Coordinating Council

Revised February 2007
26. Northern - Southern California
Accepted Rating
Existing Rating
Other
Location:
Definition:
Between PG&E and Southern California Edison
Midway-Vincent #1 500kV line metered at Midway
Midway-Vincent #2 500kV line metered at Midway
Midway-Whirlwind 500kV line metered at Midway
Transfer Limit: North to South: 4000MW (Other Rating) 1
South to North:
3000 MW
Transfer limits are affected by generation and load levels between Path 15
and Midway. North to south seasonal limits can vary from 900 to 4000 MW
and south to north from 1400 to 2400 MW.
Critical
Disturbance
that limits the
transfer
capability:
Midway-Vincent #1 and #2 500 kV double-line outage, or Midway-Vincent
#1 and Midway-Whirlwind 500kV double-line outage can overload the
remaining Path 26 500 kV line and/or cause voltage criteria violation.
When: North to south rating of 4000 MW was approved by WECC on May 5, 2006.
The existing Path 26 RAS was upgraded and released for operation on June
19, 2006 to support the north to south rating. (SCE and PG&E are currently
in the process of initiating a redefinition of the path and reestablishing the
existing path rating with the approved modification of the existing RAS, as
discussed above.)
South to north rating of 3,000 MW was approved by WECC on September
26, 2011. There is no existing Path 26 RAS for south-to-north transfer at
3,000 MW.
System
Conditions:
Study Criteria:
Remedial
Actions
Required:
Formal
Operating
Procedure:
North to south transfer was based on heavy summer and light spring
conditions.
South to north transfer was based on light winter conditions.
All facilities loaded within normal ratings under normal system conditions.
All facilities loaded within emergency ratings under outage conditions.
The system meets the post transient voltage criteria.
Fully meets NERC/WECC Planning Standards.
Based on the nomogram curve designed for north to south flow between 3000
and 3550 MW, the Path 26 RAS would trip up to 1400 MW of Midway area
generation for loss of any two of the South of Midway 500 kV lines
(Midway-Vincent #1, Midway-Vincent #2, and Midway-Whirlwind). For
north to south flow between 3550 and 4000 MW, the Path 26 RAS would trip
1400 MW of Midway generation and up to 600 MW load at SCE’s Rio
Honda and/or Walnut Substations for the same 500 kV double-line outage.
California ISO T-103, T-118A, T-120 and T-122.
1 The rating of 4000 MW included Midway –Vincent #3, which has been replaced. This new path definition is going through the Three-
Phase Process..
PART VI Item 1-73