Path Rating Catalog 2013 - Western Electricity Coordinating Council

37. TOT 4A
Revised January 2012
Accepted Rating
Existing Rating
Other
Location:
Definition:
Southwest Wyoming
Sum of the flows on the following transmission lines:
Line
Metered End
Riverton-Wyopo 230 kV
Riverton
Miners-Platte 230 kV
Miners
Spence-Mustang 230 kV
Spence
Transfer Limit: Northeast to Southwest: 810 MW (Non-simultaneous)
Southwest to Northeast: Not defined
Critical
Disturbance
that limits the
transfer
capability:
When:
System
Conditions:
Study Criteria:
Remedial
Actions
Required:
Formal
Operating
Procedure:
Allocation:
Interaction
w/Other
Transfer Paths:
Depending on flows on the adjacent TOT 4B path, the real-time rating can
range between a minimum of 0 MW and a maximum of 810 MW (Reference
attachment). Typically, the real-time rating centers around 650 MW.
The critical disturbances and limiting elements vary with the various points
on the nomogram. Reference attachment for further information.
Phase 1/2 Rating Study Underway
This rating is independent of transfer levels between major areas of WECC.
Historically, the flows have all been northeast to southwest across the path.
(Summary)
System intact:
• Per unit voltages between 0.95 p.u. and 1.05 p.u.
• All lines and transformers loaded to less than continuous rating.
Single contingency outage conditions:
• Per unit voltages between 0.90 p.u. and 1.10 p.u.
• All facilities loaded to less than 100% of emergency ratings.
Remedial actions are required to achieve the rated transfer capability.
Following an outage, all overloaded lines and transformers must have their
loading reduced to continuous ratings within 15 minutes. This is
accomplished by reducing schedules and adjusting generation.
There is a formal operating procedure TBD. PAC is the operating agent and
uses real-time flows to monitor the path.
PAC has the entire transfer capability of the path.
See attachment
PART VI Item 1-103