Path Rating Catalog 2013 - Western Electricity Coordinating Council

40. TOT 7
Revised January 2006
Accepted Rating
Existing Rating
Other
Location:
Definition:
North Central Colorado
Sum of the flows on the following transmission lines:
Line
Metered End
Ault-Fort St. Vrain 230 kV
Ault
Weld-Fort St. Vrain 230 kV
Weld
Longs Peak-Fort St. Vrain 230 kV Fort St. Vrain
Transfer Limit: North to South: 890 MW (maximum)
Depending on local generation and load levels, the real time limit can range
between a maximum of 890 MW and a minimum of 562 MW (2005 summer
study results).
South to North: Not defined
Critical
Disturbance
that limits the
transfer
capability:
When:
System
Conditions:
Study Criteria:
Remedial
Actions
Required:
Formal
Operating
Procedure:
The critical disturbance is the outage of the Ault-Windsor-Fort St. Vrain
230 kV line. The limiting element is the emergency overload on the Weld-
Fort St. Vrain 230 kV line or the Weld-Weld 230 kV bust tie meter CT, or the
Timberline-Harmony 230 kV line.
Rating established in December 1995 with publication of “Foothills Planning
Group TOT 7 Operating Study Report.” The operating study was conducted
jointly by:
Public Service Company of Colorado (PSCO)
Western Area Power Administration (WAPA) - Loveland
Tri-State Generation & Transmission Association, Inc. (TSGT)
Platte River Power Authority (PRPA)
This rating is independent of transfer levels between major areas of WECC.
This path is affected primarily by Colorado/Wyoming power exchanges, and
local load and generation historically the flows have all been north to south
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 0.92 p.u. and 1.10 p.u.
• All lines loaded to less than 15-minute emergency ratings.
• All transformers loaded to less than their continuous ratings.
None required. Following an outage, re-dispatch of generation may be
required to reduce loadings from acceptable short term emergency to levels
within their continuous ratings.
There is a formal operating procedure; the most current one dated
May 23, 2005. Public Service Company of Colorado is the operating agent
and uses real-time flows to monitor the path and local load and generation
update the real time operating limit.
PART VI Item 1-114