20171218PAC to Staff Attachment Utah_DPU 10.11d.docx

PacifiCorp Main Grid Planning
PRC-(012 through 014)-WECC-CRT2
Attachment B RAS Assessment
RAS Name
Three Peaks Remedial Action Scheme
Reporting Party
PacifiCorp
Group Conducting Assessment
PacifiCorp Main Grid Planning
Assessment Date
12/18/2014
Review the scheme purpose and impact to ensure proper classification, is it (still) necessary, does it serve the intended purposes, and does it continue to meet current performance requirements.
The Three Peaks Remedial Action Schemeis designed to eliminate overload on the Three Peaks- West Cedar138 kV line during loss ofSigurd-Three Peaks 345 kV line.
The scheme is classified as a local are protection scheme. This designation is appropriate, as system impacts of failure of the scheme to operate are limited to the local 138 kV system near Three Peaks and West Cedar substation. There are no system impacts for inadvertent operation of the scheme. There is no generation or load loss exposure associated with the scheme.
The 2014 study (prior to Sigurd Red Butte #2) indicated that the Three Peaks RAS is still necessary to mitigate thermal overload on the West Cedar to Three Peaks 138 kV line for the loss of Sigurd to Three Peaks 345 kV line.
2019 study (post Sigurd to Red Butte #2) indicated that the Three Peaks RAS is still necessary to mitigate thermal overloads on the West Cedar to Three Peak 138 kV line and West Cedar 230/138 kV transformer and low voltage issues observed in the area (West Cedar 230 kV bus at 0.872 pu and Coleman 138 kV bus at 0.879 pu) for the N-1-1 loss of Sigurd to Three Peaks and Sigurd – Red Butte #2 345 kV lines.
No performance violations were seen following operation of the scheme.
Study Years
2014 and 2019
System Conditions
Heavy summer load conditions
Contingencies analyzed
(select what applies)
N-1
N-1-1
N-2
Extreme
N-1
N-1-1
Date when the technical studies were completed
2014
Does the RAS comply with NERC standards and WECC Criteria?
Yes
Discuss any coordination problems found between this RAS and other protection and control systems during this (most recent) assessment.
No coordination issues with the thermal overload and low voltage relays are anticipated.
Provide a Corrective Action Plan if this RAS was found to be non-compliant or had coordination problems during this (most recent) assessment (should be NA for owner’s initial assessment).
N/A
Additional Notes
N/A