20180208PAC to Staff Lake Side 1 RAS - Assessment.docx

PacifiCorp Main Grid Planning
PRC-(012 through 014)-WECC-CRT2
Attachment B RAS Assessment
RAS Name
Lakeside Generation Tripping Scheme
Reporting Party
PacifiCorp
Group Conducting Assessment
PacifiCorp Main Grid Planning
Assessment Date
12/31/2014
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 Lakeside Generation Tripping Scheme is designed to mitigate overload conditions on the Timpto Hale Substations for the loss of two 138 kV linesnorth of Dynamo Substation.The scheme is designed to arm when total Lakeside plant generation is above 240 MW and when flow on the Timp to Hale 138 kV line exceeds 343 MVA. When these conditions are satisfied, a runback signal is sent to the plant, followed 14.5 minutes later by a trip signal to the Lakeside steam unit. If the overload persists, the Timp to Hale 138 kV line is tripped after 15 minutes.
The Lakeside Generation Tripping Scheme is listed as a Local Area Protection Scheme. This designation is appropriate due to the level of generation tripping (<1000 MW) and load loss exposure (<300 MW). Impacts of scheme failure to operate are limited to thermal overloads on the local 138 kV transmission system between Spanish Fork and Timp substations. There are no system impacts for inadvertent operation of the scheme.
No performance issues were seen during the winter season assessment, and winter assessment results indicate that it may be possible to disarm the scheme during the winter operating season.
During summer operation, study results indicate that the Lakeside Generation Tripping Scheme is necessary to mitigate thermal overloads on the Timp to Hale 138 kV transmission line following the N-1-1 or N-2 loss of the 138 kV transmission lines north of Dynamo substation. Further analysis of the thermal capability of the Timp to Hale 138 kV line is required to determine whether the 14.5 minute runback will maintain loading within the short-term thermal capability of the line. PacifiCorp Engineering and Transmission Planning are studying the short-term thermal capability of the Timp to Hale 138 kV line based on a recent LiDAR analysis to determine if changes are required to the Lakeside 1 LAPS prior to the summer operating season. This analysis and any necessary modification to the scheme will be completed prior to April 1, 2015.
Study Years
2014
System Conditions
Heavy summer load levels with maximum Lakeside plant generation output. Light winter load levels with maximum Lakeside plant generation output.
Contingencies analyzed
(select what applies)
N-1
N-1-1
N-2
Extreme
N-1, N-1-1, N-2
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 were observed.
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).
PacifiCorp Engineering and Transmission Planning are studying the short-term thermal capability of the Timp to Hale line based on a recent LiDAR analysis to determine if changes are required to the Lakeside 1 LAPS prior to the summer operating season. No modifications to the scheme are required for winter operation, and any necessary changes for summer operation will be implemented prior to April 1, 2015.
Additional Notes