The ColumbiaGrid board of directors has announced a 10-year transmission plan which involves 56 new transmission infrastructure projects. The projects are costing an estimated US$2.5 billion.
The 2015 Biennial Transmission Expansion Plan contains the information of transmission projects and upgrades within or related to ColumbiaGrid’s footprint. Service territories include Avista, Bonneville Power Administration (BPA), Chelan County Public Utility District, Cowlitz County PUD, Douglas County PUD, Grant County PUD, Idaho Power, PacifiCorp, Portland General Electric, Puget Sound Energy, Seattle City Light, Snohomish County PD, and Tacoma Power.
Coordination of the transmission plan
The plan was coordinated with other sub-regional planning groups, such as the Northern Tier Transmission Group, and with the overall region through the Western Electricity Coordinating Council. Projects in the plan primarily address issues that would occur in the first five years of the 2015-2025 planning horizon. Additional projects will be required to meet the needs in the latter part of the 10-year planning horizon.
Transmission projects in the plan are unique to ColumbiaGrid’s member service territories and do not connect the northwest region to the southwest region.
Transmission line construction projects included in the plan are:
· BPA’s US$99 million, 500kV Central Ferry to Lower Monumental project-due to be in service this year
· BPA’s US$124 million, 500kV Big Eddy to Knight project-scheduled to be in service this year
· Douglas County PUD’s US$23.3 million, 230kV Rapids to Columbia project-scheduled to be in service in 2016
· Grant County PUD’s US$5 million, 115kV Rocky Ford to Dover project-scheduled to be in service in 2016
· Idaho Power’s US$840 million, 500kV Hemingway to Boardman project-scheduled to be in service after 2020
· PSE’s US$13 million, 115kV Woodland to Gravelly Lake project-scheduled to be in service in 2019
· Snohomish County PUD’s US$25 million, 115kV Turner to Woods Creek project-scheduled to be in service in 2020
Transmission line rebuild and upgrade projects in the plan are:
· Avista’s US$10 million, 115kV Bronx to Cabinet rebuild project-scheduled to be in service in 2016
· Avista’s US$10 million, 115kV Benton to Othello rebuild project-scheduled to be in service in 2016
· BPA’s US$1 million, 230kV Santiam to Chemawa rebuild project-scheduled to be in service after 2018
· Cowlitz County PUD’s US$4.9 million, 115kV Longview to Lexington rebuild-scheduled to be in service by 2017
· Cowlitz County PUD’s US$10.1 million 115kV Longview to Lexington to Cardwell rebuild-scheduled to be in service by 2017
· PSE’s US$80 million, 230kV Sammamish to Lakeside to Talbot rebuild-scheduled to be in service in 2018
· PSE’s US$25 million, 115kV Portal Way rebuild-scheduled to be in service in 2018.
Study guides transmission expansion plan
Since the adoption of the 2013 Biennial Transmission Expansion Plan, ColumbiaGrid implemented an economic planning study (EPS) as part of its study programmes. The EPS focuses on evaluating future system performance, such as potential transmission congestion or utilization, prices at specific locations or areas, potential production at generation facilities, with the ability to simulate hourly or sub-hourly system behaviour using production cost simulation software.
An EPS study in 2014 helped ColumbiaGrid determined the potential effects of various scenarios of installing replacement capacity for known steam coal retirements in the Pacific Northwest.
ColumbiaGrid also incorporated a variable transfer limit study for the California-Oregon Intertie in the biennial plan to determine the ability of the system to accommodate some fluctuation in the power grid without operator intervention.
ColumbiaGrid may produce an update to the 2015 biennial plan, if warranted, based on the results of ColumbiaGrid’s annual system assessment, which will be completed in July.