Ascutney Substation Project
Vermont Electric Power Company (VELCO) is proposing to construct a substation east of the existing substation in Weathersfield, Vermont, to provide a redundant path and additional capacity to deliver power to this area.
Originally built in 1958, VELCO's existing Ascutney substation, located on Route 131 in Weathersfield, interconnects VELCO's electric transmission network in central Vermont. The need for the Ascutney substation upgrade was identified in VELCO's 2009 Long-Range Transmission Plan. Failures of key transmission components could cause low-voltage conditions that violate system standards, voltage instability/collapse, or thermal overloads, which could result in extended outages for the areas served by the transmission system.
Transmission utilties, such as VELCO, are required to design, operate and maintain a transmission network according to national and regional reliablity standards. Planning studies by VELCO and ISO New England, New England's bulk electric system provider, reveal that the existing Ascutney substation does not meet current federally mandated reliability requirements. Specifically, the system cannot meet required reliability criteria because a bus fault (a fault in which a circuit-breaker fails to open), will result in system voltage violations and possible voltage collapse (outage).
The proposed project will include the following components
- 115kV aluminum bus structure
- six circuit breakers
- control building
- connection to VELCO's existing 115kV transmission lines
- connection to CVPS' existing 46kV distribution lines
- existing transformer
VELCO owned components of the existing Ascutney substation will be decommissioned and the existing equipment retired as part of this project.
See our glossary of electrical terms for definitions of these components.
VELCO's aesthetic consultant has reviewed the preliminary design plans and performed a visual analysis of the areas of the proposed Project. The findings indicated limited potential visibility to the proposed substation from Route 5, Interstate 91 and from the adjacent residential neighborhood along Tenney Hill Road. The analysis also found potential for visibility of line upgrades east of Interstate 91 from these locations.
Although the Project substation site is set back from surrounding roads, plantings will be needed to screen the substation from view. Landscape mitigation plantings will be proposed to help screen views that are created to the substation and also help screen visibility of the line upgrades. Due to the increased potential for visibility of line improvements, attention will also be given to the style and locations of transmission line structures, and in particular the angle structures for the lines to access the new substation. A detailed report with proposed landscaping mitigation measures will be included with the Petition to be filed this spring.
VELCO will assess the potential noise impacts associated with the substation relocation and will design the facility to produce sound levels that are at or below Public Service Board acceptable thresholds.
Subject to Public Service Board approval, construction will begin in late winter of 2011 or early spring of 2012 with a targeted completion date of December 2012.