Vermont regulators issued an order April 6 approving the construction of a new 115-kV substation and associated tie line in the town of Weathersfield, Vt., proposed by Vermont Electric Power Company (VELCO) and Vermont Transco, collectively, VELCO, and Central Vermont Public Service (CVPS).
The state Public Service Board (PSB) agreed with a hearing officer, who in March recommended that the PSB approve the proposed project and issue a certificate of public good for construction. The hearing officer concluded, among other things, that the project will meet the need for present and future demand for service, which could not otherwise be provided in a more cost-effective manner through energy conservation programs and measures and energy efficiency and land management measures.
The companies filed a petition in July 2011 to build the new substation, according to the order.
VELCO’s existing Ascutney substation was built in 1958 and interconnects four 115-kV lines: two that connect the Vermont high voltage network with the New England transmission network in New Hampshire, one that connects to the VELCO Coolidge substation and one that connects to the Windsor substation that serves a 115/46-kV transformer.
The PSB also said VELCO proposes to remove its 115-kV equipment from the existing substation that it shares with CVPS and build a new 115-kV substation off of Route 5 in Weathersfield, about one mile southeast of the existing Ascutney property. The existing CVPS-owned equipment will remain at the existing site and the VELCO-owned components will be decommissioned and removed.
The new substation layout will include enough space for the addition of a future 115/46-kV transformer that would interconnect VELCO’s 115-kV transmission network to CVPS’ 46-kV sub-transmission system, the PSB added.
The proposed project will involve installing new 115-kV and 46-kV lines and associated structures within an existing transmission corridor in order to connect the new substation to existing transmission lines and to CVPS’ 46-kV network. Furthermore, it will involve installing an approximately one-mile 46-kV sub-transmission line within the existing corridor to connect the new VELCO substation with the existing CVPS sub-transmission system. The PSB also said that the installation of the new 46-kV line will require minimal expansion of the existing right-of-way.
The estimated total cost of the proposed project is about $22.96m, with about $17.96m expected to be eligible for pool transmission facilities regionalized cost recovery, the PSB said.
Kerrick Johnson, VELCO’s vice president for external affairs, told TransmissionHub April 16 that construction on the project will begin on April 23.
The PSB said the Vermont bulk electric transmission network integrates the Vermont system with the transmission system in the northeast. The existing Ascutney substation connects the Vermont system to all 115-kV tie lines that connect Vermont to New Hampshire from the south and east.
Under the restated New England Power Pool Agreement and the New England Open Access Transmission Tariff, VELCO’s transmission system must meet the design and operating reliability criteria of ISO New England and the Northeast Power Coordinating Council as well as national reliability standards established by NERC, the PSB added.
Recent planning studies show that the Ascutney area bulk transmission system fails to meet the required operating criteria. The PSB also said that reconfiguring the Ascutney substation to a ring configuration will remedy the reliability deficiency by removing the exposure related to the existing radial bus design.
The proposed project will improve system reliability by maintaining the system voltage at acceptable levels as required by federal and regional reliability standards. Furthermore, the PSB added, it will be consistent with VELCO’s transmission vegetation management plan, which is designed to prevent physical contact between transmission lines and nearby vegetation that could cause a transmission line to fail.
As for economic benefit to Vermont, the proposed project will increase electricity supply reliability, and while the economic benefits associated with electrical outages are hard to quantify, they can be considerable. The PSB also said that the project will increase property tax revenues based on the capital investment required for the substation upgrade.
Among other things, the PSB said the proposed project will not have an undue adverse impact on aesthetics, historic sites or rare and irreplaceable natural areas. Additionally, it will not have an undue adverse effect upon rare, threatened or endangered species or their habitats, according to the PSB.