Grant Street Substation

Background

Currently, we receive all our power from outside the City via a 50-year-old Consumers Energy substation. The recommended useful life of a substation is 25 to 40 years, meaning we are operating beyond this threshold and facing infrastructure needs, which must be addressed. Consumers Energy was approached about building a new substation and declined as it does not align with their current business model.

We began designing the facility in 2022 and City of Portland Board of Light and Power accepted sealed bids for construction of a new substation on July 3, 2024 at a cost of $1,838,958 to be located at 289 N. Grant Street. Our team evaluated the proposal and worked with the awarded vendor to value engineer some savings bringing the project scope to $1,646,929.

Grant Street Substation Construction Bid Evaluation (PDF)

The total project cost with equipment purchases and interconnect to Consumers Energy is approximately $3,225,000. This project is supported by a 20 year $3,470,000 general obligation bond.

As this work progresses, residents may experience planned interruptions of electric service. Following our standard practice, affected residents will be communicated with in advance of this disruption.

Schedule

We have been purchasing equipment since June 2023. Tree clearing has occurred and site work is expected to start in April or May of 2025. From May onward, there will be steady construction with final construction activities dependent on transformer delivery. However, under all scenarios, substation construction is expected to be completed by March 2026.

Substation commissioning is scheduled for spring of 2026. The West Circuit will transition to the new substation upon commissioning. The South Circuit will transition in the summer or fall of 2026. The East Circuit is tentatively scheduled for 2027, and the North Circuit is planned for transition in 2028 or 2029. High-level circuit transition planning has occurred and this information will inform our five-year capital plan within the department. The Consumers Energy substation will only be decommissioned once all circuits have transitioned.

What is a substation?

A SUBSTATION is a collection of electrical equipment with the dual purpose of transforming (raise or lower) and regulating (maintain steady) voltage at a meeting point of two power transportation systems with different voltages. Because the transformation of voltages generates heat the system must be constructed for heat dissipation. Because the equipment transports a lot of energy, is designed for high reliability, and is expensive substations are built with protective control devices upstream and downstream of the transformers, voltage regulators and critical controls.

What is the typical life of a substation?

25-40 years

“Substation protection system designs for stable, unchanging service conditions, built with long-lasting devices and components, often have a durability service life of 25 to 30 years.” Schweitzer Engineering Laboratories

“After 30-40 years of operation, the reliability and performance of a substation inevitably declines” ABB Switzerland Ltd - Power Systems

“The lifespan of a transformer largely depends on the ageing of the solid and liquid organic insulating materials. In normal operating conditions, below the maximum permissible load, and with regular maintenance and care, a transformer's lifespan can be extended to well over 30 years.” Siemens Energy

What is our path towards replacement and why?

Design, build, own and operate a new replacement substation to maintain reliable power supply with the support of Newkirk Electric. Consumers Energy has communicated that they are not interested in building or operating a new substation to serve the City of Portland.

Decommission the existing substation after the new substation is fully commissioned and the distribution system transformers are voltage verified on a circuit-by-circuit basis. The existing substation configuration provides two distribution voltages to the city and the goal is to operate at a single voltage across the city and allowing fewer points of failure potential between the transmission system and City of Portland electric customers, while simplifying our inventory and improving the capacity the City’s infrastructure.

Purchase long lead items as soon as practical to implement new substation construction in 2025. Evaluate alternative connections with Consumers Energy or Wolverine Power at other locations in the City as a long-term (5-10 year) plan to mitigate single point of failure risk. Having only one connection to the transmission system continues the City’s historical risk of a single point of failure interruption of power.

Operationally, for the Board of Light and Power, replacement of aging substation represents a significant long term investment and undertaking which require significant planning efforts like equipment lead times, contractor coordination and substation transition to minimalize disruption. These efforts and project scope have delayed the original project timeline by about one year.

The Grant Street Substation and subsequent circuit transition plan will significantly improve the power-carrying capacity of the South, East, and North Circuits. Of all the tasks Board of Light and Power will undertake in the next five years, this work is foundational for ensuring long-term operational reliability and enabling future growth.