The Mill Street Substation, serving the City of Nelson in British Columbia, required a substation upgrade due to aging 42-year-old infrastructure. The need for replacement became more urgent following a transformer failure caused by wildlife interference. The substation upgrade project focused on replacing the failed transformer, improving power reliability, and increasing capacity to meet future load growth.

Primary was selected by Nelson Hydro to provide comprehensive engineering services for the project. The scope included defining the architecture for a brownfield substation replacement, along with structural and civil engineering for foundations and steelwork. The electrical design covered electrical apparatus layout and specifications, conduit and cable schedules, power system studies - including grounding, lightning, load flow, short circuit analysis, and transient modeling. Additionally, the project involved developing the communications and control architecture, ensuring seamless SCADA integration for efficient system management.

The project design included outdoor high-voltage transmission structures, two large power transformers, and a state-of-the-art electrical house (E-House) that safely enclosed advanced switchgear. Modern protection systems, real-time power monitoring, and smart communication technology reduced wiring and improved efficiency and reliability.