22.5MW Battery Energy Storage System

To accommodate a new 22.5 MW Battery Energy Storage System at a large wind energy center, an additional 34.5kV position was added to an existing 34.5/138 kV collector substation. The added position was made via a 1200A, 34.5kV breaker with metering class CTs and corresponding bus and line switches, and the BESS banks were connected with medium voltage underground cable.

No updates were required to the existing electrical equipment enclosure control battery bank; it was utilized and had space to accommodate the additions associated with this project.

Once the controls were updated to integrate the new position into the existing protection scheme, an ION meter was included for frequency monitoring. 

The battery manufacturer was responsible for the design associated with the step-down transformers, inverters, battery systems and corresponding HVAC requirements. Ulteig’s design demarcation was the connection to the 34.5kV/480V step-down transformers.

This battery energy storage system, which helps balance the power grid frequency, went into commercial service in November of 2014.

When Epic Systems Corporation approached the city of Rochester, Minnesota, to request a substation on an aggressive deadline, Rochester Public Utilities (RPU) worked with Ulteig to strategize a solution. The substation was to be built on a small triangle of land surrounded by a major highway, the new Epic Systems headquarters building and the Douglas State Trail. Ulteig began by leveling the soil and coordinating the construction of a concrete screening wall.

To allay community concerns over an unsightly structure that could potentially decrease home values, Ulteig designed the substation to have a low profile with a screening wall that was adorned with a decorative finish. Photographs from the construction site were used to develop a 3D computer model of the substation. The city of Rochester shared the model in community meetings to address resident concerns. In this way, Ulteig innovation not only served the client, but also the community.

RPU applauded Ulteig for working at a speed that exceeded expectations and for its valuable contributions to onsite construction.