Case Study

Delivering renewable power to the utility grid

Client challenge:

Our client required additional infrastructure to deliver renewable power to the utility grid. For this interconnection, a collector system, collector interconnection substation, transmission line and upgrades to the interconnecting utility substation needed to be designed and constructed.

How we helped:

Our team were required to complete the collector system, collector interconnection substation, transmission line and the local utility substation upgrade designs. The collector interconnection substation was a greenfield design; however, it was built directly adjacent to the existing 345kV utility substation. This required our team to design a shared fence and new 345kV bus connection over the shared fence to the existing substation to facilitate the interconnection.

Major equipment in the interconnecting substation on the 345kV side includes arresters, coupling capacitor voltage transformers, circuit breaker and motor operated disconnect switches along with a 345/115kV, 180/240/300MVA transformer. Major equipment on the 115kV side includes arresters, potential transformers, disconnect switches, circuit breakers, circuit switchers, station service transformer and two 25MVAR capacitor banks each with 75 micro-henry reactors. A control shelter design was provided to house the AC/DC systems as well as the protection and control equipment. A 59-mile, 115kV transmission line connects the collector substation to the collector interconnection substation.

The collection system consisted of four 34.5kV feeder circuits connecting forty-eight 3.075MW Vestas V112 turbines to the collector substation. A 115/34.5kV collector substation connects the collector system to the transmission line.

The SGC Engineering team were responsible for the collection system and transmission line designs as well as substation civil, electrical, protection and control design. These included a 30% conceptual design, a 75% design for review, an issue for construction design and a final record drawing submittal. SGC completed all required studies, protection settings, equipment specifications and provided construction support.

Powerful results:

The project was completed on time, on budget and there were no notable issues with the final design. The client was pleased with the final product and has continued to utilize SGC Engineering on subsequent renewable projects.

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