Client Challenge
Our client is a leading renewable energy company that designs, develops, manages, and operates power plants. Our client required additional infrastructure to deliver renewable power to the utility grid. For this interconnection, a collector system, collector substation, and transmission line needed to be designed and constructed.
How We Helped
SGC completed the collector system, collector substation, transmission line designs, and the local utility interconnection substation design and construction at two significant substations. Additional changes were required at another collector substation to facilitate the metering of a new wind farm and proper communication over the three-terminal line.
The collection system consists of five 34.5 kV feeder circuits connecting seven 3.6 MW and twenty-four 4.2 MW Vestas turbines to the collector substations. Two feeder circuits contributed 50.4 MW to one of the existing collector substations, and three circuits contributed the remaining 75.6 MW to a new collector substation.
The new 138/34.5 kV collector substation connects the new collector system to the transmission line. Major high-voltage equipment in the substation includes arresters, current transformers, potential transformers, a circuit breaker, a motor-operated disconnect switch, and a 138/34.5 kV, 55/73/92 MVA transformer.
Major equipment on the low-voltage side includes arresters, potential transformers, disconnect switches, circuit breakers, a station service transformer, and two 12 MVAR capacitor banks with 4.55 ohm outrush reactors. A control shelter design was provided to house the AC/DC systems and protection and control equipment. A 2.9-mile, 138 kV transmission line connects the collector substation to the existing generator lead line as a three-terminal line.
SGC was responsible for the collection system, transmission line, and substation civil, electrical, protection, and control designs. These included a 30% conceptual design, a 75% design for construction contractor bidding, an issue for construction design, and a final record drawing submittal. SGC completed all required studies, including reactive compensation, short circuit analysis, neutral ground reactor sizing, and underground cable sizing. SGC completed equipment specifications and FERC Form 8 documentation and provided construction support.
Powerful Results
SGC completed the project on time and under budget, with no significant issues with the final design. The client was highly satisfied with the final product, which is a testament to the quality of our work, and has continued to engage SGC for subsequent renewable projects. As part of this project, SGC introduced a new “Super Breaker” structure/bus design that simplifies bringing two collection circuits into one breaker. The client was impressed with the design and has since implemented it in multiple subsequent projects.
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