EPC of a 230 GIS switchyard & two 230kV synchronous condensers
After the closure of a nuclear power station, a California utility needed to improve regional grid stability as it shifted to more distributed and intermittent renewable energy sources. The utility turned to Beta for the EPC of this complex project that involved upgrading an existing substation with two 225MVAR synchronous condensers and a 230kV gas-insulated switchgear (GIS) switchyard.
As part of this project's interconnection, Beta installed six new circuits of 230kV underground cable and reconfigured four 230kV overhead circuits at the substation. During early site development investigations, unknown underground 12kV circuits were discovered that conflicted with the project design. The solution required design changes to reroute the underground 12kV duct packages as well as substantial changes to the site development engineering for the project. Throughout the project, Beta worked with the city to obtain permits and submit related plans, including grading and building permits, an erosion control plan and permit, and landscape and irrigation plans and permits.
When inclement weather delayed the civil site development and construction of the GIS foundation, we recovered lost time by shifting our approach to the GIS construction. We performed part of the GIS installation in a neighboring warehouse and shipped pre-assembled modules to the site for installation. Once the GIS modules arrived on site, Beta’s contractors worked swing shifts to make up the schedule delays. This effort enabled us to complete the project on time.
Building the GIS system at the same time as the synchronous condensers on a small site required extensive coordination with multiple subcontractors. At the peak of construction, up to 125 workers were on site, performing work for different subcontractors using various pieces of heavy construction equipment. Beta construction management held weekly coordination meetings with prime subcontractors and quickly resolved conflicts as they occurred. Beta and its subcontractor team discussed and resolved potential safety issues ahead of each round of construction activities.
Scheduling transmission line outages to facilitate overhead and underground termination, testing and cutover activities also required extensive coordination. We hit the construction milestones for the scheduled outages thanks to long-range pre-planning with our utility customer as well as careful coordination with our subcontractors.
The massive 200-ton synchronous condensers, which came online in 2017, are helping to maintain voltage stability by controlling sudden increases and decreases in power from renewable generating sources. By working together to overcome complex civil and electrical engineering challenges, we helped the utility achieve its goal of providing its customers with added reliability.
• 230/69kV GIS switchyard
• Inclement weather
• Two 230kV synchronous condensers
• Small urban site
• Discovery of underground 12kV circuits required design solution