Bus Systems - Future Expansion
Many of the same challenges presented by a retrofit project are also encountered when expanding existing stations. There are various interfaces to be designed and restrictive outages schedules that must be adhered to.
When proposing long term extensions to existing substations, there are many factors that must be considered. These include increased system ratings, control and operating procedures and physical space limitations. CGIT Systems (AZZ High Voltage Bus Systems) can assist in developing a solution that addresses all of these issues.
Project Profile: Claireville Transmission Station (Ontario, Canada)
Gas-insulated substations often allow only unidirectional reductions in yard dimensions due to the space needed for incoming lines. At the Claireville Transmission Station, Hydro One reduced yard footprint in all directions with the “spaghetti junction” arrangement of CGIT bus circuits.
A conventional station would require approximately two hundred acres of land. However, the use of gas insulated switchgear and CGIT bus reduced the space requirement by 80 percent.
Since commissioning, the Claireville station has undergone several phases of expansion. The station consists of multiple circuits of CGIT bus arranged to untangle dozens of line exit circuits and feed twenty-six 550kV and fifty-two 250kV GIS circuit breakers. The GIS is housed in an elevated switchgear building with CGIT bus exiting through the floor. Incoming lines enter the station along power corridors from all directions. CGIT Systems, in conjunction with project partners, added the following equipment to increase switching capacity at Claireville.
- One bay of 250ikV GIS and three 250kV, 4000A CGIT line exit circuits
- One bay of 550kV GIS and three 550kV, 4000A, 1800kV BIL CGIT line exit circuits
- Three 550kV, 1800kV BIL CGIT bus sircuits connecting to existing GIS
- Four circuits of 250kV, 4000A CGIT bus interfacing to existing 230kV, 3000A CGIT bus
Over 4000 meters of CGIT bus were supplied to the Claireville stations. Extensive use of CAD was required to ensure that the new system would not interfere with access platforms, civil foundations and existing equipment above and below grade.
Additional design parameters considered installation requirements, including: clearance for welded installation of CGIT bus sections, personnel access and installation sequencing to accommodate outage schedules.