High Voltage Bus Vertical Installation

Hydroelectric generating stations often require transmission of power over large vertical distances. Transmitting power at transmission voltages rather than generation voltage, is more economical.

Tunnels and vertical shafts

Transmitting power at transmission voltages often means the step-up transformers in hydroelectric vertical shaft applications are located near the generator, with the transmission system accessible at higher elevations.

The utilization of Avail’s High Voltage Bus Vertical Installation offers the following advantages relative to conventional technologies:

  • SF6 bus is enclosed and grounded. Therefore, clearances can be smaller, reducing the required shaft size. Additionally, dead-front construction eliminates high-voltage safety hazards.
  • SF6 is an inert gas and will not burn. Therefore, the risk of fire is mitigated.
  • Since SF6 is a gas, the pressure head is very low; typically about 10psi per 1000 feet of vertical head.
  • The design of SF6 bus enclosures poses little risk of stretching or mechanical damage. Since the joints offer the same mechanical strength as the balance of the bus system, no elaborate support methods are required.
  • The Avail High Voltage Bus System is designed and tested for a reliable operating life of 50 years.

Project Profile: Revelstoke Hydroelectric Project, British Columbia, Canada

An example of Avail’s high voltage bus vertical installation in hydroelectric projects is British Columbia Hydro’s Revelstoke Project. This plant included gas insulated switchgear in the underground powerhouse and connection circuits installed in an inclined tunnel to a gas insulated substation where the output of the facility connects to the transmission grid. It was determined that Avail provided the best solution for the connections between gas insulated switchgear substations.

Within the Revelstoke powerhouse, there are gas insulated breaker/grounding switch sets at each GSU transformer output, and a dual set of 500kV GIS connecting the generator transformers output into two main feeder circuits. At the substation building end, another set of 500kV GIS modules connects the feeders to the outgoing overhead lines; a separate 230kV GIS receives incoming power for internal plant service.

Avail High Voltage Bus vertical installation is a success

The high current rating of Avail bus, combined with the switching configuration, enables the full output of the power plant to be transmitted through either one of the two feeder circuits. This provides 100 percent redundancy for plant operation. This redundancy could not be achieved using conventional cable systems. Avail Bus Systems allowed a compact installation along the walls of the tunnel, and because of its fully grounded enclosure, it permitted the use of the tunnel as the main access route to the powerhouse.

Another Avail bus circuit, located outside the substation building, connects the incoming 230kV transmission lines to the 230kV GIS substations.

To learn more about our offerings, visit Avail Bus Systems and Avail Bus Services, or follow us on LinkedIn.

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