Trevallyn Power Station upgrade and modernisation
Client: Hydro Tasmania
Location: Tasmania, Australia
Upgrading and modernising a fifty-year-old hydropower station to improve reliability and availability, and to increase efficiency and generating capacity
The Trevallyn Power Station is a run-of-river hydropower station near Launceston, Tasmania, completed in 1955. By the time of this project it was fifty years old and in need of upgrade and modernisation. Entura participated in an alliance with Hydro Tasmania and Alstom to investigate and recommend optimal upgrade and modernisation options for the power station and headworks to increase reliability and availability, but also to explore cost-effective options for increasing energy generation and revenue through efficiency gains or upgrades.
The project included investigating the upgrade and refurbishment of the station’s turbines, generators, power delivery chain, control and auxiliary systems, conduit system and other civil infrastructure. Entura worked with Hydro Tasmania and Alstom to develop potential upgrade and modernisation options as well as their respective economic models. Station risk profiles were also developed for the next twenty years. An upgrade and modernisation scope was identified by filtering the options according to economic and risk evaluations.
Entura continued working in the alliance to implement the agreed scope of work. Turbine and generator modifications were designed and manufactured by Alstom Hydro in France and Switzerland. Power station auxiliaries and ancillaries modifications were designed by Entura and manufactured and installed by Alstom Power Services, including upgrades to the control and protections systems.
Particularly significant aspects of the work were water-lubricated hydrostatic turbine guide bearings, turbine draft tube modifications, turbine relief valve removal, generator rewind and upgrade, and replacement of generator rotating excitation systems with static excitation.
The upgrade and modernisation project was successful in increasing the capacity and efficiency of the turbines and generators, and increasing station revenue by making better use of existing water discharges and capturing excess water previously wasted during periods of high river flow. The power station’s life was extended and the plant’s reliability and availability improved, so the station will now operate for many more decades into the future.
The removal of the turbine relief valves eliminated a key operational and safety risk from the power station. The water-lubricated hydrostatic turbine bearings provided numerous benefits including simpler design, greater turbine efficiency, and less environmental and safety risks.
Two of the station’s generating units have been successfully upgraded and modernised. The other two units will be upgraded soon, aligning with planned generator rewind work.