Queensland

Queensland has very large deposits of high quality coal, both of steaming and coking types. The initial source for generation in the Brisbane area was from underground mines near Ipswich, and for the Rockhampton and Townsville areas from local mines. When the huge deposits in the Bowen Basin were identified and developed, most of the output was exported, as it still is. The advent of a large aluminium smelter to Gladstone (which already had a big alumina plant), and other industries nearby led to the decision to build Queensland's then largest coal-fired power station (1100 MW) there, and to interconnect it with the major network in the south. This was achieved in the late 1970s.

In 1984, generation began from an even larger steam station at Tarong (1400 MW) using coal from deposits in the Kingaroy area. This station, now completed, has four 350 MW units of remarkably compact design, so that they are arranged side by side, instead of the conventional in-line layout for large machines.

A significant development for electric power planning was the introduction in the 1980s of railway electrification, using 25 kV single phase at the normal 50 Hz supply frequency, initially for the Brisbane suburban railway network; much original work was performed to achieve satisfactory conditions on the power system. Electrification of the heavy haulage rail links from the Bowen coalfields to the export loading facilities is steadily progressing.

Two small hydro stations in the Far North Electricity Board area have been operating for over 20 years. The Wivenhoe 500 MW pumped storage station near Ipswich has already been mentioned; this project uses as lower storage a recently constructed reservoir for water supply and flood control, and an upper storage having only a few hours capacity at full load. A special feature of this station is the provision for operating under a very large range of lower reservoir levels; this, coupled with the limited capability of the relatively small power system to undertake electrical pump-starting and loading rates led to the adoption of a separate pump and turbine in tandem for each of the two 250 MW sets.

Several innovations were introduced by the South East Queensland Electricity Board, which supplies both the Brisbane and Gold Coast areas. A standard system of substation monitoring and remote control has been developed in-house, including automatic switching under prescribed conditions. The same Board has developed a new system of ring-main sub-stations for the city centres which preserves automatic backup of supplies with considerably fewer circuit breakers, and hence at lower cost.

Another very creditable pioneer effort in electrical design was made by the Capricornia Electricity Board, when first confronted by the severe demands upon a small system made by very large draglines at the open-cut coal mines. These machines used regenerative control to decelerate the major slewing and other motions, with the result that rapid changes from +20 to -20 MW were experienced. Voltage control at the power stations was grossly affected, and substantial design changes to the imported dragline circuits were effected.

Australian Academy of Technological Sciences and Engineering