Leinster, which began production in 1979, is located 645 kilometres north east of Perth. Operations include the Perseverance underground mine, satellite deposits, and a nickel concentrator and dryer. Leinster can produce 40 000 – 45 000 tonnes of nickel in concentrate a year.
The Leinster Nickel Operation is central to BHP Billitons’ Nickel West's nickel business, with Leinster blending 75 per cent of the company's nickel in concentrate to ensure a quality feed is provided to the Kalgoorlie Smelter.
Original power supply at Leinster was gas base-load with the addition of diesel based generation for cyclic loads such as the 1160m vertical depth, steel guide, 2 x double-drum winders (single clutch, thyristor driven, 10MW skip, 3MW cage) at the Perseverance underground mine.
The objective of Powercorp and BHP Billiton was to use the PowerStore to reduce the cyclic load which would mean large savings due to reduction of diesel generation run-time. Since the project commenced the diesel based generation has been replaced by the installation of a TM2500 gas turbine for the swinging load.
With the current power supply now normally gas based, the winder operation causes frequency excursions. Along with that the gas turbines are less efficient in transient/cyclic operations and the cyclic load operation at Leinster Nickel Operation causes large increase in maintenance consumables on the gas turbines.
Since Powercorp commenced installation of the PowerStore unit at Leinster in late January 2006, the following goals have been achieved.
• Installation commenced late January 2006
• On-line March 2006
• Full +/-1MW June 2006
• No change to winder operation or components
• Installation of power meter into 11kVac distribution metering panel to monitor winder activity
• No additional down-time on winder
Installation at Leinster
The illustration to the left shows how the PowerStore is connected to the Leinster network coupling on 11kVac switchboard and the power monitoring module installed in monitoring section of the 11kV cubicle. The winder is DC machine and uses 12 pulse converters to create DC. It also requires Var compensation and generates harmonics. The PowerStore is located outside of switch room in is custom built container that is weather-proof and also has self-contained cooling.
The PowerStore operates at Leinster by exporting 1MW at 1MW from the top of the winder demand which causes the generation to see a “flat top” on demand, 1MW from the peak. It also imports 1MW at 1MW from the bottom of the winder regeneration that causes the generation to see a “flat bottom” on regeneration.
Results At Leinster
With the PowerStore operating the following results have been seen at Leinster. There has been a Peak Power Reduction with the power demand swing reduced by up to 2MW, the peak demand has been reduced by 1MW and network frequency disturbances have been reduced. The graph below highlights what is happening on the Leinster network when the PowerStore unit is off and then when it is turned on.
During the first four winder cycles (bark blue) the PowerStore (cyan) is offline and over this period the power on the 132kV export line from Transalta (yellow) is swinging from a peak of around 8MW down to roughly 3MW. When the PowerStore is back online for cycles five and six it is evident that the swing on the 132kV line has been reduced as highlighted by the less pronounced spikes at the top and bottom of each cycle.
Along with above benefits the PowerStore has given BHP Billiton Advanced High-Speed Data Recording. This high speed data recording has allowed the examination of the winder operation during “unusual” events – prior, during and after an event. It also allows BHP Billiton to examine power system frequency and voltage.
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