The global imperative to decarbonise power production is forcing power networks serving mines to evolve rapidly. Both utilities and private mine networks are switching from conventional fossil-fuel thermal plants to renewable energy, usually in the form of intermittent wind and solar power.
This has resulted in a dramatic reduction in spinning inertia, otherwise known as kinetic reserve. Inertia is vital to resisting sudden changes, such as when a generator trips offline, so that the grid frequency remains within tightly controlled limits. It is rather like a car’s shock absorbers smoothing out a sudden bump in the road to keep it safely on course.
As shown in the above image, power quality problems can impact a number of different areas in a mine. Starting with the incoming grid connection that can be fed by a weak network. This can result in problems such as voltage sags, peaks and fluctuations, as well as variation of the fault level. These can be addressed by installation of an Synchronous Condenser (SC).
An SC is a synchronous machine, but it is not a motor since it does not drive anything. Neither is it a generator, as there is no prime mover. However, it is very similar to a generator in its design and behaviour and produces reactive power.
The machine is usually water cooled, as this is one of the most effective ways to dissipate the heat losses and it is designed to be used both indoors and outdoors in different ambient conditions. However, other cooling options, such as air-to-air cooling, are also possible.
Its brushless design is particularly important for reliability in the dirty and dusty conditions found in the mining industry.
The Drive for Decarbonization Creates New Challenges
The drive for decarbonisation is delivering major benefits for all types of power networks, as the world strives for a sustainable future. However, it is creating new challenges due to the loss of inertia as thermal power plants are decommissioned in favour of renewable energy schemes. This is especially true of remote mining operations that, in many cases, are already served by weak power networks.
Syonchronous Condensers are set to play an increasingly important role in these networks by restoring rotating inertia to provide stability, strengthening the network with added short circuit capacity and providing dynamic MVArs to supportvoltage control.
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