| Summary: | South Africa's national power utility, Eskom, initiated a Demand Side Management
(DSM) drive to help alleviate the electricity supply shortage experienced in South
Africa. The focus of this study is on a load-shifting intervention applied in the
mining environment. Load shifting is an appealing way of reducing peak demand.
The mining sector is one of the largest consumers of electricity in South Africa. The
application of DSM in this sector has the potential of yielding significant electrical
load shifting. Firstly, this helps Eskom because they are struggling to keep up their
supply. Secondly, the mines also benefit because electrical load is shifted to less
expensive off-peak times. Electricity cost as a percentage of the total cost of mining
output is bound to increase considerably the next few years.
An investigation was conducted into the potential ofperforming load shifting on complex
underground rock winders the mining sector. This involved a thorough study on
existing load-shifting applications on rock winder systems. Simulations were performed
on rock winder systems in their different configurations at deep-level gold mines. The
simulation results indicated that there was potential for the application ofload shifting. Tau Tona was selected as a case study. This decision was based on simulations to establish which of the initially identified mines would be the best candidate for load shifting. Tau Tona has a complex underground rock winder system. Multiple rock winders feeding each other are used in a cascaded configuration. A potential
load shifting target of 3' MW in the evening peak period was determined by means of
simulation.
The rock winder system was sequentially automated. An average evening peak
demand load shift of 1 MW (or 4,2 MWh) was achieved. This translates to an
average annual cost saving of R 240 000. If the load-shifting target of 3 MW could
be obtained, the annual cost savings would increase by 30% to R 343 000.
A study was also conducted on the feasibility of implementing maximum demand
monitoring and control. Rock winders could be used in future to prevent the mines
from exceeding their maximum demand. This is because rock winders consume very
large amounts of electricity and can be stopped and restarted very quickly.
Huge financial obligations can be prevented by making sure that the mines do not
exceed their negotiated maximum demand. The necessary - and costly infrastructure
to do this could not be procured during this study. === Thesis (M.Ing. (Electrical Engineering))--North-West University, Potchefstroom Campus, 2010.
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