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Black Rock Mine: Grid Integration Studies for Emergency Diesel Generation Plant

South Africa

Client:

Black Rock Mine (Asmang Mining Company)
PSD sub-contracted to Mega High Voltage (Main Contractor)

Project Status: Completed in 2008

Project Outline
PSD conducted the requisite studies for the integration of new emergency diesel generation plant at Black Rock Mine, located close to the town of Hotazel in the Northern Cape. The new plant comprised twelve 1.5MVA generating units.

Services to Client

•	Data collection and modeling of the mine electrical network
•	Load flow analysis for various operating and load conditions
•	Fault level studies: three-phase and unbalance fault conditions were examined
•	Load impact and motor starting studies

Project Detail
The study included:

•	Electrical studies for the connection of twelve 1.5MVA (combined rating is 18MVA) emergency diesel generators. The plant is connected to the Blackrock Mine 22kV electrical network via a high voltage cable system.
•	Plant and generator electrical data were collected and a complete model of the system was developed using the DigSilent simulation program.
•	An analysis of the mine load demand over a one year period was conducted. From this the mine daily and weekly load patterns could be discerned, and three distinct loading conditions were identified.
•	Load flow analysis was performed for the three representative load demand conditions and the MW and MVAr loadings on the generators and connecting cables were examined. Since the generators are required to supply the mine loads when the Eskom supply is down, the focus of the load flow analysis was under this ‘islanded’ mode of operation; however, the studies also considered parallel operation of the diesel generators and the Eskom supply – it was also necessary to examine this condition form a fault level impact perspective since it is the maximum fault level condition. The voltage performance of the mine plant was also investigated.
•	Since the fault levels are increased by the addition of the new diesel generators, a complete fault level study was done to ascertain the fault currents to be imposed on the system under short-circuit conditions. From the results of this study an evaluation could be done on whether the fault current withstand and/or breaking ratings of installed power equipment were adequate and to properly dimension any new power equipments to be installed.
•	Electrical load impact studies confirmed that the generators could remain stable and that voltage profiles were within acceptable limits during load switching operations, e.g. large motor starting or energisation of a block of load.

Photos taken on-site of the new diesel generators

mine
Black Rock Mine

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