South African state-owned power utility Eskom, offers ESI Africa insight into its utility maintenance plans.
Eskom always endeavours to run the power system without load shedding, which is used as a last resort to balance supply and demand, to prevent blackouts.
Load shedding has not been required since 9 August 2015. This excellent run without load shedding has been influenced primarily by the unseasonably warm weather, particularly from the second half of August, which resulted in the demand being approximately 2,000MW lower than originally forecast for this period.
The demand is also influenced by a number of demand-side levers, such as load reductions by large power users.
The number of megawatts available to meet the demand is determined by plant availability. This is measured as percentage of plant that is available to produce electricity once the planned and unplanned maintenance has been taken into account.
Plant availability increased by over 3% from April to August 2015. This is the equivalent of adding two large coal-fired units to the grid. During this period, the unplanned unavailability, where the plant is shut down at short notice for repair work, has improved and remains a key focus area for Eskom. This decrease in breakdown maintenance is indicative of the effectiveness of maintenance carried out.
Planned maintenance is performed for a number of reasons:
- For safety and statutory requirements (typically inspections of the turbine and pressure vessels)
- For risk reasons (where components or systems are expected to fail if not repaired)
- For periodic philosophy maintenance (much like the regular services for your car)
When scheduling planned outages, Eskom prioritises safety and statutory, followed by risk maintenance. This safeguards our people and plant, and fixes problems before they occur, thus reducing unplanned breakdowns, which take longer and are more expensive to repair.
In addition, an improved visualisation tool for outage scheduling has been developed, which has helped to optimise the outage schedule and thus better manage the risk of load shedding whilst still performing all essential maintenance.
Going forward, Eskom continues to enhance and optimise its processes, policies and procedures with regards to operating and maintenance. The maintenance strategies are being reviewed in line with industry best practices; the Institute of Nuclear Power Operations and EPRI.
This ensures that the right maintenance is done at the right time. Eskom is also busy with a project to expand its existing remote monitoring and diagnostic centre (RMDC), which enables predictive fault finding and reduces the potential of unit trips.
Eskom would like to assure the public that it will continue to expend every effort to minimise or avoid load shedding, whilst continuing to execute the maintenance that is required to assure the sustainability of its generating fleet.
The utility would like to thank both its key customers and the public for reducing their consumption and thus assisting Eskom in minimising and lately avoiding load shedding.