Caught in the icy grip of winter, the last thing South Africans want is load shedding. But as we've seen over the last few years, Eskom can announce load shedding at any time and throw our lives into disarray.
One way to prevent or minimise the risk of load shedding is to have a proper and adequate schedule for the maintenance of power generating units in place, says Dr Jancke Eygelaar a business intelligence consultant at Decision Inc. in Midrand, Johannesburg. He recently obtained his doctorate in Industrial Engineering at Stellenbosch University.
According Eygelaar, the ability of a power utility like Eskom to satisfy energy demand can be inﬂuenced signiﬁcantly by unexpected breakdowns of power generating units whose reliability (whether they may fail or not) may be compromised given how long the utility has been in operation.
He adds that the eﬀective scheduling of this planned maintenance of power generating units is a considerable challenge for any power utility.
“In most cases, unexpected failures are also much more expensive to repair than taking planned preventative maintenance action. Maintenance of ageing power generating units is, however, often neglected due to high energy demand and low system capacity, as seen in the case of Eskom."
Eygelaar says his study took into account the demand of a system, as well as other factors, and aimed to schedule preventative maintenance on generators which are operating at a low reliability. These generators have a high probability of failing which may cause load shedding to be implemented as the demand cannot be met.
As part of his doctoral research, Eygelaar put forward two new scheduling criteria that could help optimise the maintenance scheduling. The first criterion involves minimising the probability that a power generating unit will fail, while the second involves maximising expected energy production during a scheduling window.
He analysed the effectiveness of these two criteria by applying them to a real-world case study based on the Eskom power system.
“Both of these criteria can improve the reliability of a power system. By taking into account the reliability of the generators when scheduling preventative maintenance, load shedding and power outages can possible be avoided completely."
“The proposed scheduling criteria are expected to facilitate reduction of the chance of load shedding having to be implemented by scheduling planned maintenance in pursuit of avoiding power generating units failures — events that may cause sudden drops in available energy capacity."
In addition to the scheduling criteria, Eygelaar developed a computerised decision support system that can provide an operations manager with good planned maintenance schedules for power generating units based on the two scheduling criteria. A decision support system helps the user to make informative decisions and to identify and solve complex problems.
Eygelaar says once the required input data (e.g. demand and generator unit specifications, manpower requirements, etc.) is prepared in the speciﬁed format and uploaded to the database, the support system can be used to recommend good generator maintenance schedules for the specific power system. This is done through a graphical user interface that allows the operator to provide the support system with the required input for the problem at hand and then to obtain the relevant output.
“The decision support system will provide employees with information regarding available capacity of the system and the demand of the system over the scheduling window, as well as information on the manpower required to perform maintenance over the duration of the maintenance window."
Eygelaar says power utilities that have constrained systems and do not always know which generators to maintain may benefit from his research. They may use the findings to identify key generators that may fail in the near future and may cause the demand of the system not to be met during that time, he adds.
- Main photo: Power station (Credit: Pixabay).
- Photo 1: Dr Jancke Eygelaar at his graduation. Photographer: Anton Jordaan.
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Dr Jancke Eygelaar
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