Scheduling Generator Outages to Minimise Financial Impact

Many papers have been written on short and medium term scheduling of hydro-electric generation on a river system so as to maximise operating profit. A related area of growing importance is the scheduling of generator maintenance outages to minimise their impact on the profit objective. Historically, the co-ordination of generator outages on a river system has been performed on a "manual" basis using "rules of thumb" without knowledge of the financial impact. Determining the exact financial impact of a historical outage is a complex task, the market equilibrium may be very different with and without the outage. For example, the market clearing price may change significantly and the resulting distribution of generation among market participants may be quite different. However, the financial impact of a set of outages can be approximated with sufficient accuracy to provide sensible data for decision making. A methodology to (i) cost a set of outages, and (ii) minimise their total cost is proposed. The total cost of a set of outages is adjusted by the timing of the outages, and a genetic algorithm is used to identify an improved solution. It is shown that the financial impact of a set of outages can be reduced given some freedom in outage timing.