Four Methods for Maintenance Scheduling

We had a problem to be solved: the thermal generator maintenance scheduling problem [Yam82]. We wanted to look at stochastic methods and this paper will present three methods and discuss the pros and cons of each. We will also present evidence that strongly suggests that for this problem, tabu search was the most effective and efficient technique. The problem is concerned with scheduling essential maintenance over a fixed length repeated planning horizon for a number of thermal generator units while minimising the maintenance costs and providing enough capacity to meet the anticipated demand. Traditional optimisation based techniques such as integer programming [DM75], dynamic programming [ZQ75, YSY83] and branch-and-bound [EDM76] have been proposed to solve this problem. For small problems these methods give an exact optimal solution. However, as the size of the problem increases, the size of the solution space increases exponentially and hence also the running time of these algorithm..