Safety-Level Aware Bin-Packing Heuristic for Automatic Assignment of Power Plants Control Functions

Finding a suitable set of controllers to which a large set of control functions with different safety levels can be assigned, while minimizing cost, is a significant task during the design of the operational control system of a critical process, such as a power plant. This task is currently performed by experts and extremely time-consuming, which explains why its automation is a real concern. This paper shows first that the above-mentioned assignment problem can be identified as a multiple-choice vector bin packing (BP) with conflicts problem, a combination of different variants of the well-known 1-D BP problem. Such a problem is known to be strongly NP-hard and exact techniques to solve it on large-sized examples are too time and/or space-consuming because of the combinatorial explosion. To solve this problem in polynomial time, this paper proposes a fast heuristic based on a first-fit decreasing approach. Two strategies to perform this heuristic and several criteria to rank the functions before assignment are defined. These strategies and criteria are then compared on the basis of numerous experiments. These experiments show that the proposed heuristic scales well and provides results that are very close to optimum; the difference in the worst case is less than 1%.