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

Mohamed Benazouz (1) , Jean-Marc Faure (1)

1 LURPA - Laboratoire Universitaire de Recherche en Production Automatisée

—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, like 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 assignment problem can be identified as a Multiple-Choice Vector Bin-Packing with Conflicts problem, a combination of different variants of the well-known one-dimensional bin-packing 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 article proposes a fast heuristic based on a FFD (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%. Note to Practitioners: Abstract—Designing the operational control architecture of a critical process, like a power plant, is an extremely time-consuming task that requires in particular to find a suitable and minimum-cost set of industrial controllers to which the numerous control functions can be assigned and thereafter implemented. This design task is currently performed by experts who imagine, evaluate and compare different solutions. Hence, several iterations of the assignment process are necessary during this task. The practical aim of this research is to automate this process to facilitate and speed up architecture design. This work has been made in the frame of a cooperative research project with a company which designs and implements control systems of power plants. Nevertheless, the generic results that are presented in this article can be used for other critical processes (oil, chemical processes, water management) where a large number of control functions with different impacts on safety is to be assigned to controllers, because the proposed heuristic scales well.

Mots clés: Index Terms—Dependable control; distributed systems; critical systems; vector bin-packing; multiple-choice

Domaines: Sciences de l'ingénieur [physics]

Mohamed Benazouz, Jean-Marc Faure. Safety-Level Aware Bin-Packing Heuristic for Automatic Assignment of Power Plants Control Functions. IEEE Transactions on Automation Science and Engineering, 2017, pp.1 - 11. ⟨10.1109/TASE.2017.2654423⟩. ⟨hal-01472162⟩