Determining Maintenance Schedules for Thermal Production Units: The Kapila Model

Outages for maintenance work on thermal generation units are scheduled by means of an annual planning procedure. The importance of the choices made in managing the power pool and the considerable progress being made in the field of data processing have led Electricite de France (EDF) to develop and implement a new procedure. The KAPILA model described in this paper applies an heuristic approach based essentially on the following elements: -development of a relation of order for all units due for maintenance work, -assessment of yearly management costs measuring the economic incidence of maintenance for each unit, -taking into account the various technical constraints through penalty functions, evaluation of all possible maintenance solutions for each unit, -iteration of the algorithm. The KAPILA model, with its fine performance in machine time (1300 K-bytes of 8 bits, 1 minute on IBM 3033), is the model currently used by the Departments concerned with scheduling at EDF. Its implementation has allowed for the development of planning schedules from 1980 onwards and the management of planning deviations since this period. Since 1980, the KAPILA model has belonged to the SGEP (Systeme de Gestion Energétique Previsionnelle, i.e. Energy Management Planning System).