Gas–steam–electricity coupling optimal scheduling of iron and steel enterprises considering equipment maintenance plan

In the iron and steel production process, significant fluctuations in the consumption and production of energy media occur during equipment maintenance, causing difficulties in the equipment operation. Therefore, it is required to reconcile the conflict between global scheduling optimisation and to fulfil the need for stable equipment operation during maintenance. This study integrates heuristic rules into the model with the objective of minimising both system energy operation costs (EOCs) and equipment fluctuation expenses. A multi-period optimal scheduling model for the energy system in steel enterprises was developed herein. Results demonstrate that, under standard production conditions, optimising EOCs (Scheme A) and multi-objective optimisation (Scheme B) both fully utilise the storage function of the gasholder. After optimisation, EOCs are reduced by 9.07% and 8.67%, respectively, with only marginal changes in equipment fuel fluctuation costs. Furthermore, during the maintenance of blast furnace No. 1, although Scheme B results in a 0.26% higher EOC than Scheme A, equipment fuel fluctuation costs are reduced by 83.3%, significantly enhancing the equipment operational stability. This not only optimises energy utilisation, but also mitigates operational challenges, aligning more closely with scheduling requirements. Thus, under abnormal operating conditions, Scheme B leads to notable improvements in both system EOCs and equipment fuel fluctuations. Further analysis suggests that iron and steel enterprises can strategically schedule equipment maintenance during periods of high electricity prices to effectively reduce overall system energy costs.