Energy-Saving Control in Multistage Production Systems Using a State-Based Method

Manufacturers are pursuing energy-efficient production in response to the fluctuating energy price, growing global competition, rigorous international laws, and severe environmental crisis. This article proposes to boost the energy efficiency of production systems by controlling the production. It extends the existing energy-saving control research by presenting integrated modeling, analyzing, and controlling approaches. The work starts from the modeling of the production systems and establishes an analytical model to systematically quantify the production loss resulted from energy-saving control and the various disruptions. A dynamic control algorithm is proposed to reduce energy consumption and maintain desirable productivity. Simulation studies are utilized to demonstrate the application of the proposed method and verify its effectiveness. Note to Practitioners—The previous research indicates that it is possible to strategically turn off stations during production for energy saving. However, production systems are complex dynamic systems consisting of interconnected stations and supporting subsystems. Similar to station random failures, turning off stations for energy saving can severely jeopardize the production, and deviate the production from the desired target. Therefore, a quantitative method is established to calculate the production loss resulted from the energy-saving control and disruptions. The method is important to understand the real control cost. Based on the analysis, a dynamic control algorithm is formulated to balance the achieved control benefit and the production loss. It provides plant managers a useful tool to make energy-saving control decisions with a thorough understanding of production system dynamics. The presented research is established for serial batch production systems. The examples of batch stations include the refrigerator foaming equipment in refrigerator assembly lines and the vacuum oven in battery assembly lines. The model cannot be directly applied in serial-parallel production systems.