Energy-Aware Integrated Proactive Maintenance Planning and Production Scheduling

TL;DR

This paper presents a hierarchical control framework that optimizes proactive maintenance and production scheduling to reduce energy costs in manufacturing, considering machine degradation and real-time energy prices.

Contribution

It introduces a bi-level control approach integrating maintenance planning with production scheduling under dynamic energy pricing, addressing the trade-off between maintenance downtime and energy savings.

Findings

Reduces energy costs by strategic scheduling of maintenance and production.

Effectively balances maintenance downtime with production targets.

Demonstrates improved operational efficiency in a battery assembly case study.

Abstract

Demand-side energy management, such as the real-time pricing (RTP) program, offers manufacturers opportunities to reduce energy costs by shifting production to low-price hours. However, this strategy is challenging to implement when machine degradation is considered, as degraded machines have decreased processing capacity and increased energy consumption. Proactive maintenance (PM) can restore machine health but requires production downtime, creating a challenging trade-off: scheduling maintenance during low-price periods sacrifices energy savings opportunities, while deferring maintenance leads to capacity losses and higher energy consumption. To address this challenge, we propose a hierarchical bi-level control framework that jointly optimizes PM planning and runtime production scheduling, considering the machine degradation. A higher-level optimization, with the lower-level model predictive control (MPC) embedded as a sub-problem, determines PM plans that minimize total operational costs under day-ahead RTP. At runtime, the lower-level MPC executes closed-loop production scheduling to minimize energy costs under realized RTP, meeting delivery targets. Simulation results from a lithium-ion battery pack assembly line case study demonstrate that the framework strategically shifts PM away from bottlenecks and high-price hours, meeting daily production targets while reducing energy costs.