Increasing energy flexibility of manufacturing systems through flexible compressed air generation

A continuing increase in energy supply from variable renewable energy (VRE) sources requires new strategies to match energy supply and demand. Demand response (DR) strategies focus on flexibilizing energy demand. In this context, manufacturing systems can be designed and controlled to achieve a better fit between energy demand and volatile supply. To maximize energy flexibility, not only manufacturing processes but also auxiliary systems such as compressed air (CA) supply offer opportunities for DR actions. Nonetheless, dynamic behavior and dependencies between manufacturing processes, auxiliary services and resulting overall energy demand requires an integrated approach. This paper presents a method to control production systems and CA supply to increase energy flexibility while maintaining manufacturing system throughput and considering dynamic system dependencies. A production system with several processes, buffers and CA supply system is modeled and simulated in a mixed continuous-time and discrete-event environment. Energy control strategies are implemented and their effectiveness is evaluated. A case study is used to demonstrate that VRE integration can be improved through process and CA supply control without compromising throughput. A focus is set on CA supply and its influence on energy flexibility: the effect of increased CA system volume and additional compressor capacity is investigated. (C) 2015 The Authors. Published by Elsevier B.V.