Improving energy management of electrically driven air compressors through real-time scheduling techniques

This paper presents a control method for a structured compressed air network, fed by a single fixed speed, electrically driven, compressor. A set of suitably controlled valves intercept air at the desired pressure level. The overall system efficiency improves and a reduction in the pressure dynamics is obtained. The target is achieved by applying real-time scheduling techniques to the management of air compression, seen as an energy service. The system and its dynamics are modeled as a Real-Time Physical System (RTPS), i.e., in terms of real-time parameters and constraints. This modeling approach allows the use of a real-time scheduling algorithm to generate the sequence of opening/closing actions. The control action is applied to the activation/deactivation of valves, delivering air to networks operating at different pressure levels. The outcome is the reduction of energy consumption by centralizing the air production and by properly manage the feeding of each pneumatic network. Several smaller compressors are replaced by one single bigger fixed speed compressor, having a better efficiency, while guaranteeing the desired service level to the end-users. A theoretical case study with three different networks, operating at roughly 7, 8 and 13 bar gauge is proposed and energy savings of 6% are achieved. Limits and extensions in the application of the theory, as well as future developments, are also identified.