Active surge control of the compressor recycle system using feedback linearization

Abstract

Surge control in the centrifugal compressor recycle system is our main focus in this project. Surge is a term that is used for instability or oscillation through a compressor and is highly unwanted. The recycle system feeds compressed gas back to the intake via the recycle valve to ensure the safety of the system. A mathematical model of the recycle system which contains the compressor characteristic is extended and simulated in SIMULINK. The recycle system is proven to be stable as long as the slope of the compressor characteristic is negative. Two control techniques were used: The first is Surge Avoidance in which a PID controller keeps the operating point far from the unstable region and ensure the total safety of the system. The second method is Active Surge Control in which feedback linearization method is used to linearize the system then linear controllers were used to stabilize the system near the unstable region where efficiency is high.