Optimization and Control of Recycle Compression systems using PSO algorithm and PID controller

Abstract

Centrifugal compressors are the most satisfactory and the widely used in oil and gas companies, however, stable operation of this type of compressors is limited towards low mass flows by the occurrence of an aerodynamic compressor flow instability called the surge. This instability can lead to severe damage of the machine due to large mechanical and thermal loads in the blading, and restrict its performance and efficiency. In this thesis, a method of controlling the stability of a compression system and optimising its efficiency was presented and developed. Before going through the controlling and the optimising parts of the work, elementary definitions of compressors and surge have been presented. A mathematical model of Greitzer has been used to model our compression system and, using Matlab Simulink, the compressor’s model has been built up. As most industries nowadays are using the PID controller to ensure the stability of compression systems, the classical solution (the use of the PID controller) to eliminate surge has been explored. To increase the output discharge pressure of the compressor, thus increase the compressor’s efficiency, the particle swarm-optimising algorithm (PSO) is introduced along with the PID controller to the Simulink model. The PID did stabilise the system in a short time. However, when using it, the compressor’s pressure ratio was quite low. This was overcame once using the PSO, where an acceptable pressure ratio was obtained.