Internal stability improvement of a natural gas centrifugal compressor system based on a new optimal output feedback controller using block transformation and grey wolf optimizer

Abstract

The improvement of the normal operating mode in gas compression systems performs an essential role in enhancing the process of pumping and transporting the natural gas inside and outside the border of Algeria. In this regards, this paper introduces a novel output-feedback controller design with optimal static matrix gains K, which uses to control and maintain its internal stability by reducing the surge phenomenon appeared clearly in the thermodynamical outputs parameters of the studied centrifugal compressor system. The feedback matrix K is calculated based on transforming the dynamical model using the similarity canonical block transformation (CBT) and determining the block own matrix F own by using the famous grey wolf optimizer (GWO). In given view of this study, a comparative investigation carried out, using different optimization methods, and two recent algorithms, to attest the advantages of the proposed controller. The obtained results confirm the internal stability robustness in the presence of disturbances and uncertainty of the system parameters up to 50%. The obtained norm of the proposed controller is ||K|| = 0.69, which guarantees a comfortable interval of internal stability in closed loop system (CLS), stability interval = [0.26, 0.60] with minimum possible energy. The three stability measures of compressor system is still ensured comparing with other algorithms [0.0171, 0.0012, 0.0276]. The proposed controller eliminates the fluctuation in the outputs of the studied system, the discharge pressure (P2) and the discharge temperature (T2), respectively, i.e. the disappearance of the surge phenomenon completely. We mention that the proposed controller is suitable and applicable only in the parametric and the transformable models.