Back-stepping sliding mode controller for active control of surge instability in Centrifugal Compressors

Surge is a dynamic instability in the compressor that is determined by limit cycle fluctuations and leads to large-amplitude distortions in flow rate and pressure. This mode is an unstable mode of operation of the compressor system that occurs in low flows and not only limits the performance and efficiency of the compressor, but also leads to damage to the compressor and accessories due to large thermal and mechanical loads. Today the use of active control methods to increase the operating range of the compressor has received much attention. Given the need for available surge controllers to be fully aware of the characteristic curve of the compressor system, presence of uncertainties and disturbances can deteriorate the performance of the controller. In this paper a finite time backstopping sliding mode controller is designed for overcome surge instability in the presence unknown uncertainties. An adaptive control rule is proposed which does not need knowledge of upper limit of disturbances or uncertainties. Lyoponov theory is used to stability analysis. The proposed controller can cover the effects of uncertainty and uncertainty on the compressor and throttle characteristics and unmodified dynamics, and in addition is resistant to time-varying disturbances in the flow and pressure applied to the system. The simulation results performed in MATLAB, indicate that the proposed regression controller, in addition to being robust, is able to ensure the stability of the system in the presence of turbulence and uncertainty.