Piston-actuated active surge control of centrifugal compressor including integral action

An improvement in control performance of piston-actuated active surge control for centrifugal compressor by using integral action is presented in this paper. The active surge control is designed by using linear quadratic requlator (LQR) method based on the linearized system around the operating point. Simulation results show the active controller is able to stabilize the surge but not able to reach the desired operating point. The reason for this is the piston drift during surge stabilization. The surge control system is then enhanced by including integral action for counter acting the drift. Simulation results show the enhanced system is performing well in stabilizing surge without piston drift and reaching the desired operating point, but the piston position has non zero stationary value. One more integral is applied to the system to bring the piston position back to the origin. Applying double integrals action also results less required piston stroke for the surge stabilization.