ABSTRACT The present paper considers the suppression of surge instability in compression systems by means of active control strategies based on a high-gain approach. A proper sensor-actuator pair and a proportional controller are selected which, in theory, guarantee system stabilization in any operating condition for a sufficiently high value of the gain. Furthermore, an adaptive control strategy is introduced which allows the system to automatically detect a suitable value of the gain needed for stabilization, without requiring any knowledge of the compressor and plant characteristics. The control device is employed to suppress surge in an industrial compression system based on a fourstage centrifugal blower. An extensive experimental investigation has been performed in order to test the control effectiveness in various operating points on the stalled branch of the compressor characteristic and at different compressor speeds. On one hand the experimental results confirm the good performance of the proposed control strategy, on the other they show some inherent difficulties in stabilizing the system at high compressor speeds due to the measurement disturbances and to the limited operation speed of the actuator. INTRODUCTION Surge instability strongly limits the operating range and the performance of compression systems. As it is known, surge occurs at low compressor flow rates, causing highly undesirable oscillations in the system. By means of a control system it is possible to attenuate or eliminate the phenomenon, so allowing the plant to operate in naturally unstable points. In particular, the active control techniques are based on the use of a suitable sensor/actuator pair in a closed loop control device. The control is effective if the actuation is capable of dissipating the unsteady energy surplus introduced in the system by the compressor when it operates in the stalled region. In the last decade much work has been devoted to the study of active suppression of compressor surge. A large part of the literature i
