Positive feedback stabilization of centrifugal compressor surge

Stable operation of axial and centrifugal compressors is limited towards low mass 1ows due to the occurrence of surge. The stable operating region can be enlarged by active control. In this study, we use a control valve which is fully closed in the desired operating point and only opens to stabilize the system around this point. As a result, only nonnegative control values are allowed, which complicates the controller design considerably. A novel positive feedback controller is proposed which is based on the pole placement technique. This controller has been successfully applied to a laboratory-scale gas turbine installation. Initial experiments show that the surge point mass 1ow can be reduced by at least 7%. Using this e:cient control strategy, stable operation in the desired operating point is maintained with small average control valve mass 1ow. ? 2001 Elsevier Science Ltd. All rights reserved.