A compression system includes a compressor with adjustable inlet guide vanes (IGVs) and variable stator vanes (VSVs) that are adjustable independently of each other. IGV and VSV control units produce respective IGV and VSV reference commands responsive to respective first and second inputs that may be responsive to measured properties of the compression system. The second input may be provided by a model of the compressor or of the compression system responsive to measured properties. The second input may particularly be an estimate of a property not directly observable, such as stall margin or efficiency.