State Observer Design for Active Surge Control in Centrifugal Compressors

A state observer for the delays found in mass flow and pressure rise measurements in active surge control of centrifugal compressor is proposed in this work. The active surge controller have proved to be mathematically stable and shown to perform adequately. However, the surge control by drive torque actuation and close coupled valve, both will face a problem regard to time delay. First, a low order centrifugal compressor model is presented where the states are mass flow, pressure rise, speed of the spool and develop the compressor characteristics on the basis of energy transfer. Based on active surge control by close coupled valve simulation, the surge is initiated under the presence of time delays in either mass flow or pressure rise measurements. As a possible solution for the measurement delays, a state observer have been implemented and tested, but with limited success.