Modelling of multistage centrifugal compressor

Surge is an unstable operating mode of the centrifugal compressor that occurs at mass flows below the surge line, and it results in considerable loss of performance and efficiency of the compression system. Modelling of the centrifugal compressor is the basis of getting the surge line and carrying out anti-surge control. Based on fluid mechanics, mass and energy conservation principles, the mechanism model of a CCPP gas system´s multistage centrifugal compressor with three single-stage compressors in series is established. The parameter estimation problem of the model is transformed into an optimization problem, and an adaptive differential evolution algorithm is used to decide the unknown parameters in the model. Model validation results show that the model can describe pressure ratio´s varying trend of the multistage compressor. It lays the foundation for calculating the surge line and is of certain value to compression system´s anti-surge control.