Application of FIDF to the detection of unstable behaviors in compression systems

Issues concerning the detection of surge and rotating stall in a compression system are studied. It is observed that the plenum pressure rise and mass flow rate of a compression system exhibit abrupt change due to the appearance of surge or rotating stall, while those of it´s linearized model do not. With this observation, a linear-based fault identification filter (FIDF) design technique is proposed to detect these two instabilities. This is achieved by treating the difference between the output of the compression system and that of its linearized model at an unstalled operating point as a fault vector and then investigating the effect of the fault on the designed FIDF. Simulation results for Moore and Greitzer´s compression model (1986) are given to demonstrate the effectiveness of the proposed scheme. The study may provide a means of detecting the occurrence of unstable phenomena at the onset so that a corrective action can be made