Analysis and remedies for torsional oscillations in rotating machinery

In the context of operation of rotating machinery vibrations are inevitable. Consequences of long-term operation under cyclic loads are often catastrophic, as the fatigue stress of machinery elements may lead to breakdowns. It is well known that the level of vibrations should be minimised either by passive design of the system or by active damping efforts. The work presented in this paper is motivated by an analysis of the problem observed at a gas compression industrial plant where observed anomalies are believed to be a common problem within the industry. The torsional vibrations observed in the compressor unit data, collected with DriveMonitor™, are subject of investigations. Such oscillations may always originate from process disturbances, however in the considered industrial case study vibrations are caused by mechanical resonance. To investigate the system behaviour interaction between the variable speed drive and mechanical system are looked into on the laboratory scale test rig. Investigations carried out there provide a valuable insight into a system dynamics. A justification of the observed signal features through physical analysis of the system is also given. The active damping of oscillations is also implemented on the laboratory hardware. The subsequent stages required during hardware implementation include data acquisition, system identification, analysis and active damper implementation. The excellent results confirm effectiveness of the implemented methodology.