scholarly journals Faults Identification and Corrective Actions in Rotating Machinery at Rated Speed

2006 ◽  
Vol 13 (4-5) ◽  
pp. 485-503 ◽  
Author(s):  
Nicolò Bachschmid ◽  
Paolo Pennacchi
Keyword(s):  
Frequency Domain ◽  
Rotating Machinery ◽  
Fault Identification ◽  
Operating Speed ◽  
Huge Amount ◽  
Rotor Systems ◽  
Rotating Speed ◽  
Normal Operating ◽  
Vibration Data ◽  
Model Based

Malfunction identification in rotor systems by means of a model based approach in the frequency domain during long lasting speed transients (coast-down procedures in large turbo-generators), where a huge amount of vibration data at different rotating speeds is usually collected, has proved to be very effective. This paper explores the possibility to adapt this method to the situation when the vibration data are available at one rotating speed only, which in real machines is generally the normal operating speed. It results that single speed fault identification can be successful, but does not allow to discriminate between different malfunctions that generate similar symptoms. Neverthless the identification results can be used to define corrective balancing masses.

scholarly journals Identification of Rub and Unbalance in 320 MW Turbogenerators

2003 ◽  
Vol 9 (2) ◽  
pp. 97-112 ◽  
Author(s):  
N. Bachschmid ◽  
P. Pennacchi ◽  
A. Vania ◽  
G. A. Zanetta ◽  
L. Gregori
Keyword(s):  
Power Plant ◽  
Frequency Domain ◽  
Theoretical Background ◽  
Fault Identification ◽  
Vibration Measurements ◽  
Rotating Speed ◽  
Model Based ◽  
First Case ◽  
Identification Technique ◽  
Fossil Power Plant

This article presents two experiences of applying a model-based fault-identification method to real machines. The first case presented is an unbalance identification in a 320 MW turbogenerator unit operating in a fossil power plant. In the second case, concerning a machine of the same size but from a different manufacturer, the turbine has been affected by a rub in the sealings. This time, the fault is modeled by local bows. The identification of the faults is performed by means of a model-based identification technique in a frequency domain, suitably modified in order to take into account simultaneous faults. The theoretical background of the applied method is briefly illustrated and some considerations are also presented about the best choice of the rotating speed set of the run-down transient to be used for an effective identification and about the appropriate weighting of vibration measurements at the machine bearings.

scholarly journals Identification of Rub and Unbalance in 320-MW Turbogenerators

2004 ◽  
Vol 10 (4) ◽  
pp. 265-281 ◽  
Author(s):  
N. Bachschmid ◽  
P. Pennacchi ◽  
A. Vania ◽  
G. A. Zanetta ◽  
L. Gregori
Keyword(s):  
Power Plant ◽  
Frequency Domain ◽  
Theoretical Background ◽  
Fault Identification ◽  
Rotating Speed ◽  
Model Based ◽  
First Case ◽  
Identification Technique ◽  
Lp Turbine ◽  
Fossil Power Plant

This article presents two experiences of application of a model-based fault identification method on real machines. The first case presented is an unbalance identification on a 320-MW turbogenerator unit operating in a fossil power plant. In the second case, concerning a machine of the same size but of a different manufacturer, the Low Pressure (LP) turbine was affected by a rub in the sealings and this time, the fault was modeled by local bows. The identification of the faults is performed by means of a model-based identification technique in frequency domain, suitably modified in order to take into account simultaneous faults. The theoretical background of the applied method is briefly illustrated and some considerations also are presented about the best choice of the rotating speed set of the run-down transient to be used for an effective identification and about the appropriate weighting of vibration measurements at the machine bearings.

scholarly journals Multiple Fault Identification Method in the Frequency Domain for Rotor Systems

2002 ◽  
Vol 9 (4-5) ◽  
pp. 203-215 ◽  
Author(s):  
Nicolò Bachschmid ◽  
Paolo Pennacchi
Keyword(s):  
Power Plant ◽  
Numerical Simulations ◽  
Frequency Domain ◽  
Rotor System ◽  
Fault Identification ◽  
Multiple Fault ◽  
Multiple Faults ◽  
Rotor Systems ◽  
Different Types ◽  
Types Of Faults

Fault identification in rotor systems has been studied by many authors, but the considered malfunction is one single fault only, generally an unbalance. Real machines can be affected by several different types of faults; moreover sometimes also two different faults may develop simultaneously. A model based method for identifying multiple faults acting simultaneously on a rotor system in the frequency domain is briefly described and its robustness with regards to measuring and modelling errors is evaluated, by means of numerical simulations performed on the models of two typical power plant machines: a steam turbogenerator and a gas turbogenerator.

scholarly journals Diagnosis and Model Based Identification of a Coupling Misalignment

2005 ◽  
Vol 12 (4) ◽  
pp. 293-308 ◽  
Author(s):  
P. Pennacchi ◽  
A. Vania
Keyword(s):  
Shape Analysis ◽  
Diagnostic Techniques ◽  
Rotating Machinery ◽  
Small Power ◽  
Diagnostic Strategies ◽  
Rotating Speed ◽  
Model Based ◽  
Fault Type ◽  
First Case

This paper is focused on the application of two different diagnostic techniques aimed to identify the most important faults in rotating machinery as well as on the simulation and prediction of the frequency response of rotating machines. The application of the two diagnostics techniques, the orbit shape analysis and the model based identification in the frequency domain, is described by means of an experimental case study that concerns a gas turbine-generator unit of a small power plant whose rotor-train was affected by an angular misalignment in a flexible coupling, caused by a wrong machine assembling. The fault type is identified by means of the orbit shape analysis, then the equivalent bending moments, which enable the shaft experimental vibrations to be simulated, have been identified using a model based identification method. These excitations have been used to predict the machine vibrations in a large rotating speed range inside which no monitoring data were available. To the best of the authors' knowledge, this is the first case of identification of coupling misalignment and prediction of the consequent machine behaviour in an actual size rotating machinery. The successful results obtained emphasise the usefulness of integrating common condition monitoring techniques with diagnostic strategies.

A Multiple Harmonic Open-Loop Controller for Hydro/Aerodynamic Force Measurements in Rotating Machinery Using Magnetic Bearings

2002 ◽  
Vol 124 (4) ◽  
pp. 827-834 ◽  
Author(s):  
D. O. Baun ◽  
E. H. Maslen ◽  
C. R. Knospe ◽  
R. D. Flack
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Open Loop ◽  
Rotating Machinery ◽  
Operating Conditions ◽  
Rotor Vibration ◽  
Aerodynamic Forces ◽  
Analog Input ◽  
Input And Output ◽  
The Time Domain

Inherent in the construction of many experimental apparatus designed to measure the hydro/aerodynamic forces of rotating machinery are features that contribute undesirable parasitic forces to the measured or test forces. Typically, these parasitic forces are due to seals, drive couplings, and hydraulic and/or inertial unbalance. To obtain accurate and sensitive measurement of the hydro/aerodynamic forces in these situations, it is necessary to subtract the parasitic forces from the test forces. In general, both the test forces and the parasitic forces will be dependent on the system operating conditions including the specific motion of the rotor. Therefore, to properly remove the parasitic forces the vibration orbits and operating conditions must be the same in tests for determining the hydro/aerodynamic forces and tests for determining the parasitic forces. This, in turn, necessitates a means by which the test rotor’s motion can be accurately controlled to an arbitrarily defined trajectory. Here in, an interrupt-driven multiple harmonic open-loop controller was developed and implemented on a laboratory centrifugal pump rotor supported in magnetic bearings (active load cells) for this purpose. This allowed the simultaneous control of subharmonic, synchronous, and superharmonic rotor vibration frequencies with each frequency independently forced to some user defined orbital path. The open-loop controller was implemented on a standard PC using commercially available analog input and output cards. All analog input and output functions, transformation of the position signals from the time domain to the frequency domain, and transformation of the open-loop control signals from the frequency domain to the time domain were performed in an interrupt service routine. Rotor vibration was attenuated to the noise floor, vibration amplitude ≈0.2 μm, or forced to a user specified orbital trajectory. Between the whirl frequencies of 14 and 2 times running speed, the orbit semi-major and semi-minor axis magnitudes were controlled to within 0.5% of the requested axis magnitudes. The ellipse angles and amplitude phase angles of the imposed orbits were within 0.3 deg and 1.0 deg, respectively, of their requested counterparts.

Probabilistic Model-Based Fault Diagnosis of the Rotor System

2007 ◽  
Author(s):  
Jiye Shao ◽  
Rixin Wang ◽  
Jingbo Gao ◽  
Minqiang Xu
Keyword(s):  
Fault Diagnosis ◽  
Bayesian Network ◽  
Network Model ◽  
Rotating Machinery ◽  
Rotor System ◽  
Bayesian Network Model ◽  
Diagnosis System ◽  
Model Based ◽  
Core Components ◽  
Fault Diagnosis System

The rotor is one of the most core components of the rotating machinery and its working states directly influence the working states of the whole rotating machinery. There exists much uncertainty in the field of fault diagnosis in the rotor system. This paper analyses the familiar faults of the rotor system and the corresponding faulty symptoms, then establishes the rotor’s Bayesian network model based on above information. A fault diagnosis system based on the Bayesian network model is developed. Using this model, the conditional probability of the fault happening is computed when the observation of the rotor is presented. Thus, the fault reason can be determined by these probabilities. The diagnosis system developed is used to diagnose the actual three faults of the rotor of the rotating machinery and the results prove the efficiency of the method proposed.

scholarly journals Model-Based Fault Location with Frequency Domain for Power Traction System

Energies ◽  
2013 ◽  
Vol 6 (7) ◽  
pp. 3097-3114 ◽  
Author(s):  
Guoqing Xu ◽  
Yimin Zhou ◽  
Yanfeng Chen
Keyword(s):  
Frequency Domain ◽  
Fault Location ◽  
Model Based ◽  
Traction System
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