Software for Operational Modal Analysis
ARTeMIS

 

Upcoming Feature - Harmonic Reduction in Rotating Machinery Measurements

In the upcoming ARTeMIS Modal Pro 3.5, we have added a new tool which can reduce harmonic peaks appearing in measurements of rotating machinery.The tool has been developed in cooperation with Prof. Dr.-Ing. Jörg Bienert from Technische Hochschule Ingolstadt, Fakultät Maschinenbau.

 

The motivation for this work is to reduce the height (energy level) of the harmonic peaks in a set of data before using it for modal analysis. The reduction will make the modal estimation an easier task, especially in the case of many harmonic peaks.

 

The idea is to determine frequency and phase of the harmonic peaks from all the channels, and then reduce the energy level at the peaks by fitting and subtracting the harmonic amplitude per channel. The algorithm makes use of a nonlinear regression approach that is applied to the already processed data.

 

Below, the Singular Value Decomposition of a set of data is shown before and after the Harmonic Reduction tool has been applied to measurements: 

Figure 1: Singular Values of the spectral densities of the "Plate with Harmonics" example data. Before harmonic reduction.

 

Figure 2: Same measurements after harmonic reduction of peaks at 374 Hz, 748 Hz, 1122 Hz and 1496 Hz.

 

As seen in this case of a completely constant harmonic excitation source, the tool is capable of removing the harmonic peaks very efficiently. This makes it applicable for all cases where there is rotating machinery with constant rotational speed.

 

Please have a look at the 4 min. demonstration video showing how the harmonic reduction is performed from this link.

 

Harmonic Reduction of Prolec GE Transformer Data

The Harmonic Reduction tool has been tested with data acquired on a Prolec GE transformer, where there are severe harmonic peaks at 60 Hz and multiples of that frequency.

 

Prolec GE, located in Monterrey, Mexico, is one of the largest transformer manufacturers in the Americas, offering a complete line of transformer products necessary for the generation, transmission, and distribution of electric power. Prolec GE has over 30 years of experience in the industry, with products installed in more than 35 countries around the world. 

 

The data has around 80 dB dynamic range from the highest harmonic peak and then down to the noise floor. Since the modal response is not more than maximum 15 dB above the noise floor it makes any modal analysis difficult. The Harmonic Reduction tool is applied to "equalize" the heights of the harmonic and modal peaks.

Since the data has been acquired outside the core of the transformer there is a significant measurement noise, but even so the harmonic reduction is capable of reducing the harmonic peaks with more than 40 dB on an average.

 

Below the Singular Value Decomposition of the transformer data can be seen before and after the Harmonic Reduction tool has been applied: 

 

Figure 3: Singular Values of the spectral densities of the Prolec GE transformer data. Before harmonic reduction.

 

Figure 4: Same measurements after harmonic reduction of peaks at 60 Hz, 120 Hz, 180 Hz and 240 Hz.

Data provided with courtesy of project leader Mr. Raymundo Carrasco Aguirre, Prolec GE, Monterey, Mexico.


ARTeMIS User Training Course - Book Before 29 August - Save 10%!

This 2-day course is for the new as well as experienced users who wish to be updated on Operational Modal Analysis technology as well as the latest features of ARTeMIS Operational Modal Analysis software and the new Damage Detection plugin.

 

The course will be held on 8-9 October, 2014 at Structural Vibration Solutions A/S in Aalborg, Denmark. Both days we start at 9.00 and end at 16.00. The course instructor is Dr. Palle Andersen, CEO and senior developer of the ARTeMIS software.

 

Price

The price for attending the course is 895 EUR per person. (Students get a 50% discount.)
Book before 29 August, 2014 and save 10%.

 

Sign

Please download the registration form and send it by email to Structural Vibration Solutions at mo@svibs.com. We need your registration no later than 19 September, 2014.

 

     

 

 

International Seminar on Modal Analysis (ISMA) 2014

SVS will be exhibiting at the ISMA conference on 15-17 September 2014. We will be showing the latest release of ARTeMIS Modal and the new Damage Detection plugin. In addition, we will be presenting some of the upcoming new features in ARTeMIS Modal Pro - A tool for Harmonic Peak  Reduction and a new Modal Parameter History task with automatic mode tracking over time.

 

 

Download Free Demo

Download a 30-day demo version of the ARTeMIS Modal software from this link.

Please contact us at mo@svibs.com if you like to test the Damage Detection plugin with your own data.

 

 


 


Structural Vibration Solutions A/S • Tel: +45 9635 4422 • sales@svibs.com

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