The large-scale research engine FOMO4524 by FH Flensburg was modernized with completely new measurement value processing for slow engine signals and supply systems due to previous vulnerabilities
A research engine poses particular challenges to accurate measurements and analysis. Both the relatively frequent change in operators and frequent[ds_preview] modifications to the engine and its associated systems compared to industrial or power-plant engines call for transparent data processing. A high quality level in documentation and easily adapted data processing are also at the installation’s heart. A measuring technology analysis of the medium-speed, 700kW large-scale research engine FOMO4524 at FH Flensburg revealed weaknesses that had crept in over the years. In addition to hardware defects no longer comprehensible settings and results could be traced both in the programmable logic controller (PLC) and in the analysis software. Repairs turned out to be as consuming as a full rebuild. Given the little additional effort to repairs, it was therefore decided to arrange a completely new measurement value processing for slow engine signals and supply systems instead.
The objective of the reorganization was not limited to the correction of errors. To improve the future work on the test facility, many factors had to be considered: operability and modifiability for students and staff with motor skills who lack PLC experience had to be ensured. The facility had to be ready for the application of sophisticated mathematical tasks, such as numerical differentiation or filtering signals. The increased automation of the evaluation had to save on personnel and fuel costs especially. The latter add up to 1,000€ per test day. The software used should also facilitate the transparent demonstration of algorithms and respective meaningful comments as well as documentation. In addition, the software requirements include clear operability and display of results based on a uniform and contemporary surface design. Finally, calculation parameters and result values have to be easy to manage and easy to secure by means of backup features.
In assessing the available products on the market the costs of procurement for the Fachhochschule (FH) were of special importance but most of all the simplicity and transparency of the PLC programming and care. Bachmann electronic was awarded the contract, since programming of the M1 automation system can be done with the aid of MATLAB/Simulink software, which is already available at FH. Students combined various hardware and software components to a tailor-made measurement solution which meets the standard of professionally designed equivalents. Commands and formulas have been grouped into graphical blocks in MATLAB/Simulink and then uploaded to the control unit. Novel functions could be added to basic ones in data processing. The assessment of a thermal stream by temperature, mass flow and specific heat capacity could thus be expanded by signal filtering through parameterizable low-pass filter or the automatic determination of the steady state operation by the time derivative of status signals.
Given the rapid learning curve needed for this type of PLC programming skills, numerous additional functions have been defined, aimed at improved quality results. Thus, the specific heat capacities still used as constant parameters in the simpler design can be integrated with little effort as temperature-dependent variables in the future. Thanks to the graphical user interface even more complex functions can be represented even without knowledge of an extensive syntax.
The visualization of the measurement data is realised by the software »M1 webMI pro«, which is installed directly on the PLC. With this feature each device may be transformed into a Human Machine Interface (HMI) by using a web browser and a network or Internet connection to the PLC. The software supports a clear, multiple display representation of the operational data. At the same time an internet connection gives simultaneous access from different locations. This feature is interesting for the Flensburg FOMO4524 as the Maritime Centre cooperates with partners in southern Germany, Austria and Switzerland. The visualization of measured data is provided as Scalable Vector Graphics (SVG) to guarantee free of loss scaling.
Projection and configuration of the visualization takes place in »atvise builder«. This offers numerous prefabricated display sets which can easily be configured.
As a further option, display and interface animations may easily be created. The object-oriented program structure offers the chance of aggregation of similar parameters in different displays. In this way, changes to a reference display device can be transferred to all linked devices. This ensures demand uniformity of appearance within the HMI. In compiling the HMI, flags were used to allow a well structured organization and links to quickly change between screens, and bar graphs for mean value faults all to integrate contemporary features. Also superimposed waveforms, auto-scaling features and color changes when limits are exceeded were welcomed by the project team. Backed by a visually appealing design these features increased the functionality. The clear program structure also allows major adjustments by relatively inexperienced users after a short training period.
Both the raw data measured at the engine and various calculated quantities are documented with the software »Scope 3.0«. This involves saving the data to the PLC, and the creation of archives in CSV format on the PC. In the visualization it is now possible to choose between real-time and the data archive and to display the measured values as configurable curves. Time steps can be divided into groups of measurements independent of the visualization and documentation. So result parameters of different signals are stored while unnecessary data collection is avoided. The individual adjustment of data storage enables to pursue different strategies for storing experimental data of stationary and mobile operation within a recording. In order to achieve a clear and attractive design and low personnel expenses also in the creation of experimental protocols, the most appropriate method to process the archive data will be analyzed in the coming months as part of another student project.
The university’s hopes associated with the introduction of the new hardware and software in terms of cost-effective improvements to data processing were absolutely fulfilled. The FH Flensburg therefore plans to modernize other engine test facilities along the same lines over the next two years.
Authors:
C. Brenner, J. Wilhelm, M. Baumann, B. Eng. N. Endruweit, B. Eng. D. Meyer, Prof. Dr.-Ing. Michael Thiemke
FH Flensburg, Studiengang Schiffstechnik
C. Brenner, J. Wilhelm, M. Baumann, B. Eng. N. Endruweit, B. Eng. D. Meyer, Prof. Dr.-Ing. Michael Thiemke
