Voith Siemens Hydro Power Generation Signature Test Data Acquisition and Processing Software was created to replace an old MS-DOS test data acquisition system with a new Windows-based application. The new application runs on a laptop computer with a 16-channel PCMCIA data acquisition card. The software was written using
National Instruments LabVIEW software. In order to distribute the software to multiple computers, executable files were created using LabVIEW Application Builder.
The data acquisition software displays or records up to 16 channels of data. Each channel is independently configurable and information relevant to the data acquisition is recorded for each channel and for the project as a whole, and stored in a setup data file. In addition, real-time plots of time vs. amplitude and frequency spectrum are available. Raw data is recorded and stored in data files for processing using a separate data processing application.
The data processing software reads previously recorded raw data files and setup data files and allows the user to view the data in several formats - time vs. amplitude, frequency spectrum, channel vs. channel, and as a data table. Each plot is in a printable format, and the data table information can be exported to an Excel spreadsheet.
Data Acquisition Application
The test setup screen shown below allows a user to record plant name, customer name, unit number, and project description for the current project. It also allows the user to give each channel a descriptive name and specify the input voltage range, engineering units, DC offset, and a list of data acquisition related equipment for each channel. The instrument calibration function allows the user to set either a constant scaling factor or perform a more complex polynomial fit for each channel. The setup data is stored in a setup data file for the current project.
The instrument calibration screen allows a user to specify for each channel either a linear scaling factor or a polynomial fit to sample data collected from that channel. The sample data points are displayed in a chart with the sample average and a +/- 95% confidence interval. Each calibration point is displayed in a calibration data table with the calibration standard, average voltage of the sample data, the current polynomial fit value, the error measured as difference from the standard, and the 95% confidence interval for the calibration data. The polynomial fit can be varied from first to fourth order. The scaling factor or polynomial fit will be applied to all data recorded on that channel.
Once channels have been selected and configured, they are displayed on the main data acquisition screen. From here a user can select which of the configured channels are to be recorded. In addition, the user may view the data file log, modify the test setup, launch the data processing application, or view the real-time time-amplitude or FFT plots. A separate window to start data acquisition for the selected channels is also shown. The user may select the path where the raw data file will be stored. The user also selects a base file name, to which a file number is appended. The user may also enter a description to place in the header of the raw data file.
The real-time time-amplitude screen shows time vs. amplitude plots of up to four active channels. For each displayed channel the minimum, maximum, average, and peak-to-peak values along with a 95% confidence interval for the displayed data are given in a data table. These plots are not available when data is being recorded.
The real-time FFT screen shows an FFT plot for one of the active channels with frequencies up to 1/4 the sample rate. This plot is not available when data is being recorded.
Data Processing Application
The main data processing screen allows the user to select a raw data file and a setup data file for processing. The user can then display the calibrated data in several formats - time vs. amplitude, frequency spectrum, channel vs. channel, and as a data table.
The time-amplitude screen shows time vs amplitude plots of up to four channels. For each displayed channel the minimum, maximum, average, and peak-to-peak values along with a 95% confidence interval for the displayed data are given in a data table. The screen is printable, and a header with project data is given at the top of the screen. The time scale of the displayed data can be modified, and the data in the data table is modified to reflect the new time scale.
The FFT screen shows frequency vs amplitude and time vs amplitude plots for up to two channels. For each displayed channel the minimum, maximum, average, and peak-to-peak values along with a 95% confidence interval for the displayed data are given in a data table. A table of the 10 highest amplitude frequencies is also given for each displayed channel. The time scale of the displayed data can be modified and even restricted to powers of 2, and the data in the data table and frequency table are modified to reflect the new time scale.
The Lissajous Orbit screen shows channel vs. channel data for up to four pairs of channels. The time scale of the displayed data can be modified, and the data in the orbit plot is modified to reflect the new time scale.
The Data Table screen shows the raw data for up to 16 channels. The raw data can be displayed in time steps that are integer multiples of the fundamental sampling frequency. The start and end time of the data in the table can also be specified. The raw data can be copied into an Excel spreadsheet. A file information table displays information about the raw data file, and a channel data file shows the minimum, maximum, average, and peak-to-peak values along with a 95% confidence interval for each channel in the data table. Channels are selected for display in the raw data table from the channel information list.