Time Series Analysis

This example demonstrates how to effectively analyze time series data from OpenFAST simulations.

Time Domain Analysis Overview

Time series analysis in Remote OpenFAST Plotter allows you to:

  • Visualize signal behavior over time

  • Compare multiple signals simultaneously

  • Identify important events in the simulation

  • Isolate specific time ranges for detailed examination

Loading and Plotting Time Series Data

To analyze time series data:

  1. Load Your OpenFAST Files:

    • Navigate to the Files tab

    • Enter the paths to your OpenFAST output files

    • Click “Load Files”

  2. Navigate to Time Domain Tab:

    • Select the “Time Domain” tab in the main navigation

  3. Configure Plot Parameters:

    • Select X-axis signal (usually “Time”)

    • Select one or more Y-axis signals

    • Choose plot style (Overlay or Separate)

    • Adjust time range if needed

  4. Generate Plot:

    • Click “Update Plot” to create the visualization

Example: Comparing Blade Root Moments

Here’s a specific example for analyzing blade root moments across different wind conditions:

  1. Load Multiple Files:

    test_files/5MW_Land_DLL_WTurb.outb
test_files/5MW_Land_BD_DLL_WTurb.outb

  2. Select Comparable Signals:

    • For Y-axis: Select “RootMyc1” from both files

    • For X-axis: Select “Time”

    • Display option: “Separate”

  3. Analyze the Results:

    • Compare the blade root moment magnitudes between simulations

    • Look for patterns, peaks, and transient events

    • Identify any phase differences or timing shifts

Advanced Time Series Techniques

The application provides several advanced time series analysis features:

  1. Time Range Selection:

    • Enter specific start and end times to focus on a particular period

    • Useful for isolating startup transients, fault events, or specific maneuvers

  2. Overlaid Vs. Separate Plots:

    • Overlay: Good for direct comparison of signal magnitudes

    • Separate: Better for seeing patterns when magnitude ranges differ significantly

  3. File Order Management:

    • Ensure consistent color assignment across plots by managing file order

    • Particularly useful when comparing results across multiple analysis sessions

  4. Multiple Signal Selection:

    • Compare different signal types (e.g., blade moments vs. tower moments)

    • Assess correlation between different measurements

  5. Plot Customization:

    • Adjust axis scaling (linear vs. log)

    • Enable/disable grid lines

    • Configure legend position

Example: Analyzing Startup Transients

For analyzing wind turbine startup behavior:

  1. Load a startup simulation file

  2. Select relevant signals:

    • Generator speed

    • Blade pitch angles

    • Tower base moments

    • Rotor thrust

  3. Focus on startup period:

    • Enter time range (e.g., 0-60 seconds)

    • Click “Update Plot”

  4. Observe and analyze:

    • Generator speed ramp-up

    • Pitch control activation

    • Structural loading during transition

  5. Export findings:

    • Use the “Export as HTML” option to save the visualization

Troubleshooting Time Series Analysis

Common issues with time series analysis:

  • Mismatched Time Scales: If comparing files with different simulation lengths or time steps, adjust the time range accordingly

  • Signal Selection: Ensure signal names match across files (may vary with model changes)

  • Large Files: For very large files, consider using a time range to focus on relevant periods and improve performance

  • Missing Data: If a signal appears to be missing, check if it’s actually present in the file or if it has a different name