Wind-grapher is a powerful wind data analysis program that reads data files from met
towers, wind dataloggers etc.
It produces clear and attractive graphs and wind roses, allows for advanced quality control, and performs many calculations such as wind shear, turbulence intensity, extreme wind speeds, and wind turbine energy production.

Data Files

Wind-grapher reads a wide variety of data files and formats such as:
- the date format
- wind speed
- wind direction
- standard deviation
- temperature

Wind-grapher can handle any number of wind speed and direction sensors at any heights above ground, and any number of gaps or missing values. It can accept any time step between one minute, and six hours.

Graphs

Once you have opened your data set, you can get straight to analyzing it. wind-grapher produces many graphs and tables to help you visualize and describe the data. The time series graph, for example, lets you zoom in on any subset of the data, scroll forwards or backwards in time, and add or remove any data column with a single click:

 

 

 

 

 

Other graphs include average daily profiles, frequency histograms, and scatterplots of measured data or of calculated quantities such as air density or wind shear power law exponent. Examples appear below. In each case, you can choose to plot all available data, or just a particular year or month. You can export any graph to a metafile, bitmap, or PNG file.

 

 

 

 

Wind Roses

Wind-grapher also produces many types of wind rose diagrams. You can plot the frequency with which the wind blows from each direction sector, the mean value per direction sector of any data column, the total amount of wind power per direction sector, and even polar scatterplots. Some examples appear below. As with other types of graphs, you can choose to plot the entire data set or just a particular year or month. You can also choose to display twelve wind roses simultaneously, one for each month of the year or for each two-hour segment of the day. You select the number of direction sectors, and the wind roses update in real time.
 

 

 

 

Wind Shear Analysis

The Wind Shear Analysis window displays the vertical wind speed profile and the best-fit wind shear parameters versus time of day, month, and direction sector:

Turbulence Analysis

The Turbulence Analysis module calculates turbulence intensity and shows how it varies with wind speed, wind direction, year, and month. It also allows you to compare the turbulence in your data set with the standard IEC turbulence categories.

 

 

 

 

Tower Shading Analysis

The Tower Shading Analysis window plots the ratio or the difference between two anemometers by direction, so that tower shading effects become apparent:

 

 

 

 

Extreme Wind Analysis

If your data set extends over several years, wind-grapher"s Extreme Wind Analysis module can calculate the best-fit Gumbel distribution to predict the maximum wind speed expected within a 25-year, 50-year, or 100-year return period.

 

 

 

 

Quality Control

The new Quality Control window allows you to find and fix problems in the data set, such as the icing events shown below. You can search for problems by scrolling through the time series graph and inspecting the data visually, or you can define formal search rules. You might define a search rule to find, for example, instances where two anemometers differ by more than 20%, or where the temperature goes below 0°C and the standard deviation of the wind speed stays below 0.1 m/s for two hours at a time. You can delete problem data segments, and optionally fill the resulting gaps with synthetic data.

Wind Turbine Output

The Wind Turbine Output window calculates the expected gross and net energy output and capacity factor of a wind turbine in the measured wind regime. In making these calculations, wind-grapher accounts for the effects of varying wind shear and air density.

Gap Filling

Wind-grapher can also fill gaps in the data set using an innovative Markov algorithm that takes the diurnal pattern into consideration. This technique can reliably fill gaps up to several days in length, not only in wind speed data, but in wind direction or any other type of data as well. The graph below shows the synthetic data wind-grapher generated to fill a three-day gap in wind speed and temperature data: