bReeze (version 0.4-4)

availability: Calculate availability for pairs of wind speed and direction

Description

Calculates the availability for pairs of wind speed and wind direction of a met mast.

Usage

availability(mast, v.set, dir.set, subset, digits=1, print=TRUE)
avail(mast, v.set, dir.set, subset, digits=1, print=TRUE)
# S3 method for availability
plot(x, set, ...)

Value

Returns a list of sub lists for each pair of v.set/dir.set containing:

total

Total availability (%), effective period (days) and total period (days) of a set/pair of wind speed and direction.

daily

Availability per day, i.e. number of samples per day.

Arguments

mast

Met mast object created by mast.

v.set

Set(s) to be used for wind speed, specified as set number(s) or set name(s). Argument is optional -- if missing, all sets containing wind speed and wind direction data are used.

dir.set

Set(s) to be used for wind direction, specified as set number(s) or set name(s). Argument is optional -- if missing, the set(s) used for wind speed data will also be used for wind direction.

subset

Optional start and end time stamp for a data subset, as string vector c(start, end). The time stamps format shall follow the rules of ISO 8601 international standard, e.g. "2012-08-08 22:55:00".

digits

Number of decimal places to be used for results as numeric value. Default is 1.

print

If TRUE (the default), results are printed directly.

x

Availability object created by availability.

set

Number of dataset to be plotted, specified as set number or set name (optional).

...

Arguments to be passed to methods. For optional graphical parameters see below.

Optional graphical parameters

The following graphical parameters can optionally be added to customize the plot:

• border: Colour of the cell borders -- default value is "black".

• cex: Numeric value, giving the amount by which text on the plot should be scaled relative to the default (which is 1).

• cex.axis: Amount by which axis annotations should be scaled, as numeric value.

• cex.lab: Amount by which axis labels should be scaled, as numeric value.

• col: Vector of three text colours (or just one colour), where the first indicates 'full availability', the second 'partial availability' and the third 'not available' -- default is "black".

• col.axis: Colour to be used for axis -- default is "gray45".

• col.lab: Colour to be used for axis labels -- default is "black".

• fill: Vector of three fill colours (or just one colour), where the first indicates 'full availability', the second 'partial availability' and the third 'not available'.

• lwd: Line widths of the cell borders. See par for usage.

• mar: A numerical vector of the form c(bottom, left, top, right) which gives the number of lines of margin to be specified on the four sides of the plot -- default is c(0, 0, 0, 0).

• plot.names: If TRUE (the default), the names of the datasets is plotted as second label of the y axis.

• xlab: Alternative label for the x axis.

• ylab: Alternative label for the y axis.

Author

Christian Graul

Details

The availability is the number of pairs of valid wind speed and valid wind direction data samples as a percentage of the total possible for the measurement period, i.e.: $$Availability = \frac{N(v_{valid} \wedge dir_{valid})}{N}$$ where \(N\) is the total possible number of samples and \(v_{valid} \wedge dir_{valid}\) is a pair of valid wind speed and direction data.

Causes of invalid or missing data are manifold. Typical causes are icing and defects of sensors or other measurement equipment.

References

Brower, M., Marcus, M., Taylor, M., Bernadett, D., Filippelli, M., Beaucage, P., Hale, E., Elsholz, K., Doane, J., Eberhard, M., Tensen, J., Ryan, D. (2010) Wind Resource Assessment Handbook. http://www.renewablenrgsystems.com/TechSupport/~/media/Files/PDFs/wind_resource_handbook.ashx

See Also

mast, clean

Examples

if (FALSE) {
## load and prepare data
data("winddata", package="bReeze")
set40 <- set(height=40, v.avg=winddata[,2], v.std=winddata[,5],
  dir.avg=winddata[,14])
set30 <- set(height=30, v.avg=winddata[,6], v.std=winddata[,9],
  dir.avg=winddata[,16])
set20 <- set(height=20, v.avg=winddata[,10], v.std=winddata[,13])
ts <- timestamp(timestamp=winddata[,1])
neubuerg <- mast(timestamp=ts, set40=set40, set30=set30, 
  set20=set20)
neubuerg <- clean(mast=neubuerg)


## calculate availability
neubuerg.avail <- availability(mast=neubuerg)

# compare the total availability of 'set40' and 'set30'
neubuerg.avail$set40$total
neubuerg.avail$set30$total

# check the daily availability of 'set40'
neubuerg.avail$set40$daily

# note: availability for 'set20' is missing - its availability is NULL,
# since it does not contain wind direction data

# calculate availability for 'set20' using wind direction data from 'set40'
set20.avail <- availability(mast=neubuerg, v.set=3, dir.set=1)
# same as above
set20.avail <- availability(mast=neubuerg, v.set="set20", dir.set="set40")

# calculate availability for all sets using wind direction data from 'set40'
neubuerg.avail <- availability(mast=neubuerg, v.set=c(1,2,3), dir.set=1)

# data subsets
availability(mast=neubuerg, v.set=1, 
  subset=c("2009-12-01 00:10:00", "2009-12-31 23:50:00"))
availability(mast=neubuerg, v.set=1, 
  subset=c("2010-01-01 00:10:00", NA)) # just 'start' time stamp
availability(mast=neubuerg, v.set=1, 
  subset=c(NA, "2009-12-31 23:50:00")) # just 'end' time stamp

# change number of digits and hide results
neubuerg.avail <- availability(mast=neubuerg, digits=0)
neubuerg.avail <- availability(mast=neubuerg, print=FALSE)
neubuerg.avail


## plot availability objects
plot(neubuerg.avail)  # default
plot(neubuerg.avail, set=2)	 # one dataset
plot(neubuerg.avail, set="set30")  # same as above
plot(neubuerg.avail, set=c(1,2))  # several datasets

# customize plot
plot(neubuerg.avail, border="darkgray", cex.axis=0.7, 
  cex.lab=0.9, col=c("darkgreen", "orange", "red4"), col.axis="blue", 
  col.lab="blue", fill=c("lightgreen", "yellow", "red"), lwd=0.5, 
  mar=c(1,1,1,1), plot.names=FALSE, xlab="jour", ylab="mois")
}