aep: Calculation of annual energy production

Description Usage Arguments Details Value Optional graphical parameters Note Author(s) References See Also Examples

View source: R/aep.R

Description

Calculates annual energy production (AEP) from a site's wind profile and wind turbine characteristics.

Usage

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aep(profile, pc, hub.h, rho=1.225, avail=1, bins=c(5,10,15,20), 
  sectoral=FALSE, digits=c(3,0,0,3), print=TRUE)

## S3 method for class 'aep'
plot(x, show.total=TRUE, ...)

Arguments

profile

Wind profile object created by profile.

pc

Power curve object created by pc.

hub.h

Hub heigth of wind turbine as numeric value.

rho

Air density as numeric value. Default is 1.225 kg/m3 according to the International Standard Atmosphere (ISA) at sea level and 15°C.

avail

Availability of turbine as numeric value between 0 (not available at all) and 1 (100% available).

bins

Edges of wind speed bins as numeric vector or NULL if only total AEP is desired. Default values are c(5, 10, 15, 20).

sectoral

If TRUE, wind speeds are extrapolated to hub height using the wind profiles of each direction sector. Otherwise the general profile ("all") is used for extrapolation (default).

digits

Number of decimal places to be used for results as numeric vector. The first value is used for wind.speed, the second for operation, the third for aep and the fourth for capacity results. Default is c(3,0,0,3).

print

If TRUE, results are printed directly.

x

AEP object, created by aep.

show.total

If TRUE (the default) the total AEP is added to the plot.

...

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

Details

For a wind turbine the mean energy production can be expressed by

E = T*integral(v_in, v_out) f(v)*p(v)

where f(v) is the probability density function of the wind speed v, p(v) is the power curve of the turbine and T is the production time period. Energy production starts at the turbine's cut-in wind speed v_in and stops at cut-out wind speed v_out.

Based on this fundamental expression, aep calculates the annual energy production as follows:

AEP = A_turb*rho/rho_pc*H*sum(W(v_b)*P(v_b))

where A_turb is the average availability of the turbine, rho is the air density of the site and rho_pc is the air density, the power curve is defined for. W(v_b) is the probability of the wind speed bin v_b, estimated by the Weibull distribution and P(v_b) is the power output for that wind speed bin. H is the number of operational hours – the production time period of the AEP is per definition 8760 hours.

The wind speed v_h at hub height h of the turbine is extrapolated from the measured wind speed v_ref at reference height h_ref using the Hellman exponential law (see profile):

v_h = v_ref*(h/h_ref)^alpha

The productive suitability of a wind turbine for a site can be evaluated by the capacity factor CF. This factor is defined as the ratio of average power output of a turbine to the theoretical maximum power output. Using the AEP as the average power output, the rated power P_{rated} of a turbine and the maximum operational hours of a year we get:

CF = AEP/(P_rated*8760)

Value

Returns a list containing:

wind.speed

Mean wind speed for each direction sector.

operation

Operational hours per year for each direction sector.

total

Total annual energy production for each direction sector.

...

Annual energy production per wind speed bin for each direction sector.

capacity

Capacity factor of the wind turbine.

Optional graphical parameters

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

Note

Sectoral extrapolation should be used carefully. Some sector's profile might be abnormal – particularly in case of short measurement periods (<= one year) and/or few samples per sector – causing biased results. Always check the profiles and set sectoral to FALSE to get more robust results.

Author(s)

Christian Graul

References

Burton, T., Sharpe, D., Jenkins, N., Bossanyi, E. (2001) Wind Energy Handbook. New York: Wiley

Fördergesellschaft Windenergie e.V. (2007) Technical Guidelines for Wind Turbines, Part 6: Determination of Wind Potential and Energy Yields, Revision 7

International Organisation for Standardization (1975) ISO 2533:1975 Standard Atmosphere. ISO Standard

Jangamshetti, S.H., Rau, V.G. (1999) Site Matching of Wind Turbine Generators: A Case Study. IEEE Transaction on Energy Conversion 14(4), 1537–1543

See Also

windprofile

Examples

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## Not run: 
## load and prepare data
data("winddata", package="bReeze")
set1 <- set(height=40, v.avg=winddata[,2], v.std=winddata[,5],
  dir.avg=winddata[,14])
set2 <- set(height=30, v.avg=winddata[,6], v.std=winddata[,9],
  dir.avg=winddata[,16])
ts <- timestamp(timestamp=winddata[,1])
neubuerg <- mast(timestamp=ts, set1, set2)
neubuerg <- clean(mast=neubuerg)


## calculate AEP
# calculate wind profile
neubuerg.wp <- profile(mast=neubuerg, v.set=c(1,2), dir.set=1, 
  print=FALSE)

# load power curve
pw.56 <- pc("PowerWind_56_900kW.wtg")

# calculate AEP
aep(profile=neubuerg.wp, pc=pw.56, hub.h=71)

# calculate AEP with site specific air density and availability of 97
aep(profile=neubuerg.wp, pc=pw.56, hub.h=71, rho=1.195, avail=0.97)

# calculate total AEP using sectoral profiles
aep(profile=neubuerg.wp, pc=pw.56, hub.h=71, sectoral=TRUE)

# calculate AEP for 1 m/s speed bins and without binning
aep(profile=neubuerg.wp, pc=pw.56, hub.h=71, bins=seq(0,25))
aep(profile=neubuerg.wp, pc=pw.56, hub.h=71, bins=NULL)

# change number of digits and hide results
aep(profile=neubuerg.wp, pc=pw.56, hub.h=71, digits=c(1,1,1,1))
neubuerg.aep <- aep(profile=neubuerg.wp, pc=pw.56, hub.h=71, print=FALSE)
neubuerg.aep


## plot AEP objects
# default
plot(neubuerg.aep)

# omit total AEP
plot(neubuerg.aep, show.total=FALSE)

# change colours and text sizes
plot(neubuerg.aep, col=gray(5:0 / 5), cex=0.8)

# manual definition of circles
plot(neubuerg.aep, circles=c(250, 750, 250))

# plot sectors in foreground
plot(neubuerg.aep, fg=TRUE)

# change position of axis labels
plot(neubuerg.aep, pos.axis=135)

# no legend
plot(neubuerg.aep, width.leg=0)

# freaky
plot(neubuerg.aep, border.leg=heat.colors(5), bty.leg="o", 
  cex.axis=0.5, cex.lab=2, cex.leg=0.5, circles=c(80, 800, 80), 
  col=rainbow(5), col.axis="green", col.border="orange", 
  col.circle="purple", col.cross="yellow", col.lab="pink", 
  col.leg="lightblue", fg=TRUE, lwd.border=2, lwd.circle=3, 
  lwd.cross=4, lty.circle="12345678", lty.cross="87654321", 
  sec.space=0.6, title.leg="* WiNd SpEeD *", x.intersp=2, y.intersp=5)

## End(Not run)

Example output

 
This is bReeze 0.4-0
 
Type changes("bReeze") to see changes/bug fixes, help(bReeze) for documentation
or citation("bReeze") for how to cite bReeze.
 

Attaching package: 'bReeze'

The following objects are masked from 'package:stats':

    frequency, profile, ts

The following object is masked from 'package:utils':

    timestamp

Pattern found: %d.%m.%Y %H:%M
Cleaning set 1...
2938 samples lower than 0.4 replaced by 'NA' in average wind speed
14790 samples with average wind speed lower than 4 m/s replaced by 'NA' in turbulence intensity
Cleaning set 2...
3361 samples lower than 0.4 replaced by 'NA' in average wind speed
15366 samples with average wind speed lower than 4 m/s replaced by 'NA' in turbulence intensity

	Annual energy production

      wind speed operation   total     0-5    5-10   10-15   15-20     >20
           [m/s]     [h/a] [MWh/a] [MWh/a] [MWh/a] [MWh/a] [MWh/a] [MWh/a]
N          6.522      2467     657      19     367     258      13        
NNE        4.614       538      54       7      43       4                
ENE        4.337       275      27       3      20       4                
E          3.421       143       7       1       5                        
ESE        3.733       149      11       1       8       2                
SSE         3.29       367      18       3      13       2                
S          3.739       997      75       9      53      13                
SSW        5.983      1350     324      10     131     141      36       7
WSW        6.706      1416     412      10     167     189      41       5
W          4.214       531      54       5      37      12                
WNW        2.179       185       3       1       2                        
NNW        3.599       342      24       3      17       4                
total      5.387      8760    1666      72     863     629      90      12

capacity factor: 0.211 

call: aep(profile=neubuerg.wp, pc=pw.56, hub.h=71, rho=1.225, avail=1, bins=c(0, 5, 10, 15, 20), sectoral=FALSE, digits=c(3, 0, 0, 3), print=TRUE)


	Annual energy production

      wind speed operation   total     0-5    5-10   10-15   15-20     >20
           [m/s]     [h/a] [MWh/a] [MWh/a] [MWh/a] [MWh/a] [MWh/a] [MWh/a]
N          6.522      2467     622      18     347     244      12        
NNE        4.614       538      51       6      41       4                
ENE        4.337       275      25       3      19       3                
E          3.421       143       7       1       5                        
ESE        3.733       149      10       1       7       1                
SSE         3.29       367      17       3      12       2                
S          3.739       997      71       9      50      12                
SSW        5.983      1350     307       9     124     133      34       6
WSW        6.706      1416     390       9     158     178      39       5
W          4.214       531      51       5      35      11                
WNW        2.179       185       3       1       2                        
NNW        3.599       342      23       3      16       4                
total      5.387      8760    1577      68     816     592      85      11

capacity factor: 0.2 

call: aep(profile=neubuerg.wp, pc=pw.56, hub.h=71, rho=1.195, avail=0.97, bins=c(0, 5, 10, 15, 20), sectoral=FALSE, digits=c(3, 0, 0, 3), print=TRUE)


	Annual energy production

      wind speed operation   total     0-5    5-10   10-15   15-20     >20
           [m/s]     [h/a] [MWh/a] [MWh/a] [MWh/a] [MWh/a] [MWh/a] [MWh/a]
N          6.766      2467     712      18     374     301      19        
NNE        4.748       538      59       6      47       5                
ENE        4.249       275      25       3      19       3                
E          3.438       143       7       1       5                        
ESE        3.674       149      10       1       7       1                
SSE        3.191       367      16       3      12       1                
S          3.619       997      68       9      48      10                
SSW        5.831      1350     310      10     129     133      32       6
WSW        6.535      1416     394      10     166     178      36       4
W          4.246       531      55       5      37      12                
WNW        2.336       185       4       1       2                        
NNW        3.605       342      24       3      17       4                
total      5.397      8760    1684      70     863     648      87      10

capacity factor: 0.214 

call: aep(profile=neubuerg.wp, pc=pw.56, hub.h=71, rho=1.225, avail=1, bins=c(0, 5, 10, 15, 20), sectoral=TRUE, digits=c(3, 0, 0, 3), print=TRUE)


	Annual energy production

      wind speed operation   total     0-1     1-2     2-3     3-4     4-5
           [m/s]     [h/a] [MWh/a] [MWh/a] [MWh/a] [MWh/a] [MWh/a] [MWh/a]
N          6.522      2467     657                               4      14
NNE        4.614       538      54                               2       5
ENE        4.337       275      27                               1       2
E          3.421       143       7                                       1
ESE        3.733       149      11                                       1
SSE         3.29       367      18                               1       2
S          3.739       997      75                               3       6
SSW        5.983      1350     324                               3       7
WSW        6.706      1416     412                               3       7
W          4.214       531      54                               2       4
WNW        2.179       185       3                                       1
NNW        3.599       342      24                               1       2
total      5.387      8760    1666                              20      52
          5-6     6-7     7-8     8-9    9-10   10-11   11-12   12-13   13-14
      [MWh/a] [MWh/a] [MWh/a] [MWh/a] [MWh/a] [MWh/a] [MWh/a] [MWh/a] [MWh/a]
N          32      56      79      96     106      97      73      47      27
NNE         8      11      11       8       5       3       1                
ENE         4       5       5       4       3       2       1                
E           1       1       1       1                                        
ESE         1       2       2       1       1       1                        
SSE         3       3       3       2       2       1                        
S          10      12      12      11       9       6       4       2       1
SSW        13      20      27      33      38      39      35      28      22
WSW        14      24      34      43      51      53      47      38      29
W           6       8       8       8       7       5       3       2       1
WNW         1                                                                
NNW         3       4       4       3       3       2       1       1        
total      96     146     186     210     225     209     165     118      80
        14-15   15-16   16-17   17-18   18-19   19-20   20-21   21-22   22-23
      [MWh/a] [MWh/a] [MWh/a] [MWh/a] [MWh/a] [MWh/a] [MWh/a] [MWh/a] [MWh/a]
N          15       7       3       1       1                                
NNE                                                                          
ENE                                                                          
E                                                                            
ESE                                                                          
SSE                                                                          
S                                                                            
SSW        16      12       9       7       5       3       2       2       1
WSW        21      15      11       7       5       3       2       1       1
W                                                                            
WNW                                                                          
NNW                                                                          
total      52      34      23      15      11       6       4       3       2

capacity factor: 0.211 

call: aep(profile=neubuerg.wp, pc=pw.56, hub.h=71, rho=1.225, avail=1, bins=c(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23), sectoral=FALSE, digits=c(3, 0, 0, 3), print=TRUE)


	Annual energy production

      wind speed operation   total
           [m/s]     [h/a] [MWh/a]
N          6.522      2467     657
NNE        4.614       538      54
ENE        4.337       275      27
E          3.421       143       7
ESE        3.733       149      11
SSE         3.29       367      18
S          3.739       997      75
SSW        5.983      1350     324
WSW        6.706      1416     412
W          4.214       531      54
WNW        2.179       185       3
NNW        3.599       342      24
total      5.387      8760    1666

capacity factor: 0.211 

call: aep(profile=neubuerg.wp, pc=pw.56, hub.h=71, rho=1.225, avail=1, bins=c(), sectoral=FALSE, digits=c(3, 0, 0, 3), print=TRUE)


	Annual energy production

      wind speed operation   total     0-5    5-10   10-15   15-20     >20
           [m/s]     [h/a] [MWh/a] [MWh/a] [MWh/a] [MWh/a] [MWh/a] [MWh/a]
N            6.5    2466.9   656.9    18.8   367.2   258.1    12.8     0.1
NNE          4.6     538.2    53.8     6.6    43.4     3.8                
ENE          4.3     275.5    26.6       3    19.9     3.6                
E            3.4     143.4       7     1.5     5.1     0.4                
ESE          3.7     148.8    10.6     1.5     7.6     1.5                
SSE          3.3       367    18.1     3.4    13.1     1.6                
S            3.7     996.7    75.1     9.3    52.6    12.9     0.3        
SSW            6    1350.1   324.2     9.6     131   140.9    36.1     6.6
WSW          6.7      1416   411.9     9.8     167   188.6    41.3     5.1
W            4.2     530.9    53.8     5.1    36.7    11.6     0.4        
WNW          2.2     184.8     2.8       1     1.7     0.1                
NNW          3.6     341.7    24.3       3    16.7     4.4     0.1        
total        5.4      8760  1665.1    72.6     862   627.5      91    11.8

capacity factor: 0.2 

call: aep(profile=neubuerg.wp, pc=pw.56, hub.h=71, rho=1.225, avail=1, bins=c(0, 5, 10, 15, 20), sectoral=FALSE, digits=c(1, 1, 1, 1), print=TRUE)


	Annual energy production

      wind speed operation   total     0-5    5-10   10-15   15-20     >20
           [m/s]     [h/a] [MWh/a] [MWh/a] [MWh/a] [MWh/a] [MWh/a] [MWh/a]
N          6.522      2467     657      19     367     258      13        
NNE        4.614       538      54       7      43       4                
ENE        4.337       275      27       3      20       4                
E          3.421       143       7       1       5                        
ESE        3.733       149      11       1       8       2                
SSE         3.29       367      18       3      13       2                
S          3.739       997      75       9      53      13                
SSW        5.983      1350     324      10     131     141      36       7
WSW        6.706      1416     412      10     167     189      41       5
W          4.214       531      54       5      37      12                
WNW        2.179       185       3       1       2                        
NNW        3.599       342      24       3      17       4                
total      5.387      8760    1666      72     863     629      90      12

capacity factor: 0.211 

call: aep(profile=neubuerg.wp, pc=pw.56, hub.h=71, rho=1.225, avail=1, bins=c(0, 5, 10, 15, 20), sectoral=FALSE, digits=c(3, 0, 0, 3), print=FALSE)

bReeze documentation built on May 2, 2019, 3:32 p.m.