Environmental Engineering Reference
In-Depth Information
16
1800
IWAKI DATA 2007.05.27
V (m/s)
P (W)
1600
14
1400
12
1200
10
1000
8
800
6
600
4
400
2
200
0
0
0
2000
4000
6000
8000 10000 12000 14000 16000 18000 20000
T (sec)
Figure 14: A sample of fi eld test data of a 1 kW SWT.
The power performance is statistically expected values of power output and
Bin method is applied.
Figure 14 shows a fi eld test data of a 1 kW SWT. The sampling period is 1 s and
the period is continuous 8 h. Wind speed is varying from 5 to 15 m/s. Due to vari-
ous uncertainties in measurement, data scatter widely. Therefore, a statistically
expected power curve represents the performance of a WT.
A power performance curve is decided by applying Bin-averaging method (Bin
method).
In Fig. 15, 1-min averaged data are plotted with symbol
For SWTs, data shall be collected continuously at a sampling rate of 1 Hz or faster
and every 1-min data set gives a 1-min mean value, 1-min standard deviation, 1-min
maximum value and 1-min minimum value for wind speed and power output. Then
plenty of mean values are further averaged by Bin method as follows:
×.
1
N
∑
i
V
=
V
( 19 )
,
,
Bin i
i j
N
j
=
1
i
1
N
∑
i
P
=
P
,
,
Bin i
i j
(20 )
N
j
=
1
i
where
i
is the Bin number (when using 0.5 m/s Bins, 0.5
i
- 0.25
V
i,j
< 0.5
i
- 0.25);
V
i,j
is the normalized wind speed of data set
j
in Bin
i
;
P
i,j
is the normalized power
output of data set
j
in Bin
i
;
V
Bin
,
j
is the Bin-averaged wind speed in Bin
i
;
P
Bin
,
j
is the
Bin-averaged power output in Bin
i
;
N
i
is the number of data sets in Bin
i
.
The white circles in Fig. 15 are Bin-averaged values.
A power performance curved is completed if suffi cient data sets cover all the
operation range of wind speed. Then an uncertainty analysis follows.
≤
Search WWH ::
Custom Search