Wind Energy

34 Methodical Failure Detection in Grid Connected Wind Parks 189
of the failure source, whether it was an external or device-internal event.
Measurements were conducted with an eight-channel power quality analyzer.
Figure 34.2 shows a failure-time-circle with the measured tripping events of
the eight WECs over a time span of 18 months. With this long-term failure
monitoring a methodical evaluation of the failure sources was possible and
enabled the operator to plan countermeasures. Our investigations deal with
Current / in A
(a)
Voltage U in V, Current / in A
(b)
2000
1500
1000
500
0
−500
−1000
−1500
L1 L3
L2
−2000
−0.10 −0.07 −0.04 −0.01 0.02 0.06 0.09 0.12
6000
5000
4000
3000
2000
1000
0
−1000
−2000
−3000
−4000
−5000
−6000
U L1 U L3
U L2
l L1
l L2
l L3
Time t in s
−0.047 −0.039 −0.031 −0.023 −0.014 −0.006 0.002 0.011 0.019 0.027 0.035 0.044
Time t in s
Fig. 34.3. Measured (a) currents and (b) voltage and currents between pwm
converter and transformer at internal short-circuit of different 1,5-MW-WEC with
DFIG