Starting and Low Wind Speed Performance - Small Wind Turbines: Analysis, Design, and Application - page 115

Fig. 6.9 Calculated starting
sequence using adaptive
Runge-Kutta (RK) and
Adams-Moulton method
(AM) for dt indicated

1

0.8

0.6

Adaptive RK T s = 4.02 s
AM δ t = 0.1 s, T s = 4.01 s
AM δ t = 0.5 s, T s = 3.96 s
AM δ t = 1.0 s, T s = 3.90 s

0.4

0.2

0

0 1 2 3 4 5

Time (s)

30

25

20

15

10

N = 2, Q R = 1.9 Nm
N = 3, Q R = 1.9 Nm
N = 2, Q R = 0.9 Nm
N = 3, Q R = 0.9 Nm
as above, pitched out 2 o
actual rpm

5

8

0

15 20

7

6

5

4

3

0 5 10 15 20 25 30

time (s)

Fig. 6.10 A failed measured starting sequence of the Aerogenesis 5 kW turbine with two blades
and an induction generator and gearbox

It is not difficult to extend start_calc.m to cope with variable wind speeds as
was done for Fig. 6.4 and for Fig. 6.10 which shows a failed starting sequence for
the Aerogenesis 5 kW turbine shown in Fig. 1.3 with a gearbox resistive torque of
1.9 Nm. The thick solid line shows that the calculated starting performance over-
estimates the measured X, possibly because of yaw effects which were ignored in
the calculation. It can be seen that using three blades would have allowed the
turbine to start, indicating that the resistive torque is significant; otherwise starting
performance would have been independent of N. After these measurements were