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# Generator rotation speed

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```Generator
Torque at the
Mechanical
Load voltage
Load current
Electrical
rotation speed
wind turbine
power at the
(V)
(A)
power to the
(r/min)
rotor (Nm)
wind turbine
load (W)
rotor (W)
Maximum
0.05
5
43
0
0
540
0.2
11.3
24
0.54
13.4
475
0.27
13
20
0.68
13.8
360
0.38
14
13.7
0.9
12.4
245
0.4
10.3
7.2
0.96
7.1
180
0.35
6.5
4.4
0.8
4
70
0.2
1.5
0
0.6
0
speed: 840
Minimum
speed
Table 3: Measuring the parameters of the wind turbine at a wind speed of 4 m/s (14.4
Generator
Torque at the
Mechanical
Load voltage
Load current
Electrical
rotation speed
wind turbine
power at the
(V)
(A)
power to the
(r/min)
rotor (Nm)
wind turbine
load (W)
rotor (W)
Maximum
0.05
8
73
0
0
1060
0.44
49
48.2
1.08
52.4
950
0.58
60
42
1.4
60
790
0.9
74
30.8
2.0
63
620
1.15
75
20
2.7
52
515
1.25
69
4.5
2.84
40
152
0.73
12
0
1.7
0
speed: 1420
Minimum
speed
km/h or 9.0 mph)
Table 4. Measuring the parameters of the wind turbine at a wind speed of 7 m/s (25.2
km/h or 15.7 mph).
Generator
Torque at the
Mechanical
Load voltage
Load current
Electrical
rotation speed
wind turbine
power at the
(V)
(A)
power to the
(r/min)
rotor (Nm)
wind turbine
load (W)
rotor (W)
Maximum
0.05
10
103
0
0
1625
0.71
120
73
1.6
120
1500
0.94
145
65
2.16
140
1280
1.4
190
50
3.37
168
1050
1.9
220
33
4.3
144
970
2.2
210
25
4.348
110
517
2.6
141
0
4.348
0
speed: 2000
Minimum
speed
Table 5: Measuring the parameters of the wind turbine at a wind speed of 10 m/s (36
km/h or 22.4 mph).
20.
Mechanical power vs. speed for 4 (bottom), 7
(middle), 10 (top) m/s
3
2,6
Torque (W)
2,5
2,2
1,9
2
1,4
1,251,15
1,5
0,71
0,58
0,44
0,4 0,38
0,35
0,27
0,2
0,2
0,5
0,94
0,9
0,73
1
0,05
0,05
0,05
0
0
500
1000
1500
2000
2500
Speed (rpm)
DC current vs. DC voltage for 4 (bottom), 7
(middle), 10 (top) m/s
5
4,348
4,5
4,348 4,3
Load current (A)
4
3,37
3,5
2,84
3
2,7
2,5
1,5
1 0,6
2,16
2
2 1,7
1,6
1,4
1,08
0,96 0,9
0,8
0,680,54
0,5
0
0
0
0
0
20
40
60
Load voltage (V)
80
100
120
21.
Mechanical power vs. Speed for 4 (bottom), 7
(middle), 10 (top) m/s
250
220
210
190
Mechanical power (W)
200
145
141
150
120
100
69 75
74
60
49
50
12 10,3 14 1311,3
1,5 6,5
10
8
5
0
0
500
1000
1500
2000
2500
Speed (rpm)
Electrical power vs. Speed for 4 (bottom), 7
(middle), 10 (top) m/s
168
180
160
144
140
ELec trical power (W)
140
120
110
120
100
80
63
60
52
60
52,4
40
40
7,1
0 04
20
13,4
12,413,8
0
0
0
0
0
0
500
1000
1500
Speed (rpm)
2000
2500
22.
Because there is energy lost in the process of mechanical power to electrical power.
Such as friction loss in Gearbox
Wind Speed
Maximum
Maximum
Optimum
Optimum
Generator
mechanical
electrical
speed at the
torque at the
efficiency (%
power (W)
power (W)
wind turbine
wind turbine
rotor (r/min)
rotor (N&middot;m or
lbf&middot;in)
4 m/s
7 m/s
10 m/s
14
75
220
13.8
63
168
475
790
1280
0.27
0.9
1.4
98.57
84
76
23.
When the wind speed increase, the generator efficiency decrease. Because higher speed
led to higher mechanical lost. The wind speed reaches 7m/s and 10m/s, The wind
turbines stall as wind speeds increase. Air and wind motor blade stripping phenomenon,
efficiency also decreased
24.
Maximum electrical power vs. wind speed
168
Maximum electrical power (W)
180
160
140
120
100
80
63
60
40
13,8
20
0
0
2
4
6
Wind speed (m/s)
8
10
12
Maximum mechanical power vs. wind speed
Maximum mechanical power (W)
250
220
200
150
100
75
50
14
0
0
2
4
6
8
10
12
Wind speed (m/s)
Ideally, bring the data into the following cubic formula for maximum mechanical
power versus speed. The maximum mechanical power is proportional to the cube of
the speed with the air density and the windward surface fixed. Because the efficiency
of the generator is greater than 30%, the maximum electrical power is also
proportional to the cube of the speed and
REVIEW QUESTIONS
1.
Pw=1/2ρAv3=0.5*1.225kg/m3*10m2*(4.5m/s)3=558.14W
2.
When the wind speed doubles:
Pw=1/2ρAv3=0.5*1.225kg/m3*10m2*(9m/s)3=4465.12W
When the wind speed triples:
Pw=1/2ρAv3=0.5*1.225kg/m3*10m2*(13.5m/s)3=15069.8W
The power is proportional to the wind speed.
3.
The rotor efficiency coefficient (Cp) is the ratio of the actual power produced by the
wind turbine divided by the total wind power flowing into the turbine blades at a
particular wind speed. Cp indicates the wind turbine efficiency.
Pm=500W/0.47=1064W
4.
The torque is inversely proportional to the rotor speed. The Mpp indicates the speed
makes the wind turbine reaches the maximum power. Because the optimum speed is
the speed that makes the wind turbine reaches the maximum power point.
5.
Based on the Figures. As the rotor speed increased, Mpp of mechanical power also
increases. Because the rotor speed is proportional to the Mpp of the mechanical
power.
Yes, it does. The maximum electrical power produced by the wind turbine generator
vary in the same way as the MPP with rotor speed.
```