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SWT Wind Turbine SWT Wind Turbine Generator RangeGenerator Range
Wind Turbine Output Variables
The primary goal for a wind turbine is to:
• Produce the maximum kWh’s in a given time period at a given location
• At the most reasonable cost
Potential for Higher Efficiency
AWEA in 2009 identified 3 main areas:
Now PotentialBlade design 32% 42-45%Generators 65-80% 90-92%*Inverters 90+% not much
*GMI design efficiencies for the 10, 20 & 40 kW models are 94%, 95.5% and 96.5% respectively, already higher than AWEA’s target for improvement.
Key GMI Design Principals
To get a higher power to weight generator it is necessary to increase the diameter of the generator which increases the output to the square of the diameter increase.
In traditional PMG generators this can be limited by the extra weight imposed by the requirement of increased internal structural re-enforcement.
The GMI design turns the generator in on itself resulting in this limiting point being ‘pushed’ further up the scale
The result is a lighter weight, smaller, more efficient generator.
Generator ModelsAs per the SWT brief, GMI has designed a
family of wind turbine generators based on GMI’s core technology, three models are being developed:
G101-10 G102-20 G103-40
To ensure the widest range of applications, these models have been optimised for outputs of 10, 20 and 40 kW.Reflected by the last two digits in the model designation codes
Model Propeller Ranges(12m/s wind and 40% efficient props)
5.5-9 m dia
8-13m dia
11.5-17.5 m dia
G102-20
Model Output Ranges(12m/s wind and 40% efficient props at various
prop diameters)
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
90.00
100.00
G101-10 G102-20 G103-40
Output in kw
20-47kW
42-89kW
9.5-22kW
Design Constants
Output increases to the square of the diameter increase
- OR -
Output increases directly proportional to the length.
Key Generator Loss Principles
There are three key types of generator losses:
Iron Losses
Copper Losses
Friction and Winding Losses
Copper Losses
Copper losses are related to generator RPM.
Copper losses = I squared r
r = resistance of windingsI = current
Iron Loss PrinciplesAre related to the generator rpm and
pole numbersReduction of iron losses leads to a
steeper efficiency curveIncreasing the generator stack length
results in a proportional increase in iron losses
Iron losses increase to the square of the rpm
Iron losses increase to the square of the number of generator poles
Iron Loss Calculation
Iron Losses = (frequency/50)^2 x iron quality constant x weight of stator laminations
Frequency = (rpm/3000x50) x number of poles/2
Overall Loss PrinciplesPractical implementation of these principles in the design process for a generator means:
•Increasing the efficiency of a generator from 90-95% you need to be able to halve the iron losses
•To further increase efficiency from 95-97.5% it is necessary to halve the iron losses again.