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.