big experience with small wind turbines 235 swt and 15 years of operational results paul kühn iset...

Big Experience with Small Wind Turbines235 SWT and 15 Years of Operational Results

Paul Kühn

ISETInstitut für Solare Energieversorgungstechnik Kassel/ Hanau, Germany

EWEC 2007- Milan, Italy, 9 May 2007, Technical Track:Small wind turbines, distributed generation and autonomous systems

Paul Kühn

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ISET has been monitoring the development of wind energy use in Germany since 1989, in the framework of the “250 MW Wind” programme.

Operational results gathered by questionnaire (more than 1 500 WT) and measurements (200 sites) about:

• effects by external conditions

• fluctuation of fed in wind power

• economy of wind energy

• energy yields

• reliability of WT

This contribution:Operational results of 235 SWT

Evaluation Programme Wind Energy in Germany, WMEP

Paul Kühn

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40 m2 < swept area < 200 m2 swept area ≤ 40 m2

Big Experience - SWT models in the WMEP

Krogmann 15/50 Südwind N715 AEE Peters PG 10

LMW 2500Wenuns

Inventus 6Lagerwey

15/75

Paul Kühn

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0 %

50 %

100 %

1988 1990 1992 1994 1996 1998 2000 2002 2004

1 - 75 kW 76 - 499 kW 500 - 999 kW1000 - 1999 kW 2000 kW ...

data source: IWET

1. DevelopmentShare of Newly Installed WT

Big Experience - Evaluations

3. Energy YieldsSpecific Power Output

0

30

60

90

W / m2

Large WT

SWT

40 m2 < A < 200 m2

SWT

A ≤ 40 m2

2. EconomicsOperational Costs

0

5

10

15

20

ct / kWh

0

1

2

3

1 2 3 4 5 6 7 8 9 10

4. ReliabilityAnnual Failure Rate

operational year

Paul Kühn

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More than 62 000 reports concerning maintenanceand repairs:

4 200 reports from SWT

repairdowntime

cause of failure

costs

reason for report

consequenses

WMEP - Data Acquisition Maintenance and Repair Reports

Paul Kühn

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control system malfunction: 22 %

ice: 2 %

lightning: 8 %

grid failure: 4 %

storm: 10 %

unknown: 9 %

others: 10 %

loose parts: 4 %

defective parts: 31 %

Small wind turbines: both size categories

Reliability - Causes of Failure

Paul Kühn

- 7 -Reliability - Repairs

Small wind turbines: 40 m2 < swept area < 200 m2

supporting structure: 3 %

yaw mechanism: 5 %

hydraulic system: 5 %

drive train: 3 %

mechanical brake: 7 %

gear box: 5 %

control unit: 17 %

sensors: 11 %

electrical system: 26 %

generator: 5 %

rotor blades: 5 %

rotor hub: 8 %

Paul Kühn

- 8 -Reliability - Repairs

Small wind turbines: swept area ≤ 40 m2

supporting structure: 5 %

mechanical brake: 11 %

gear box: 5 %

control unit: 14 %

sensors: 6 %

electrical system: 13 %

generator: 7 %

rotor blades: 9 %

rotor hub: 23 %

yaw mechanism: 3 %drive train: 3 %

hydraulic system: 2 %

Paul Kühn

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supporting structure/ housing

drive train

gearbox

generator

hydraulic system

rotor blades

yaw system

rotor hub

mechanical brake

sensors

electronic control

electrical system

annual failure frequency downtime per failure in days

1 0,75 0,5 0,25 0 4 8 12 16 20 24

Reliability - Frequency of Failure & Related Downtime

Small wind turbines: both size categories

Paul Kühn

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technical availability 8

286

1

21

18

0

18

3

12

0

16

6

19

9

20

6 20

7

19

8

19

9

18

9

18

6

4

19

22

22

252

7

29

30

30

30

28

17

80 %

85 %

90 %

95 %

100 %

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

operational year

number of SWT reported about

40 m2 < SWT swept area < 200 m2

SWT swept area ≤ 40 m2

Small wind turbines in the WMEP

Reliability - Age Dependent Technical Availability

Large WT: 97 %

Paul Kühn

- 11 -Conclusions & Outlook

Main Barriers: Costs and Reliability

SWT @ ISET: Further Development and Optimization

Approach: Most Simple Turbine Design

Paul Kühn

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contact: pkuehn@iset.uni-kassel.de

www.iset.uni-kassel.dehttp://reisi.iset.uni-kassel.de

Electrical systems technology for the use of renewable energies and for the decentral power supply

ISET advancing energy systems

Applications-oriented R&D

• Wind Energy• Photovoltaics• Bio Energy• Hydro Power and Marine Energies• Energy Conversion and Storage• Hybrid Systems• Energy Economy

Thank you for your attention!