Japanese small wind turbine standard for design and structural safety. Use in complement with IEC 61400-2. Specialized for ClassNK’s Japanese certification scheme.

1. JSWTA 0001
Explanation of
Simple Load Model for VAWT
Henry Kurniadi

2. JSWTA 0001
• Japanese small wind turbine standard for design and
structural safety.
• Use in complement with IEC 61400-2.
• Specialized for ClassNK’s Japanese certification
scheme.

3. Coordinates and Axis System
• Definition of coordinate
and axis system in
Vertical Axis Wind
Turbine system.

4. Load Case A: Fatigue during Operation
• During normal operation, a range of fluctuating
loads will affect the turbine system.
• Unlike in HAWT, the fatigue loading does not
consider the effects of changing rotor rotational
speed.

5. Load Case A: Fatigue during Operation
Blade (B)
• The loading fluctuates between maximum and
minimum values, based on experimental result as a
function of TSR (λ).

6. Load Case A: Fatigue during Operation
Support Connector (S)
• The force acting on the blade handled by the support
connector. The force acting on each support connector
could be written as the radial force on the blade divided
evenly by the number of connectors (S) for each blade.
• The torsional moment generated from rotor design
torque, which divided evenly by each connector on each
blade.

7. Load Case A: Fatigue during Operation
Shaft (shaft)
• The torsional moment of the rotor shaft is equal to the rotor design
torque.
• Rotor thrust generated during operation is a function of design
wind speed.
• Bending moment of the rotor shaft determined by the thrust and
the distance of the main bearing to the rotor center. (2 is the
multiplying factor)

8. Load Case D: Maximum Thrust
• This is a maximum thrust applied to the shaft during
normal operation regime.
• Similar assumption with HAWT.

9. Load Case D: Maximum Thrust
Shaft (shaft)
• The thrust load consist of aerodynamic coefficient
and dynamic pressure.
• Bending moment of the rotor shaft determined by
the thrust and the distance of the main bearing to
the rotor center.

10. Load Case E: Maximum Rotation Speed
• This load case represents the maximum operation
condition.
• Similar assumption with HAWT with load case
definition dominated by the maximum rotational
speed.

11. Load Case E: Maximum Rotation Speed
Blade (B)
• The load to each blade purely centrifugal force.

12. Load Case E: Maximum Rotation Speed
Support Connector (S)
• The force acting on the blade handled by the support
connector. The force acting on each support
connector could be written as the radial force on the
blade divided evenly by the number of connectors (S)
for each blade.

13. Load Case E: Maximum Rotation Speed
Shaft (shaft)
• The loading to rotor shaft is a bending moment. It is
assumed that there is an eccentricity in the rotor
shaft.

14. Load Case F: Shorted Connection
• This load case represent the short circuit condition.
• Similar assumption with HAWT.

15. Load Case F: Shorted Connection
Shaft (shaft)
• The torsional moment to the rotor shaft due to
generator short circuit. It is a function of the rotor
design torque.

16. Load Case F: Shorted Connection
Support Connector (S)
• The torsional moment to support connector
calculated from rotor torsional moment, which
divided evenly by each connector on each blade.

17. Load Case G: Braking
• This represents the braking action of the turbine
system.
• Similar assumption with HAWT.

18. Load Case G: Braking
Shaft (shaft)
• The torsional moment applied to the rotor shaft
during braking assumed to be the sum of the brake
torque and the rotor design torque.

19. Load Case G: Braking
Support Connector (S)
• Similar to previous Load Case, the torsional moment
to support connector calculated from rotor torsional
moment, which divided evenly by each connector on
each blade.

20. Load Case H: Extreme Wind
• In this load case, the turbine is not working and
exposed to extreme wind condition.
• Similar assumption with HAWT.

21. Load Case H: Extreme Wind
Blade (B)
• The blade is in standby situation.
• The force applied directly from the wind in X-direction.
• The aerodynamic loading applied to the blade consist of lift and drag and
located in Y-direction.
• All loads are function of the blade projection area.

22. Load Case H: Extreme Wind
Support Connector (S)
• The force acting on the blade handled by the support
connector. The force acting on each support connector
could be written as the applied force on the blade divided
evenly by the number of connectors (S) for each blade.
• The bending moment applied in each support connector
is a function of the connector length.

23. Load Case H: Extreme Wind
Shaft (shaft)
•
•
•
Wind load to rotor generated by the drag acting on the blade.
Largest bending moment applied to the first bearing.
The torsional moment to the rotor shaft caused by rotational force applied to the blade.