Power Electronics in Wind Energy Application- Power Converters

1. power Electronics In winD energy
Conversion System
By
Vimal Mayakrishnan
Senior Specialist
Converter - Generator
Senvion India PVT LTD
Bangalore
Two most abundant forms of power on earth are solar
and wind….

2. NEED TO CHANGE PERCEPTIONS…

3. Content
• Introduction to Wind Energy systems
• Electrical drive train components
• Design considerations
• Generator
• Converter
• Cable
• Transformer

4. AN INTRODUCTION TO WIND ENERGY SYSTEMS
• Wind has considerable amount of Kinetic energy
Kinetic
energy of the
wind
Mechanical
energy on the
rotor
Electrical
energy on
the grid
Energy Flow diagram:

5. ARCHITECTURE OF WIND ENERGY SYSTEMS

6. Growth in installed capacity till 2020

7. Largest wind turbines Planned and
Commissioned
• Gold Wind – 16MW –Planned - offshore
• Rotor Dia 252 m
• Mingyang – 16MW - planned – offshore(MySE 16.0-242)
• Height: 866 feet (264 m)
• Blade length: 387 feet (118 m)
• Rotor diameter: 794 feet (242 m)
• Vestas – 15MW -V236-15.0MW –offshore planned
• Rotor diameter: 236 m
• SGRE – 14MW- SG 14-222 – offshore - planned
• Rotor diameter: 222 m
• GE – 14MW - Haliade-X 14 MW – offshore – Operating
• Rotor diameter: 220 m
• Height: 260 m

8. Type A : Fixed speed turbines
SCIG
Soft Starter
Capacitor Bank
Transformer
Grid
G Box
Turbine
• Asynchronous Generator
• Direct grid connection (use soft-starter for smoother grid connection)
• SCIG draws reactive power, so capacitor bank is used for VAr
compensation
• Wind fluctuations = power fluctuations = voltage fluctuations
• Type A0: stall control Type A1: pitch control Type A2: active stall
control

9. Type B : Limited variable speed turbines
Variable
Resistance
Soft Starter
Capacitor Bank
Transformer
Turbine
G Box
Grid
WRIG
• Asynchronous Generator with variable resistance control
• Direct grid connection (use soft-starter for smoother grid connection)
• SCIG draws reactive power, so capacitor bank is used for VAr
compensation
• Variable resistance control = slip control = power control
• Power control smooths out effect of wind fluctuations

10. Type C : Limited variable speed with partial size
converter
Transformer
Turbine
G Box
Grid
WRIG
Transformer
Inverter 1/3 Size
• Known more commonly as Doubly Fed Induction Generator DFIG
• Inverter rated at 1/3 power
• Inverter performs VAr compensation and soft-start function
• Smooths out effect of wind fluctuations
• Wider wind speed range than fixed speed = more energy capture
• Drawbacks: slip rings, protection in case of grid faults

11. Type D : Variable speed with full size converter
Transformer
Turbine
G Box
Grid
Inverter Full Size
SCIG / PMG
• Full size inverter - IGBT devices
• Inverter provides VAr compensation and smooth grid connection
• More efficient energy capture
• Generator completely isolated from grid I.e. from grid faults
• Mechanics decoupled from grid - longer gearbox life
• Choice of generator types (change inverter control software)
• Can eliminate gearbox to have direct driven generator e.g. PMG

12. Wind energy power conversion options

13. Wind Converter
• The power converter can not only transfer the power from a wind
generator, but also improve the stability and safety of the system.
Full power converter ( SCIM, Sync Gen)
Partial converter (DFIG)

14. Diode converter on machine side

15. Full & Partial converter
3 phase rotor
Supply system
PWM inverter
Run
contactors
Gearbo
x
PWM inverter

16. Converter Power Circuit
• Power circuit ( IGBT, DC capacitors and line reactors(grid &
Machine side))
• Filter ( PWM filter and DV/DT filter)
• Reactors ( grid side reactor and current sharing)
• DC link
• Dynamic Braking (chopper) and resistors
• Switching Components (Circuit breaker and contactor)
• Pre-charge Circuit
• Bus bar and cables

17. Converter Power Circuit
Converter Power Circuit SLD

18. 2 level and 3 level converters

19. Converter power can be increased by
paralleling the converters
| day month year
| 19

20. IGBT and power circuit

21. Chopper circuit in wind converter

22. Crow bar circuit in wind converter

23. PWM Filter

24. DV/DT Filter

25. PWM filter Function
 To maintain supply voltage quality to within acceptable limits by
providing a shunt path for distorting currents caused by PWM voltage
 The filter must also withstand any further pre-defined distortion that
may be present on the grid
 Typically 5th and 7th type harmonics
 The design of the filter is dependent upon:
Switching frequency of the PWM source

26. DC bus capacitors will be place to the back side
of power modules

27. Converter Control circuit

28. DFIG Control Circuit

29. Control Strategies
• Motor Control (FOC or DTC )
• Sensor less vector control
• Indirect vector control
• PWM methods
• SPWM
• 3rd harmonic injection
• Space vector modulation
• Advanced space vector modulation
• Various controllers
• DSP control
• Industrical PC (Beckoff or B&R controller)

30. Teams involve to develop a Power converter
Hardware Engineering
Control engineering
Modelling and simulation
Electrical Calculation
Other requirement ( mechanical, cooling, interfacing and SCADA)

31. Thank you for your attention