Power Electronic Converter

1
Wind Turbine Systems Based
on
Power Electronics Converters
Presented by-
Anas Ali Usmani
Sharique Ahmad
Rahul Singh

Contents
 Introduction
 Wind energy
 Need of PE converters
 Wind Energy Conversion
 Modern Power Electronic
 Wind turbine concepts
 Commonly used converters
 Conclusion
 References
2

Introduction
 Most promising renewable energy technology .
 Steady growth of installed wind power reached to
250GW .
 Started in the 1980s with a few tens of kW power
production per unit .
 Today multi-MW size wind turbines are being installed.
 Regulating the frequency and voltage in grid become
important.
3

Wind energy
fig 1:Annual Global cumulative installed wind power capacity
4

 Aim is to achieve 100% non fossil in 2050
fig 2:Wind Power Capacity till 2014 5

Wind power in India
 India has the fifth largest installed wind power capacity
in the world.
 As of 31 March 2015 the installed capacity of wind
power in India was 22644.63 MW

 fig 3: India Wind power Generation Capacity By year
6

 Wind power has until now grown to a cumulative worldwide
installation level of 320 GW.
 The worldwide penetration of wind power electricity was
1.8%, and the prediction for 2019 is more than 8%.
7
Fig 4: Wind turbine market share distributed by manufacturers in 2014.

Demand of Power electronics
converters
fig 5: Trend of power electronic conversion in last 30 year 8

 Use of power electronics is growing continuously in wind
turbine system.
 In 1980s, used as Thyristor based soft starter.
 In 1990s, used as rotor resistance control with diode
rectifier and a Power Electronic switch.
 Finally, Back to Back power converter emerged, first in
reduced then in full mode power for DFIG.
9

Wind Energy Conversion
 systems convert wind energy into electrical energy, which is
then fed into the grid.
 fig 6 : Block diagram of wind energy conversion
10

 The turbine rotor, gear box and generator are the main
three components for energy conversion.
 Rotor converts wind energy to mechanical energy.
 Gear box is used to adapt to the rotor speed to generator
speed.
 Generator with the variable speed wind turbine along with
electronic inverter absorbs mechanical power and convert
to electrical energy.
 The power converter can not only transfer the power from
a wind generator, but also improve the stability and safety
of the system.
11

Modern Power Electronics
 The interface of Wind power converter between
generator and power grid should satisfy the
requirements on both the sides.
 It has to store the active power and boost up the
voltage from generator side to grid side.
fig 7 : wind turbine system with power converter
12

 Generator side:
 It should control stator current and adjust the rotating
speed.
 Extract maximum power from turbine
 Power grid side:
 Ability to control the inductive/capacitive reactive
power and perform fast active power response.
 Frequency and voltage should be fixed for normal
operation
 Harmonic distortion should be maintained low 13

Doubly Fed Induction Generator
14fig 8: Basic diagram Doubly Fed Induction Generator

 Wind turbines generally use a doubly-fed induction
generator (DFIG) consisting of a wound rotor , induction
generator and an AC/DC/AC IGBT-based PWM converter.
 The stator winding is connected directly to the grid
while the rotor is fed at variable frequency through the
AC/DC/AC converter.
 Vr is the rotor voltage and Vgc is grid side voltage
 To control the speed of wind turbine gear boxes or
electronic control can be used
15

Wind Turbine concepts
 fixed speed wind turbines use induction generators.
 Since the frequency of the grid is fixed to 50 or 60Hz, so the speed
of the turbine is controlled by the gearbox gears ratio.
fig 9: Fixed Speed method 16

Variable speed wind turbine
 It has more complicated system than the fixed wind
turbine system.
 The system uses an optically controlled converter which
varies the resistance of the rotor in the generator.
fig 10: Variable speed with variable rotor resistance
17

Variable speed WT with partial scale
frequency converter
 The power rating of this PSFC define the speed range (typically 30% of
synchronous speed).
 This converter performs reactive power compensation .
18
Fig 10: variable speed wind turbine concepts with partial-scale frequency converter.

Variable speed WT with full scale
power converter
 The full scale power converter performs the reactive
power compensation for entire speed range.
 The generator can be asynchronous generator or PMSG.
19Fig 11: Variable speed wind turbine concepts with Full-scale power converter.

Commonly used power converters
20
Unidirectional Power converters
fig 12 : full rated power converter
 Because of permanent magnets active power flows only from
generator to grid.
 For variable speed, dc/dc Buck-Boost converter is used.

 Two current source converters in back to back
connection.
 The advantage of proposed solution can be exploit
the inductance of long cable in wind park
fig 13 : full rated power converter
21

Two level Power converters
Fig 14 : Two level back to back source converter
 Most frequently used three phase power converter topology.
 Two 2L-PWM-VSCs are placed back to back.
 Robust and reliable but larger switching losses
22

Multi level converters
Neutral point diode clamped structure
23
fig 15: 3-level neutral point clamped converter for wind turbine
 for higher power and voltage rating.
 It achieves one more output level
 loss distribution is unequal

Advantages of PE converters
 Generator side:
1. Controllable ‘I’
2. Variable frequency and o/p voltage.
 Grid side:
1. Fast power response
2. Controllable ‘Q’
3. Frequency and voltage stabilization
4. Low THD
24

Conclusion
 Modern trend is that the technology is moving toward a higher power
level.
 Reliability at higher power levels is also being considered.
 The use of a multi cell approach in the power converter design to reduce
loss.
25

References
26
[1] M. Liserre, R. Cardenas, M. Molinas, and J. Rodriguez, “Overview of multi-
MW wind turbines and wind parks,” IEEE Trans. Ind. Electron., vol. 58, no. 4,
Apr. 2011.
[2] Frede Blaabjerg, Marco Liserre, Ke Ma, “Power Electronics Converters for
Wind Turbine Systems”, IEEE transactions on industry applications, vol. 48, no.
2, march/april 2012.
[3] F. Blaabjerg, Z. Chen, S.B. Kjaer, “Power Electronics as Efficient Interface
in Dispersed Power Generation Systems”, IEEE Trans. on Power Electronics,
2004, Vol. 19, no. 4, pp. 1184-1194.
[4] B. Wu, Y. Lang, N. Zargari, and S. Kouro, Power Conversion and Control of
Wind Energy Systems. Hoboken, NJ: Wiley, 2011.
[5] S.M BARAKATI, M.KAZERANI, “A New Wind Turbine Generation System Based
on Matrix Converter ” IEEE Trans.Ind,no.5,2012

Power Electronic Converter

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