Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Curtin & PUCRS
Fernando Soares dos Reis,
Pontifical Catholic University of Rio Grande do Sul
Syed Islam and Kelvin Tan,
Curtin University of Technology
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Table of Contents
 Introduction
 Objectives
 Power Quality
 Harmonic Characterization
 The Harmonic Mitigation Schemes
 Power Losses
 Conclusions
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
INTRODUCTION
• Permanent magnet synchronous generators (PMSG)
wind energy conversion system (WECS) using variable
speed operation is being used more frequently in wind
turbine application. Variable speed systems have
several advantages over the traditional method of
operating wind turbines, such as the reduction of
mechanical stress and an increase in energy capture.
To allow the variable speed operation of the PMSG
WECS a conventional three-phase bridge rectifier (BR)
with a bulky capacitor associated with voltage source
current controlled inverter (VS-CCI) is used.
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
INTRODUCTION
• This simple scheme introduces a high intensity low
frequency current harmonic content into the PMSG
and consequently increases the total loses in it.
Subsequently, decreases the power capability of the
system. This work presents a comparative simulation
study between three different approaches applied to
harmonic mitigation on PMSG WECS. The studied
techniques are: a) harmonic trap filters (HTF), b)
single-switch three-phase boost rectifier (PFC) and
c) PWM Boost Rectifier.
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Turbinas de 10 a 100 kW
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
WECS
Wind Energy Conversion System
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Line-commutated inverter
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Current controlled inverter
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
AC-DC Conversion
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Power Quality
• The power quality concepts are well established and
Widely applied in the relationship between utility and
consumer;
• Because it allows the maximization of the energy
resources;
• But these concepts were not normally applied to WECS
once there are studies showing that the system
efficiency is practically the some with or without
harmonics in the PMSG.
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Harmonic Characterization
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Harmonic Characterization
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
The Harmonic Mitigation Schemes

Passive Harmonic Trap Filters (HTF)
 Single-Switch Three-Phase Boost Rectifier
 Three-Phase Boost type PWM Rectifier
(AC-DC converter)
 Active Power Filter
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Passive Harmonic Trap Filters (HTF)
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Harmonic Trap Filters
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Using HTF for the 5th and 7th harmonic
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Harmonic amplitude in percent of the fundamental component
1.6
1.4
1.2
Using HTF for the 5th and 7th harmonic
PMSG output current
1.0
THD = 2.26 %
0.8
0.6
0.4
0.2
0.0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Using HTF for the 5th and 7th harmonic
PMSG output voltage
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Single-Switch Three-Phase Boost Rectifier
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Single-Switch
Three-Phase Boost Rectifier
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Three-phase PMSG output currents
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Three-phase bridge rectifier input currents
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
PMSG output current
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
PMSG output voltage
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Three-Phase Boost type PWM Rectifier
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Three-Phase Boost type PWM Rectifier
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Three-Phase Boost type PWM
Rectifier IGBT + Diode current
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Three-Phase Boost type PWM
Rectifier input currents
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
PMSG output current
0.010
Harmonic amplitude in percent of the fundamental component
0.009
0.008
THD = 0.06 %
0.007
0.006
0.005
0.004
0.003
0.002
0.001
0.000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Power Losses
 PMSG losses
 Bridge Rectifier Losses
 Harmonic Trap Filter Losses
 Semiconductor Losses
 Mechanical losses
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
PMSG losses reference circuit
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
PMSG losses
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
PMSG losses
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Conclusions
• In this work three well-known harmonic
mitigation solutions were applied to PMSG
WECS AC to DC conversion. They were the
HTF, the PFC and the PWM Boost Rectifier.
Harmonic
trap
filters
are
easily
implemented by passive components but
they are normally implemented with bulk
components.
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Conclusions
• Notwithstanding the HTF had presented the
good THD results they are not the best
solution once they are a matched solution
for a specific operation point (wind speed
and output power). The losses study also
has demonstrated that the PMSG efficiency
(η) remains practically constant and the
system η is the lowest when the HTF are
used.
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Conclusions
• For these reasons, it is not a recommended
way out to obtain harmonic mitigation on
PMSG WECS. On the other hand, the
single-switch three-phase boost rectifier
has presented encouraged results. Such
as: low current and voltage THD, simple
power topology and control circuit, can work
in all wind conditions and presents a real
reduction of the PMSG total losses.
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Conclusions
• Which allow expecting an increasing in the
PMSG lifetime without reduction of the
power capability. The main drawbacks of
this topology are a) the conduction losses in
the BR diodes and switch Q1 since the high
RMS current value caused by the DCM
operation and b) the high output voltage 1
kV. Both problems could be minimized
using proper diodes and switch like IGBT.
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Conclusions
• The PWM rectifier was studied once with
this complex converter is possible to obtain
ideal PF and THD. But the losses study has
show results very closed to that obtained
with the Single Switch Boost Converter.
The main advantage is that with this
converter is possible to work with output
voltages around 600V in spite of 1000V.
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
2.4 MW Power Plant in the Northest
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
4.8 MW Power Plant in the South (8 x 600 kW)
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
5.0 MW Power Plant in the Northest 10 x 500 kW
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
THANK YOU!
• It was a pleasure be here!
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
Three-Phase Boost type PWM
Rectifier line to line voltage
Harmonic Mitigation in Wind Turbine
Energy Conversion Systems
PMSG output voltage
100.00
Harmonic amplitude in percent of the fundamental
component
90.00
80.00
70.00
60.00
50.00
40.00
30.00
THD = 96.25 %
20.00
10.00
0.00
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