C u r t i n & P U C R S

Harmonic Mitigation in Wind Turbine Harmonic Mitigation in Wind Turbine Energy Conversion Systems Energy Conversion Systems

C u r t i n & P U C R SC u r t i n & P U C R S

Fernando Soares dos Reis, Fernando Soares dos Reis, Pontifical Catholic University of Rio Grande do SulPontifical Catholic University of Rio Grande do Sul

Syed Islam and Kelvin Tan, Syed Islam and Kelvin Tan, Curtin University of TechnologyCurtin University of Technology


Table of ContentsTable of Contents

Introduction Introduction ObjectivesObjectives Power QualityPower Quality Harmonic Characterization Harmonic Characterization The Harmonic Mitigation SchemesThe Harmonic Mitigation Schemes Power LossesPower Losses ConclusionsConclusions


INTRODUCTIONINTRODUCTION

• Permanent magnet synchronous generators (PMSG) Permanent magnet synchronous generators (PMSG) wind energy conversion system (WECS) using variable wind energy conversion system (WECS) using variable speed operation is being used more frequently in wind speed operation is being used more frequently in wind turbine application. Variable speed systems have turbine application. Variable speed systems have several advantages over the traditional method of several advantages over the traditional method of operating wind turbines, such as the reduction of operating wind turbines, such as the reduction of mechanical stress and an increase in energy capture. To mechanical stress and an increase in energy capture. To allow the variable speed operation of the PMSG WECS allow the variable speed operation of the PMSG WECS a conventional three-phase bridge rectifier (BR) with a a conventional three-phase bridge rectifier (BR) with a bulky capacitor associated with voltage source current bulky capacitor associated with voltage source current controlled inverter (VS-CCI) is used. controlled inverter (VS-CCI) is used.


INTRODUCTIONINTRODUCTION

• This simple scheme introduces a high intensity low This simple scheme introduces a high intensity low frequency current harmonic content into the PMSG frequency current harmonic content into the PMSG and consequently increases the total loses in it. and consequently increases the total loses in it. Subsequently, decreases the power capability of the Subsequently, decreases the power capability of the system. This work presents a comparative simulation system. This work presents a comparative simulation study between three different approaches applied to study between three different approaches applied to harmonic mitigation on PMSG WECS. The studied harmonic mitigation on PMSG WECS. The studied techniques are: a) harmonic trap filters (HTF), b) techniques are: a) harmonic trap filters (HTF), b) single-switch three-phase boost rectifier (PFC) and single-switch three-phase boost rectifier (PFC) and c) PWM Boost Rectifier.c) PWM Boost Rectifier.


Turbinas de 10 a 100 kWTurbinas de 10 a 100 kW


WECS WECS Wind Energy Conversion SystemWind Energy Conversion System


Line-commutated inverter Line-commutated inverter


Current controlled inverter Current controlled inverter


AC-DC ConversionAC-DC Conversion


Power QualityPower Quality

• The power quality concepts are well established and The power quality concepts are well established and Widely applied in the relationship between utility and Widely applied in the relationship between utility and consumer;consumer;

• Because it allows the maximization of the energy Because it allows the maximization of the energy resources;resources;

• But these concepts were not normally applied to WECS But these concepts were not normally applied to WECS once there are studies showing that the system once there are studies showing that the system efficiency is practically the some with or without efficiency is practically the some with or without harmonics in the PMSG.harmonics in the PMSG.


Harmonic CharacterizationHarmonic Characterization


Harmonic CharacterizationHarmonic Characterization




The Harmonic Mitigation SchemesThe Harmonic Mitigation Schemes

Passive Harmonic Trap Filters (HTF)Passive Harmonic Trap Filters (HTF) Single-Switch Three-Phase Boost RectifierSingle-Switch Three-Phase Boost Rectifier Three-Phase Boost type PWM Rectifier Three-Phase Boost type PWM Rectifier

(AC-DC converter)(AC-DC converter) Active Power FilterActive Power Filter


Passive Harmonic Trap Filters (HTF)Passive Harmonic Trap Filters (HTF)


Harmonic Trap FiltersHarmonic Trap Filters


Using HTF for the 5Using HTF for the 5thth and 7 and 7th th harmonicharmonic


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THD = 2.26 %

Harmonic amplitude in percent of the fundamental component


PMSG output currentPMSG output current



PMSG output voltagePMSG output voltage



Single-Switch Three-Phase Boost RectifierSingle-Switch Three-Phase Boost Rectifier


Single-Switch Single-Switch Three-Phase Boost RectifierThree-Phase Boost Rectifier


Three-phase PMSG output currents Three-phase PMSG output currents


Three-phase bridge rectifier input currents Three-phase bridge rectifier input currents






Three-Phase Boost type PWM RectifierThree-Phase Boost type PWM Rectifier


Three-Phase Boost type PWM RectifierThree-Phase Boost type PWM Rectifier


Three-Phase Boost type PWM Three-Phase Boost type PWM Rectifier IGBT + Diode currentRectifier IGBT + Diode current


Three-Phase Boost type PWM Three-Phase Boost type PWM Rectifier input currents Rectifier input currents



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THD = 0.06 %



Power LossesPower Losses

PMSG lossesPMSG losses Bridge Rectifier LossesBridge Rectifier Losses Harmonic Trap Filter LossesHarmonic Trap Filter Losses Semiconductor LossesSemiconductor Losses Mechanical lossesMechanical losses


PMSG losses reference circuitPMSG losses reference circuit


PMSG lossesPMSG losses


PMSG lossesPMSG losses


ConclusionsConclusions

• In this work three well-known harmonic In this work three well-known harmonic mitigation solutions were applied to PMSG mitigation solutions were applied to PMSG WECS AC to DC conversion. They were WECS AC to DC conversion. They were the HTF, the PFC and the PWM Boost the HTF, the PFC and the PWM Boost Rectifier. Harmonic trap filters are easily Rectifier. Harmonic trap filters are easily implemented by passive components but implemented by passive components but they are normally implemented with bulk they are normally implemented with bulk components. components.


• Notwithstanding the HTF had presented the Notwithstanding the HTF had presented the good THD results they are not the best good THD results they are not the best solution once they are a matched solution solution once they are a matched solution for a specific operation point (wind speed for a specific operation point (wind speed and output power). The losses study also and output power). The losses study also has demonstrated that the PMSG efficiency has demonstrated that the PMSG efficiency ((ηη) remains practically constant and the ) remains practically constant and the system system ηη is the lowest when the HTF are is the lowest when the HTF are used. used.



• For these reasons, it is not a recommended For these reasons, it is not a recommended way out to obtain harmonic mitigation on way out to obtain harmonic mitigation on PMSG WECS. On the other hand, the PMSG WECS. On the other hand, the single-switch three-phase boost rectifier single-switch three-phase boost rectifier has presented encouraged results. Such has presented encouraged results. Such as: low current and voltage THD, simple as: low current and voltage THD, simple power topology and control circuit, can power topology and control circuit, can work in all wind conditions and presents a work in all wind conditions and presents a real reduction of the PMSG total losses.real reduction of the PMSG total losses.



• Which allow expecting an increasing in the Which allow expecting an increasing in the PMSG lifetime without reduction of the PMSG lifetime without reduction of the power capability. The main drawbacks of power capability. The main drawbacks of this topology are a) the conduction losses in this topology are a) the conduction losses in the BR diodes and switch Q1 since the high the BR diodes and switch Q1 since the high RMS current value caused by the DCM RMS current value caused by the DCM operation and b) the high output voltage 1 operation and b) the high output voltage 1 kV. Both problems could be minimized using kV. Both problems could be minimized using proper diodes and switch like IGBT. proper diodes and switch like IGBT.



• The PWM rectifier was studied once with this The PWM rectifier was studied once with this complex converter is possible to obtain ideal complex converter is possible to obtain ideal PF and THD. But the losses study has show PF and THD. But the losses study has show results very closed to that obtained with the results very closed to that obtained with the Single Switch Boost Converter. The main Single Switch Boost Converter. The main advantage is that with this converter is advantage is that with this converter is possible to work with output voltages around possible to work with output voltages around 600V in spite of 1000V.600V in spite of 1000V.











2.4 MW Power Plant in the Northest2.4 MW Power Plant in the Northest


4.8 MW Power Plant in the South (8 x 600 kW)4.8 MW Power Plant in the South (8 x 600 kW)


5.0 MW Power Plant in the Northest 10 x 500 kW5.0 MW Power Plant in the Northest 10 x 500 kW


THANK YOU!THANK YOU!

• It was a pleasure be here!It was a pleasure be here!


Three-Phase Boost type PWM Three-Phase Boost type PWM Rectifier line to line voltage Rectifier line to line voltage



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THD = 96.25 %


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