industrial electronics in renewable energy generation

Industrial Electronics in renewable energy generation systems

Unit 4.- Dynamic modeling of electronic converters

Semester 2 – Industrial electronics in renewable energy generation systems

Lecturer: Jorge García, [email protected]

M.Sc. In Electrical Energy Conversion and Power Systems

4.3 AC-DC conversion. AC-DC conversion. The three-phase controlled rectifier

Industrial electronics in renewable energy generation systems

mailto:[email protected]


2

Unit4.- Three-phaseconverters

4.1 DC-ACconversion.Thesingle-phaseinverterGeneralconceptsininverters.CharacteristicsandtypesHalf-bridgesquarewavesingle-phaseinverterFull-bridgesquarewavesingle-phaseinverterSine-waveformPWMmodulationOutputLCfilterandharmonicsanalysisInputfilterandDC-linkcurrent

4.2 DC-ACconversion.Thethree-phaseinverterGeneralconceptsininverters.6-pulsesinverter.Sine-waveformPWMmodulationOutputLCfilterandharmonicsanalysisInputfilterandDC-linkcurrentEffectofthedead-times.Limitations.Alternativemodulations,3rdharmonicinjection,SVPWM.

4.3 AC-DCconversion.Thethree-phasecontrolledrectifierReverseoperationofthethree-phaseinverterEquivalentsingle-phasecircuitControlofthefiltercurrentMainelectricalmagnitudesrelationsEvolutionofwaveforms


3

Gearbox Grid

WT PMSG

BasicPower Schemes

Frequencyconverter


GridPMSG

Frequencyconverter(BACKtoBACKinverter)

Filter+Transformer

BasicPower Schemes

4

Three-PhasePWMInverter


GridPMSG

Frequencyconverter(BACKtoBACKinverter)

Filter+Transformer

BasicPower Schemes

5

Three-PhasePWMInverter

Three-PhasePWMRectifier


6

uI

iI

u1

u2

u3ThePWMinverter


7

ThePWMinverteruTRI 7.0=am 15=fmuTRI

uA

uB

uAB

uREFA uREFB uREFC

uI

iI

u1

u2

u3

Theappropriatecontrol,bymeansofsine-triangleorSVMalgorithmsprovideLFoutputsinewaveforms


Overview:energyflowinDC/ACconversion

Inductive load

iS

uS

uR

uL

An inverter must be able to work in all

four quadrants

=+

-uE

iS

uS

L

R

Primary energysource

Inverter

Load

Inverter


Rectifier operation

iS

uS

uM

uL=

+

-uE

iS

uS

L

R

Primary energysource

Inverter

Load

Overview:energyflowinDC/ACconversion

Inverter


iIC

iIB

iIA

10

uO

iO

ugAuCuBuAuN

uAB

L

ugC

ugB

L

LOperation asacontrolled rectifier

C

Thesametopology,butwithoppositecurrentreferencesisarectifier.


iIC

iIB

iIA

11

uO

iO

ugAuAuN

uAB

L

ugC

ugB

L


C

Thesametopology,butwithoppositecurrentreferencesisarectifier.

EvenifallswitchesareOFF,thecircuitbehavesasathree-phasediodebridge.Thus,onstartup(ifthecontrolstageisnotoperating),thereisvoltageattheoutputoftheinverter!!!

Whichistheoperationwhenthesemiconductorareswitching?Thesinglephaseinverterwillbeconsideredfirstly

uCuB


iIA

12

uO

iO

uA

ug

L

Operation asacontrolled rectifier

CuB

Single-PhasePWMRectifier


iIA

13

uO

iO

uA

ug

L


CuB

Single-PhasePWMRectifierConsidertheoperationofoneleg.• Freq.switching>>freq.ug(t).• Ifug>0,S1L switchingatfs,D


iIA

14

uO

iO

uA

ug

L


CuB

Single-PhasePWMRectifierConsidertheoperationofoneleg.• Freq.switching>>freq.ug(t).• Ifug>0,S1L switchingatfs,D• IfS1L ON,thecurrentflowschargingtheinductanceL.


iIA

15

uO

iO

uA

ug

L


CuB

Single-PhasePWMRectifierConsidertheoperationofoneleg.• Freq.switching>>freq.ug(t).• Ifug>0,S1L switchingatfs,D• IfS1L ON,thecurrentflowschargingtheinductanceL.• IfS1H OFF,thecurrentflowstotheDClink.


iIA

16

uO

iO

uA

ug

L


CuB

iDR

uCEuO

uI

iI iO

C

L DR

iL

iC

uL uDR

iT

ISTHEOPERATIONOFTHEBOOSTCONVERTER!!!

Single-PhasePWMRectifierConsidertheoperationofoneleg.• Freq.switching>>freq.ug(t).• Ifug>0,S1L switchingatfs,D• IfS1L ON,thecurrentflowschargingtheinductanceL.• IfS1H OFF,thecurrentflowstotheDClink.


iIA

17

uO

iO

uA

ug

L


CuB

iDR

uCEuO

uI

iI iO

C

L

DRiL

iC

uL

uDR

iT

ISTHEOPERATIONOFTHEBIDIRECTIONALBOOST

CONVERTER!!!

Single-PhasePWMRectifierConsidertheoperationofoneleg.• Freq.switching>>freq.ug(t).• Ifug>0,S1L switchingatfs,D• IfS1L ON,thecurrentflowschargingtheinductanceL.• IfS1H OFF,thecurrentflowstotheDClink.• Thetwotransistorsimplybidirectionalcurrentflow(activepowerinbothdirections,reactivepower)


iIA

18

uO

iO

uA

ug

L


C

Single-PhasePWMRectifier

uB

Considertheoperationofoneleg.

iDR

uCEuO

uI

iI iO

C

L

DRiL

iC

uL

uDR

iT


CONVERTER!!!

• Freq.switching>>freq.ug(t).• Ifug>0,S1L switchingatfs,d• IfS1L ON,thecurrentflowschargingtheinductanceL.• IfS1H OFF,thecurrentflowstotheDClink.• Thetwotransistorsimplybidirectionalcurrentflow(activepowerinbothdirections,reactivepower)

• Ifug<0,theoperationisanalogous,butwiththeotherleg…


iIA

19

uO

iO

uA

ug

L


CuB

iDR

uCEuO

uI

iI iO

C

L

DRiL

iC

uL

uDR

iT


CONVERTER!!!

Thestudyofthesizeofcomponents,designofreactivecomponents,switchingscheme,dynamicmodeling,etc.hasalreadybeenseen.

Single-PhasePWMRectifierConsidertheoperationofoneleg.• Freq.switching>>freq.ug(t).• Ifug>0,S1L switchingatfs,d• IfS1L ON,thecurrentflowschargingtheinductanceL.• IfS1H OFF,thecurrentflowstotheDClink.• Thetwotransistorsimplybidirectionalcurrentflow(activepowerinbothdirections,reactivepower)

• Ifug<0,theoperationisanalogous,butwiththeotherleg…


iIC

iIB

iIA

20

uO

iO

ugAuAuN

uAB

L

ugC

ugB

L


CuCuB


iIC

iIB

iIA

21

uO

iO

ugAuAuN

L

ugC

ugB

L


CuCuB

Theper-phaseequivalentcircuitcanbeconsideredasaBOOSTconverter. iDR

uCEuO

uI

iI iO

C

L

DRiL

iC

uL

uDR

iT

However,itcanalsobeanalyzedconsideringthatthemid-pointofeachlegcanbecalculatedfromthePWMswitchingpatternoftheIGBTsatthatleg(asinaninverter)


22

Operation asacontrolled rectifier.DCBusVoltageiIA

uO

iO

ugA

L

CuL

iIB

ugBiIC

ugC


23

Operation asacontrolled rectifier.DCBusVoltage

Considerthesinglephaseequivalent

iIA

uO

iO

ugA

L

CuL

uA


24



ugA

Given a fixed value of uO, the amplitude and phase of the uAvoltage can be controlled with the PWM pattern,

iIA

uO

iO

ugA

L

CuL

uA


25



ugA

Given a fixed value of uO, the amplitude and phase of the uAvoltage can be controlled with the PWM pattern, and the controlscheme can be understood looking at the line circuit

iIA

uO

iO

ugA

L

CuL

uA


26



ugA

uAφ

Given a fixed value of uO, the amplitude and phase of the uAvoltage can be controlled with the PWM pattern, and the controlscheme can be understood looking at the input line circuit

iIA

uO

iO

ugA

L

CuL

uA


27



ugA

uAuLφ

Given a fixed value of uO, the amplitude and phase of the uAvoltage can be controlled with the PWM pattern, and the controlscheme can be understood looking at the line circuitThus, the inductor voltage, uL, can be fixed in a desired value.Therefore, the phase current, iIA, can be controlled as desired.

iIA

uO

ugA

L

CuL

uA

iO


28



( )q·cos··23

PEAKgAPEAKIAIN uiP =

OOOUT iuP ·=

ugA

uAuL

iIA

º0=q

φ


Suppose a iIA in phase with uA: There is ACTIVE power beingdrained from the grid.

Thus, the inductor voltage, uL, can be fixed in a desired value.Therefore, the phase current, iIA, can be controlled as desired.

iIA

uO

ugA

L

CuL

uA

iO


29



OOOUT iuP ·=

2··21

OuCE =

ugA

uAuL

iIA

φ

( )q·cos··23


º0=q


Suppose a iIA in phase with uA: There is ACTIVE power beingdrained from the grid. If this input power, PIN, is smaller than theoutput power, POUT, then the DC bus voltage will decrease.


iIA

uO

ugA

L

CuL

uA

iO


30



Suppose a iIA in phase with uA: There is ACTIVE power beingdrained from the grid. If this input power, PIN, is smaller than theoutput power, POUT, then the DC bus voltage will decrease.On the other hand, if PIN is greater than POUT, the DC voltage willincrease, yielding to the destruction of the capacitor/switches

OOOUT iuP ·=

2··21

OuCE =

º0=q

( )q·cos··23




iIA

uO

ugA

L

CuL

uA

iO

ugA

uL

iIA

φuA


31


A reference for the input current must be generated in a loop thatmeasures and controls the DC bus. Controlling the DC busmeans controlling the ACTIVE power drained from the grid

However, the PWM voltage uA depends on the DC bus voltage,that depends on the load (iO). Therefore, the construction of thePWM pattern to create uAmust consider this output power.

iIA

uO

ugA

L

CuL

uO(MEASURE)

PWMAT

PWMAB

uA

iO

ugA

uA

uL

iIA

φ


32



ugA

uA

uL

iIA

φ


iIA

uO

ugA

L

CuL

uO(MEASURE)

PWMAT

PWMAB

uA

iO




33


ugA

uA

uL

iIA

φ

ugAiIA

iIA

iIA-iIA(1ST-HARM)

iIA

uO

ugA

L

CuL

uO(MEASURE)

PWMAT

PWMAB

uA

iO




34


ugA

uA

uL

iIA

φ

ugAiIA

iIA

iIA-iIA(1ST-HARM)

iIA

iIA-iIA(1ST-HARM)

iIA(1ST-HARM)

ugAiIA

iIA

uO

ugA

L

CuL

uO(MEASURE)

PWMAT

PWMAB

uA

iO


θ’

35


ugA

uA

uL

iIA

φiIA’

( )q·cos··23


Additionally, provided that the DC voltage is controlled, the ACTIVE poweris fixed, but the REACTIVE power can be selected to be any desired value.



iIA

uO

ugA

L

CuL

uO(MEASURE)

PWMAT

PWMAB

uA

iO


36


ugA

uA

uL

iIA

φiIA’’θ’’

( )q·cos··23





iIA

uO

ugA

L

CuL

uO(MEASURE)

PWMAT

PWMAB

uA

iO


θ’’’

37


ugA

uA

uL

iIA

φiIA’’’

( )q·cos··23





iIA

uO

ugA

L

CuL

uO(MEASURE)

PWMAT

PWMAB

uA

iO


θ’’’

38


ugA

uA

uL

iIA

φiIA’’’

( )q·cos··23





iIA

uO

ugA

L

CuL

uO(MEASURE)

PWMAT

PWMAB

uA

iO


39


iIC

iIB

iIA

uO

iO

ugAuAuN

uAB

L

ugC

ugB

L

L

CuCuB

PSIM Simulations, for a 1100 VDC NominalDC bus voltage.What situations can be present, consideringthe input current control?

At first, the switches are turned off (operation as an uncontrolled diodebridge).At a certain instant, a fixed PWM pattern is applied (open loop)


40


VBUS

VGRID IPHASE

VGRID VPWM

VL

VDCnominal(1100VDC)

PWMSwitching,Controlled Rectifier

VGRID

VPWMVL

IPHASEφ

Noswitching,Uncontrolled Rectifier

1100VDC

θ=0º

φ=1º

620VDC

ActivePower Control

Step-upvoltage effect !!(boost converter)


41


VBUS

VGRID IPHASE

VGRID VPWM

VL

VDCSmaller than nominal(750VDC)


VGRID

VPWM VL

IPHASEφ


750VDC

θ=0º

φ=0.5º

620VDC

ActivePower Control


42


VBUS

VGRID IPHASE

VGRID VPWM

VL

VDCnominal(1100VDC)


VGRID

VPWMVL

IPHASEφ


1100VDC

θ=0º

φ=1º

620VDC

ActivePower Control

Step-upvoltage effect !!(boost converter)



43


VBUS

VGRID IPHASE

VGRID VPWM

VLVGRID

VPWM

VL

IPHASE

φ


1500VDC

θ=0º

φ=2º

620VDC

VDCgreater than nominal(1500VDC)

ActivePower Control


44


VBUS

VGRID IPHASE

VGRID VPWM

VL

VDCnominal(1100VDC)


VGRID

VPWMVL

IPHASEφ


1100VDC

θ=0º

φ=1º

620VDC

Reactive Power Control


45


VBUS

VGRID IPHASE

VGRID VPWM

VL

VDCnominal(1100VDC).Current LAG


VGRID

VPWMVL

IPHASE

φ


1100VDC

θ=85º

φ=1.2º

620VDC

Reactive Power Control


46

Operation asacontrolled rectifier.

iIC

iIB

iIA

uO

iO

ugAuAuN

uAB

L

ugC

ugB

L

L

CuCuB

• Control of the DC bus means control of the ACTIVE power• REACTIVE power is independent of the DC bus voltage, and hence ACTIVE and

REACTIVE power are fully decoupled

In addition…• At start-up, with no control of the topology, the circuit behaves like a uncontrolled

rectifier, and thus there is voltage at the capacitor.• The dynamic modeling must consider the grid inductance (and resistance, if present)

and the output capacitor, plus the load itself

CONCLUSIONS


47

Comparison with uncontroled rectifier +boost

iIC

iIB

iIA

uO

iO

ugAuAuN

uAB

L

ugC

ugB

L

L

CuCuB

Full reactive power control.The current may flow back to thegrid, even delivering activepower towards the input.BIDIRECTIONALACTIVEPOWERFLOW.


48


iIC

iIB

iIA

uO

iO

ugAuAuN

uAB

L

ugC

ugB

L

L

CuCuB

Full reactive power control.The current may flow back to thegrid, even delivering activepower towards the input.BIDIRECTIONALACTIVEPOWERFLOW.

iIC

iIB

iIA

uO

iO

ugAuN

uAB

L

ugC

ugB

L

L

C

The diode bridge does not allowthe current to flow back to thegrid.UNIDIRECTIONALACTIVEPOWERONLY.

L DR

S


49


iIC

iIB

iIA

uO

iO

ugAuAuN

uAB

L

ugC

ugB

L

L

CuCuB

In addition…• At start-up, with no control of the topology, the circuit behaves like a uncontrolled

rectifier, and thus there is voltage at the capacitor.• The dynamic modeling must consider the grid inductance (and resistance, if present)

and the output capacitor, plus the load itself• It could also be used as a inverter, delivering active power BACK to the grid (and

this cannot be done by the diode bridge+DC-DC boost topology!!!)

• Control of the DC bus means control of the ACTIVE power• REACTIVE power is independent of the DC bus voltage, and hence ACTIVE and

REACTIVE power are fully decoupled


References:“PowerElectronicsHandbook,SecondEdition:Devices,CircuitsandApplications”Editor:MuhammadH.Rashid, Ed.ElsevierInc.,2007.ISBN-10:0120884798

“PowerElectronics:Converters,ApplicationsandDesign,3rd edition”.Mohan,undeland,Robbns.JohnWiley&Sons,Inc.2003.ISBN:978-0-471-22693-2

“FundamentalsofPowerElectronics”Secondedition.RobertW.Erickson,DraganMaksimovic,Ed.SpringerScience+BusinessMedia,LLC,2001.ISBN:978-0-7923-7270-7

“Switch-ModePowerSupplies.SPICEsimulationsandPracticalDesigns”.ChristopheP.Basso.Mc Graw Hill,2008.ISBN:978-0-07-150858-2

industrial electronics in renewable energy generation

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