The Harmonic Distortion Reduction of Phase-Angle Fired SCRs Feeding a Resistive Load using ...

100 Pages·2016·3 MB·English

by  Matthew A. Clark

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Matthew A. Clark
Wright State University
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The Harmonic Distortion Reduction of Phase-Angle
Fired SCRs Feeding a Resistive Load using Fuzzy
Logic
A thesis submitted in partial fulfillment
of the requirements for the degree of
Master of Science in Engineering
by
Matthew A. Clark
B.S.E.E, Wright State University, 2000
2010
Wright State University
WrightStateUniversity
SCHOOLOFGRADUATESTUDIES
April12,2010
I HEREBY RECOMMEND THAT THE THESIS PREPARED UNDER MY SUPER-
VISIONBYMatthewA.ClarkENTITLEDTheHarmonicDistortionReductionofPhase-Angle
Fired SCRs Feeding a Resistive Load using Fuzzy Logic BE ACCEPTED IN PARTIAL
FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF Master of Science
inEngineering.
KuldipS.Rattan,Ph.D.
ThesisDirector
KefuXue,Ph.D.
DepartmentChair
Committeeon
FinalExamination
KuldipS.Rattan,Ph.D.
MarianKazimierczuk,Ph.D.
XiaodongZhang,Ph.D.
JohnA.Bantle,Ph.D.
VicePresidentforResearchand
GraduateStudiesandInterimDean
ofGraduateStudies
ABSTRACT
Clark,Matthew. M.S.Egr.,,WrightStateUniversity, 2010. TheHarmonicDistortionReductionof
Phase-AngleFiredSCRsFeedingaResistiveLoadusingFuzzyLogic.
High power silicon controlled rectifiers (SCR) are used in the application of infrared
radiation testing. A case study has been performed on a department of defense facility
utilizing SCRs to transfer electrical energy to thermal energy. The facility is capable of
generating up to 5000◦F across large cross-sectional areas, requiring tens of megawatts
of power. The combination of high power, unbalanced loads, and SCR switching gen-
erate high harmonic disturbances that offer significant challenges for conventional linear
control systems. In addition, unbalanced three-phase distribution systems are difficult to
model, specifically during switching transients. Fuzzy logic is used to characterize the
non-linearplantdynamics,controlthesystemoutput,andreduceharmonics. Althoughthe
use of fuzzy logic for harmonic reduction has been used extensively in the power industry,
most applications focus on compensating for harmonic disturbance rather than avoiding it.
Harmonic compensation adds hardware in the system, which adds maintenance costs and
inefficiency. This thesis introduces a technique to eliminate harmonic content in the con-
trol loop without adding additional hardware. A simulation of the system was created and
fuzzylogicwasusedtocharacterizethebehaviorofthesimulation. Thesimulationresults
demonstrated the non-linear control problem and identified key harmonic areas to avoid.
A fuzzy proportional-integral controller along with a fuzzy harmonic reduction controller
is implemented in this thesis to improve the control response while avoiding harmful har-
monic interference. The fuzzy harmonic reduction controller yielded a hybrid pulse width
modulation output that eliminated the most harmful harmonics while maintaining closed
loopcontrol.
iii
List of Symbols
Chapter 1
Q HeatFlux
A Areaofaradiatingbody
(cid:15) Emissivity
σ Stefan-Boltzmanconstant5.67x10−8W/m2K4
iv
Contents
1 Introduction 1
1.1 ProblemDefinition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 ProposedSolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2 SignificanceofResearch 11
2.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.1.1 CaseStudyBackground . . . . . . . . . . . . . . . . . . . . . . . 11
2.1.2 CaseStudyRequirements . . . . . . . . . . . . . . . . . . . . . . 14
2.2 HarmonicMitigationOptions . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.2.1 ImplementPassiveCircuits . . . . . . . . . . . . . . . . . . . . . . 18
2.2.2 Multi-phasingofLoadviaanIGBT . . . . . . . . . . . . . . . . . 18
2.2.3 SwitchtheSCRstoZero-CrossTechnology . . . . . . . . . . . . . 18
2.2.4 ActiveLineCompensation . . . . . . . . . . . . . . . . . . . . . . 19
3 SystemModeling 21
3.1 TheSiliconControlledRectifier . . . . . . . . . . . . . . . . . . . . . . . 21
3.2 TheTransformerandTotalLoads . . . . . . . . . . . . . . . . . . . . . . . 26
4 IntroductiontoFuzzyLogic 30
4.1 FuzzySets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
4.2 FuzzyPartitioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
4.3 Linguisticvariables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4.4 FuzzyRules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.5 FuzzyControl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
5 FuzzyLogicImplementation 40
5.1 PlantCharacterizationusingFuzzyLogic . . . . . . . . . . . . . . . . . . 40
5.2 ThePIControllerImplementation . . . . . . . . . . . . . . . . . . . . . . 51
5.2.1 TheRadiantHeatSystemPlant . . . . . . . . . . . . . . . . . . . 51
5.2.2 TheInitialLinearController . . . . . . . . . . . . . . . . . . . . . 59
5.2.3 TheFuzzyPIController . . . . . . . . . . . . . . . . . . . . . . . 64
5.3 TheFuzzyHarmonicReductionController . . . . . . . . . . . . . . . . . 69
v
6 Conclusions 79
Bibliography 81
7 AppendixA:MatlabCode 84
vi
List of Figures
1.1 Singlephase,phaseanglefiredSCRrepresentativecircuit. . . . . . . . . . 2
1.2 Representative circuit of three single phase SCRs connected in a Delta
Loadconfiguration,fedbyaDeltatransformer. . . . . . . . . . . . . . . . 3
1.3 RMSPowerofuncontrolledsinglephaseignitronwithgraphiteheaterload. 4
1.4 Result of SCR prematurely turning off due to phase A and B combined
transientspike. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.5 Result of SCR prematurely turning on due to phase A and B combined
transientspike. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.6 LinesidetransientsfromSCRfiringatcomplementaryphases45,90,135 ◦. 6
1.7 LoadsidetransientsfromSCRfiringatcomplementaryphases45,90,135 ◦. 7
1.8 GASMGSchematicofa600Vdelta-deltatransformeranddeltaloads. . . . 8
2.1 Graphiteheaterarray. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.2 Quartzheaterarray. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.3 SimultatedtransformervariancesofTHDgivenbytheavailableKVA. . . . 17
3.1 SimulatedSCRusingidealswitch. . . . . . . . . . . . . . . . . . . . . . . 23
3.2 ZeroCrossDetectionforSCRtriggering. . . . . . . . . . . . . . . . . . . 27
3.3 OnedimensionalmodelrepresentationoftransientTURNONcurrenteffects. 28
3.4 GraphofsinglephaselineandloadvoltageswithandwithoutSCRsnubber
present. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
3.5 FullthreephaseDelta-Deltatransformer. . . . . . . . . . . . . . . . . . . . 29
4.1 Comparisonofconventionalandfuzzysets[1]. . . . . . . . . . . . . . . . 31
4.2 Complementofafuzzyset[1]. . . . . . . . . . . . . . . . . . . . . . . . . 32
4.3 Unionoftwofuzzysets[1]. . . . . . . . . . . . . . . . . . . . . . . . . . 32
4.4 Intersectionoftwofuzzysetsusingtheproductmethod[2]. . . . . . . . . . 33
4.5 FuzzypartitioningofaphaseanglespaceU. . . . . . . . . . . . . . . . . . 34
4.6 Fuzzylinguisticvariablesofcoffeepouringrate[1]. . . . . . . . . . . . . . 35
4.7 Blockdiagramofthefuzzycontroller[2]. . . . . . . . . . . . . . . . . . . 36
4.8 Anexampleoffuzzification. . . . . . . . . . . . . . . . . . . . . . . . . . 37
4.9 Min-Maxmethodofinferencetoproducefuzzysets[1]. . . . . . . . . . . 38
5.1 Representationoftheplantinputsandoutputs. . . . . . . . . . . . . . . . . 41
vii
5.2 Representationoftheplantinputfuzzification. . . . . . . . . . . . . . . . . 41
5.3 Representationoftheplantoutputfuzzification. . . . . . . . . . . . . . . . 41
5.4 Fuzzificationofcrispphaseanglevalues. . . . . . . . . . . . . . . . . . . 43
5.5 Fuzzificationofcrisp%V errorvalues. . . . . . . . . . . . . . . . . . 44
RMS
5.6 FuzzificationofcrispTHDvalues. . . . . . . . . . . . . . . . . . . . . . . 44
5.7 V vsphaseα withvariedloads. . . . . . . . . . . . . . . . . . . . . . 45
RMS
5.8 %V errorofeachtransformerphasevsSCRphaseanglecombinations. 46
RMS
5.9 THD ofeacheachtransformerphasevsSCRphaseanglecombinations. . . 47
5.10 Standard deviation of %V error of each transformer phase vs SCR
RMS
phaseanglecombinations. . . . . . . . . . . . . . . . . . . . . . . . . . . 48
5.11 THD vsphaseα withvariedloads. . . . . . . . . . . . . . . . . . . . . . . 50
5.12 THD ofeachφvsphaseα withasinglephase400KWload. . . . . . . . . 51
5.13 RepresentativeSCRinnerloop. . . . . . . . . . . . . . . . . . . . . . . . . 52
5.14 Representativeheattransferfromheatingelementtotestarticle. . . . . . . 53
5.15 Representative heat transfer from heating element to test article resultant
graph. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
5.16 OpenloopplantwithSCR,heater,andsimulatedplant. . . . . . . . . . . . 55
5.17 RepresentativeSCRinnermodel. . . . . . . . . . . . . . . . . . . . . . . . 56
5.18 Drive%vs. T (◦F). . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
element
5.19 V andP withrespecttodrive%. . . . . . . . . . . . . . . . . . . . 58
RMS RMS
5.20 Simulinkmodeloftherepresentativeanalogcontrolsystem . . . . . . . . . 59
5.21 Rootlocusoftheopenlooptransferfunction . . . . . . . . . . . . . . . . 60
5.22 Simulinkmodeloftheanalogcontrolsystem . . . . . . . . . . . . . . . . 63
5.23 ResultantresponseoftheclosedloopclassicPIcontrolsystem. . . . . . . . 64
5.24 FuzzyPIcontrollerimplementationinSimulink. . . . . . . . . . . . . . . . 65
5.25 EquallyspacedmembershipfunctionsforthePIcontroller. . . . . . . . . . 65
5.26 RuleBaseforthestandardFuzzyProportionalPlusIntegralController. . . . 66
5.27 ResponseoftheevenlyspacedFuzzyLogicPIcontroller. . . . . . . . . . . 66
5.28 ThephaseangleoutputoftheevenlyspacedFuzzyPIcontroller. . . . . . . 67
5.29 ModifiedFuzzyPIcontrollerSystemResponse. . . . . . . . . . . . . . . . 68
5.30 ControlSurfacefortheerrorsignal. . . . . . . . . . . . . . . . . . . . . . 69
5.31 ResultantphaseangleoutputresponseoftheclosedloopclassicPIcontrol
system. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
5.32 Region of phase angles to be avoided to minimize harmonics. Classical
controllerresponseshownintheavoidanceregion. . . . . . . . . . . . . . 70
5.33 Controlsurfaceforharmonicmitigationcontroller. . . . . . . . . . . . . . 72
5.34 Closeupoftheharmfulharmonicregioninthecontrolsurfaceforharmonic
mitigationcontroller. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
5.35 Errormembershipfunctionfortheharmonicmitigationcontroller. . . . . . 73
5.36 Outputmembershipfunctionfortheharmonicmitigationcontroller. . . . . 73
5.37 CompletesystemwithharmonicmitigationfuzzyController. . . . . . . . . 75
5.38 Resultant phase control output with and without harmonic reduction con-
troller. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
5.39 Resultantphasecontroloutputwithharmonicreductioncontroller. . . . . . 76
5.40 Resultantoutputresponsewiththeharmonicreductioncontroller . . . . . . 77
viii
5.41 Closeupoffigure5.38,visualizingtheswitchingmodeofcontroller. . . . . 77
ix