电压质量监测与分析系统的开发

西安理工大学硕士学位论文电压质量监测与分析系统的开发姓名：周世平申请学位级别：硕士专业：电力电子与电力传动指导教师：同向前2004030112004.3CVTFFTFFT,MATLABdb4CVTCVT2TITLEDEVELOPMENTOFVOLTAGEQUALITYMONITORANDANALYSISSYSTEMAuthorTutorAbstractPowersystemvoltageon-linemonitoringisimportantforanalyzingvoltagequalityandinvestigatingthecauseofpowersystemfault.Althoughtheexistingpowerqualitymonitoringinstrumentshaveexcellentperformances,theyarenotconvenienttobepopularized.AvoltagequalitymonitoringsystemintegratingwiththeCapacitorVoltageTransformer(CVT)isdeveloped.First,theharmonicanalysismethodbasedonFFTisdiscussed,andsomepracticalissuesintheapplicationofFFTareinvestigated.Thefactorswhichaffectthecalculationprecisionofharmonics,suchassamplingandweightingofwindowfunction,areanalyzed,andthentheinstructiveconclusionsfordesigningvoltagemonitorareobtained.Tocapturethedisturbancevoltagewaveforms,thegeneratingmethodofstartsignalforwaveform-recordingisproposedonthebasisofcharacteristicsandclassificationoftypicalvoltagedisturbances,anditsfeasibilityandvalidityareillustratedbysimulation.WiththehelpofMATLABsimulation,theapplicationofwaveletanalysisinvoltagedisturbancedetectingisdiscussed,andtheresultindicatedthatthedb4waveletwithsix-layerdecompositioncoulddetectallthetypicaldisturbancesandpointoutthestartingandendingtime.Onthefoundationoftheoreticalanalysismentionedabove,avoltagemonitorsystemisdeveloped.ItiscomposedofaCVTembeddedvoltagemonitorandvoltagequalityanalysissoftware.Themonitorcandetectvoltageamplitudeandvoltageharmonicsonline,andrecordwaveformofdisturbancevoltage.Thesampleddatacanbestoredincomputerbycommunicationandcanbereprocessedbytheanalysissoftware.Inthispaper,thedesignscheme,keycircuits,andflow-chartofkeysoftwaremodulearedescribedindetail.KEYWORDS:powerqualityharmonicsvoltagedisturbancesFFTWaveletTransform11.1GB/T14549-93GB12325-2000GB12326-2000GB/T15543-95GB/T18481-2001,aPCCPCC2bn11c3d120°67T2e3419861993GB/T14549-93---GB17625.7-1998GB17626.7-19981.2192040508080/A/D412531.3CVT123CVTCVT62.1,,FFT2.2FFT2.2.1)(tfR2)()2(tftf=+π,02)(tfL2(0,2),dttfeFti)()(∫−−=ππωω2-1F()7ωωπππωdFetfti)(21)(∫−−=2-2)(tf)(tfF()2.2.2DFT)(tfRf0,f1,fN-1,∞∑−=||10NnnfnNkiNnnneffFkXπ210)()(−−=∑==k=0,1,N-12-3{fn}nNkiNnnekXNfπ210)(1∑−==k=0,1,N-12-4{X(k)}IDFT(2-3)2-42-52-6∑−==10)(NikiNnWfkX2-5∑−=−=10)(1NkkiNnWkXNfNjNeWπ2−=2-6X(k),k=0,1,N-1fn,n=0,1,,N-18N2N(N-1)DFT2.2.3(STFT)DennisGabor1946(WFFT)9dtetgtfSRti∫−∗−=ωττω)()(),((2-7)f(t)g(t-)g(t)tf(t)g(t)()S(,)f(t)[-,+][-,+](Heisenberg)(UncertaintyPrinciple)8g(t)g(t)2.2.4(FFT)(FFT)DFTFFTDFT2-5rNWmNrNrNWW+=rmDFTrNW,]1,0[−∈Nr10r=0r=N/2rNW11rNW2-5fn∑∑∑−=+−=−=++==120)12(120)2(10)12()2()(NrrkNNrrkNNikiNnWrxWrxWfkX2-8rNNjNjrNWeeW2/)2/(22)2(2===−×−ππ(2-8)kNWkBkAkX)()()(+=2-9∑−==1202/)2()(NrkrNWrxkA∑−=+=1202/)12()(NrkrNWrxkBfnA(k)B(k))()2(kAKNA=+)()2(kBKNB=+2-10X(k)A(k)B(k)fnN(2-9)N/2DFT2N22N/22[N/2(N/2-1)]+N/2DFTFFT2-9ABDFTWNDFT22FFTJ.W.CooleyJ.W.Tukey19652FFTFFT11N2242Winograd9Winograd,FFTDFTFFT2.3FFTFFTFFTFFT2.3.1FFTuLfHfLAHAsfHsLfffsLHfffn+=nsfk,)2sin(A])(2sin[A)2sin(AHHHsLssLsHfkffknfffkfπππ=+=2-11FFTHfLf1212850Hz6400Hz3200Hzhmax1maxs2ffh×f1f150Hz25fs2.5kHz49fs5kHz128fs6.4kHz1.5kHz256fs12.8kHz3kHz2.3.2FFTFFTN)x(nTs)w(nTs•)x(nTs)w(nTs)X(Ω)W(jΩ)x(nTs13)2cos()1()(w0kknNanKkk∑−=πn=0,1N-12-12KK=0ka:∑=Kka01∑=−Kkka00)1(2-13KakK=1a0=0.5a1=0.5a0=0.54a1=0.46K=2a0=0.42a1=0.5a2=0.081D())2sin()2sin(*)()(210ωωωωωNeDWNj−−==2-14DFTDFT−++−=∑=)2()2()1()(0NkDNkDaWKkkkKπωπωω2-15142-1KKFFT])12(100sin[2)502sin(100)(91thttuh++×=∑=ππ2-12-1FFT152-1(V)%(V)%99.9849-0.000299.99330.000131.9608-0.01961.9842-0.007951.9857-0.00721.9920-0.00471.9919-0.00411.9982-0.000991.9943-0.00292.00070.00035111.9946-0.00272.00010.0001131.9937-0.00321.9996-0.0002151.9902-0.00491.9965-0.00175171.9845-0.00781.9909-0.00455191.9727-0.01371.9821-0.008952.3.3x(n)X(k)x(n)x(n)x(n),164.1.2aN11122sT2-22-2)2502sin(3.0)1502sin(3.0)1002sin(3.0)502sin(5)(tttttu×+×+×+×=ππππ321600Hz0.502sT2-2172-20.5(V)(V)(V)54.99820.0364.99820.03620.30.29332.2330.29342.230.30.29810.6330.29820.650.30.29850.50.29870.4332-20b3:)3502sin(10)2502sin(9)1502sin(11)502sin(100)(1tttttu×+×+×+×=ππππ)3502sin(9)2502sin(11)1502sin(10)502sin(100)(2tttttu×+×+×+×=ππππ)3502sin(11)2502sin(10)1502sin(9)502sin(100)(3tttttu×+×+×+×=ππππ1FFT21/332-32-312VVV10099.98470.01599.98470.0153109.97900.219.97860.2145109.98620.1389.98540.1567109.96680.3329.96510.3492-3122182.4FFT12FFT3193.13.1.1200Hz5kHz,a3-10.510901101101800.510900.5100.5336060203-1b3-20.53-20.5213.1.2112232317173.1.32210a3.23-3233-3200Hz5kHz5kHz400HzVrms(k)Vrms(k-1)VTHDUTHDU4.1.2THDU530550THDU24aMATLAB3-43-43-4b3-5253-53-55kHz400Hz3-55kHz400Hz3.33.3.1Morlet198026f(t)[f(t)L2(R)])(tψ(motherwavelet)=−=∫∗)(),()()(1),(ttfdtattfaaWTafτψτψτ3-1f(t)a0))(1)(atataτψψτ−=a)(tψa)(atψ)(tψ)(taτψ3-63-6aa3-7a273-7aττψτψdataaWTdaactff)(1),(11)(02−=∫∫∞∞−∞3-2∞=∫∞02|)(|ωωψψcπ−π+0H1H0π/2π/2πx(n)3-8283-8x(n)(0π)0V0V1V02π1W2ππ1V2V04π2W4π2π,,221110WVVWVV⊕=⊕=jjjWVV⊕=−1⊕⊕⊕=3210⊕⊕jW1−jVjV1−jVjWjV1−jVjVjWj)2(2)(2/,ktjtjkj−Φ=Φ−−)(,tkjψjVjW)()(2RLtx∈)()()()()(1,,tkdtkCtxJjkkjjkJkJ∑∑∑=+Φ=ψ3-3)()2()(01mCkmhkCjmj−=∑+3-4)(