Topic 19Main contentsConverter based Power Factor Correction
Main contents • Converter based Power Factor Correction Topic 19
18-1IntroductionPower quality has become an important issue1GenerationofCurrentHarmonics（电流谐波的产生）Diode-Rectifier BridgeidLineinputvdFigure 18-2Dioderectifier bridge
18-1 Introduction Power quality has become an important issue 1 Generation of Current Harmonics (电流谐波的产生) Diode-Rectifier Bridge
Single-phase Diode-Rectifier Bridge waveform150m.V(tall(a-3Va,cti2)Single-phase diode-bridge rectification for two values of L
Single-phase Diode-Rectifier Bridge waveform
3-phase Diode-Rectifier Bridge waveform(a)(6)EffectofL,variation(a)L,=o.lmH:(b)L,=3mH
3-phase Diode-Rectifier Bridge waveform
Typical Harmonics in the Input CurrentTable 18-1 Typical Harmonics in a Single-Phase Input CurrentWaveform with No Line Filtering15175791113h3L%2.95.74.10.80.48.173.236.6-·Single-phase diode-rectifier bridge
Typical Harmonics in the Input Current • Single-phase diode-rectifier bridge
（低功率因数的2 Deleterious effects of poorpower factor危害)☆PTPFV.·PF1·Increasing power lossintransmission lines,transformers,generators
2 Deleterious effects of poor power factor (低功率因数的 危害)☆ •Increasing power loss in transmission lines, transformers, generators. V PF PF P 1 I = s s
3Deleteriouseffectsofharmonicdistortion（谐波的危害)☆·lncreasing power loss in transmission lines,transformers,generators.: The utility voltage waveform will also become distorted,diadversely affecting other linear loads.Vpcc= V,- Ls1dt6PCOtherequipmentFigure 5-25 Line-voltage notching and distortionFigure 5-26Voltage waveform at the point of common coupling in thecircuitofFig.5-25
8 3 Deleterious effects of harmonic distortion (谐波的危 害)☆ •Increasing power loss in transmission lines, transformers, generators. • The utility voltage waveform will also become distorted, dt dis adversely affecting other linear loads. vPCC = vs − Ls1
Maycausing resonanceconditionsbetweenthecapacitive reactance of the shunt capacitors and theinductive reactanceof thetransmission lines.·Overloading the shunt capacitors used by utilities forvoltage support.·May causing EMIidCdROther equipmentFigure5-25 Line-voltage notching and distortionFigure5-26Voltage waveform at thepoint of common coupling in thecircuit of Fig.5-25
9 •May causing resonance conditions between the capacitive reactance of the shunt capacitors and the inductive reactance of the transmission lines. •Overloading the shunt capacitors used by utilities for voltage support. • May causing EMI
（谐波准则）：IEEE5194HarmonicGuidelinesTable18-2HarmonicCurrentDistortion(l/l)TotalOddHarmonicOrderh(%)Harmonich1000Note:Harmonic current limits for nonlinear load connected to a public utility at the point of common coupling (PCC)with other loads at voltages of 2.4-69kV.Is is themaximum short-circuit current at PCC.I, is the maximumfundamental-frequency load current at PCC.Even harmonics are limited to 25% of the odd harmonic limits above.Source:Reference 1.>Commonlyusedforspecifyinglimitsontheinput current distortion
4 Harmonic Guidelines (谐波准则) : IEEE 519 ➢Commonly used for specifying limits on the input current distortion
4HarmonicGuidelines（谐波准则）：IEEE519Table 18-3Harmonic Voltage Limits (Vh/V)(%)for PowerProducers (PublicUtilities orCogenerators)> 138 KV2.3-69 kV69-138 kV1.01.53.0Maximumforindividual harmonic2.51.55.0Total harmonicdistortionNote: This table lists the quality of the voltage that the power producer isrequired to furnish a user. It is based on the voltage level at which the user issupplied.Source:Reference 1.>Limits ondistortion inthe input voltage suppliedby the utility
➢Limits on distortion in the input voltage supplied by the utility 4 Harmonic Guidelines (谐波准则): IEEE 519