1、 GUIDANCE NOTES ON CONTROL OF HARMONICS IN ELECTRICAL POWER SYSTEMS MAY 2006 American Bureau of Shipping Incorporated by Act of Legislature of the State of New York 1862 Copyright 2006 American Bureau of Shipping ABS Plaza 16855 Northchase Drive Houston, TX 77060 USA This Page Intentionally Left Bla
2、nk ABSGUIDANCE NOTES ON CONTROL OF HARMONICS IN ELECTRICAL POWER SYSTEMS .2006 iii Foreword Harmonics (or distortion in wave form) has always existed in electrical power systems. It is harmless as long as its level is not substantial. However, with the recent rapid advancement of power electronics t
3、echnology, so-called nonlinear loads, such as variable frequency drives for motor power/speed control, are increasingly finding their way to shipboard or offshore applications. Harmonics induced by these nonlinear loads are a potential risk if they are not predicted and controlled. The ABS Guidance
4、Notes for Control of Harmonics in Electrical Power Systems has been developed in order to raise awareness among electrical system designers of the potential risks associated with the harmonics in electrical power systems onboard ships or offshore installations. These Guidance Notes encompass topics
5、from the fundamental physics of harmonics to available means of mitigation to practical testing methods. These Guidance Notes are intended to aid designers to plan an appropriate means of harmonics mitigation early in the design stage of the electrical power distribution systems to make the system r
6、obust and predictable. This Page Intentionally Left Blank ABSGUIDANCE NOTES ON CONTROL OF HARMONICS IN ELECTRICAL POWER SYSTEMS .2006 v GUIDANCE NOTES ON CONTROL OF HARMONICS IN ELECTRICAL POWER SYSTEMS CONTENTS SECTION 1 Introduction 1 1 Background1 2 The Use of Electric Drives in Marine Applicatio
7、ns.5 3 Main Propulsion Drives7 4 The Future? .9 FIGURE 1 Input Waveforms (440 V) to 6-Pulse DC SCR Drive.2 FIGURE 2 Line-to-line Voltage (440 V) at Input to a 6-Pulse DC SCR Drive 2 FIGURE 3 415 V Line-to-line Volts on Ship with Four 1100 kW/ 1500 HP AC SCR Converter-fed Thruster Motors.3 FIGURE 4 P
8、rimary Voltage (11 kV) of Transformer Supplying a 2 MW (2680 HP) Variable Frequency Drive 3 FIGURE 5 Typical Power System Single Line Diagram for DP Class 3 Drilling Rig.5 FIGURE 6 Electrically-driven Podded Propulsor.8 FIGURE 7 Dynamically-positioned Shuttle Tanker Equipped with AC Electric Variabl
9、e Speed Main Propulsion and Thrusters.8 SECTION 2 The Production of Harmonics.11 1 Production of Harmonics .11 2 Characteristic Harmonic Currents15 3 Effect of Harmonic Currents on Impedance(s) 19 4 Calculation of Voltage Distortion20 5 Harmonic Sequence Components.22 6 Line Notching.22 7 Interharmo
10、nics .25 8 Subharmonics27 TABLE 1 Harmonic Sequence Components for 6-Pulse Rectifier22 vi ABSGUIDANCE NOTES ON CONTROL OF HARMONICS IN ELECTRICAL POWER SYSTEMS .2006 FIGURE 1 Voltage and Current Waveforms for Linear Load 11 FIGURE 2a Single Phase Full Wave Rectifier.11 FIGURE 2b Load and AC Supply C
11、urrents .11 FIGURE 3a Simple Single Line Diagram12 FIGURE 3b Load Current and Volt Drop Waveforms12 FIGURE 4 How Voltage Distortion is Produced (Simplified) .12 FIGURE 5 Typical Computer Nonlinear Load .13 FIGURE 6 Single-phase Switched Mode Power Supply.13 FIGURE 7 Harmonic Spectrum of Currents Dra
12、wn by Computer Switched Mode Power Supply 14 FIGURE 8 Construction of Complex Wave .14 FIGURE 9 Computer Power Supply with Single-phase Full Wave Bridge Rectifier 16 FIGURE 10 Computer SMPS Input Current Waveform 16 FIGURE 11 Typical Waveform from Computer Switched Power Supply 17 FIGURE 12 Typical
13、6-Pulse PWM AC Drive .17 FIGURE 13 6-Pulse AC PWM Drive Input Current Waveforms for One Phase18 FIGURE 14 Typical Harmonic Spectrum for 6-Pulse AC PWM Drive.18 FIGURE 15 Distorted Currents Induce Voltage Distortion 19 FIGURE 16 How Individual Harmonic Voltage Drops Develop Across System Impedances 1
14、9 FIGURE 17 Simple Three-phase SCR Bridge for Phase Control23 FIGURE 18 Exaggerated Example of “Line Notching” 23 FIGURE 19 Voltage Notching due to SCR Bridge Commutation24 FIGURE 20 SCR Line Notching and Associated “Ringing”.24 FIGURE 21 Cycloconverter Current Spectrum Includes Interharmonics .25 F
15、IGURE 22 Waveform Containing both Harmonics and Interharmonics .26 FIGURE 23 Peak Voltage Deviations due to Interharmonics Voltage.27 SECTION 3 Effects of Harmonics. 29 1 Generators .29 1.1 Thermal Losses.29 1.2 Effect of Sequence Components.30 1.3 Voltage Distortion 30 1.4 Line Notching and Generat
16、ors.32 1.5 Shaft Generators .33 ABSGUIDANCE NOTES ON CONTROL OF HARMONICS IN ELECTRICAL POWER SYSTEMS .2006 vii 2 Transformers33 2.1 Thermal Losses.33 2.2 Unbalance, Distribution Transformers and Neutral Currents 34 2.3 Transformer Derating or K-factor Transformer34 3 Induction Motors 36 3.1 Thermal
17、 Losses.36 3.2 Effect of Harmonic Sequence Components 37 3.3 Explosion-proof Motors and Voltage Distortion .38 4 Variable Speed Drives .39 5 Lighting 41 5.1 Flicker .41 5.2 Effects of Line Notching on Lighting42 5.3 Potential for Resonance42 6 Uninterruptible Power Supplies (UPS).42 7 Computers and
18、Computer Based Equipment43 8 Cables45 8.1 Thermal Losses.45 8.2 Skin and Proximity Effects 45 8.3 Neutral Conductors in Four-wire Systems.47 8.4 Additional Effects Associated with Harmonics 48 9 Measuring Equipment48 10 Telephones 51 11 Circuit Breakers .51 12 Fuses .52 13 Relays 52 14 Radio, Televi
19、sion, Audio and Video Equipment 53 15 Capacitors53 FIGURE 1 Equivalent Circuit for a Generator .31 FIGURE 2 Low Pass Filter for Generator AVR Sensing on Nonlinear Loads.33 FIGURE 3 Typical Transformer Derating Curve for Nonlinear Load .35 FIGURE 4 Proposed NEMA Derating Curve for Harmonic Voltages .
20、38 FIGURE 5 AC PWM Drive Current Distortion on Weak Source40 FIGURE 6 PWM Drive “Flat Topping” due to Weak Source41 FIGURE 7 Voltage “Flat Topping” due to Pulse Currents .43 FIGURE 8 Effect of DC Bus Voltage with Flat Topping.43 FIGURE 9 Flat Topping Reducing Supply Ride-through.44 FIGURE 10 Cable A
21、C/DC Resistance, kcas a Function of Harmonic Numbers 46 FIGURE 11 4/0 AWG Cable Proximity and Skin Effect due to Harmonics47 viii ABSGUIDANCE NOTES ON CONTROL OF HARMONICS IN ELECTRICAL POWER SYSTEMS .2006 FIGURE 12 12 AWG Cable Proximity and Skin Effect due to Harmonics47 FIGURE 13 Peak and rms Val
22、ues of Sinusoidal Waveform49 FIGURE 14 Difficulties Conventional Meters Have Reading Distorted Waveforms .49 SECTION 4 Sources of Harmonics. 55 1 Distribution Systems with Single-phase Nonlinear Loads .55 1.1 Three-wire Distribution Systems55 1.2 Four-wire Distribution Systems55 2 Single-phase Nonli
23、near Loads.58 2.1 Computer-based Equipment58 2.2 Fluorescent Lighting 60 2.3 Televisions 64 2.4 Single-phase AC PWM Drives.64 3 Three-phase Nonlinear Loads .65 3.1 DC SCR drives 66 3.2 AC PWM drives .70 3.3 AC Cycloconverter Drives .76 3.4 AC Load Commutated Inverter (LCI).84 4 Additional Three-phas
24、e Sources of Harmonics .90 4.1 Rotating Machines.90 4.2 Transformers.90 4.3 UPS Systems 91 4.4 Shaft Generators .92 FIGURE 1 Four-wire System Linear Phase Currents Return via Neutral Conductor where Balanced Phase Current Cancel Out 56 FIGURE 2 Triplen Harmonics Add Up Cumulatively in Neutral Conduc
25、tors with Single-phase Nonlinear Loads in Four-wire System.56 FIGURE 3 Neutral Current due to Triplen Harmonics (150 Hz for 50 Hz Supply) on Four-wire System.57 FIGURE 4 Harmonic Spectrum Associated with Neutral Current Waveform Shown in Figure 3 .57 FIGURE 5 Typical Switched Mode Power Supply for C
26、omputer Based Equipment58 FIGURE 6 Typical Voltage and Current Waveforms Associated with a Switched Mode Power Supply.59 FIGURE 7 Harmonic Current Spectrum of Typical Switched Mode Power Supply - Ithdis 128%59 FIGURE 8 Typical Neutral Current due to Triplen Harmonics in Connected Loads on a Four-wir
27、e System60 FIGURE 9 Waveforms for Lighting Panel Comprising Fluorescent Lighting with Magnetic Ballasts and T-12 Lamps.61 ABSGUIDANCE NOTES ON CONTROL OF HARMONICS IN ELECTRICAL POWER SYSTEMS .2006 ix FIGURE 10 Neutral Current Waveform on Distribution Panel with Fluorescent Lighting with Magnetic Ba
28、llasts and T-12 Lamps on a Four-wire System .61 FIGURE 11 Same Lighting Panel as per Figure 9, but with Electronic Ballasts (Instead of Magnetic Types) and T-8 Lamps.62 FIGURE 12 Neutral Current Waveform on Same Fluorescent Lighting Panel as Figure 10, but with Electronic Ballasts and T-8 Lamps on F
29、our-wire System.62 FIGURE 13 Comparison of Phase Current Harmonic Spectrum for Magnetic and Electronic Ballasts for Typical Fluorescent Lighting Distribution Panel Ithdwas 12.8% and 16.3%, Respectively .63 FIGURE 14 Comparison of Neutral Current Harmonic Spectrum for Magnetic and Electronic Ballasts
30、 for Typical Fluorescent Lighting Distribution Panel Ithdwas 171.28% and 44%, Respectively 63 FIGURE 15 Television Typical Current Waveform.64 FIGURE 16 Television Typical Harmonic Current Spectrum .64 FIGURE 17 Single-phase AC PWM Drive Typical Ithdis 135% 65 FIGURE 18 Single-phase AC PWM Drive Cur
31、rent Spectrum .65 FIGURE 19 Typical 6-Pulse DC SCR Drive with Shunt-wound DC Motor66 FIGURE 20 Concept of “Constant Torque” and “Constant Power” with DC Shunt-wound Motors 67 FIGURE 21 Typical Dual Converter for DC Shunt-wound Motor68 FIGURE 22 Concept of “Four Quadrant Control” for DC Motors and Du
32、al Converters 68 FIGURE 23 Typical 6-Pulse DC SCR Drive Current Waveform at 100% Load.69 FIGURE 24 Harmonic Current Spectrum of Typical 6-Pulse DC SCR Drive at Rated Load 69 FIGURE 25 Typical AC PWM Drive Block Diagram70 FIGURE 26 Pulsed Nature of AC PWM Drive Input Current.71 FIGURE 27 Typical AC P
33、WM Drive Output (Inverter) Bridge Configuration72 FIGURE 28 Basic Principle of Pulse Width Modulation 72 FIGURE 29a AC Motor/PWM Drives Standard Speed/Torque Characteristics .73 FIGURE 29b AC Motor/PWM Drives Standard Speed/Power Characteristics .74 FIGURE 30 Input Current 150 HP AC PWM Drive with 3
34、% DC Bus Reactor Ithd= 39.23%.75 FIGURE 31 Harmonic Current Spectrum of 150 HP AC PWM Drive with 3% DC Bus Reactor Ithd= 39.23% .75 FIGURE 32 Single-phase-to-Single-phase Cycloconverter 76 FIGURE 33 Waveforms for Single-phase-to-Single-phase Conversion.77 x ABSGUIDANCE NOTES ON CONTROL OF HARMONICS
35、IN ELECTRICAL POWER SYSTEMS .2006 FIGURE 34 Three-phase 6-Pulse Cycloconverter 79 FIGURE 35 Simplified Connection of Intergroup Reactor on One Phase of Circulating Current Cycloconverters.80 FIGURE 36 Waveforms for Blocking Mode Cycloconverters80 FIGURE 37 Waveforms for Circulating Current Mode Cycl
36、oconverters .81 FIGURE 38a Input Current Associated with a 20 MW, 12-Pulse Cycloconverter .82 FIGURE 38b Harmonic Current Frequency Spectrum Associated with a 20 MW, 12-Pulse Cycloconverter82 FIGURE 39 2-Pulse Cycloconverter with Three-phase Synchronous Motor83 FIGURE 40 Harmonic Spectrum of 12-Puls
37、e Cycloconverters Including Interharmonic Sidebands84 FIGURE 41 Typical 6-Pulse ASCI CSI Inverter with a Squirrel Cage Induction Motor.85 FIGURE 42 Output Voltage Commutation Spikes CSI with Squirrel Cage Induction Motor .85 FIGURE 43 12-Pulse Load Commutated Inverter with Synchronous Motor86 FIGURE
38、 44 12-Pulse Load Commutated Inverter with Squirrel Cage Motor and Output Filter 87 FIGURE 45 Output Voltage of LCI with Synchronous Motor or Squirrel Cage Motor with Output Filter 87 FIGURE 46 Six Step Square Wave Current LCI with Synchronous Motor88 FIGURE 47 Input Waveform of 6-Pulse Load Commuta
39、ted Inverter.89 FIGURE 48 Harmonic Spectrum Associated with a 6-Pulse Load Commutated Inverter 89 FIGURE 49 Input Voltage and Current Waveforms of 6-Pulse 37.5 kVA, 480 V, 60 Hz UPS .91 FIGURE 50 Harmonic Input Current Spectrum for 6-Pulse 37.5 kVA, 460 V, 60 Hz UPS .91 FIGURE 51 Traditional Shaft G
40、enerator System.92 FIGURE 52 Inverter Output Voltage Waveform 93 SECTION 5 Harmonics and System Power Factor . 95 1 Power Factor in Systems with Linear Loads Only .95 2 Power Factor in Power System with Harmonics95 3 How the Mitigation of Harmonics Improves True Power Factor.97 FIGURE 1 Power Factor
41、 Components in System with Linear Load .95 FIGURE 2 Power Factor Components in System with Harmonics96 ABSGUIDANCE NOTES ON CONTROL OF HARMONICS IN ELECTRICAL POWER SYSTEMS .2006 xi SECTION 6 The Effect of Loading on Harmonic Current Distortion99 1 Total Harmonic Voltage Distortion (Vthd) 99 2 Total
42、 Harmonic Current Distortion (Ithd) and Reduced Loading 99 2.1 AC PWM Drives 99 2.2 DC SCR Drives . 102 2.3 Load Commutated Inverters 103 2.4 Cycloconverters 103 2.5 Conclusion: Harmonic Current Magnitude and its Effect on Voltage Distortion. 105 FIGURE 1 Typical 6-Pulse PWM Drive (with 3% AC Line R
43、eactor) at 100% Load Ithd Measured at 37.5%100 FIGURE 2 Typical Harmonic Spectrum of AC PWM Drive (with 3% AC Line Reactor) at 100% Load IthdMeasured at 37.5%100 FIGURE 3 Typical AC PWM Drive (with 3% AC Line Reactor) at 30% Load IthdMeasured at 65.7%. .101 FIGURE 4 Typical Harmonic Spectrum of AC P
44、WM Drive (with 3% AC Line Reactor) at 30% Load IthdMeasured at 65.7%101 FIGURE 5 6-Pulse DC Drive at 70% Loading Ithdis 35.1%102 FIGURE 6 Harmonic Current Spectrum of 6-Pulse DC Drive at 70% Loading Ithdis 35.1%.103 FIGURE 7 Multiple 6-Pulse Cycloconverters Input Current and Voltage Harmonic Spectru
45、ms at Low Output Frequency/Low Load .104 FIGURE 8 Multiple 6-Pulse Cycloconverters Input Current and Voltage Harmonic Spectrums at High Output Frequency/High Load.104 SECTION 7 Influence of Source Impedance and kVA on Harmonics.107 1 “Stiff” and “Soft” Sources .107 2 Illustrations of the Effect of k
46、VA and Source Impedance Harmonics.108 3 Parallel Generator Operation and Calculation of Equivalent Short Circuit Ratings116 TABLE 1 Variation of Ithdand Vthdwith Variation of kVA and Impedance (or Xd).115 FIGURE 1a 2000 kVA and 5.2% Impedance ISC/IL= 33.3:1, Ithd= 24.2%, Vthd= 4.7%.108 FIGURE 1b Cur
47、rent and Voltage Waveforms for 2000 kVA/ 5.2% Impedance Source with 950 HP AC PWM Drive Load and 180 kW Linear Load .109 FIGURE 2a 2000 kVA and 14% Subtransient Reactance ISC/IL= 29.1:1, Ithd= 19.1%, Vthd= 9.8% 110 xii ABSGUIDANCE NOTES ON CONTROL OF HARMONICS IN ELECTRICAL POWER SYSTEMS .2006 FIGUR
48、E 2b Current and Voltage Waveforms for 2000 kVA/ 14% Subtransient Reactance Source with 950 HP AC PWM Drive Load and 180 kW Linear Load 111 FIGURE 3a 4000 kVA and 5.2% Impedance ISC/IL= 67.1:1, Ithd= 27.1%, Vthd= 2.7% .112 FIGURE 3b Current and Voltage Waveforms for 4000 kVA/ 5.2% Impedance Source w
49、ith 950 HP AC PWM Drive Load and 180 kW Linear Load .113 FIGURE 4a 4000 kVA and 14% Subtransient Reactance ISC/IL= 26.6:1, Ithd= 22.9%, Vthd= 5.8% .114 FIGURE 4b Current and Voltage Waveforms for 4000 kVA/ 14% Subtransient Reactance Source with 950 HP AC PWM Drive Load and 180 kW Linear Load 115 FIGURE 5 Paralleling of Generators .116 FIGURE 6 Example of Paralleled Generators.117 SECTION 8 The Effect of Unbalance and Background Voltage Distortion 119 1 Balanced Systems .119 2 Unbalanced Systems.119 2.1 Definition of Voltage Unbalance 120 2.2 Effect of
