Harmonics. Craig Hartman, P.E. VFDs, Generators & IEEE 519

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1 Harmonics VFDs, Generators & IEEE 519 Craig Hartman, P.E. Specializing in Motors, Drives, Generators, and Electrical Asset Management

The Great Horse Manure Crisis of 1894 New York Nineteenth-century cities depended on thousands of horses for their daily functioning.

In addition, there were countless carts, drays, and wains, all working constantly to deliver the goods needed by the rapidly growing population.

This profound observation is fairly justified by the present dependence of city population upon the animal for pleasure, traffic, and locomotion.

2 The Great Horse Manure Crisis of 1894 New York Nineteenth-century cities depended on thousands of horses for their daily functioning. London in 1900 had 11,000 cabs, all horsepowered. There were also several thousand buses, requiring a total of more than 50,000 horses. In addition, there were countless carts, drays, and wains, all working constantly to deliver the goods needed by the rapidly growing population. San Francisco Sydney Some wise cynic has remarked that in this country cities are made by taking a horse out upon the plain and building around him. This profound observation is fairly justified by the present dependence of city population upon the animal for pleasure, traffic, and locomotion. The great parks owe their existence chiefly, if not wholly, to the desire of wealthy horse-owners to have a place for airing their beasts. New York Times 1881 Harmonics with VFDs & Generators: 2

The Great Horse Manure Crisis of 1894 Unfortunately, the horses produced huge amounts of manure. A horse, on average, will produce between 15 and 25 pounds of manure per day.

In New York in 1900, the population of 100,000 horses produced 2.5 million pounds of horse manure per day!

The delegates were driven to desperation by horse manure. The situation seemed dire. American cities were drowning in horse manure.

3 The Great Horse Manure Crisis of 1894 Unfortunately, the horses produced huge amounts of manure. A horse, on average, will produce between 15 and 25 pounds of manure per day. Consequently, the streets of nineteenth-century cities were covered by horse manure. This, in turn, attracted huge numbers of flies, and the dried and ground up manure was blown everywhere. In New York in 1900, the population of 100,000 horses produced 2.5 million pounds of horse manure per day! In 1898, delegates from across the globe gathered in New York City for the world s first international urban planning conference. It was not housing, land use, economic development, or infrastructure. The delegates were driven to desperation by horse manure. The situation seemed dire. American cities were drowning in horse manure. In 1894, the Times of London estimated that by 1950 every street in the city would be buried nine feet deep in manure. One New York prognosticator of the 1890s concluded that by 1930 the horse droppings would rise to Manhattan s third-story windows. A public health and sanitation crisis of almost unimaginable dimensions loomed. No solutions could be devised. The conference was abandoned after 3 days. Harmonics with VFDs & Generators: 3

4 The Great Horse Manure Crisis of 1894 By 1896 the horseless carriage was commercially available in America. By January 1900 over 4,192 cars had been sold. By 1912 autos in New York outnumbered horses and in 1917 the city s last horse-drawn streetcar made its final run. In 2010 the number of automobiles exceeded one billion. Harmonics with VFDs & Generators: 4

www.emcsolutions.com Who Invented The Electric Chair?

5 Who Invented The Electric Chair? a) The Marquis de Sade b) Al Gore c) Thomas Edison d) Andre-Marie Ampere Specializing in Motors, Drives, Generators, and Electrical Asset Management

6 Answer: C - Thomas Edison In the 1880 s the Battle of the Systems was raging between Edison s DC Systems and Westinghouse s AC Systems. Not being above using a number of dirty tricks, Edison began macabre public electrocutions of stray dogs and cats using alternating current for the purpose of showing newspaper reporters the rival technology s dangers to the public. He once electrocuted an elephant. In 1888, Edison convinced the State of New York to switch from hanging to electrocution by alternating current as its official form of execution: the great Wizard himself testified to its lethal effectiveness before the legislature. Two years later, an ax murderer name William Kemmler became the first to die in the electric chair wired to one of Westinghouse s AC generators. Source: Mastering the Dynamics of Innovation - James M. Utterback, page 75 Specializing in Motors, Drives, Generators, and Electrical Asset Management

7 and one more thing... Nikola Tesla, one of the greatest geniuses of all time (if not the very greatest) was born in 1856 in the hamlet of Smiljan, in the Austro-Hungarian border province of Lika. A reporter wrote His accomplishments seem like the dream of an intoxicated god. In a single burst of dazzling brilliance he created the modern era. His patents for multiphase ac electricity were the most profitable patents in the history of mankind. He created fortunes for multitudes of others but himself died penniless. He created our entire electrical power system before moving on to cosmic rays, radioactivity, x-rays, the electron microscope, radar, robots, high frequency wireless communication, highpressure water jets, wireless power transmission, and too many more to mention. He offered the world a device which he maintained would make any country, no matter how small, safe within its borders and his offer was rejected. Even the gods of old, in the wildest imaginings of their worshipers, never undertook such gigantic tasks of world-wide dimension as those which Tesla attempted.and accomplished. Specializing in Motors, Drives, Generators, and Electrical Asset Management

8 Harmonics Theory Specializing in Motors, Drives, Generators, and Electrical Asset Management

9 Cecilia Not Harmonics Theory Girls who are Breaking My Heart Girls who are Shaking My Confidence Daily Harmonics with VFDs & Generators: 9

10 Definition of Harmonics? Any distortion of a sinusoidal waveform will result in a Fourier series which is composed of a fundamental sine-wave plus a series of harmonic components which are integer multiples of the fundamental Harmonics with VFDs & Generators: 10

11 What Are Harmonics? Harmonic No. Frequency 1 60 Hz Hz Hz Hz Hz Hz Hz Hz Hz Assumes 60Hz Power System Note: Harmonic #1 is also referred to as the Fundamental Harmonics with VFDs & Generators: 11

12 Volts Fundamental Degrees Harmonics with VFDs & Generators: 12

13 Volts Fundamental + 3 rd Harmonic Harmonic Fundamental SUM Degrees Harmonics with VFDs & Generators: 13

14 Volts Fundamental + 5 th Harmonic Harmonic Fundamental SUM Degrees Harmonics with VFDs & Generators: 14

15 Classic Harmonics Harmonic Amplitude 3rd 1/3 = 33% 5th 1/5 = 20% 7th 1/7 = 14% 9th 1/9 = 11% 11th 1/11 = 9% 13th 1/13 = 8% 15th 1/15 = 7% 17th 1/17 = 6% 19th 1/19 = 5% Harmonics with VFDs & Generators: 15

16 Volts Classic Harmonics Rectifiers & DC Drives Fundamental SUM Degrees Harmonics with VFDs & Generators: 16

17 VFD Harmonics Single-phase Input Harmonic Amplitude 3rd -80% 5th +52% 7th -23% 9th +4% 11th -5% 13th +4% 15th -3% 17th +3% 19th -2% Harmonics with VFDs & Generators: 17

18 Ampere (%) VFD Harmonics Single-Phase Input No Harmonic Correction Fundamental SUM Degrees Harmonics with VFDs & Generators: 18

19 Typical Harmonics Load Pulse Rectifier Pulse Rectifier Pulse Rectifier Pulse Rectifier Electronic/Computer Lighting/Electronic Office with PC's VFD's Harmonics in % of fundamental Harmonics with VFDs & Generators: 19

20 Harmonic Sequence for 3-Phase Rectifiers & VFD s Harmonic No. Sequence 1 POS 2 NEG 3 ZERO 4 POS 5 NEG 6 ZERO 7 POS 8 NEG 9 ZERO Sequence defined by Symmetrical Components Harmonics with VFDs & Generators: 20

21 Effects of Harmonics Interference with communications, data processing, plant control systems High neutral-to-ground voltages (single-phase systems) Misoperation of equipment with electronic circuits Nuisance tripping, blowing of fuses, OL trips De-rating of power supplies & transformers; ties up system capacity Premature aging of electrical insulation Overheating of neutral conductors Increased heating in conductors and other equipment Increased heating and reduced torque in motors Overheating & destruction of capacitor banks Equipment insulation failure due to high voltages Erratic operation of standby generators Metering errors Telephone interference Loss of clock synchronization Utility charges and fines; possible liability claims Harmonics with VFDs & Generators: 21

22 The Bad Neighbor Theory Harmonics with VFDs & Generators: 22

23 Effects of Harmonics Harmonic pollution is like polluting a lake. Little by little, the entire lake becomes polluted Harmonics with VFDs & Generators: 23

24 Electric Utility Why does the electric utility care? Why does the water company require a backflow preventer? Harmonics with VFDs & Generators: 24

25 Harmonic Mitigation Techniques Not typically used with VFDs Specializing in Motors, Drives, Generators, and Electrical Asset Management

26 Harmonic Transformer Cancellation of 3rd harmonic (phases must be balanced) 100 A L1 0 A L1 100 A 100 A 100 A 100 A 100 A L2 0 A 100 A 100 A Neutral 300 A N L2 L3 0 A 100 A L3 Note: Cancels all Zero Sequence or Triplen Harmonics. Primarily used for harmonics cancellation of single-phase loads on 3-phase systems, for example: personal computers on 208Y120V Harmonics with VFDs & Generators: 26

27 Harmonic Transformer Harmonic Transformer Harmonics with VFDs & Generators: 27

current flow of the 3rd harmonic current.

28 Neutral Harmonic Blocking Filter L1 L1 L2 L3 L2 HSS N SysteMax TransMax The HSS inserts a passive high impedance element into the phase or neutral conductor to block harmonic current flow of the 3rd harmonic current. This can reduce kw consumption by 2-6% on heavily loaded, non-linear systems. L3 *Patented by Harmonic Limited Harmonics with VFDs & Generators: 28

29 Shunt Filter L1 L2 Load L3 Harmonic Filter Harmonics with VFDs & Generators: 29

30 Shunt Filter Shunt Filter in Substation Harmonics with VFDs & Generators: 30

31 Harmonic Mitigation Techniques Used with VFDs Specializing in Motors, Drives, Generators, and Electrical Asset Management

32 VFD No Harmonic Mitigation AC to DC Converter Filter DC to AC Inverter { R S T 3 Phase Input DC Filter Capacitor M TH THID=70-120% Harmonics with VFDs & Generators: 32

33 VFD with Line Reactors AC to DC Converter Filter DC to AC Inverter L1 L2 L3 Line Reactors DC Filter Capacitor M THID = 30-40% Harmonics with VFDs & Generators: 33

34 VFD s with Line Reactors Line Reactors VFD s 1 HP to 25 HP VFDs with Line Reactors Harmonics with VFDs & Generators: 34

35 Current Waveform without Reactors 3-phase VFD Harmonics with VFDs & Generators: 35

36 Current Waveform with Line Reactors 3-phase VFD Harmonics with VFDs & Generators: 36

37 Harmonic Magnitude 12-Pulse VFD Converter #1 L1 L2 L3 A Transformer 30 Degree Phase Shift Converter #2 VFD Inverter M Transformer B Zero Degree Phase Shift THID = 12-20% Fundamental B (5th Harmonic) Degrees A (5th Harmonic) o Phase Shift = 360 /12 Pulse = 30 Degrees Harmonics Cancelled: 5, 7, 17, 19, 29, Harmonics with VFDs & Generators: 37

38 Harmonic Magnitude Pseudo 12-pulse VFD System L1 L2 L3 A Transformer 30 Degree Phase Shift VFD #1 M1 B Transformer Zero Degree Phase Shift VFD #2 M THID = 12% and up Fundamental B (5th Harmonic) Degrees A (5th Harmonic) o Phase Shift = 360 /12 Pulse = 30 Degrees Harmonics Cancelled: 5, 7, 17, 19, 29, Harmonics with VFDs & Generators: 38

39 Pseudo 12-pulse VFD System Transformers Delta-Wye Harmonics with VFDs & Generators: 39

40 Harmonic Magnitude 18-Pulse VFD L1 L2 L3 Transformer #1 A +20 Degree Phase Shift Converter #1 Transformer #2 Converter #2 800 B Zero Degree Phase Shift VFD Inverter M Transformer #3 C -20 Degree Phase Shift Converter #3 THID = 5-15% -800 Degrees Fundamental A (5th Harmonic) B (5th Harmonic) C (5th Harmonic) o Phase Shift = 360 /18 Pulse = 20 Degrees Harmonics Cancelled: 5, 7, 11,13,23,25,29,31... Harmonics with VFDs & Generators: 40

41 18-Pulse VFD Harmonics with VFDs & Generators: 41

42 18-Pulse VFD System Converter Bridge #2 Converter Bridge #3 6-Pulse VFD Dc-link reactor Phase-shifting Transformer 100 HP 18-Pulse VFD with Autotransformer Harmonics with VFDs & Generators: 42

43 Hybrid Filter L1 VFD L2 Line Reactor Fuse Load Reactor L3 Tuning Reactor Optional Contactor Capacitor THID = 5-15% Harmonics with VFDs & Generators: 43

44 VFD with Hybrid Filter 6-Pulse VFD Harmonic Filter Capacitors Harmonic Filter Reactors Harmonics with VFDs & Generators: 44

45 Active Front End VFD Uses IGBT Active Converter with high frequency switching THID = 5-15% Harmonics with VFDs & Generators: 45

46 Active Front End VFD Harmonics with VFDs & Generators: 46

47 Active Filter on Bus 480V 60Hz 3-Phase VFD VFD VFD Active Filter M M M THID up to 5% Maximum attenuation ratio 10:1 Harmonics with VFDs & Generators: 47

48 Bus-type Active Filter TCI Active Filter Harmonics with VFDs & Generators: 48

49 Harmonic Mitigation Comparison Level 0 - No harmonic mitigating equipment THID = % Level 1 - AC line and/or DC link reactors THID = 30-40% Level pulse THID = 12-20% Level 3 Hybrid Filters, 18-pulse, Active Filters THID = 5-15% Predominant harmonic is the 5th Harmonics with VFDs & Generators: 49

50 IEEE 519 Summary of TDD Limits I sc /I L <11 11 h<17 17 h<23 23 h<35 35 h TDD < < < < > Even harmonics are limited to 25% of the odd harmonic limits above Where: Current Distortion Limits for General Distribution Systems (120V through 69000V) Maximum Harmonic Current Distortion in Percent of I L Individual Harmonic Order (Odd Harmonics) Current distortions that result in a dc offset, e.g. half-wave converters, are not allowed. *All power generation equipment is limited to these values of current distortion, regardless of actual I sc /I L I SC = maximum short-circuit current at PCC. I L = maximum demand load current (fundamental frequency component) at PCC. TDD= Total Demand Distortion: harmonic current distortion in % of maximum demand load current (15 or 30 min demand). PCC= Point of Common Coupling. Harmonics with VFDs & Generators: 50

51 IEEE 519 Summary of TDD Limits Location I SC /I L IEEE Allowed TDD < < < < > Harmonics with VFDs & Generators: 51

52 Sample Utility Notification Harmonics with VFDs & Generators: 52

53 Harmonic Mitigation Price Comparison VFD Filtering % Increase Cost Comparison 200% 180% 160% 140% 120% 100% 80% 60% 40% 20% 0% HP System w/ Line Reactors (~30-40% THID) System w/ 12-Pulse (~12-20% THID) System w/ Hybrid Filter (~5-15% THID) System w/ 18-Pulse (~5-15% THID) System with active correction (~5-15% THID) Harmonics with VFDs & Generators: 53

54 VFD Voltage & Current Waveforms No filter, 5 HP motor, single-phase input Harmonics with VFDs & Generators: 54

55 VFD Harmonic Spectrum Analysis No filter, 5 HP motor, single-phase input Harmonics with VFDs & Generators: 55

56 VFD Voltage & Current Waveforms With filter, 5 HP motor, single-phase input Harmonics with VFDs & Generators: 56

57 VFD Harmonic Spectrum Analysis With filter, 5 HP motor, single-phase input Harmonics with VFDs & Generators: 57

58 Recommendations 1. Specify performance, not technology (f.e. 12% THID) (VFD s cannot control voltage distortion) 2. Specify that harmonic performance be tested and verified at the VFD input terminals at time of startup 3. If the VFD s have only reactors, then a) Transformers should be loaded no more than 50% with VFD s (5%THVD) b) Generators should be loaded no more than 50% with VFD s (10% THVD) 4. If VFD s have THID less than or equal to 15% then no loading limitations 5. Be aware of technological limitations Harmonics with VFDs & Generators: 58

59 Transformer Loading Using VFD s with Line Reactors 100 KVA Z = 5.75% THVD = 5.06% VFD THID = 35% Total VFD Load = 50% VFD VFD Do not load transformers to more than 50% VFD load unless harmonic correction is provided Harmonics with VFDs & Generators: 59

60 VFD Filter Complications Specializing in Motors, Drives, Generators, and Electrical Asset Management

61 Total Harmonic Current Distortion (THID) 12-Pulse THID vs Load 12-Pulse VFD Load (%) Harmonics with VFDs & Generators: 61

62 Total Harmonic Current Distortion (THID) 18-Pulse THID vs Load 18-Pulse VFD Load (%) Harmonics with VFDs & Generators: 62

63 Total Harmonic Current Distortion (THID) EMC Hybrid Filter THID vs Load Hybrid Filter Load (%) Harmonics with VFDs & Generators: 63

64 Power Factor Power Factor vs Load Hybrid Filter Load (%) Harmonics with VFDs & Generators: 64

65 kvar per hp (leading) Reactive Power vs Load Hybrid Filter kvar (leading) Load (%) Harmonics with VFDs & Generators: 65

66 Standby Generator Alternator Reactive Capability Curve Harmonics with VFDs & Generators: 66

67 VFD s with Single-phase Input Level 0 - VFD with no reactors THID = % Level 1 - AC line/dc link reactors THID = 35-45% Level 2 - Optimized (hybrid) filters THID = 10-15% Predominant harmonic is the 3rd This 3rd harmonic adds to harmonics from computers, copiers, lighting, etc. Hybrid filters are recommended where VFDs are more than a very small percentage of load Consider using 230/240V VFD input voltage and 200/208V motor to accommodate voltage drop Harmonics with VFDs & Generators: 67

68 Uninterruptible Power Supplies (UPS s) Level 1-6 pulse THID = 30-40% Level 2-12 pulse THID = 11-20% Level 3 - Active converter THID = 5-10% Level 3 is very little cost adder over level 1! Harmonics with VFDs & Generators: 68

69 Power Factor Correction Capacitors Specializing in Motors, Drives, Generators, and Electrical Asset Management

70 Power Factor Correction Traditional vs Harmonic-tolerant Capacitors Traditional Capacitor Harmonic-tolerant Capacitor Harmonics with VFDs & Generators: 70

71 Power Factor Correction Automatic Stepped PF Control Autovar 600 Autovar Interior View *Courtesy of Cutler Hammer Harmonics with VFDs & Generators: 71

72 Are there harmonics? THDI > 10% or THDV > 3% woc Power Factor Correction Filters Selection & Application woc Yes No Filtered cap bank Standard cap bank Are there 3rd harmonics and is THDI > 0.2 THDI? 3 5 Is lsc/ l < 20? L Yes No Yes No 2.67 tuned cap 4.2 detuned or 4.7 tuned bank Use detuned 3.78 or 4.2 bank Use tuned 4.7 bank Are there any large size VFDs? Yes Smallest cap size > 40% of largest VFD size Are there any soft starters? Is total cap capacity > 15% of Trafo kva? Yes Yes Use filtered cap banks or use standard caps in line with electromechanical bypass with time delay Check for Resonance THD = Total Harmonic Distortion Current/Voltage, woc = without capacitors. Isc = Available short circuit current, IL = max demand load current Harmonics with VFDs & Generators: 72

73 Harmonic Effects With Standby Generators Specializing in Motors, Drives, Generators, and Electrical Asset Management

74 Standby Generators Standby Generator Example #1 5% Z reactors, 300 kva (300hp) load Alternator Size 300 kw Non-Linear Load 300 kva Alternator THVD 3% Alternator Base 344 KVA Alternator Reactance 12.0% Alternator Reactance 10.5% (on Non-Linear Base) Harmonic Number Harmonic Magnitude (% of Non-Linear Load) 3 0.0% % % 9 0.0% % % % % % Total Harmonic Current 34.5% Estimated THVD 22.97% Harmonics with VFDs & Generators: 74

75 Standby Generators Standby Generator Example #2 5% Z reactors, 150 kva (150 hp) load Alternator Size 300 kw Non-Linear Load 150 kva Alternator THVD 3% Alternator Base 344 KVA Alternator Reactance 12.0% Alternator Reactance 5.2% (on Non-Linear Base) Harmonic Number Harmonic Magnitude (% of Non-Linear Load) 3 0.0% % % 9 0.0% % % % % % Total Harmonic Current 34.5% Estimated THVD 11.8% Harmonics with VFDs & Generators: 75

76 Standby Generators Standby Generator Example #3 Hybrid filters, 300 kva (300 hp) load Alternator Size 300 kw Non-Linear Load 300 kva Alternator THVD 3% Alternator Base 344 KVA Alternator Reactance 12.0% Alternator Reactance 10.5% (on Non-Linear Base) Harmonic Number Harmonic Magnitude (% of Non-Linear Load) 3 0.0% 5 5.0% 7 2.6% 9 0.0% % % % % % Total Harmonic Current 6.2% Estimated THVD 5.34% Harmonics with VFDs & Generators: 76

77 Standby Generators Standby Generator Rules of Thumb Use a 3-phase rms-sensing voltage regulator THVD < 10% A: Upsize generator alternator if necessary (2 to 2.5 x non-linear load for 35% THID loads) B: Use harmonic correction Harmonics with VFDs & Generators: 77

78 Standby Generators Sizing of PF Correction Capacitors on AC Induction Motors Harmonics with VFDs & Generators: 78

79 IEEE 519 Specializing in Motors, Drives, Generators, and Electrical Asset Management

80 IEEE 519 Specification History and Performance Reference IEEE 519 Typical vendor response Electric utility involvement Specific technology specifications Performance-based specifications Harmonics with VFDs & Generators: 80

81 IEEE 519 Recommended Practices IEEE Recommended Practices for Harmonic Control in Electrical Power Systems Utility driven 1981 version - voltage THD only 1992 version - voltage and current THD Harmonics with VFDs & Generators: 81

82 IEEE 519 Summary of TDD Limits I sc /I L <11 11 h<17 17 h<23 23 h<35 35 h TDD < < < < > Even harmonics are limited to 25% of the odd harmonic limits above Where: Current Distortion Limits for General Distribution Systems (120V through 69000V) Maximum Harmonic Current Distortion in Percent of I L Individual Harmonic Order (Odd Harmonics) Current distortions that result in a dc offset, e.g. half-wave converters, are not allowed. *All power generation equipment is limited to these values of current distortion, regardless of actual I sc /I L I SC = maximum short-circuit current at PCC. I L = maximum demand load current (fundamental frequency component) at PCC. TDD= Total Demand Distortion: harmonic current distortion in % of maximum demand load current (15 or 30 min demand). PCC= Point of Common Coupling. Harmonics with VFDs & Generators: 82

83 IEEE 519 Summary of TDD Limits Location I SC /I L IEEE Allowed TDD < < < < > Harmonics with VFDs & Generators: 83

84 IEEE 519 Where is the PCC? Point A Utility Dedicated Transformer Point B Customer Facility Harmonics with VFDs & Generators: 84

85 IEEE 519 Where is the PCC? The point of common coupling (PCC) with the consumer utility interface is the closest point on the utility side of the customer s service where another utility customer is or could be supplied. The ownership of any apparatus such as a transformer that the utility might provide in the customer s system is immaterial to the definition of PCC IEEE 519 working group Harmonics with VFDs & Generators: 85

86 IEEE 519 Engineering Challenge It is important that an engineer who specifies VFD s consider the other loads in the building or facility and then specify which level(s) of harmonic distortion will be acceptable to the owner and to the serving utility Harmonics with VFDs & Generators: 86

87 Harmonic Mitigating VFD Specification Recommendations General or work included section Quality assurance section Submittals section Acceptable manufacturers section Construction section Harmonic distortion section System commissioning & certification section Harmonics with VFDs & Generators: 87

88 Thank You! Questions? Specializing in Motors, Drives, Generators, and Electrical Asset Management

Harmonic Filters for Power Conversion Equipment (Drives, rectifiers, etc) Effects of Harmonics IEEE Solutions

Harmonic Filters for Power Conversion Equipment (Drives, rectifiers, etc) Effects of Harmonics IEEE - 519 Solutions Harmonics Tutorial 1 Power Conversion Equipment can save energy and control motors, heaters,