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Applying Harmonic Solutions to Commercial and Industrial Power Systems

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  1. Applying Harmonic Solutions to Commercial and Industrial Power Systems David G. Loucks, P.E.DaveGLoucks@eaton.com Moon Township, PA

  2. Overview • Introduction • Harmonic Sources • Harmonic Symptoms/Concerns (Problems) • IEEE 519-1992 Standard • Harmonic Solutions • Drive and Rectifier Solutions • Solutions for Commercial Power Systems • Harmonic Solutions for Correcting Power Factor • Avoiding Harmonic Resonance • Low Voltage Vs. Medium Voltage Solutions • The Economics of Harmonic Reduction • Summary Tables and Cost Comparisons

  3. “Harmonics are not a problem unless they are a problem!”

  4. Harmonics 100%, 60 Hz 20%, 180 Hz 12%, 300 Hz 4%, 420 Hz 2%, 660 Hz 2%, 780 Hz

  5. Harmonic Sources Power Electronic Equipment (drives, rectifiers (UPS), computers, etc.) Arcing Devices (welders, arc furnaces, fluorescent lights, etc.) Rotating Machines (generators) Most Common Variable Frequency Drives UPS Computer Power Supplies Fluorescent Lighting Harmonic Sources

  6. Voltage Distortion • When current flows from other than an infinite source, the source voltage drops • The higher the source impedance or the higher the load current, the greater the drop

  7. Non-Linear Load • Example: 1 switched mode power supply

  8. 1 Switched Mode Power SupplyCurrent Harmonics 30A peak6x 5A rms Isc = 22000 IL = 5A Isc/IL = 4400 60 Hz3.6A 180 Hz – 3rd3.1A 300 Hz – 5th 2.25A 420 Hz – 7th 1.38A 540 Hz – 9th 0.74A

  9. 1 Switched Mode Power SupplyCurrent Harmonics 60 Hz3.6A 180 Hz – 3rd3.1A 300 Hz – 5th 2.25A 420 Hz – 7th 1.38A 540 Hz – 9th 0.74A

  10. 1 Switched Mode Power SupplyCurrent Harmonics 60 Hz3.79A This is with 65 kA available 180 Hz – 3rd3.35A 300 Hz – 5th 2.67A 420 Hz – 7th 1.88A 540 Hz – 9th 1.22A

  11. Current Distortion vs Available Fault Current • 22 kA  115% • 65 kA  128% • Why is the current distortion higher with higher available fault current? • Is that the same situation with voltage distortion?

  12. Let’s increase the source impedance • Remember, our power supply was drawing 5A rms • On a 22 kA source, the ratio of Isc/IL= 4400… essentially an infinite source • Keeping the same load impedance, let’s drop the source short current down (Isc/IL= 20)

  13. 100 A rms Source

  14. Voltage Distortion Isc/IL = 4400 22 kA source 1st = 381 V 3rd = 5.4 V 5th = 0.9 V

  15. Voltage Distortion Isc/IL = 20 Isc/IL = 20 1st = 377 V 3rd = 9.1 V 5th = 7.8 V7th = 4.1 V9th = 1.7 V

  16. Harmonic Distortion Standards Harmonic Voltage Distortion Limits IEEE Standard 519 – 1992 Maximum Voltage Distortion in % at PCC* Below 69kV 69-138kV >138kV Maximum for Individual Harmonic 3.0 1.5 1.0 Total Harmonic Distortion (THD) 5.0 2.5 1.5 * % of Nominal Fundamental Frequency Voltage

  17. Harmonic Distortion Standards Maximum Harmonic Current Distortion IEEE Standard 519 – 1992 Harmonic Order (Odd Harmonics) Isc/IL <11 11<h<17 17<h<23 23<h<35 35<h %TDD <20* 4.0 2.0 1.5 0.6 0.3 5.0 20-50 7.0 3.5 2.5 1.0 0.5 8.0 50-100 10.0 4.5 4.0 1.5 0.7 12.0 100-1000 12.0 5.5 5.0 2.0 1.0 15.0 >1000 15.0 7.0 6.0 2.5 1.4 20.0 In Percent of Fundamental

  18. Harmonic Limits • PCC (Point of Common Coupling) is defined as the point where another customer can be served From IEEE519A Draft

  19. Harmonic Limits Update for IEEE 519 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 customers system is immaterial to the definition of the PCC. Note: This definition has been approved by the 519 Working Group. http://home.nas.net/~ludbrook/519error.html From IEEE519A Draft

  20. Equipment Failure and Misoperation Notching Overheating/Failure Nuisance Operation Communication / control interference Economic Considerations Oversizing Losses/Inefficiencies/PF Penalties Application of Power Factor Correction Capacitors Other Issues Metering – do you really have a problem? Marketing hype – buy my product! Specmanship - Misinterpretation of the IEEE-519 Standard Harmonic Symptoms/Concerns

  21. >> than 519 recommendations especially in specs (drives for example) Voltage or current harmonics ?? PCC?? 102% Current IEEE 519-1992 Standard

  22. Reduce Harmonics – Save Money??? Aside from the “power quality” issues (misoperation, damage, etc), harmonics also “cost” you in other ways…. • Cost of oversized neutrals (2x), transformers (1.25-2x), generators (1.4-2x), UPS (1.5-2x), k-factor transformers, etc. • kW losses in cables, transformers and other power system components (1-8% losses).

  23. Symmetrical Components

  24. Reduce Harmonics – Save Money??? • Motor damage, losses (heating) from “negative sequence currents”. • High harmonics = low total power factor (utility penalties). “Negative Sequence Current” • Tries to Rotate Motor in Opposite Direction • Causes Motor Losses, Heating and Vibrations 5th Harmonic Rotation 60 Hz Rotation

  25. Drive and Rectifier Solutions • Line Reactors • K-Rated/Drive Isolation Transformers • DC Choke • 12-Pulse Converter • Harmonic Mitigating Transformers/Phase Shifting • Tuned Filters • Broadband Filters • 18-Pulse Converter • Active Filters

  26. Solutions for Commercial Power Systems • Neutral Blocking Filter • Harmonic Mitigating Transformers/Phase Shifting • Oversized Neutrals • K-Rated/Drive Isolation Transformers • Tuned Filters • Broadband Filters • Active Filters • Low Distortion Loads (Lighting Ballasts, Drives, etc.)

  27. LEGEND Incoming Utility Service - Power Factor Correction PFC MV Switchgear - K Factor Transformer MV Power Factor (optional harmonic filter) - Tuned Filters PFC - Active Filters Active - Blocking Filter for 3rd Harmonic K K - Blocking Filter for Drives Bus Voltage without Correction LV Secondary Unit Substation - Harmonic Mitigating Transformer HMT - Multi-pulse Drives (12/18/24) Bus Voltage with Correction Control/Sensing for Active or Switched Filter Active HMT Transformer w/Neutral Blocker PFC MCC Active Electronic Ballasts PFC (AFD) Adjustable Frequency Drive (12/18/24 pulse) Free Standing PF Correction and/or Harmonic Filter HMT HMT Panelboard Feeding 120/208V Harmonic Loads AFD AFD AFD Panelboard Feeding Computers (3rd harmonics) LV Switchboard With Harmonic Loads M M M

  28. Expected Harmonics Source Typical Harmonics* 6 Pulse Drive/Rectifier 5, 7, 11, 13, 17, 19… 12 Pulse Drive /Rectifier 11, 13, 23, 25… 18 Pulse Drive 17, 19, 35, 37… Switch-Mode Power Supply 3, 5, 7, 9, 11, 13… Fluorescent Lights 3, 5, 7, 9, 11, 13… Arcing Devices 2, 3, 4, 5, 7... Transformer Energization 2, 3, 4 * Generally, magnitude decreases as harmonic order increases H = NP+/-1 i.e. 6 Pulse Drive - 5, 7, 11, 13, 17, 19,…

  29. Harmonic Solutions Welder M + - Oversized Generator Xs G XT Active Filter 480 V Blocking Filter K-Rated 12 Pulse Low Distortion Electronic Ballast M UPS w/Filter M Filter

  30. Effect of Drive Line Reactors (IEEE519A)

  31. Phase Shifting – 12 Pulse From IEEE519A Draft

  32. CP9000 - 18 Pulse++

  33. Passive Filters (Parallel / Tuned)

  34. Passive Filters (Series / Broadband) 18-Pulse Equivalent 6-Pulse Drive From IEEE519A Draft

  35. Active Filters From IEEE519A Draft

  36. Harmonic Solutions for PF • Application of Harmonic Solutions for PF Correction • Reduce Utility Penalties – Most Common Reason Today • Resonance Issues • Reduce Harmonic = Reduce Vars • LV/MV?

  37. Harmonic Resonance kVA = SC h R kvar CAP • The “Self Correcting” Problem • - Blow Fuses • - Fail Capacitors • - Damage Transformer

  38. Harmonic Resonance - Solutions • Apply another method of kvar compensation (harmonic filter, active filter, synchronous condenser, etc) • Change the size of the capacitor bank to over-compensate or under-compensate for the required kvar and live with the ramifications.

  39. Harmonic Correction Selectionfor Drives in MCC’s Parallel / Passive Filter (10-20% Distortion) SeriesPassive Filter (8-12% Distortion*) Active Correction (5-20% Distortion) 18 Pulse Drive(5% Distortion*) 125 Hpand up 50 Hp 30 Hp * per Drive 10 Hp 5 10 15 20 Recommendation based on price and MCC integration Drive Quantity

  40. Fundamental Neutral Summation

  41. Harmonic Summation in Neutral

  42. Neutral Heating – Oversize Equipment 10A at 60 Hz 10A at 180 Hz 10A at 60 Hz 10A at 180 Hz 10A at 60 Hz 10A at 180 Hz 0A at 60 Hz 30A at 180 Hz A B C N

  43. Neutral Blocking Filter - Blockade TRANSFORMER ENCLOSURE PHASE C 60Hz CURRENT & NON - 60Hz AND TRIPLEN HARMONIC CURRENT NON-TRIPLEN PHASE B HARMONIC CURRENTS Neutral Blocking Filter PHASE A SAFETY NO 3rd HARMONIC CURRENTS COMPUTER COMPUTER COMPUTER GROUND CIRCULATE IN DELTA WINDING TO BUILDING STEEL 60Hz IMBALANCE CURRENT ONLY

  44. Individual Phase Currents

  45. Neutral Harmonic Currents

  46. Solution Summary Tables Type 2 – Comparison of Solution Options (and Effectiveness) by CORRECTIVE EQUIPMENT • Shunt/Parallel Filters • Series Filters/Reactors • Transformer Solutions • Other Table 3 – Comparison of Solution Options by LOAD TYPE • Drives, Rectifiers, 3-Phase UPS • Computers • Fluorescent Lighting • Welding/Arcing Loads • System Solutions

  47. Cost of Harmonic Correction Description Typical $/kVA* K-Factor 20 Reactor 3-4 Capacitors (LV) 12 Switched Capacitors (LV) 25 Single-Tuned Fixed Filter (LV) 35 Single-Tuned Switched Filter (LV) 40-50 Single-Tuned Fixed Filter (MV) 12 Single-Tuned Switched Filter (MV) 15 Blocking Filter (3rd's) 100 Blocking Filter (Drives) 100 Active Harmonic Filter 150 Phase-Shifting Transformers 50 Note that prices are generalized for comparison only but not absolute. Some equipment must be fully rated for loads - others can be partially rated Capacitors are shown for reference only.

  48. Solutions: AF Drives Pros Cons

  49. Solutions: AF Drives (continued) Pros Cons

  50. Solutions: 1 Power Supplies Pros Cons