Applying Harmonic Solutions to Commercial and Industrial Power

Applying Harmonic Solutions to Commercial and Industrial Power Systems David G. Loucks, P. E. Dave. GLoucks@eaton. com Moon Township, PA © 2005 Eaton Corporation. All rights reserved.

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

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

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

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

Voltage Distortion l l 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

Non-Linear Load l Example: 1 switched mode power supply

1 Switched Mode Power Supply Current Harmonics 30 A peak 6 x 5 A rms 60 Hz 3. 6 A Isc = 22000 IL = 5 A 180 Hz – 3 rd 3. 1 A 300 Hz – 5 th 2. 25 A 420 Hz – 7 th 540 Hz – 9 th 1. 38 A 0. 74 A Isc/IL = 4400

1 Switched Mode Power Supply Current Harmonics 60 Hz 3. 6 A 180 Hz – 3 rd 3. 1 A 300 Hz – 5 th 2. 25 A 420 Hz – 7 th 540 Hz – 9 th 1. 38 A 0. 74 A

1 Switched Mode Power Supply Current Harmonics 60 Hz 3. 79 A 180 Hz – 3 rd 3. 35 A 300 Hz – 5 th 2. 67 A This is with 65 k. A available 420 Hz – 7 th 540 Hz – 9 th 1. 88 A 1. 22 A

Current Distortion vs Available Fault Current l 22 k. A 115% l 65 k. A 128% l l Why is the current distortion higher with higher available fault current? Is that the same situation with voltage distortion?

Let’s increase the source impedance l l l Remember, our power supply was drawing 5 A rms On a 22 k. A 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)

100 A rms Source

Voltage Distortion Isc/IL = 4400 22 k. A source 1 st = 381 V 3 rd = 5. 4 V 5 th = 0. 9 V

Voltage Distortion Isc/IL = 20 1 st = 377 V 3 rd = 9. 1 V 5 th = 7. 8 V 7 th = 4. 1 V 9 th = 1. 7 V

Harmonic Distortion Standards Harmonic Voltage Distortion Limits IEEE Standard 519 – 1992 Maximum Voltage Distortion in % at PCC* Below 69 k. V Maximum for Individual Harmonic 3. 0 Total Harmonic Distortion (THD) 69 -138 k. V 1. 5 1. 0 5. 0 2. 5 >138 k. V 1. 5 * % of Nominal Fundamental Frequency Voltage

Harmonic Distortion Standards Maximum Harmonic Current Distortion IEEE Standard 519 – 1992 Harmonic Order (Odd Harmonics) Isc/IL <20* <11 111000 15. 0 7. 0 6. 0 2. 5 1. 4 20. 0 In Percent of Fundamental

Harmonic Limits • PCC (Point of Common Coupling) is defined as the point where another customer can be served From IEEE 519 A Draft

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/519 error. html From IEEE 519 A Draft

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

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

Reduce Harmonics – Save Money? ? ? Aside from the “power quality” issues (misoperation, damage, etc), harmonics also “cost” you in other ways…. l l Cost of oversized neutrals (2 x), transformers (1. 25 -2 x), generators (1. 4 -2 x), UPS (1. 5 -2 x), k-factor transformers, etc. k. W losses in cables, transformers and other power system components (1 -8% losses).

Symmetrical Components

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 60 Hz Rotation 5 th Harmonic Rotation

Drive and Rectifier Solutions l 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

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

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

Expected Harmonics Source Typical Harmonics* 6 Pulse Drive/Rectifier 5, 7, 11, 13, 17, 19… 12 Pulse Drive 11, 13, 25… /Rectifier 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, …

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

Effect of Drive Line Reactors (IEEE 519 A)

Phase Shifting – 12 Pulse From IEEE 519 A Draft

CP 9000 - 18 Pulse++

Passive Filters (Parallel / Tuned)

Passive Filters (Series / Broadband) 18 -Pulse Equivalent From IEEE 519 A Draft 6 -Pulse Drive

Active Filters From IEEE 519 A Draft

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?

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

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.

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

Fundamental Neutral Summation

Harmonic Summation in Neutral

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

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

Individual Phase Currents

Neutral Harmonic Currents

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

Cost of Harmonic Correction Description K-Factor Reactor Capacitors (LV) Switched Capacitors (LV) Single-Tuned Fixed Filter (LV) Single-Tuned Switched Filter (LV) Single-Tuned Fixed Filter (MV) Single-Tuned Switched Filter (MV) Blocking Filter (3 rd's) Blocking Filter (Drives) Active Harmonic Filter Phase-Shifting Transformers Typical $/k. VA* 20 3 -4 12 25 35 40 -50 12 15 100 150 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.

Solutions: AF Drives Pros Cons

Solutions: AF Drives (continued) Pros Cons

Solutions: 1 Power Supplies Pros Cons

Solutions: Fluorescent Lighting Pros Cons

Solutions: Welding, Etc. Pros Cons

Review of Solutions

Review of Solutions - 2

Review of Solutions - 4

Wrap-up Power quality problems are costly ($$$) Energy management considerations should include power factor analysis Power factor correction capacitors are typically cost effective solutions to energy management Harmonics must be considered when applying capacitors Harmonics problems are increasing with the addition of power electronic loads on the power system Model the power system based on typical data or measurements Verify computer model with measurements

Let’s Be Careful Out There!!!

Thank You! Questions?