Transcript Cutler-Hammer - Eaton Corporation

Applying Harmonic
Solutions to Commercial
and Industrial Power
Systems
David G. Loucks, P.E.
[email protected]
Moon Township, PA
© 2005 Eaton Corporation. All rights reserved.
Overview





Introduction
Harmonic Sources
Harmonic Symptoms/Concerns (Problems)
IEEE 519-1992 Standard
Harmonic Solutions



Harmonic Solutions for Correcting Power Factor




Drive and Rectifier Solutions
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
I 2  I 3  I 4  ...
2
%THDI 
2
I1
2%, 660 Hz
2
 100%
2%, 780 Hz
Harmonic Sources
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
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
Non-Linear Load

Example: 1 switched mode power supply
1 Switched Mode Power Supply
Current Harmonics
40A
30A peak
6x
5A rms
0A
-40A
0s
0.1s
RMS(I(L4))
60 Hz
4.0A3.6A
0.2s
I(L4)
0.3s
0.4s
0.5s
0.6s
Time
180 Hz – 3rd
3.1A
300 Hz – 5th
2.25A
Isc =0.7s
22000 0.8s
IL = 5A
0.9s
Isc/IL = 4400
2.0A
420 Hz – 7th
540 Hz – 9th
1.38A
0.74A
0A
0Hz
0.2KHz
0.4KHz
0.6KHz
I(L4)
Frequency
0.8KHz
1.0KHz
1.2KHz
1
1 Switched Mode Power Supply
Current Harmonics
THD% 
I2  I3  I 4  I5  I6  I7  I8  I9    
I1
 100
0  3.12  0  2.25 2  0  1.38 2  0  0.74 2
4.14

 100 
3.6
3.6
 115%
60 Hz
4.0A3.6A
180 Hz – 3rd
3.1A
300 Hz – 5th
2.25A
2.0A
420 Hz – 7th
540 Hz – 9th
1.38A
0.74A
0A
0Hz
0.2KHz
0.4KHz
0.6KHz
I(L4)
Frequency
0.8KHz
1.0KHz
1.2KHz
1 Switched Mode Power Supply
Current Harmonics
0  3.35 2  0  2.67 2  0  1.88 2  0  1.222

 100
3.79

4.0A
11.22  7.13  3.53  1.49 4.83

 128%
3.79
3.79
60 Hz
3.79A
2.0A
This is with 65 kA available
180 Hz – 3rd
3.35A
300 Hz – 5th
2.67A
420 Hz – 7th
540 Hz – 9th
1.88A
1.22A
0A
0Hz
0.2KHz
0.4KHz
0.6KHz
I(L4)
Frequency
0.8KHz
1.0KHz
1.
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?
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)
100 A rms Source
Voltage Distortion Isc/IL = 4400
THD% 

V2  V3  V4  V5  V6  V7  V8  V9    
V1
 100
0  5.4 2  0  0.9 2  0  0  0  0
5.47
 100 
 1.44%
381
381
20V
22 kA source
1st = 381 V
3rd = 5.4 V
5th = 0.9 V
10V
0V
52Hz
100Hz
V(L4:2)
150Hz
200Hz
250Hz
Frequency
300Hz
350Hz
400Hz
450Hz
Voltage Distortion Isc/IL = 20
THD% 

V2  V3  V4  V5  V6  V7  V8  V9    
V1
 100
0  9.12  0  7.8 2  0  4.12  0  1.7 2
12.78
 100 
 3.4%
377
377
15V
Isc/IL = 20
1st = 377 V
3rd = 9.1 V
5th = 7.8 V
7th = 4.1 V
9th = 1.7 V
10V
5V
0V
0Hz
100Hz
200Hz
300Hz
400Hz
V(L5:2)
Frequency
500Hz
600Hz
70
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
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
Harmonic Limits
•PCC (Point of Common Coupling) is defined as the point where
another customer can be served
From IEEE519A 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/519error.html
From IEEE519A Draft
Harmonic Symptoms/Concerns

Equipment Failure and Misoperation





Economic Considerations




Notching
Overheating/Failure
Nuisance Operation
Communication / control interference
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
IEEE 519-1992 Standard
MAXIMUM HARMONIC CURRENT DISTORTION
IN PERCENT OF IL
Individual Harmonic Order (Odd Harmonics)

I SC /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

Even harmonics are limited to 25% of the odd harmonic limits above.
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 ISC / IL.
Where,
ISC = Maximum Short Circuit at PCC.
IL = Maximum Load Current (Fundamental Frequency) at PCC.
>> than 519
recommendations
especially in specs
(drives for example)
Voltage or current
harmonics ??

PCC??

102% Current
MAXIMUM VOLTAGE DISTORTION IN % AT PCC
< 69 kV
69 kV – 161 kV
161 kV
Maximum for Individual Harmonic
3.0
1.5
1.0
Total Harmonic Distortion (THD) %
5.0
2.5
1.5
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).
VTHD = 2.3%
Utility Source
VTHD = 5.8%
Generator Source
Symmetrical Components
Harmonic Sequence Harmonic Sequence
1
+
10
+
2
11
3
0
12
0
4
+
13
+
5
14
6
0
15
0
7
+
16
+
8
17
9
0
18
0
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
5th Harmonic
Rotation
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
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.)
LEGEND
PFC
K
Incoming Utility Service
- Power Factor Correction
MV
Switchgear
- K Factor Transformer
- Tuned Filters
MV Power Factor
(optional harmonic filter)
PFC
Active - Active Filters
- Blocking Filter for 3rd Harmonic
- Blocking Filter for Drives
HMT
LV Secondary
Unit Substation
- Harmonic Mitigating Transformer
Bus Voltage
without Correction
- Multi-pulse Drives (12/18/24)
Active
Transformer
w/Neutral Blocker
HMT
Bus Voltage
with Correction
Control/Sensing for
Active or Switched Filter
K
PFC
MCC
Active
PFC
Panelboard
Feeding
Computers
(3rd harmonics)
Panelboard
Feeding
120/208V
Harmonic Loads
Electronic Ballasts
LV Switchboard
With Harmonic
Loads
HMT
HMT
AFD
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, 23, 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
12 Pulse
M
Welder
M
Filter
K-Rated
UPS
w/Filter
M
+ -
Effect of Drive Line Reactors (IEEE519A)
Phase Shifting – 12 Pulse
From IEEE519A Draft
CP9000 - 18 Pulse++
Passive Filters (Parallel / Tuned)
Passive Filters (Series / Broadband)
18-Pulse Equivalent
From IEEE519A Draft
6-Pulse Drive
Active Filters
From IEEE519A 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
hR 
kVA
kvar
SC
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
10A at 180 Hz
10A at 60 Hz
A
B
C
N
10A at 180 Hz
10A at 60 Hz
10A at 180 Hz
10A at 60 Hz
0A at 60 Hz
30A at 180 Hz
Neutral Blocking Filter - Blockade
TRANSFORMER ENCLOSURE
PHASE C
60Hz CURRENT & NON TRIPLEN HARMONIC CURRENT
60Hz AND
NON-TRIPLEN
HARMONIC
CURRENTS
PHASE B
Neutral
Blocking
Filter
NO 3rd HARMONIC CURRENTS
CIRCULATE IN DELTA WINDING
TO BUILDING STEEL
PHASE A
SAFETY
GROUND
COMPUTER
COMPUTER
COMPUTER
60Hz 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 (3rd's)
Blocking Filter (Drives)
Active Harmonic Filter
Phase-Shifting Transformers
Typical $/kVA*
20
3-4
12
25
35
40-50
12
15
100
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
Drives and
Rectifiers –
Includes
3-Phase UPS
Loads
Cons
 Inexpensive
 For 6-pulse standard
 May require additional
drive/rectifier, can reduce
Line Reactors
compensation
harmonic current distortion
from 80% down to about
35-40%
 Offers series reactance
 No advantage over
K-rated/Drive
(similar to line reactors)
reactors for reducing
Isolation
and provides isolation for
harmonics unless in pairs
transformer
some transients
for shifting phases
 Not always an option
 Slightly better than AC
for drives
DC Choke
line reactors for 5th and 7th
 Less protection for
harmonics
input semiconductors
 Cost difference
approaches 18-pulse
 85% reduction versus
12-Pulse Convertor
drive and blocking
standard 6-pulse drives
filters, which guarantee
IEE 519 compliance
 Harmonic cancellation
Harmonic
highly dependent on load
 Substantial (50%-80%)
Mitigating
balance
reduction in harmonics
Transformers/Phase
 Must have even
when used in tandem
Shifting
multiples of matched
loads
Solutions: AF Drives (continued)
Pros
Cons
Drives and
Rectifiers –
Includes
3-Phase UPS
Loads
(continued)
Tuned Filters
 Bus connected –
accommodates load
diversity
 Provides PF correction
Broadband Filters
 Makes 6-pulse into the
equivalent of 18-pulse
 Excellent harmonic
control for drives above
18 Pulse Converter
100HP
 IEEE 519 compliant
 Handles load/harmonic
diversity
Active Filters
 Complete solution up to
50th harmonic
 Requires allocation
anaylysy
 Sized only to the
requirements of that
system
 Higher cost
 Requires one filter per
drive
 High Cost
 High cost
Solutions: 1 Power Supplies
Pros
Cons
Neutral Blocking
Filter
Computers/
Switch-mode
Power
Supplies
Harmonic
Mitigating
Transformers
Oversized
Neutral/Derated
Transformer
K-Rated
Transformer
 Eliminates the 3rd
harmonic from load
 Relieves system capacity
 Possible energy savings
 3rd harmonic recalculated
back to the load
 When used as phaseshifted transformers,
reduces other harmonics
 Reduces voltage “flattopping”
 Tolerate harmonics rather
than correct
 Typically leased
expensive
 Tolerate harmonics rather
than correct
 High Cost
 May increase voltage
distortion
 Requires fully rated
circuits and over sized
neutrals to the loads
 Upstream and
downstream equipment
fully rated for harmonics
 Does not reduce system
harmonics
Solutions: Fluorescent Lighting
Pros
Cons
K-Rated
Transformer
 3rd harmonic recalculated
back to the load
 When used as phaseshifted transformers,
reduces other harmonics
 Reduces voltage “flattopping”
 Tolerate harmonics rather
than correct
Low Distortion
Ballasts
 Reduce harmonics at the
source
Harmonic
Mitigating
Transformers
Fluorescent
Lighting
 Requires fully rated
circuits and over sized
neutrals to the loads
 Does not reduce system
harmonics
 Additional cost and
typically more expensive
than “system” solutions
Solutions: Welding, Etc.
Pros
Cons
Active Filters
Welding/
Arcing Loads
Tuned Filters
Tuned Filters
System
Solutions
 Fast response and broadband harmonic corrention
 Reduces voltage flicker
 SCR controlled tuned
filters simulates an active
filter response
 Provides PF correction
 Lower cost compared to
other systems
 High cost
 SCR controlled units
are high cost but fixed
filters are reasonable
 System analysis
required to verify
application
Harmonic
Mitigating
Transformers
 Excellent choice for new
design or upgrade
Active Filters
 Ideal solution and handles
 Highest cost
system diversity
 No PF correction
benefit
Review of Solutions
SOLUTION
Shunt/Parallel Filter Solution
Passive Harmonic Filters
Active Harmonic Filter
ADVANTAGES
DISADVANTAGES
 Typically sized to reduce
the most prevalent
harmonics to an acceptable
level
 Requires system
 Provides PF correction
knowledge and analysis
 Avoids resonance by
selecting “tuned”
frequency
 Excellent cancellation for
2nd through 50th harmonic
currents
 Highest cost
 Cannot be overloaded
 Handle diversity of loads
Review of Solutions - 2
SOLUTION
Series Filters/Reactors
ADVANTAGES
Active Harmonic Filter
 Excellent power
conditioning for removing
source voltage harmonics
Neutral Blocking Filters
 Eliminated 3rd harmonic
current from load
Broadband Blocking Filters
 Makes 6-pulse into 18pulse equivalent
AC Line Reactors
DC Reactors for Drives
DISADVANTAGES
 Highest cost
 High cost
 May increase voltage
distortion loads
 High cost
 Requires one filter per
drive
 Inexpensive
 For 6-pulse standard
drive/rectifier can reduce
harmonic distortion from
80% to 35% to 40%
 May require additional
compensation
 Better than AC line
reactors for 5th and 7th
harmonics
 Not always an option for
drives
 Less protection for input
semiconductors
SOLUTION
Transformer Solutions
Isolation Transformers
Transformer Derating
Harmonic Mitigating
Transformers/Phase Shifting
ADVANTAGES




Neutral Cancellation

Transformer – Zero sequence
Trap


18 Pulse Drive Systems
K-Factor Transformers


DISADVANTAGES
 No advantage over reactors
Offers series reactance and
for reducing harmonics
provides electrical isolation
unless used in pairs for
phase shifting
 Does not remove the
Lowest cost solution
harmonics
 Harmonic cancellation
highly dependent on load
Substantial (50% to 80%)
balance
reduction in harmonics
when used in tandem
 Must have even multiples
of unmatched loads
3rd harmonic recalculated
back to the load
Can reduce the 5th and 7th
 Requires fully rated
harmonics when used as
circuits downstream to the
phase shifting pairs
loads
Reduces voltage “flattopping”
Excellent harmonic control
for drives above 100HP
 Higher Cost
IEEE 519 compliant
Tolerate harmonics rather  Does not reduce system
than correct
harmonics
Review of Solutions - 4
SOLUTION
ADVANTAGES
DISADVANTAGES
Other
 Live with high 3rd
harmonics
Oversized Neutrals
 Downstream panels and
shared neutrals must be
oversized
 Transformer windings and
neutral must be sized for
high harmonics
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?