Power Quality
Clean power, Efficient business
Immediate Energy Efficiency with Power Factor
Correction
Outline
Power Factor:
●Definition & Examples
●Cost Savings
●Power Factor Correction Equipment
Harmonics:
●Introduction
●Harmonics and Power Factor Correction Capacitors
●IEEE 519 Standard
●Traditional Harmonic Mitigation Methods
●Active Filter Technology & Applications
Schneider Electric – Global PQ – June 2013
2
What is Power Factor?
Definitions:
● kW = Active Power: It does the "work" for the system - providing the
motion, heat, or whatever else is required.
● kVAR = Reactive Power: It doesn't do useful "work." It simply sustains
the electromagnetic field.
● kVA = Apparent Power: It is the vector addition of Working Power and
Reactive Power.
● Power Factor : The ratio of Active Power (output) to Total Power
(input). It is a measure of efficiency.
Total Power (kVA)
θ
Active Power (kW)
Schneider Electric – Global PQ – June 2013
Power Factor =
Reactive
Power
(kVAR)
=
=
Active (Real) Power
Total Power
kW
kVA
Cosine (θ)
3
Power Factor:The Beer Analogy
kVAR
Mug Capacity = Apparent Power (kVA)
Reactive
Power
Foam = Reactive Power (kVAR)
Beer = Real Power (kW)
kVA
Apparent
Power
kW
Active
Power
Schneider Electric – Global PQ – June 2013
Power Factor =
Beer (kW)
Mug Capacity (kVA)
Capacitors provide the Foam (kVAR),
freeing up Mug Capacity so you don’t
have to buy a bigger mug and/or so you
can pay less for your beer !
4
Why is Power Factor Important?
● Low power factor results in:
● Poor electrical efficiency
● Lower system capacity
● Higher utility bills
●Most utilities have power factor penalties to encourage power
factor correction. Otherwise the utility may have to:
– Build more power plants
– Purchase new transformers
– Use larger cables
● Power factor correction
● Reduces power cost
● Releases system capacity
● Reduces power losses
● Improves voltage
Schneider Electric – Global PQ – June 2013
5
Power Factor Correction
● The easiest solution to improve power factor is to add power
factor correction capacitors to your electrical distribution system.
The Capacitor Supplies
Reactive Current
M
Current that is drawn from the voltage source is then only used to do
real work (kW) and not to create a magnetic field (kVAR). The source
current is then minimized
» The customer only pays for the capacitor
» Since the utility doesn’t supply the kVAR, the customer doesn’t
pay for it
» In short, capacitors save money
Schneider Electric – Global PQ – June 2013
6
A2
Power Factor Correction
In this example, demand is
reduced from 100 kVA to 80
kVA by installing a 60 kVAR
capacitor.
Before: PF = kW/kVA = 80%
After: PF = kW/kVA = 100%
Transformer loading is reduced
Schneider Electric – Global PQ – June 2013
7
Benefits of Power Factor Correction
● Reduced Power Costs: lower utility bills since utility no longer
supplies the reactive current.
● Released System Capacity
● Capacitors off-load transformers and cables
● Improved Voltage
● Reduced losses
kW
100
kVAR
100
kVA = 141
PF = 70%
Schneider Electric – Global PQ – June 2013
kW
100
kVAR
75
kVA = 125
PF = 80%
kW
10
0
kVA = 100
PF = 100%
8
How do utilities charge for Power Factor?
● Example with $5.50 per demand kW
Service
Month
05/14/11
06/14/11
07/16/11
08/15/11
09/16/11
10/16/11
11/16/11
12/16/11
01/16/12
02/16/12
03/16/12
04/16/12
Billing
Demand
kW
900.0
800.0
850.0
875.0
910.0
780.0
890.0
870.0
760.0
750.0
690.0
870.0
Power
Factor
0.8000
0.7950
0.7625
0.7511
0.7574
0.7722
0.7950
0.7950
0.7625
0.7511
0.7574
0.7722
Actual
Actual
Demand Demand
kVA
kW
1,000.0
800.0
888.9
706.7
944.4
720.1
972.2
730.2
1,011.1
765.8
866.7
669.2
988.9
786.2
966.7
768.5
844.4
643.9
833.3
625.9
766.7
580.7
966.7
746.5
0.0
0.0
Savings
2012
Possible
Cost
Savings
$550.00
$513.33
$714.24
$796.20
$793.01
$609.18
$571.08
$558.25
$638.61
$682.46
$601.30
$679.47
Required
Required
% Reduction
Capacitor kVAR Capacitor kVAR of Transformer
for 0.92 pf
for 1.0 pf
kVA Load
259
600
20%
238
539
21%
304
611
24%
331
642
25%
334
660
24%
266
551
23%
265
600
21%
259
586
21%
272
546
24%
284
550
25%
253
501
24%
296
614
23%
$7,707.13
Approximate cost of standard power factor correction equipment $12 to $15K === Payback about 2 years.
Approximate cost of filtered power factor correction equipment $18 to $21K === Payback about 3 years.
Schneider Electric – Global PQ – June 2013
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Power Factor Correction
● Capacitors:
● Low Voltage Power Factor Correction Capacitor Banks
●Fixed
●Standard Automatic
●Detuned
●Transient Free
● Medium Voltage Power Factor Correction Capacitor Banks
●Fixed
●Standard Automatic
●Detuned
● Active Filters
● LV and MV Hybrid VAR Compensation Products
Schneider Electric – Global PQ – June 2013
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Schneider Electric – Global PQ – June 2013
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Outline
Power Factor:
●Definition & Examples
●Cost Savings
●Power Factor Correction Equipment
Harmonics:
●Introduction
●Harmonics and Power Factor Correction Capacitors
●IEEE 519 Standard
●Traditional Harmonic Mitigation Methods
●Active Filter Technology & Applications
Schneider Electric – Global PQ – June 2013
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Harmonic Basics
Waveform seen
with oscilloscope
● What are harmonics?
● A harmonic is a component of a periodic
wave with a frequency that is an integer
multiple of the fundamental frequency
● Created by power semiconductor devices
Fundamental
rd
3 Harmonic
th
7 Harmonic
t1h
5 Harmonic
●Converts power (AC to DC)
Harmonic Frequency
Sequence
1
2
3
4
5
6
7
:
19
60Hz
120Hz
180Hz
240Hz
300Hz
360Hz
420Hz
:
1140Hz
Schneider Electric – Global PQ – June 2013
+
0
+
0
+
+
● Characteristic harmonics are the
predominate harmonics seen by the power
distribution system
●Predicted by the following equation:
Hc = np ± 1
– HC = characteristic harmonics
to be expected
– n = an integer from 1,2,3,4,5,
etc.
– p = number of pulses or
rectifiers in circuit
14
Harmonic Filtering
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Multi-pulse Converters
Harmonic Orders Present
Hn = np +/- 1
Hn = characteristic
harmonic order
present
n = an integer
p = number of pulses
Elimination of lower orders
removes largest amplitude
harmonics
Schneider Electric – Global PQ – June 2013
Hn
3
5
7
9
11
13
15
17
19
21
23
25
27
29
31
33
35
37
39
41
43
45
47
49
Harmonics present by rectifier design
Type of rectifier
1 phase
2 phase 3 phase 3 phase
4-pulse
4-pulse
6-pulse 12-pulse
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
AccuSine SWP
AccuSine PCS
3 phase
18-pulse
x
x
x
x
16
Harmonic Basics
● Nonlinear loads draw harmonic current from source
● Does no work
Voltage: flat
topping of
waveform
Basic PWM VFD
Current: high TDD
between 90-120%
Inverter
Converter
DC bus
M
A
B
C
Schneider Electric – Global PQ – June 2013
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Harmonic Basics
●Why the concern?
● Current distortion
●Added heating = reduced capacity
●Equipment failures
– Transformers
– Conductors and cables
– Nuisance tripping of electronic
circuit breakers (thermal
overloads)
●Heating proportional to harmonic
order in cables & bus bars
Ih
Loads
Vh = Ih × Zh
● Squared effect on transformers & AC
motors
Schneider Electric – Global PQ – June 2013
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Harmonic Basics
Voltage distortion
● Created as current harmonics flow
through the system
● Interference with other electronic loads
Ih
●Malfunctions to failure
● Induces harmonic currents in linear loads
●AC motor winding over heating & bearing
failures
Loads
Vh = Ih × Zh
Schneider Electric – Global PQ – June 2013
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Harmonics and Standard Capacitors
●Capacitors absorb harmonics
● Overheating of PFC capacitors
● Tripping of PF protection devices
● Reduced life expectancy
●Magnification of harmonics by
resonance
Utility
M
M
Schneider Electric – Global PQ – June 2013
M
VFD
● Amplification of current between
capacitor and transformer
● Current distortion rises
● Voltage distortion rises
● Main transformer &/or capacitor
fuses blow
● Equipment damage
20
Capacitor Resonance
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Detuned Capacitors
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Conventional Switch Structure
L1
HRC Fuses
Contactors
Optional
De-tuned
Inductor
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L2
L3
Electromechanical
switching
elements
(contactors) are
used to connect a
capacitor group.
23
IEEE 519-1992
● Defines current distortion as TDD (Total Demand Distortion)
● Largest amplitude of harmonic current occurs at maximum load of
nonlinear device – if electrical system can handle this it can handle all
lower levels of amplitudes
● Always referenced to full load current
● Effective meaning for current distortion
● Defines voltage distortion as THD
● Total harmonic voltage distortion
● Does not use THD(I)
● Total harmonic current distortion
● Instrument measurement (instantaneous values)
● Uses measured load current to calculate THD(I)
THDv =
2
V
∑ h
Vf
Schneider Electric – Global PQ – June 2013
TDD =
2
I
∑h
If ( FLA )
THDi =
2
I
∑h
If
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IEEE 519-1992
● Issues addressed:
● THD(V) delivered by utility to user (Chapter 11)
●THD(V) must be < 5% [< 69 KV systems]
● Defines the amount of TDD a user can cause (Chapter 10)
●Based upon size of user in relation to power source
●Table 10.3 for systems < 69 kV
● Defines limits for voltage notches caused by SCR rectifiers –
Table 10.2
● Defines PCC (point of common coupling)
Schneider Electric – Global PQ – June 2013
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IEEE 519-1992
• TDD and THD(I) are not the same except at 100% load
• As load decreases, TDD decreases while THD(I) increases.
• Example:
Total I,
rms
Full load
Schneider Electric – Global PQ – June 2013
936.68
836.70
767.68
592.63
424.53
246.58
111.80
Measured
Fund I, Harm I,
rms
rms
936.00
836.00
767.00
592.00
424.00
246.00
111.00
35.57
34.28
32.21
27.23
21.20
16.97
13.32
THD(I)
3.8%
4.1%
4.2%
4.6%
5.0%
6.9%
12.0%
TDD
3.8%
3.7%
3.4%
2.9%
2.3%
1.8%
1.4%
26
IEEE 519-1992 Table 10.3
Current Distortion Limits for General Distribution Systems (<69 kV)
Isc/Iload
<20
20<50
50<100
100<1000
>1000
<11
4.0%
7.0%
10.0%
12.0%
15.0%
11<=h<17 17<=h<23 23<=h<35
2.0%
1.5%
0.6%
3.5%
2.5%
1.0%
4.5%
4.0%
1.5%
5.5%
5.0%
0.2%
7.0%
6.0%
2.5%
h>=35
0.3%
0.5%
0.7%
1.0%
1.4%
TDD
5.0%
8.0%
12.0%
15.0%
20.0%
Isc = short circuit current capacity of source
Iload = demand load current (fundamental)
TDD = Total Demand Distortion
(TDD = Total harmonic current distortion measured against
fundamental current at demand load.)
Schneider Electric – Global PQ – June 2013
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Harmonic Standards
•Designed
to protect utility
•Most harmonic problems are not at PCC with utility
•Occur
inside the plant
•Occur where nonlinear loads are concentrated
•Occur with generators & UPS (high probability of problems)
•Need to protect the user from self by moving the PCC to
where harmonic loads are located.
•Apply
principals of IEEE 519-1992 Table 10.3 inside
the plant
•Assures
trouble free operations
•Assures compliance to standard
•We
have the products to meet 5% TDD inside the plant
Schneider Electric – Global PQ – June 2013
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Harmonic mitigation methods - (Applied per
VFD)
Typical %
Typical Price
Solution
Advantage
Disadvantage
TDD
Multiplier*
Dependent
upon SCR***
Cost of transformer and
installation change out
Increase short
circuit capacity
Reduces THD(V)
●Increases TDD
●Not likely to occur**
C-Less
Technology
●Lower TDD
●Simplified design
●Less cost
●Compliance is limited
●Application limited
●Size limited
30 - 50% TDD
0.90 - 0.95
Impedance (3%
LR or 3% DC
choke)
●Low cost adder
●Simple
●Compliance difficult
30 - 40% TDD
1.05 - 1.15
5th Harmonic
filter
Reduces 5th & total
TDD
●Does not meet harmonic
levels at higher orders^
18 - 22% TDD
1.20 - 1.45
Broadband filter
Reduces TDD (thru
13th)
●Large heat losses
●Application limited
8 - 15% TDD
1.25 - 1.50
12-pulse rectifiers
●Reduces TDD
●Reliable
●Large footprint/heavy
●Good for >100 HP
8 - 15 % TDD
1.65 - 1.85
18-pulse rectifiers
●Reduces TDD
●Reliable
●Large footprint/heavy
●Good for >100 HP
5 - 8% TDD
1.65 - 1.85
Active front end
converter
●Very good TDD
●Regeneration
possible
●Large footprint/heavy
●Very high cost per unit
●High heat losses
< 5% TDD
2.0 - 2.5
* Price compared to a standard 6-pulse VFD.
** Utilities and users are not likely to change their distribution systems.
*** Increasing short circuit capacity (lower impedance source or larger KVA capacity) raises TDD but lowers THD(V).
^ Can be said for all methods listed.
Active Filter Concept
Load(s)
Source
XFMR
SOURCE
Sense
LOAD
Sense
Is
Il
Ia
•Parallel connected
  
Is + Ia = Il
Optional CT
location

• Ia
includes 2nd to 50th
harmonic current

• Is
<5% TDD
Schneider Electric – Global PQ – June 2013
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Harmonic Mitigation Solutions
System solution
Comparison of 18-P VFD to AccuSine PCS + standard VFD
●Price (first cost)
●Footprint required
●Heat losses
●Cost to operate
●Site cooling required
●Net Present Value (NPV)
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Solutions by AccuSine Model
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Schneider Electric Offer
●AccuSine SWP
● 20-120 Amps
● 400 VAC
● Neutral correction
●AccuSine PCS
● 50-300 Amps
● 208-480 VAC/600 VAC/690 VAC
●AccuSine PFV
● 50-300 Amps
● 208-480 VAC/600 VAC/690 VAC
● No harmonics
●Use customized transformers for higher voltages (to 15 kV for
harmonics & 35 kV for non-harmonic modes)
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AccuSine SWP
● The Schneider Electric solution for harmonic filtering in buildings.
Schneider Electric – Global PQ – June 2013
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AccuSine PCS
● The Schneider Electric solution for active harmonic filtering in
industrial installations.
● Most common – VFD sites
● Centrifugal pumps and fans
●Pumping Stations
– Potable
– Wastewater
●Wastewater Plants
●Water Purification (potable)
Schneider Electric – Global PQ – June 2013
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AccuSine® PCS/PFV
Power Diagram
IGBT Module
C
Pre-charge
Contactor
C
E
S1
C
E
S3
E
S5
DC Bus
Capacitors
Fuse
AC
Lines
Fuse
Line
Inductor
+
C
Fuse
Inductor
C
Filter
Board
E
S2
Schneider Electric – Global PQ – June 2013
C
C
E
S4
E
S6
36
AccuSine® PCS
Performance Summary - Harmonics
● Discrete Spectrum Logic (DSL)
● TDD <= 5%, if loads have =>3% Z installed
● 2nd to 50th orders, discrete
● <2 cycle response
● Resonance avoidance logic
● Adjustable trip limits per harmonic order
● On-board commissioning program
●Phase rotation (clockwise required)
●Automatic CT orientation (phase rotation/polarity/calibration)
●Run lockout if not possible to re-orient
● Oscilloscope feature built into HMI
● Load/source bar graphs
● Load balancing
● Can parallel up to 99 units of each size and mix sizes
Schneider Electric – Global PQ – June 2013
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System Solution
AccuSine® PCS Sizing Example
● A 125 HP variable torque 6-pulse VFD with 3% LR
● Required AHF filtering capability = 47.5 amperes
● Two 125 HP VT 6-pulse VFD w/3% LR
● Required AHF size = 84.4 amps
● Three 125 HP VT 6-pulse VFD w/3% LR
● Required AHF size = 113.5 amps
● Six 125 HP VT VFD w/3% LR
● Required AHF size = 157.6 amps
● (not 6 x 47.5 = 285 amps)
Schneider Electric – Global PQ – June 2013
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AccuSine® PCS/PFV
Product Package
● Standard (UL/CSA, ABS)
● Three current ratings
● Enclosed – NEMA 1/IP20
● 50 amp – 52”(1321mm) x 21”(533mm) x
19”(483mm)
●Weight – 250#(114 K\kg)
● 100 amp – 69”(1753mm) x 21”(533mm) x
19”(483mm)
●Weight – 350#(159 kg)
● 300 amp – 75”(1905mm) x 32”(813mm) x
20”(508mm)
●Weight – 775#(352 kg)
● Wall mount – 50 & 100 amp
● Free standing – 300 amp with disconnect
Schneider Electric – Global PQ – June 2013
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AccuSine® PCS/PFV
Product Package
● Other enclosures (380 - 480VAC)
● NEMA 12, IP30, IP54
●50 amp – 75”(1905mm) x
31.5”(800mm) x 23.62”(600mm)
– Weight – 661Ib(300 kg)
●100 amp – 75”(1905mm) x
31.5”(800mm) x 23.62”(600mm)
– Weight – 771Ib(350 kg)
●300 amp – 75”(1905mm) x
39.37”(1000mm) x 31.5”(800mm)
– Weight – 1012Ib(460 kg)
● Free standing with door interlocked
disconnect
● CE Certified, C-Tick, ABS, UL, CUL
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AccuSine PCS 600/690 VAC
● Includes autotransformer &
input fused disconnect
● Simple installation
● 600 VAC: UL/cUL/CE
● 690 VAC: CE
● Ratings:
PCS 600V 690V
50 A
39 A 33 A
100 A 78 A 67 A
300 A 235 A 200 A
Schneider Electric – Global PQ – June 2013
Height
300A
1000 mm
800 mm
Height
1900 mm
Depth
800 mm
50/100A
800 mm
600 mm
1972 mm 600 mm
41
AccuSine Performance
At VFD Terminals
AccuSine injection
Source
current
Schneider Electric – Global PQ – June 2013
Order
Fund
3
5
7
9
11
13
15
17
19
21
23
25
27
29
31
33
35
37
39
41
43
45
47
49
TDD
AS off
AS on
% I fund % I fund
100.000%100.000%
0.038% 0.478%
31.660% 0.674%
11.480% 0.679%
0.435% 0.297%
7.068% 0.710%
4.267% 0.521%
0.367% 0.052%
3.438% 0.464%
2.904% 0.639%
0.284% 0.263%
2.042% 0.409%
2.177% 0.489%
0.293% 0.170%
1.238% 0.397%
1.740% 0.243%
0.261% 0.325%
0.800% 0.279%
1.420% 0.815%
0.282% 0.240%
0.588% 0.120%
1.281% 0.337%
0.259% 0.347%
0.427% 0.769%
1.348% 0.590%
35.28% 2.67%
42
700 HP Drive – AccuSine ON – OFF
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700 HP Drive – AccuSine ON – OFF
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700 HP Drive – AccuSine ON – OFF
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45
AccuSine® PCS
Dual Mode Operation
● Assignment of capacity
● Assign priority to Harmonic or PF/LB
(fundamental) modes
● Use % of harmonic mode to set split
●100% means capacity utilized for
harmonic correction, then left
over can be used for PF/LB
●0% assigns fundamental (PF
correction/LB) current as primary
mode, left over used for harmonic
correction
●Can split to limit harmonic mode
capacity, left over to PF
correction/LB
Schneider Electric – Global PQ – June 2013
I as = I h + I f
2
2
Ias = rms output current of
AccuSine PCS
Ih = rms harmonic current
If = rms fundamental current
Ias
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
Examples
Ih
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
95.0
If
99.5
98.0
95.4
91.7
86.6
80.0
71.4
60.0
43.6
31.2
46
AccuSine® PFV
Power Factor & VAR Compensation
●HVC (AccuSine PFV + PF caps)
● Larger systems approach
●HVC is Hybrid VAR Control
– Combines AccuSine PFV with PF caps
– Caps on line all the time
● AccuSine adjusts fundamental current to attain unity DPF
● Cycle-by-cycle response
● Voltages to 33 kV (6.6 kV shredder in France, 12.47 kV in US
automotive, 13.8 kV steel mill in Colombia)
● Fundamental current balancing (optional since 1 Nov 10))
●Sometimes critical – i.e. two phase loads
Schneider Electric – Global PQ – June 2013
47
Thank You
Questions?
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