Harmonic and Energy Saving Solutions - … 3/Harmonic Workshop/PQSynergy Harmonic… · Private and...

Harmonic and Energy Saving Solutions

Power Quality You Can Trust | Real World Experience | A History of Innovation

Harmonic and Energy Saving Solutions

Harmonics Workshop PQSynergy 2015 Tony Hoevenaars, P.Eng., President & CEO Talayeh Ameri, B.Eng., Sales & Application Support Engineer

Private and Confidential | Mirus International

What we will Discuss

A. Power System Harmonics Basics B. How do Harmonics Create Problems on the

Power System? C. Various Forms of Harmonic Mitigation D. Computer Simulation Software for VSD

Harmonic Analysis

© 2013 Mirus International | All Rights Reserved

Power System Harmonics Basics


• Deviations of voltage and current waveforms from sinusoidal are described in terms of ‘Waveform Distortion’ or ‘Harmonic Distortion’

• A ‘Harmonic’ refers to a component of a periodic signal, that is sinusoidal and also periodic with a frequency that is an integer multiple of the fundamental frequency

Power System Harmonics

• In the majority of cases, harmonic distortion is produced by a customer’s equipment (non-linear load) injecting electrical noise into the power system – Major culprits are the Variable

Speed Drive and other power electronic equipment


Current Waveforms and Harmonic Spectrums for Various Types of Loads

Power electronics and energy efficient

technologies are typically non-linear

ITHD = 30% - 125% KFactor = 4 to 13

ITHD = 30% - 80% KFactor = 4 to 9

0 20 40 60 80

100

1 3 5 7 9 11 13 15

Non-linear (1-phase)

0

20

40

60

80

100

1 3 5 7 9 11 13 15 17 19 21 23 25harmonic

% F

und.

Non-linear (3-phase)

Linear Load 0 20 40 60 80

100

1 3 5 7 9 11 13 15

ITHD = 0 KFactor = 1


Non-linear Loads and Harmonics Typical Circuit Diagram of Switch-mode Power Supply

Load

Lls

vac

iac

Rectifier Bridge

Switch-mode dc-to-dc converter

Smoothing Capacitor

Cf

0

20

40

60

80

100

1 3 5 7 9 11 13 15

h = harmonic number p = # of pulses in rectification scheme n = any integer (1, 2, 3, etc.) Ih = magnitude of harmonic current (addition of DC bus cap increases Ih)

For simple diode bridge rectifiers, h = np 1, Ih = I h

+ _

When, p = 2 h = 3, 5, 7, 9, 11,13, 15, 17, 19...


1-Phase Rectifier Operation: 2-Pulse

0º 180º 360º

VLN

L

N

Average DC Bus voltage (1.414 x VRMS less ripple)

1 2

h = np 1,

+ _

When p = 2, h = 3,5,7,9,11,13,15,…


Harmonics: Components of a Distorted Waveform

Distorted Waveform

-2

-1

0

1

2

Fundamental - 60 Hz

-1.5-1

-0.50

0.51

1.5

Distorted Waveform

-3

-2

-1

0

1

2

3

3rd Harmonic - 180 Hz

-1.5-1

-0.50

0.51

1.5

5th Harmonic - 300 Hz

-1.5-1

-0.50

0.51

1.5

Fourier Series f(t) = Ao+A1sin(wt+θ1)+A2sin(2wt+θ2)+A3sin(3wt+θ3) ...


3-phase, 6-Pulse Rectifier and Harmonics

h = np 1, Ih = I h

+ _ For simple diode bridge rectifiers:

When, p = 6 h = -- 5,7,--,11,13,--,17,19... 0

20

40

60

80

100

1 3 5 7 9 11 13 15 17 19 21 23 25harmonic

% F

und.

. ia

Current Waveform and Spectrum

h = harmonic number p = # of pulses in rectification scheme n = any integer (1, 2, 3, etc.) Ih = magnitude of harmonic current (addition of DC bus cap increases Ih)



120º 120º

0º 180º 360º

1 2 3 4 5 6

VAN

VBC VBA VCA VCB

VBN VCN

A

B

C

VAB VAB VAC VAC Average DC Bus voltage (1.414 x VRMS less ripple)


Harmonics: Components of a Distorted Waveform

Distorted Waveform

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

Fourier Series f(t) = Ao+A1sin(wt+θ1)+A2sin(2wt+θ2)+A3sin(3wt+θ3) ...

Fundamental - 60 Hz

-1.5

-1

-0.5

0

0.5

1

1.5


-1.5

-1

-0.5

0

0.5

1

1.5


-1.5

-1

-0.5

0

0.5

1

1.5

Resultant Waveform

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

Resultant Waveform

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2Resultant Waveform

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

Harmonic Spectrum

0

20

40

60

80

100

1 3 5 7 9 11 13

Harmonic #

% o

f Fun

dam

enta

l

Harmonic Spectrum

0

20

40

60

80

100

1 3 5 7 9 11 13

Harmonic #

% o

f Fun

dam

enta

l

Harmonic Spectrum

0

20

40

60

80

100

1 3 5 7 9 11 13

Harmonic #

% o

f Fun

dam

enta

l


Total Harmonic Distortion

• ‘Fundamental Current’ refers to the current carried in the fundamental frequency, Ih1 (60 Hz).

• ‘Current Total Harmonic Distortion’ refers to the ratio of all harmonic currents to the fundamental current.

( )%100

1

2

2max

⋅=∑

=

h

h

hh

I

IiTHD

Ratio of the root-sum-square (RSS) value of the harmonic content of the current to the RMS value of the fundamental current.


Defining Level of Harmonic Content - Non-Linearity

I(THD) = I + I +....+ I 2 2 2 2

3 h 1 I

x 100%

Total Harmonic Distortion

K-rating I h h h

h

= =

∑ 2 2

1

max

K Factor

PF = 1 1 + (I(THD))2

Distortion Power Factor

Harmonic %Fund. %RMS I2H2

1 100% 77% 0.593 70% 54% 2.615 35% 27% 1.817 20% 15% 1.169 15% 12% 1.08

11 10% 8% 0.7213 7% 5% 0.4915 3% 2% 0.1217 2% 2% 0.0719 1% 1% 0.0221 0% 0% 0.00

I(THD) 83% 64%I(RMS) 130%

PF 0.77K Factor 9


Defining Level of Harmonic Content - Non-Linearity

Harmonic %Fund. %RMS I2H2 %Fund. %RMS I2H2 %Fund. %RMS I2H2

1 100% 91% 0.83 100% 96% 0.93 100% 66% 0.433 35% 32% 0.91 0% 0% 0.00 90% 59% 3.155 25% 23% 1.29 25% 24% 1.45 55% 36% 3.277 12% 11% 0.58 10% 10% 0.45 35% 23% 2.599 9% 8% 0.54 0% 0% 0.00 20% 13% 1.40

11 3% 3% 0.09 7% 7% 0.55 15% 10% 1.1813 2% 2% 0.06 3% 3% 0.14 10% 7% 0.7315 1% 1% 0.02 0% 0% 0.00 6% 4% 0.3517 1% 1% 0.02 3% 3% 0.24 4% 3% 0.2019 1% 1% 0.03 2% 2% 0.13 2% 1% 0.0621 0% 0% 0.00 0% 0% 0.00 1% 1% 0.02

I(THD) 46% 42% 28% 27% 115% 75%I(RMS) 110% 104% 152%

PF 0.91 0.96 0.66K Factor 4 4 13

1 Phase 3 Phase 1 Phase


How Harmonics Affect Power Factor & kVA

True Power Factor = (Displacement Power Factor) x (Distortion Power Factor)

With Non-linear Loads

Q = kVAR (nonwork

producing)

P = kW (work producing)

H = kVARH (nonwork

producing)

S = kVA

φ

S P Q H = + + 2 2 2

kVA kW kVAR kVAR H = + + 2 2 2

pf P S

kW kVA

= = ≠ cos φ

Q = kVAR (nonwork

producing)

P = kW (work producing)

S = kVA

φ

With Linear Loads φ cos = = =

kVA kW

S P pf

S P Q = + 2 2

kVA kW kVAR = + 2 2


THID & PF Measurements on 60 HP AC VSD

Input CurrentWaveform Spectrum THID

PowerFactor

6-PulseRectifier, PWM

VSD -150

-100

-50

0

50

100

150

Amps


Power System Harmonic Resonance

Typical Single Line Diagram

M XC

XS

XT XL Non-linear

Loads

Equivalent Diagram

Harmonic Current Source

XTh

XSYSh Ih

Irh

Eh XCh

Problems that can result include: - Destroyed capacitors and their fuses - Damaged surge suppressors - Failure of connected equipment - System shutdowns

Resonance will occur when:

XCh = XSYSh (XSYSh = XS || XL ) At resonance, the circulating current is limited only by the resistance in the circuit.

Reac

tanc

e

Frequency

X

XL= 2πfL

XC = 1 2πfC

fo = 1 2π LC


Example of Power System Resonance An Oil Field in Mid-West USA was equipped with many Electrical Submersible Pumps (ESP’s) creating high levels of ITHD & VTHD

Problem:

• Utility installed PF correction capacitors were failing frequently

• Oil company was forced to install harmonic mitigation

Solution:

• Resonance was eliminated by turning off PF capacitors

• Passive harmonic filters were installed on all ESP’s to reduce VTHD to < 5%


Harmonics and Symmetrical Components

Important Note: Reversing the phase sequence to a transformer will reverse its phase shift (eg. -30o +30o)

+ + = Positive sequence System (A, B, C)

C + B +

A +

120o

C -

B - A -

120o

Negative sequence System (A, C, B)

Zero sequence System

(3 single phase)

Unbalanced 3 Phase System (A, B, C)

Relationship between harmonic number and phase sequence:

Harmonic 1 (fund.)

2 3 4 etc.

Sequence

5 6 7 8 9 10 11 12 13 14 15

0 0 0 0 0

A + A -

+ + + + + - - - - -

C + B +

C -

B -

A 0 B 0

C 0

A 0 B 0

C 0 C

B

A


Summary of Power System Harmonics Basics • Harmonics are components of a distorted waveform • It’s easier to analyze the effect of distorted current and

voltage waveforms using sinusoidal harmonic components – Fourier Analysis

• Power electronic loads draw distorted current waveforms and are therefore non-linear in nature

• Harmonic resonance needs to be considered especially when applying PF correction capacitors


How do Harmonics Create Problems on the Power System?


• Distortion of supply voltage causing premature failure or misoperation of connected equipment

• Over heating of distribution equipment such as cables (especially neutral conductors), transformers and generators

• False operation of circuit breakers and other protection devices

• Over heating of motors and other connected equipment • Low power factor requiring transformer kVA upsizing • Failure of PF correction capacitors • Metering errors (no longer a problem with digital meters) • Voltage regulation problems on generators • Power system resonance which amplifies the problem

What Problems can Harmonics Create?


At the Load, Vh = Ih x (ZCh + ZTh + ZSh) At the Transf., Vh = Ih x (ZTh + ZSh) At the Source, Vh = Ih x (ZSh)

Vh = Ih x Zh (Ohm's Law) Vthd = V +V +....+V 2

2 2 2 3 h 1 V

x 100% Voltage total harmonic distortion

Sinusoidal Voltage Source (f1 = 60 Hz) Harmonic

Current Source

h I

ZSh

ZCh

~ ^ ^ V h

@ Source V h @ Transf.

V h @ Load

ZTh

Non-linear load

How Harmonic Currents Create Voltage Distortion

ZSh

ZCh

ZTh

CUSTOMER/UTILITY

UTILITY

VFD1

Presenter

Presentation Notes

Basically ohms law applies to harmonics as well. Harmonic voltage is equal to the harmonic current times the impedance. At the load the impedance is higher and therefore the harmonic voltage is higher. The total voltage harmonic distortion is the root sum squared of all the voltage harmonics divided by the fundamental voltage x100%.


Pulsed Current: • Switch-mode draws current

only while capacitor is charging

Voltage Flat-topping: • Pulsed current creates

voltage drop at peak of voltage waveform

Power Electronics and Harmonic Distortion

Voltage Current

Typical Circuit Diagram of Switch-mode Power Supply

Load

Lls

vac

iac

Rectifier Bridge

Switch-mode dc-to-dc converter

Smoothing Capacitor

Cf

Presenter

Presentation Notes

The current is drawn only while the capacitor is charging which means current is only drawn at the peak of the voltage and therefore the voltage drop happen at the peak and causes flat topping


Lineator™ Installation at Chevron Canada (Simonette 10-19 Well - ESP Installation)

Presented by Peter O’Brien (CCR I & E Group) at Chevron EE Conference, San Antonio, Sept. 2000

T

TT

1) Ch 1: 50 Volt 2 ms 2) Ch 2: 200 A 2 ms

TTT

1) Ch 1: 200 Volt 2 ms 2) Ch 2: 500 A 2 ms

Input Without Filter Installed Input With Filter Installed

Voltage Current


How Flat-topping Reduces Life Expectancy

• Voltage flat-topping reduces DC bus voltage

10% drop in peak voltage produces 11% increase in current and

• Lower DC voltage, increases current and I2R losses (heat)

P = V I If V = 0.9 pu, I = P = 1.0 = 1.11 pu V 0.9

23% increase in I2R losses

• Pre-mature component failure results from higher operating temperatures

PLoss = I2R = (1.11)2 (1) = 1.23 pu

DC Bus Voltage with: Sinusoidal Input Voltage (blue) Flat-topped Input Voltage (red)

-200-150-100-50

050

100150200

Volta

ge

Presenter

Presentation Notes

Flat topping reduces the DC bus voltage. Lower DC bus increases I2R losses which is basically heat. And the higher operating temp causes pre-mature component failure.


SCR Rectifier and Harmonics (DC Drive)

• Variable speed and torque is controlled by firing of SCR’s to adjust DC armature voltage

• Harmonic currents are characteristic of 6-Pulse VFD – Magnitudes can be

somewhat different than AC VFD’s

• Phase back angle lowers displacement PF and introduces commutation notches

Presenter

Presentation Notes

Variable speed and torque is controlled by firing of SCR’s to adjust DC armature voltage. Notches are typically present in the waveform during SCR commutation. As we delay the firing of thyristors in order to control the DC bus voltage, for a very small duration of time, a short circuit is created between the two phases. With a short circuit, the current increases and the voltage decreases. The decrease in voltage is defined as a line notch.


Distortion due to Commutation Notching

Ref: The Problems of Voltage Notch Phenomena in Power AC/DC Converters, R. Ghanderhari, Iran University of Science & Technology, UPEC 2007

Line Notching with Associated Ringing

Power system capacitance and inductance can cause resonance at commutation notch frequency resulting in ringing

Line Notching due to SCR Bridge Operation


Electrical Distribution with 1-Ph Linear Loads

Balanced Currents cancel in neutral

= + +

Phase A Current

Phase B Current

Phase C Current

Neutral Current

Ground Wire

Transformer

Vn-g

Presenter

Presentation Notes

If the loads are linear and balanced, the vector sum of the phase currents at


Electrical Distribution: 1-Ph Non-linear Loads

Transformer Phase A Current

Phase B Current

Phase C Current

Neutral Current

Ground Wire

Vn-g

•Heavy neutral currents - overheating neutrals •Overheating transformers •High neutral-gnd voltage •High Voltage distortion


Harmonic Effect on Transformer Losses

3rd and 9th harmonics circulate in primary delta windings

Type of Loss Effect of Non-linear Loading No Load Loss Core

Stray eddy currents increase proportional to Ih

2h2 Load Loss I2R Eddy Current Other Stray

Losses

Negligible increase

Skin effect increases effective resistance and I2R losses

P P I h EC EC h h

h

= −

= ∑ 1

2 2

1

max


• Most power electronic equipment now generates lower levels of harmonics – Previously ITHD levels over 100% were

not uncommon • However, harmonics have not been

totally eliminated – Standards can be met even if equipment

generates harmonic currents • Somewhat higher non-linear loading

is now possible before harmonic problems begin to appear

How have IEC Harmonic Standards Changed Things?


IEC 61000-3-2 (2000(A14)) Standard: Limits for harmonic current emissions (equipment input current < 16A per phase, single & 3 phase

Class D: Equipment having a special waveshape (high crest factor) and input power < 600W

Class A: All other equipment except portable tools and lighting

Often referred to as ‘Power Factor Corrected’


IEC 61000-3-2 (2000(A14)) Standard: Example of acceptable designs

500W power supply at 240V: If = 2.1A

I3 < 1.7A (.0034 x 500) I3/If = 81%

1kW power supply at 240V: If = 4.2A

I3 < 2.3A I3/If = 55%


Computer Power Supply Harmonic Data: 500 to 850W Power Factor Corrected (Higher End)

Reference: Delta Products Corp., Aug. 2009

P.F. 0.9849 0.9829 0.9808 0.9774 0.9729 0.9638 0.9555 0.9427 0.9143 0.853THD 18.345 20.16 20.384 23.072 23.669 27.225 30.193 35.687 45.796 77.688Irms 3.657 3.296 2.934 2.566 2.207 1.851 1.5 1.163 0.818 0.494Harm-1 3.594 3.231 2.871 2.509 2.151 1.788 1.433 1.086 0.737 0.393Harm-3 0.588 0.556 0.514 0.472 0.434 0.42 0.376 0.323 0.263 0.174Harm-5 0.214 0.204 0.186 0.167 0.149 0.125 0.109 0.117 0.115 0.096Harm-7 0.119 0.107 0.09 0.08 0.078 0.093 0.109 0.084 0.053 0.06Harm-9 0.065 0.053 0.052 0.057 0.064 0.073 0.055 0.045 0.052 0.037Harm-11 0.039 0.041 0.044 0.045 0.042 0.035 0.037 0.048 0.023 0.028Harm-13 0.043 0.044 0.044 0.038 0.032 0.041 0.042 0.023 0.032 0.024Harm-15 0.042 0.045 0.043 0.041 0.035 0.039 0.028 0.04 0.022 0.015Harm-17 0.041 0.04 0.043 0.038 0.024 0.025 0.025 0.01 0.016 0.009Harm-19 0.037 0.038 0.036 0.025 0.01 0.024 0.019 0.025 0.021 0.018Harm-21 0.034 0.034 0.029 0.014 0.014 0.025 0.024 0.022 0.014 0.011Harm-23 0.034 0.03 0.027 0.02 0.021 0.024 0.019 0.014 0.014 0.007Harm-25 0.031 0.027 0.026 0.021 0.024 0.024 0.016 0.017 0.013 0.01Harm-27 0.028 0.028 0.026 0.023 0.026 0.015 0.021 0.017 0.011 0.008Harm-29 0.024 0.023 0.022 0.026 0.027 0.016 0.02 0.014 0.009 0.006Harm-31 0.022 0.024 0.023 0.028 0.024 0.015 0.019 0.011 0.015 0.01

Load 100% 90% 80% 70% 60% 50% 40% 30% 20% 10%

I3 = 23% of Fundamental


Computer Power Supply Harmonic Data: 500 to 850W Power Factor Corrected (Lower End)

Reference: Delta Products Corp., Aug. 2009

P.F. 0.89 0.884 0.878 0.871 0.861 0.851 0.842 0.833 0.818 0.818THD% 37.738 39.413 41.518 44.337 47.267 50.743 53.79 56.305 56.111 55.14Irms 3.703 3.343 2.995 2.634 2.29 1.946 1.597 1.241 0.876 0.541Harm-1 3.465 3.111 2.768 2.413 2.07 1.736 1.407 1.081 0.763 0.475Harm-3 1.21 1.126 1.046 0.965 0.88 0.787 0.68 0.551 0.396 0.24Harm-5 0.399 0.393 0.386 0.379 0.351 0.32 0.278 0.225 0.148 0.081Harm-7 0.185 0.182 0.173 0.18 0.171 0.161 0.145 0.105 0.056 0.037Harm-9 0.136 0.131 0.127 0.117 0.108 0.091 0.073 0.058 0.018 0.013Harm-11 0.087 0.072 0.076 0.085 0.076 0.065 0.044 0.02 0.005 0.009Harm-13 0.063 0.069 0.064 0.049 0.052 0.046 0.025 0.015 0.008 0.003Harm-15 0.047 0.042 0.051 0.044 0.035 0.034 0.028 0.009 0.004 0.002Harm-17 0.053 0.044 0.033 0.03 0.041 0.03 0.016 0.01 0.004 0.003Harm-19 0.035 0.041 0.033 0.025 0.029 0.026 0.013 0.013 0.005 0.003Harm-21 0.057 0.036 0.026 0.031 0.024 0.023 0.015 0.016 0.003 0.005Harm-23 0.045 0.051 0.028 0.016 0.025 0.02 0.015 0.014 0 0.003Harm-25 0.052 0.032 0.032 0.018 0.03 0.024 0.016 0.011 0.005 0.002Harm-27 0.036 0.046 0.031 0.022 0.018 0.029 0.011 0.007 0.005 0.001Harm-29 0.033 0.036 0.045 0.015 0.02 0.025 0.01 0.006 0.005 0.003Harm-31 0.016 0.04 0.033 0.02 0.013 0.023 0.015 0.01 0.004 0.002

Load 100% 90% 80% 70% 60% 50% 40% 30% 20% 10%

I3 = 45% of Fundamental


Summary on How Harmonics Create Problems on the Power System

• Harmonics are an accumulative problem – Large non-linear loads or an abundance of smaller loads can

create harmonic problems, such as overheating of power system components and equipment malfunctions


Various Forms of Harmonic Mitigation


Harmonics and Symmetrical Components

Important Note: Reversing the phase sequence to a transformer will reverse its phase shift (eg. -30o +30o)

+ + = Positive sequence System (A, B, C)

C + B +

A +

120o

C -

B - A -

120o

Negative sequence System (A, C, B)

Zero sequence System

(3 single phase)

Unbalanced 3 Phase System (A, B, C)

Relationship between harmonic number and phase sequence:

Harmonic 1 (fund.)

2 3 4 etc.

Sequence

5 6 7 8 9 10 11 12 13 14 15

0 0 0 0 0

A + A -

+ + + + + - - - - -

C + B +

C -

B -

A 0 B 0

C 0

A 0 B 0

C 0 C

B

A


• Provide alternate low zero sequence impedance path – Diverts 3rd harmonic and other neutral current away

from neutral conductor and upstream distribution system

– Treats all zero sequence harmonics • 3rd, 9th, 15th, etc. (triplens)

• Apply phase shift between sets of non-linear loads – 30o shift between two powerpanels will cancel

balanced portion of 5th and 7th harmonic currents – Best when loads are balanced but effective even if

loads are not well balanced • Does not require capacitors or any tuned circuit

Passive Method for Treating 1-Phase Non-linear Loads


Low Zero Sequence Path to Treat Triplen Harmonics (3rd, 9th, etc.)

• Multiple windings on common core

A +

C +

Positive Sequence Currents

C + B +

A +

• Windings of at least 2 phases on each core leg connected in opposite directions

• Fluxes created by zero sequence currents oppose each other and cancel, resulting in low impedance alternate path when connected in parallel on a 3-ph, 4-wire system

• Positive and negative sequence fluxes remain 120o out of phase and do not cancel

A B C N

ZIG-ZAG Reactor

A B C N Zero Sequence Currents A 0

B 0 C 0

A 0

C 0

A 0


• Additive in Neutral • Circulate in TX

primary winding • High VNG • High VTHD

phase conductors

neutral

ground

Zco

phase-neutral electronic loads

panel

individual circuits A B C

N

G

Transformer

Zto IAO IBO ICO

IN= IAO + IBO + ICO ZNo

• Lowers neutral current

• Reduces current in TX

• Lowers VNG • Lowers VTHD

phase conductors

neutral

ground

Zco Zto

phase-neutral electronic loads

panel

individual circuits A B C

N G

NCE

Transformer

ZNo

A B C

Treating Triplen Harmonics through Low Zero Sequence Impedance


Distribution Panel (DP)

TX-A (0o shift)

TX-B (-30o shift)

Power Panels with similar Non-Linear Loads

PPA PPB

Assumptions made to simplify analysis: • Transformers are ideal and 1:1 • All voltages and currents are

referenced to voltage at PPA • Only fundamental voltage and

5th harmonic current are shown • Fundamental voltage is +ve

sequence (TX sec. lags pri.) • 5th harmonic current is -ve

sequence (TX pri. lags sec.)

Canceling Harmonics by Phase Shifting How 30o Phase Difference Cancels 5th




TX-A (0o shift)

TX-B (-30o shift)

PPA PPB

• Since TX-A phase shift = 0o

V1AS = V1AP = V1BP

• And, I5AS = I5AP

V1AP

V1AS

V1BPV1AP

I5AP

V1AS

I5AS




TX-A (0o shift)

TX-B (-30o shift)

PPA PPB

V1BPV1AP

I5AP

V1AS

I5AS

• V1BS is shifted 30o by TX-B V1BS lags V1BP by 30o

• I5BS also lags by the same amount in time which is 1505

o relative to I5AS.

30o @ 300Hz(-ve sequence)

30o @ 60HzV1BS


30o @ 60Hz150o @ 300Hz V1BS




TX-A (0o shift)

TX-B (-30o shift)

PPA PPB

V1BPV1AP

I5AP

V1AS

I5AS


30o @ 60HzV1BS


30o @ 60Hz150o @ 300Hz V1BS

• Since 5th is negative sequence and TX-B shifts 30o, I5BP must lag I5BS by 305

o

V1BP

I5BP




TX-A (0o shift)

TX-B (-30o shift)

PPA PPB

V1BPV1AP

I5AP

V1AS

I5AS


30o @ 60HzV1BS


30o @ 60Hz150o @ 300Hz V1BS

V1BP

I5BP

• Total shift of I5BP is 1805o (1505

o + 305

o) relative to I5AP • 5th harmonic current cancels at

upstream Distribution Panel

V1AP = V1BP

I5AP

I5BP

I5AP + I5BP = 0




TX-A (0o shift)

TX-B (-30o shift)

PPA PPB

• Shift of 30o in voltage shifts 7th harmonic current 2107

o • 7th harmonic current is +ve seq.

therefore I7BP must lead I7BS by 307o

• Total shift of I7BP is 1807o

(2107o - 307

o) relative to I7AP

V1AS

I7AS

V1AP

I7AP

30o @ 420Hz(+ve sequence)

30o @ 60Hz210o @ 420Hz V1BS

I7BS

V1BP

I7BP

V1AP = V1BP

I7AP

I7BP

I7AP + I7BP = 0


What about Load Diversity and Imbalance 5th Harmonic with and without 30o Phase Shift

Without Phase Shifting:

V1

I5A

V1

I5AI5BP

V1I5T

Assumptions: • 5th harmonic current at Panel B is

slightly out of phase with Panel A • 5th harmonic current on Panel B is

1.5x Panel A

With Phase Shifting:

V1

I5A

V1

I5BPI5A

V1

I5T

I5T without phase shifting

I5T with phase shifting

Still a 3 to 1 Improvement!!!


Harmonic Mitigation Demonstration - Without Harmonic Mitigation

3ph Line Reactor Z = 5%

23 watt compact fluorescent lamp (typ 6)

Phase Current I(thd) = 76.4% I(rms) = 0.49 amp

Neutral Current I3 = 0.81 amp

Voltage V(thd) = 13.6%

VN-G = 13 volts Gnd

L1 L2 L3

L1 N

SETUP DESCRIPTION: 1. 6 x 23 W compact fluorescent lamps used as non-linear load 2. 3-ph line reactor used to produce high voltage distortion & VN-G


Harmonic Mitigation Demonstration - With Harmonic Mitigation

23 watt compact fluorescent lamp (typ 6)

Phase Current I(thd) = 12.0% I(rms) = 0.56 amp

Neutral Current I3 = 0.03 amp

Voltage V(thd) = 3.9%

VN-G = 0.1 volts Gnd

L1 L2 L3

L1 N

3ph Line Reactor Z = 5%

Harmony-2 Autotran.

or CNCE-BID

RESULTS: 1. Current distortion reduced by 84% 2. Voltage distortion reduced by 71% 3. Neutral-ground voltage virtually eliminated


CNCE-FAI Typical Performance

Transformer

CNCE-FAITM

Non-linearLoads

From other Current THD = 106%, k-factor = 12Current THD = 14%, k-factor = 1.3

At transformer Sample load

non-linear loads

0

0.5

1

1 3 5 7 9 11 13 15Ha rmo nic

0

0.5

1

1 3 5 7 9 11 13 15Ha rmo nic

0%

1%

2%

3%

4%

5%

6%

7%

8%

9%

10%

1 3 5 7 9 11 13 15 17 19 21 23 25Harmo nic

% fu

ndam

enta

l

Before : 11.0%

After: 2.6%Parameter Before After Performance

Voltage Distortion 11.05% 2.60% 76% re ductionFe e de r Ne utra l Curre nt (A) 111 18 84% re ductionNe utra l-Ground Voltage (V) 6.04 1.6 74% re ductionCurre nt Distortion 64% 14% 78% re ductionCurre nt Imbalance 22.60% 5.00% 78% re ductionCurre nt Cre st Factor 2.1 1.7 19% re ductionPowe r Factor 0.76 0.95 25% improve me nt

Voltage Distortion at Panelboard


Challenge: • Transformer running very hot

despite relatively light loading • High current harmonic distortion • High neutral current • High neutral-to-ground voltage • High ground currents • Low power factor • Visible video noise

Broadcasting Studio Harmonic Reduction

PP5

PP1

PP2

PP3

PP4

225 kVA 480-120/208V Z = 2.7%

120 ft

165 ft

115 ft

150 ft

10 ft

∆

200 amp (typ 4)


Broadcasting Studio Harmonic Reduction Solution: • Zero sequence harmonic filters

installed on 2 power panels – Parallel connected – Provide alternate path for 3rd, 9th

and other triplen harmonics • Zero sequence filter with 30 deg

phase shift installed on panel with heaviest load – Series connected – Treats 3rd, 5th, 7th and 9th

harmonics

PP5

PP1

PP2

PP3

PP4

225 kVA 480-120/208V Z = 2.7%

120 ft

165 ft

115 ft

150 ft

10 ft

∆

150 amp NCE 75 kVA

CNCE

150 amp NCE

200 amp (typ 4)


Broadcasting Studio Harmonic Reduction PP1 V(thd) I(thd) V(n-g) In Ig pf

Before 3.6% 79.9% 0.1 120.7 4.1 0.79After 2.5% 21.4% 0.1 29.1 1.9 0.97

Improved 31% 73% 0% 76% 54% 23%

PP5-CNCE V(thd) I(thd) V(n-g) In IgBefore 4.4% 78.4% 3.3 98.6 7.5After 2.4% 52.8% 1.3 5.4 1.4

Improved 45% 33% 61% 95% 81%

Results:

• Current distortion reduced by 73% • Voltage distortion reduced

throughout facility • Neutral current reduced upstream

of harmonic mitigation equipment – by 76% at PP1

• Neutral-to-ground voltage reduced at all power panels

• Ground current reduced throughout – 7.5A to 1.3A at PP5

• Transformer running much cooler • Power factor improved from 0.79

to 0.97 freeing up system capacity • Noticeable reduction in video noise


• AC line reactors or DC chokes – Typically reduce harmonics by half but this is often not sufficient

enough to prevent problems • Multipulse VSD (12-P, 18-P, 24-P, 36-P, etc.)

– Transformer phase shifting creates harmonic cancellation – Effectiveness of phase shifting diminishes as pulse number increases – Voltage imbalance and voltage distortion reduces effectiveness

• Phase shifting transformers – Can be used to create quasi multipulse schemes – Minimal effect on DC Drives due to thyristor firing differences – Similar performance challenges as per multipulse

• Parallel Active Filters – Generate and supply non-linear loads with harmonic currents so that

they do not need to be supplied by the source – Introduce high levels of high frequency harmonics

• Active Front-end VSD’s – IGBT rectifiers replace diode bridge rectifiers – Introduce high levels of high frequency harmonics

• Wide Spectrum Passive Harmonic Filter

VSD Harmonic Mitigation Options



Phase – Neutral Voltages 0º 180º 360º

VAN

VBN VCN

h = np 1,

+ _

When p = 12, h = …11,13,…23,25…

Average DC Bus voltage (1.414 x VRMS less ripple)

30º

Current

1 3 5 7 9 11 2 4 6 8 10 12

Δ Y

Δ

30o PHASE-SHIFTED THREE WINDING TRANSFORMER

DUAL RECTIFIERS


Multi-pulse VSD: 18-Pulse Rectifier

h = np 1,

+ _

When p = 18, h = …17,19,…35,37…


• Performance drops off significantly with: – Lighter loading – Voltage imbalance – Background voltage

distortion • Requires relatively large

transformers – Increases footprint – Increases losses

• Requires relatively large line reactors or DC chokes to achieve reasonable performance

Limitations of Multi-pulse VSD’s


Operation: • Distorted current is sampled • Fast acting IGBT’s are used

to generate harmonic currents and inject them 180 deg out-of-phase

Pros: • Sized to harmonic content

only • Maintains good performance

at light loads Cons: • Expensive • Introduces higher frequency

harmonics • Susceptible to background

voltage THD • Complexity requires start-up

and regular service by manufacturer

Parallel Active Filter


Parallel Active Filter Performance: 3 x 800HP DC SCR Drives

Current waveform and spectrum with active filter, THDi = 3.6%

Current waveform and spectrum without active filter, THDi = 34% Voltage Distortion

(THDv) dropped from 11.2% to 3.7%

2 .0 0 0

4 .0 0 0

6 .0 0 0

8 .0 0 0

1 0 .0 0

%

1 6 :3 0 :0 0 .0 0 01 4 /0 7 /2 0 0 6

1 6 :5 1 :2 0 .0 0 01 4 /0 7 /2 0 0 6

4 Min /Div2 1 :2 0 .0 0 0 (M:S )

2 .0 0 0

4 .0 0 0

6 .0 0 0

8 .0 0 0

1 0 .0 0

%

1 6 :3 0 :0 0 .0 0 01 4 /0 7 /2 0 0 6

1 6 :5 1 :2 0 .0 0 01 4 /0 7 /2 0 0 6

4 Min /Div2 1 :2 0 .0 0 0 (M:S )

without with without


Challenge: • Solar Panel and Inverter Mfr

was having 48 Vdc power supply failures in a Photovoltaic Panel Tester

• These failures began to occur after a 450A AHF was installed on a Solar Inverter Test line

Active Harmonic Filter Installation – Solar Inverter Mfr

Parallel Active Harmonic Filter (AHF) was used to cancel harmonic currents generated by the rectifiers on a Solar Inverter Test line


Challenge: • Harmonics from operation

of the AHF IGBT’s was causing a high frequency ripple on the supply voltage

• 48 Vdc power supply resonated near the 41st harmonic causing it to overheat and fail immediately after startup


Voltage waveform – VTHD <1%

PS Current waveform at no load PS Current spectrum at no load


Solution: • Turn off AHF


Voltage waveform – No high freq. ripple

PS Current waveform at no load PS Current spectrum at no load


Operation: • 6-pulse diode bridge rectifier is

replaced by a fully controlled IGBT bridge

Pros: • Can achieve lowest ITHD but

only when measured at harmonics lower than 50th

• Can provide regenerative braking

Cons: • Expensive • Introduces higher order

harmonics • Higher EMI radiation • Much higher losses • Very complex requiring start-up

and service by manufacturer

VSD with Active Front-end (AFE)


VSD with Active Front-end (cont.)

Typical current waveform

of AFE Drive

Higher order voltage and current harmonics

introduced by AFE


Wide Spectrum Harmonic Filter Internal Connection Diagram

Multiple windings on a common core

(Patented Design)

Input tuned below 5th to prevent importation of

upstream harmonics

High impedance L1 winding

Compensating winding L2 lowers through

impedance reducing voltage drop

Unique reactor design allows for smaller cap bank to reduce voltage boost and reactive power at no load

Output tuned near 7th to remove load side

harmonics


WSHF Performance on 150 HP PWM VSD

Load w/o With w/o With w/o With w/o With w/o With w/o With w/o With w/o With w/o WithFull 233 168 118 9.0 80 0.6 12 2.2 12 1.5 79% 6.2% 79% 6.2% 15 1.5 - .75 1.0075% 187 130 96 7.7 70 0.6 15 1.5 7 1.4 86% 7.0% 65% 5.3% 17 1.6 - .73 + .9950% 134 89 69 6.9 54 0.3 17 1.2 5 1.0 95% 9.0% 48% 4.5% 20 2.0 - .69 + .9525% 67 46 33 4.2 29 0.2 14 0.8 9 1.0 120% 11% 30% 2.8% 29 2.5 - .58 + .83

RMS 5th 7th K-factor PFCurrent Harmonics (Amps)

11th 13th Ithd Itdd

Without Harmonic Treatment With LINEATOR Input Current

050

100150200

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Harmonic #

Amps

Ithd = 79%

Input Current

050

100150200

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Harmonic #

Amps

Ithd = 6.2% Input Voltage

0%

5%

10%

3 4 5 6 7 8 9 10 11 12 13 14 15Harmonic #

% fu

nd

Vthd = 5.4%

Input Voltage

0%

5%

10%

3 4 5 6 7 8 9 10 11 12 13 14 15Harmonic #

% fu

nd

Vthd = 0.6%


WSHF vs 18-P with Voltage Imbalance

ITHD Comparison (18-Pulse vs Lineator)

0

20

40

60

80

100

0 20 40 60 80 100

% Load%

ITH

D

Lineator (balanced) 18-Pulse (balanced)Lineator (2% imbalance) 18-Pulse (2% imbalance)

ITHD Comparison (18-Pulse vs Lineator)

0

10

20

30

40

50

0 20 40 60 80 100

% Load

% IT

HD

Lineator (balanced) 18-Pulse (balanced)Lineator (1% imbalance) 18-Pulse (1% imbalance)


WSHF vs 18-P with High Background Voltage Distortion

Lineator Performance with Background Voltage Distortion

0

5

10

15

20

25

30

0 1 2 3 4 5

% VTHD Background

% IT

HD

Lineator (50% Load) Lineator (100% Load)

18-Pulse Performance with Background Voltage Distortion

0

5

10

15

20

25

30

0 1 2 3 4 5

% VTHD Background

% IT

HD

18-Pulse (50% Load) 18-Pulse (100% Load)


Efficiency Comparison: 18-P vs WSHF/6-P

System Efficiency Comparison (18-Pulse vs Lineator)

60

70

80

90

100

0 20 40 60 80 100

% Load

% E

ffici

ency

_

Lineator 18-Pulse

When compared to an 18-P VSD, a 400HP Lineator/6-P system will save more than $3,000 in annual operating costs when averaging 75% loading at $0.07 / kwhr.

Efficiency using Lineator is

2% to 3% better


Challenge: • 4 x 350HP VSD’s used to

achieve required wind speeds • Local Utility required evidence

that IEEE Std 519 harmonic limits would be met

• Energy savings also considered to be very important

IEEE Std 519 - SkyVenture Free-fall Simulator Wind tunnel powered by large blowers provides novice and expert thrill-seekers the experience of free-fall

Solution: • Computer simulation was used to

demonstrate: – Line reactors alone would not

meet limits – Passive harmonic filter would

meet limits – Significant energy savings when

compared to 18-Pulse


SkyVenture Free-fall Simulator - Montreal

Computer Simulation with AC Line Reactors



Computer Simulation with Passive Harmonic Filter



Energy Savings Analysis: 18-Pulse VSD vs

Passive Harmonic Filter

• Operating Conditions: – 10 hrs/day, 364 days/yr – 80% load – $0.06 / kWhr

• Estimated energy savings at Utility Supply: – 47,334 kWhr/yr – $2,840 /yr

18-P PHF


SkyVenture Free-fall Simulator - Orlando

Energy Savings Analysis – 18-Pulse VSD vs Passive Harmonic Filter

DRIVE A FAN

6-Pulse + LINEATOR

Hz RPM kW SAVINGS

55 818 143.27 9.2 KW

60 891 183.41 6.6 KW

DRIVE B FAN 18-Pulse

Hz RPM kW

55.92 818 152.47

60 889 190.03

250 HP MOTOR

6-PULSE VSD + LINEATOR

18-PULSE VSD

FAN

480 Volt, 3 Phase, 60 Hz Supply


SkyVenture Free-fall Simulator - Orlando Energy Savings Analysis – 18-Pulse VSD vs Passive Harmonic Filter

DRIVE A FAN

6-Pulse + LINEATOR

Hz RPM kW

55 818 143.27

60 891 183.41

DRIVE B FAN 18-Pulse

Hz RPM kW

55.92 818 152.47

60 889 190.03

250 HP MOTOR

6-PULSE VSD + LINEATOR

18-PULSE VSD

FAN

480 Volt, 3 Phase, 60 Hz Supply KW SAVED WITH 6-PULSE VFD + LINEATOR 60 HZ 55 HZ 6.62 KW 9.2 KW

6-PULSE DRIVE + LINEATOR saved 3.5% to 6% of energy needed to run fan

SAVINGS 9.2 KW 6.6 KW


Protection Against Line Side Transients

LINEATOR

AUHF

INPUT OUTPUT

Figure 2: Voltage waveform at input to harmonic filter

Figure 3: Voltage waveform at output of harmonic filter supplying AC Drive

Voltage Notching Caused by DC Drives on Off-shore Oil Platform

Notches Dramatically reduced on Output of Lineator AUHF


Challenge: • Voltage distortion,

particularly deep notches, were causing frequent failures of centrifuge equipment

• Voltage distortion > 20%

Preventing Centrifuge Failures on a Drilling Rig

Solution: • Transformer supplying the

centrifuge equipment was replaced with a combined transformer/harmonic filter

• Voltage distortion reduced to < 8%

• All equipment failures ceased

Drilling Rig in N. Alberta experiencing routine failures in centrifuge equipment used on the Rig


Summary Various Forms of Harmonic Mitigation • Combining a low zero sequence path with phase shifting

can be a very effective method of treating 3rd and other harmonics from 1-ph non-linear loads

• Selection of the right harmonic treatment for VSD’s is critical to ensuring that the problem is effectively resolved without introducing other issues

• Wide Spectrum Harmonic Filter has many benefits including: – better performance under real world conditions – higher efficiency – simpler and more reliable – lower cost


Computer Simulation for VSD Harmonic Analysis


SOLV Computer Simulation Software

• Calculates current and voltage distortion levels by simulating Variable Speed Drive (VSD) applications with and without harmonic mitigation (Lineator AUHF)

• Comparison to IEEE Std519 harmonic limits

• Performs energy savings analysis

• Allows for voltage imbalance and background voltage distortion


Computer Simulation – with Reactor


Computer Simulation – with AUHF


Computer Simulation – with 18P


Computer Simulation – with Reactor


Computer Simulation – with AUHF


Computer Simulation – with 18P


Computer Simulation with

Reactor



AUHF



18P


Questions?

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