harmonic levels in lv networks and methodology for...
TRANSCRIPT
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Harmonic levels in LV networks and methodology for assessing the impact
of new equipment
Panel on New Harmonic Sources in Modern Buildings: Characterization and Modeling
14PESGM1020
1
Jan Meyer Ana Maria Blanco
Max Domagk Technische Universitaet Dresden, Germany
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2
Agenda
• Background
• Characterization and impact of new equipment
− Compact fluorescent lamps (CFL)
− Electrical vehicle chargers (EVC)
− Impact of circuit topopolgy changes
• Survey of harmonic levels in public LV grids
− Framework of the survey
− Some analysis results (3rd harmonic, 5th harmonic)
− Historical trend
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Below 2 kHz Harmonics
(Linked to power frequency)
Above 2 kHz (up to 150 kHz) HF emission/supraharmonics
(Independent of power frequency)
● Devices with nonlinear i/u characteristic
● Simple electronic devices (line-commutated, e.g. no PFC)
● Mains signalling
Compact fluorescent lamp (P < 25 W) Compact fluorescent lamp (P > 25 W)
● Energyefficient circuit topologies, like active PFC
● Narrowband Power Line Communication
0 30 60 90 120 150 180-100
0
100
200
300
400
500
i(t) /
mA
angle / °
i(t)
t 20 22 24 26 28 30-50
0
50
100
150
200
250
i(t) /
mA
t / ms
i(t)
t
Types of Distortion
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4
0 2.5 5 7.5 10-0.5
0
0.5
1
1.5
2
2.5
3
3.5
t / ms
i(t)
/ A
-0.2 -0.1 0 0.1 0.2-0.2
-0.1
0
0.1
0.2
Re(I5)/A
Im(I
5)/
A
(5) (5)
1 2(5)
p (5) (5)
1 2
I Ik 1
I I
0,131A1 0,57
0,307 A
Time domain (Halfwave)
Frequency domain (5. Harmonics)
Phase diversity index:
Computer power supply (P > 75 W) and notebook charger (P < 75 W)
Different circuit topologies have different behavior (passive power factor correction pPFC, no power factor correction nPFC)
(5)1I 0,172 A(5)gesI 0,131A
(5)2I 0,135 A
Cancellation effect:
(5)
1I
(5)
2I
(5)
gesI
Harmonic phase angle and phase diversity
Do prevailing phase angles exist for electronic mass-market equipment ?
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Agenda
• Background
• Characterization and impact of new equipment
− Compact fluorescent lamps (CFL)
− Electrical vehicle chargers (EVC)
− Impact of circuit topopolgy changes
• Survey of harmonic levels in public LV grids
− Framework of the survey
− Some analysis results (3rd harmonic, 5th harmonic)
− Historical trend
-
100
200
300
400
30
210
60
240
90
270
120
300
150
330
180 0
5th Harmonic Current mA
CFL nPFC
pPFC
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Characterisation of equipment
• Manufacturers prefer specific circuit topologies as consequence of given standards (e.g. 61000-3-2)
• Different topologies have different prevailing harmonic phase angles
• Effective cancellation for 5th harmonic, but less efficient for 3rd harmonic)
• Efficiency of cancellation depends on mix of equipment (circuit topologies)
5th current harmonic
228 electronic mass-market devices
Is it possible to identify dominating technologies by grid measurments ?
(5)p
k 0,78
Lighting 25 W Lighting > 25 W Other equipment 25 W Other equipment > 75 W
(3)p
k 0,44
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Equipment Harmonic Database
Web-based platform for exchanging measurements of harmonic emission of single phase equipment
http://panda.et.tu-dresden.de
More than 10 labs from all over the world
More than 500 different devices
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Field study - customer terminal (CFL)
• ON/OFF comparison for switching CFLs and ISLs (incandescent lamps): Similar magnitudes (210mA), but different phase angles (-40°-> 148°)
• Identification of connected equipment based on harmonic phase angle seems to be possible
-300 -150 0 150 300-300
-150
0
150
300
Ireal
/ mA
I ima
g /
mA
o – OFF¡ - ON
ISLCFL
Preferential phase angle for CFL
5th harmonic current
0 45 90 135 180-2
0
2
4
6
8
Winkel / °
i(t)
/ A
Waveform
CFLs OFF CFLs ON
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Field study - LV feeder (EV charging)
• 10 single family houses
• 10 electrical vehicles (EV) of 4 different brands
• Coordinated ON/OFF switching of all EVs in one phase
Measurement up to 150 kHz
Measurement up to 2.5 kHz
Transformer
Junction box
Feeder end
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LV feeder study – Individual current harmonics
• Low emission of households in 4th quadrant
• Similar 5th harmonic phase angle for different EV types in the 3rd quadrant (About 90°phase difference to typical household emission)
5th harmonic
Electrical vehicles
5th harmonic
Sum of households
Type A
Type B
Type C
Type D
Phase angle change from 4th to 3rd quadrant is expected, when cars are connected
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LV feeder study – Total harmonic current
1
2
3
4
5
30
210
60
240
90
270
120
300
150
330
180 0
5th Harmonic Current (A) at D 5th Harmonic Voltage (V) at D
5
10
30
210
60
240
90
270
120
300
150
330
180 0
Switch On
Switch Off
2
4
6
8
10
30
210
60
240
90
270
120
300
150
330
180 0
3rd Harmonic Current (A) at D 3rd Harmonic Voltage (V) in D
2
4
30
210
60
240
90
270
120
300
150
330
180 0
Switch On
Switch Off
5th harmonic
at junction box
3rd harmonic
at junction box
Switching ON Switching OFF
• 5th harmonic current shifts phase (considerable diversity between households and EVs)
• 3rd harmonic current does not shift phase (almost no diversity between households and EVs)
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-350 -175 0 175 350-350
-175
0
175
350
Ireal / mA
I im
ag /
mA CFL
• Most effective cancellation for CFLs in combination with passive PFC equipment
• Virtually no cancellation effect for 5th harmonic by active PFC equipment
5th harmonic current
No PFC (past) Passive PFC (today) Active PFC (future)
Cancellation effect
0 5 10 15 20 25
0.4
0.5
0.6
0.7
0.8
0.9
1
number CFL k
p(5)
Impact of technology changes
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Agenda
• Background
• Characterization and impact of new equipment
− Compact fluorescent lamps (CFL)
− Electrical vehicle chargers (EVC)
• Survey of harmonic levels in public LV grids
− Framework of the survey
− Some analysis results (3rd harmonic, 5th harmonic)
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Total harmonic emission of a LV grid
• Distinctive clouds represent a non-random behavior with a prevailing direction
• Location of prevailing direction may indicate dominating equipment mix (this case: nPFC and pPFC devices)
• Increasing number of CFLs or EVs could slightly reduce the 5th current harmonic
• „Balance“ between the different types of equipment is essential
5th current harmonic of a residential grid
Is this result representative for other LV grids ?
-30 -15 0 15 30-30
-15
0
15
30
Ireal
/ A
I ima
g /
A
-10 -5 0 5 10-10
-5
0
5
10
Ireal
/ A
I ima
g /
A
nPFC
pPFC
CFL
L1 L2 L3
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Improvement of vizualisation
• Color-dependent density charts (2-D histogram)
• Improvement for explorative analysis (more information is revealed)
• BUT, processing of many sites requires further reduction of data amount and respective assessment indizes
3th current harmonic of a residential grid
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Assessment indices (2 stage procedure)
2
( )
( ) 1
nh
ih i
V
I
In
( ) ( ) ( ) ( )
1
nh h h h
VEC VECVEC i
i
I I I
( )
1( )
( )
1
1
nh
i
ih
nh
i
i
I
VR
I
(B) Prevailing vector IV (only useful in case of low diversity):
(A) Variation ratio (diversity index) :
( ) ( )h h
V VEC
Magnitude
Angle
• Calculation of vector sum
• Measure for level of diversity (significance of prevailance)
• Opposite to prevailing ratio
• High value -> no prevailing direction
• Low value -> prevailing direction
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Range of diversity index
5
10
15
30°
210°
60°
240°
90°
270°
120°
300°
150°
330°
180° 0°
5
10
15
30°
210°
60°
240°
90°
270°
120°
300°
150°
330°
180° 0°
5
10
15
30°
210°
60°
240°
90°
270°
120°
300°
150°
330°
180° 0°
Low diversity Medium diversity High diversity
10.20
43
0.022
V
V
I A
VF
10.20
84
0.3
V
V
I A
VF
10.20
19
0.8
V
V
I A
VF
Very low diversity (VL) VF 0,05
Low diversity (L) 0,05 < VF 0,11
Medium diversity (M) 0,11 < VF 0,2
High diversity (H) VF > 0,2
Prevailing vector meaningful
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Headoffice of network operators
Systematic survey in Germany
More than 30 network operators
More than 150 sites
Comparability
Duration: 14 days
Interval: 1 minute
Location: MS/NS-substation (LV busbar)
Same type of monitors
Classification of sites acc. to:
Consumer topology (4 classes)
Generation topology (4 classes)
Grid topology (3 classes)
Survey on harmonic behavior of public LV grids
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• Classification based on topology classes and priorisation according to the expected impact on harmonic levels
High priority: Consumer topology A1: Single family houses (small, medium, large) A2: Multi family houses (small, medium, large) A3: Shopping A4: Office A5: Special consumer
Medium priority: Generation topology E1: No generation E2: Generation smaller than 10% Sr E3: Generation between 10% Sr and 50% Sr E4: Generation larger than 50% Sr
Low priority: Network topology N1: Total length of lines smaller 800m N2: Total length of lines between 800m and 1600m N3: Total length of lines larger than 1600m
• 96 possible combinations
• Preference on grids with „pure“ consumer topologies A1 to A4
Network classification schema
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c.d
.f.
Number
Coverage of consumer topologies
• Major focus on grids with residential customers
• Good representation of different grid sizes
Distribution of customer number per grid for SFH
Distribution of sites for consumer topology
A1: SFH A2: MFH A3: Shopping A4: Office
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0%
20%
40%
60%
80%
100%
A1 A2 A3 A4
H
W
L
VL
0%
20%
40%
60%
80%
100%
A1 A2 A3 A4
H
W
L
VL
Variation ratio of all sites
• Most residential grids show clear prevailing phase angles.
• Higher probability of larger variations for shopping and office
3rd harmonic
5th harmonic
M
M
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3rd harmonic (SFH)
3rd harmonic (Offices)
3rd harmonic (Shopping)
Prevailing 3rd harmonic vectors
• Residential: Small variation
• Office and Shopping: Higher variation between sites
• Virtually no impact of generation and network topology observed
• No prevailing phase angles in 1st quadrant
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Prevailing 5th harmonic vector
• Residential: Small variation; no dominance of CFLs
• Office and Shopping: Higher variation; Dominating number of measurements in 2nd quadrant
• Virtually no impact of generation and network topology observed
5th harmonic (SFH)
5th harmonic (Offices)
5th harmonic (Shopping)
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25
0 5 10 15 20 25 30 35 40 450
10
20
30
40
50
60
70
IV
3 in A
I S3
in
A
0 5 10 15 20 25 30 350
5
10
15
20
25
30
35
40
IV
5 in A
I S5
in
A
Some further data analytics (2)
Span vs. average current 95-%-percentile vs. average current
0 5 10 15 20 25 30 35 40 450
10
20
30
40
50
60
70
IV
3 in A
I 95
3
in
A
0 5 10 15 20 25 30 350
5
10
15
20
25
30
35
40
IV
5 in A I 9
5
5
in
A
A1 A2 A3 A4
• Span vs. average significantly higher for shopping (1,5) compared to residential topologies (0,3 .. 0,6)
• No distinctive evening peak for 5th harmonic current in many residential grids (95-%-perc./average ratio about 1,2)
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• Measurement on Saturdays in 1999 and 2010 for 2 loading states:
No changes in consumer or network topology (350 residential customers in multi family houses)
Magnitude: Decrease of 5th harmonic, but increase of 3rd harmonic
Phase angle: Shift indicates possible increase of passive PFC equipment (technology change)
3rd harmonic current 5th harmonic current
-20 -10 0 10 20-20
-10
0
10
20
Ireal
/ A
I ima
g /
A
o - 1999¡ - 2010MorningEvening
passive PFC
no
PFC
CFL
-10 -5 0 5 10-10
-5
0
5
10
Ireal
/ A
I ima
g /
A
o - 1999
¡ - 2010
Morning
Evening
passive PFC
no
PFC
CFL
Historical data
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• Present management for 5th harmonic seems to be more effective than for 3rd harmonic
• Different circuit topologies and their share have to be considered in modelling studies
• Emission of equipment considerably changes with changing voltage distortion, especially for active PFC equipment and inverters
• Every participation in PANDA project is highly appreciated (check out the website and send us an email)
• Measurements of prevailing harmonic phase angle in other countries are very welcome (contribution to IEC SC77A WG1)
Conclusions
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28
Thank you for your attention !
Contact details:
Jan Meyer Technische Universität Dresden Institute of Electrical Power Systems and High Voltage Engenieering 01062 Dresden
tel. +49-351-463 35102 fax. +49-351-463 37036
email: [email protected]
Sometimes also aesthetic aspects should be considered
in terms of compatibility