Embed Size (px)
Citation preview
Harmonic Distortion Problems in Current Distribution Systems
1APIC Power & Energy Innovation Forum
ATCO experiences by Case Muskens
Epcor experiences by Isabella Ciocoiu
FortisAlberta experiences by Gordon McKinlay
Telus experiences by Dwayne Schultz
U of A research findings by Wilsun Xu
APIC 2011 Power & Energy Innovation Forum
APIC 2011
Harmonic Load Growth in ATCO Electric POD Substations
by Case Muskens
APIC 2011
Overview:
PurposeMeasurement IEEE 1459Result SummariesConclusions
APIC 2011
Purpose:
• Establish trending of harmonic load growth in the AE system
• Evaluate different measurement methods discussed in IEEE 1459
• Future implications
APIC 2011
Project Description:
� 6 substations monitored in 2004� Repeat measurements in 2011 at same substations� Review changes
APIC 2011
Measurement Methodology
The ION meter captures hourly RMS values of load, %THDV, %THDI at the main substation transformer
One second waveform snapshots were recorded during the measurement time and processed per IEEE 1459 power definitions
APIC 2011
IEEE Std 1459 – 2000 : IEEE Standard Definitions for the Measurement of Electric Power Quantities Under Sinusoidal, Non Sinusoidal, Balanced or Unbalanced Conditions
A brief overview of this standard is now provided
APIC 2011
VIS =
vip =
∫+
=kT
pdtkT
Pτ
τ
1
Power Definitions Single Phase IEEE 1459
Apparent Power
Instantaneous Power
Active Power
Power FactorS
PPF =
APIC 2011
21
22 VVVH −=
21
22 IIIH −=
1V
VTHD H
V =
Harmonic Voltage
Harmonic Current
THDV
THDI1I
ITHD H
I =
APIC 2011
The apparent power :
Fundamental effective power:
Non fundamental effective power:
eee IVS ⋅= 3
111 3 eee IVS ⋅=21
22eeeN SSS −=
18
)(3 222222cabcabcba
e
VVVVVVV
+++++=3
2222ncba
e
IIIII
+++=
where
Power definition for 3 phase systems
APIC 2011
Substations Land Location Load type
Flyingshot 702T Grande Prairie MixedHangingstone 701T Ft. McMurray MixedMichichi 703T Drumheller MixedHigh Level 701T High Level MixedNorcen 701T Red Earth OilfieldBrintnell 901T Wabasca Oilfield
Mixed refers to residential + commercial with some light industrial
APIC 2011
High Level Brintnell Flyingshot 2004 2011 2004 2011 2004 2011
THDi% 7.136 5.462 2.56 4.446 5.43 4.856 THDei% 11.96 9.24 2.76 5.04 8.58 8.32 SeN KVA 466 411 590 679 1484 2004 SeN/Se1 % 11.96 9.7 3.05 5.317 8.67 8.4 THDv% 1.61 0.896 1.226 1.703 1.4 1.4 THDev% 0.88 1.698 1.18
APIC 2011
Norcen Hangingstone Michichi 2004 2011 2004 2011 2004 2011
THDi% 2.3 1.37 4.73 6.31 3.32 3.758 THDei% 2.38 1.92 8.32 10.95 4.59 5.174 SeN KVA 267 185 1046 1796 711 1113 SeN/Se1 % 2.91 2.136 9 11 4.65 5.5 THDv% 1.673 0.945 3.436 1.763 0.81 1.911 THDev% 0.95 1.38 1.877
APIC 2011
0 2 4 6 8 10 120
2
4
6
8
10
12Substation Distortion Summary: THDI vs. Harmonic Pollution Ratio
THDI%
SeN
/Se1
%
20042011
Norcen
Brintnell
Michichi
Flyingshot
Hangingstone
Highlevel
APIC 2011
0 2 4 6 8 10 120
2
4
6
8
10
12Substation Distortion Level: Measured vs. IEEE 1459 Effective Value
THDI%
TH
DIe
%
2004
2011
Norcen
Brintnell
Michichi
FlyingshotHangingstone
Highlevel
APIC 2011
1 2 3 4 5 6 7 80
500
1000
1500
2000
2500Substation Distortion Summary: THDI vs. Pod Nonlinear load
THDI%
SeN
KV
A
2004
2011
Norcen
Brintnell
Highlevel
HangingstoneMichichi
Flyingshot
APIC 2011
Hangingstone has had a 5 Mvar 5th harmonic filter added after 2004 which reduced VTHD but with increased ITHD due to harmonic in feed from 144 kV system.
High Level has had an SVC installed on the 144 kV bus along with an extra line to Sulphur Point substation after 2004, SCR has improved.
Brintnell had a pseudo 12 pulse cancellation scheme (mixed Dy and Yy transformers) with the original pad site loads, but the 5th harmonic has been increasing suggesting reduced effectiveness with new loads
APIC 2011
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 50
1
2
3
4
5
6
7
8
9
10High Level Substation 701T History Start date Sept 8, 2004/2011 4:00 PM
days
%TH
D o
r M
VA
%THDI phs 2 2004
%THDV phs 2 2004
MVA Loading 2004%THDI phs 2 2011
%THDV phs 2 2011MVA Loading 2011
APIC 2011
0 1 2 3 4 5 6 7 8 9 10 110
5
10
15
20
25Hangingstone Substation 701T History Start date Sept 1, 2004/2011 6:00 PM
days
%T
HD
or M
VA
%THDI phs 2 2004%THDV phs 2 2004
MVA Loading 2004
%THDI phs 2 2011
%THDV phs 2 2011MVA Loading 2011
APIC 2011
0 0.5 1 1.5 2 2.5 3 3.5 40
5
10
15
20
25
30
Brintnell Substation 901T(2004) and 902T(2011)History Start date Sept 10, 2004/2011 6:00 AM
days
%T
HD
or
MV
A
%THDI phs 2 2004
%THDV phs 2 2004
MVA Loading 2004%THDI phs 2 2011
%THDV phs 2 2011
MVA Loading 2011
APIC 2011
Conclusions:� Despite a load increase at Flyingshot, the harmonic
pollution ratio (%SeN/Se1) has remained nearly constant� Hangingstone, Brintnell, and Michichi have seen
increases in the harmonic pollution ratio� High Level and Norcen have seen reductions in the
harmonic pollution ratio� Harmonic pollution ratio is nearly equivalent to THDIe%� The THDIe% is a better indicator than THDI% of actual
harmonic load penetration
Telephone Interference Epcor’s cases
by Isabella Ciocoiu
Contributing Factors:
• 9th (main contributor) and 15th harmonics produced by small, single phase, electronic, residential loads;
• Position of the telephone cable to the power lines (they run in parallel);
• Length of the parallel path (3 or more miles);
• Strength of the magnetic field.
2005-2006Telephone Interference on
Ellerslie Road
12EEast Industrial
17 St34 St
50 St66 St101 St
23 E25P
Ellerslie Road
17 St34 St
Telus telephone line
-2005 April: I*T=5300-2005 November: I*T=3000-2006 March: I*T=2600-2006 April: I*T=1800-2006 December: I*T=1000
Noise complaints
Telus cabinet
75 St
91 St
53003000
What Epcor did on its circuits:
• 1. Balanced loads on 3 phase circuits. • 2. Fixed several broken neutral connections.• 3. Installed more grounds. • 4. Conducted a trial at the substation
transformers, adjusting the taps to increase the bus voltage (25kV to 25.8 kV): eliminated the suspicion that saturated transformers are the cause of harmonic currents.
• 5. Reduced the load on 23E by transferring about half of the load to another circuit.
2006-2010Telephone Interference on
41Ave
12E (20MVA)
East Industrial
17 St34 St
50 St66 St101 St
23 E (17.5 MVA)
25P
Ellerslie Road
Telus telephone line
-2006 Dec: I*T=1000-2007 March: I*T=1800-2009 Sept: I*T=2300-2010 July: VAC=105V
Noise complaints
Telus cabinet
75 St
91 St
Dec 2006 -7 Sept 2010
Measured induced voltage
41 AveI*T levels
12E (1.1 MVA)
East Industrial
Summerside
103 GI
17 St34 St101 St
91 St 66 St 50 St
21SU (3.46 MVA)
11SU (11.67 MVA)
12SU (2.16 MVA)
7 September 2010 - 5 November 2010
104 GI
23E (2.4 MVA)
Telus telephone line
Telus cabinet
Noise complaints
75 St
Ellerslie Road
41 Avenue
-2010 Sept 17: I*T=3600
I*T levels
12E
East Industrial
Summerside 103 GI
17 St34 St101 St
91 St 66 St 50 St
21SU
11SU
12SU
5 November 2010 - 24 November 2010
104 GI
23E
Telus telephone line
Telus cabinet
Noise complaints
75 St
Ellerslie Road
41 Avenue
4546S
-2010 Nov 19: I*T=3500
I*T levels
12E
East Industrial
Summerside
17 St34 St101 St
91 St 66 St 50 St
21SU
11SU
12SU
After 24 November 2010
104 GI
23E
Telus telephone line
Telus cabinet
Noise complaints
75 St
Ellerslie Road
41 Avenue
4546S
-2010 Nov 29: I*T=5000
93 GII*T levels
What Epcor did:• Approached APIC for technical support in
investigating the telephone interference problem;
• Provided distribution system models and facilitated field measurements.
Harmonic Issues in FortisAlberta Service Area
by Gordon McKinlay
1. Trends in Harmonic Distortion in FortisAlberta Service
Territory
2. FortisAlberta Pro-Active Harmonic Standards Adopted
3. Telephone Interference
4. Power Line Carrier Automated Meter Reading System
5. IEC Standards for Residential Equipment
Presentation Format
Tracking Harmonics
�At metering commissioning , harmonic voltage distortion is
sampled
� If VTHD > = 10% at the PCC was designated as a “Worst Harmonic Feeder”.
�Compiled Our Telephone Interference Records
� If a feeder has a history of telephone interference which was mitigated via
insulating telephone lines and not reducing harmonics on lines then it was
added to “Worst Harmonic Feeder” list.
APIC Harmonic Trends
APIC Harmonic Trends
VTHD10%
VTHD & TELUS10%
Normal80%
FortisAlberta Worst Harmonic Feeders
Passive Approach
�FortisAlberta for many years required customers to meet IEEE 519, but did
not enforce these limits until a problem showed up
Pro-Active Approach
�Requires the customer to meet design compliance before energization.
�We do not actively pursue compliance to pre-pro-active approach customer,
unless they do create a problem.
APIC Standards
Water, Gas and Electric Companies Act
�Requires TELUS approval before jobs can go through, TELUS less likely to
allow jobs to get approval if there might be or is existing telephone issues.
APIC Telephone Interference
Utility Office
Substation
Service Sites
Wide Area Network (WAN)
Upstream PLC Communication (20
minutes per bit)
Downstream PLC Communication (200
ms per bit or 5 baud)
Fiber Optic Cable
APIC AMR
APIC AMR Spectrum Noise
APIC Residential Loads
APIC Harmonic Trends
Zero Sequence from Residential
�We are seeing as symptom of the proliferation of harmonics on residential
feeders an increase in zero sequence caused telephone interference.
�The majority of telephone interference problems we currently have are caused
by zero sequence current.
�This has caused us to adopt new standards such as a multi-grounded neutral
on all new construction.
APIC Residential Standards
FortisAlberta Involvement in Standard Adoptions
�Members of the CSA Technical Committee on Electromagnetic
compatibility (EMC) and are trying to get CSA to adopt low voltage
standards
� IEC 61000-3-2 (≤16 A per phase) and IEC 61000-3-12 (>16 A and ≤ 75 A
per phase )
�These IEC standards ask the manufacturers of electronic equipment
commonly installed in homes, such as TV’s, Lights, Computers, etc. to
meet certain harmonic limits.
Power Induction on Communication Cables
- Telus Experiences
by Dwayne Schultz
Power Induction on Communication Cables� Very common problem, especially in rural areas where long parallels
between power lines and communication cables exist.
� Power induction results in audible noise (hum or buzz) for telephone users due to harmonics that fall within the voice frequency band (300 Hz to 4000 Hz)
� Induction also affects data transmission, (E.g. data circuits, modems, fax machines)
� Excessive 60 Hz induction levels can cause errors or failure of T1 copper carriers (PCM, HDSL)
� Problems may be steady state or transient in nature.
� Most often problems are related to distribution power lines but occasionally transmission lines can be a source of problem.
� Problems are becoming more prevalent as non-linear power loads increase
Magnetic Field Induction
Probe Wire Measurement
Power Line Probe Wire I*T Levels
� Probe Wire I*T = Ir X TIF
� I*T is a weighted value of the residual current multiplied by the Telephone Influence Factor
� Ir = residual current is the vector sum of the currents in all phases and neutral conductor at a point on the power system
� I*T can be evaluated directly using 100 foot probe wire measurements taken under power line with specialized test sets (E.g. Triplett – Mitigator)
� Depending on length and separation between systems:� I*T > 500-1000 may cause problems on communication cables � I*T >1000 is likely to cause problems on communication cables
C Message Weighting Curve
Telephone Interference Factor
0 50003000 400020001000
5000
10000
F re q u e n c y in H e rtz
TIF
(W f)
Telephone Influence FactorCurve
� Telephone Interference Factor (TIF) is a weighting factor that reflects the C message filter and the higher mutual coupling factor which increases at higher frequencies
Industry Guidelines
� CSA C22.3 No. 3 - Electrical Coordination� Provides Guideline for resolving interference
between power and telecommunication systems (uses I*T levels)
� IEEE 776 – Inductive Coordination� Provides guidelines based on specific levels of
individual harmonics rather than overall I*T levels
� IEEE 519 – Harmonic Control In Power Systems� Provides guidelines for Voltage and Current total
harmonic distortion (THD) and I*T on the power system as well as individual load components
� Power loads may meet the THD requirements of IEEE 519, and still be the prime cause of noise due to high residual I*T level
Effect of the Power Multi-Grounded Neutral
� Current returned in the earth does not provide magnetic cancellation (E.g. Earth return Power systems)
� Since neutral current is 180 degrees out of phase with phase currents it serves to reduce the residual I*T
� Typically the current on the neutral conductor will be 30 to 40% of the total return current on a wye connected power system
� Current on the neutral conductor will be higher near the load and increase as the substation is approached.
Induction Neutralizing Transformers� Neutralizing transformers can be used to reduce induced
voltage as well as noise on communication cables
� INT's consist of telephone wire pairs wrapped around a laminated iron core and this present a high impedance to longitudinal currents
Induction Neutralizing Transformer
Placing an INT� INT’s are most effective when all pairs in the cable
are being treated
� Use a Digital INT if there are digital carrier circuits in the cable being treated
� For voltage reduction place INT at a point where induced voltage is half the total
� For noise reduction, the INT must be placed at a point before the circuit noise (Nm) has become too high. E.g. 15 to 17 dBrnC.
� INT’s are most effective for treating harmonics below the 15th Harmonic (900 Hz).
� Depending on location and harmonic content, a reduction of 10 - 25 dBrnC Ng can be expected.
Power Induction Problems 2005-2011
ATCOAlix, Bonneville, Castor, ,Hythe , Stettler, Debolt, Elk Point, Forestburg, Fort McMurray, Galahad, Girouxville, Grande Prairie, Grande Cache, Hardisty, High Prairie, Kitscoty, Oyen,Valleyview
FORTISAcme, Alder Flats, Ardrossan, Bassano, Beaumont, Blue Ridge, Bruderheim, Calmar, Camrose, Chauvin , Chestemere, Cochrane, Czar, Drayton Valley, Edgerton, Entwistle, Fort Assiniboine, Gleichen, Glenwood, Hardisty, Hobbema, Irma, Innisfail Mountain view, Nanton, Olds, Onoway, Pincher Creek, Patricia, Provost, Rimbey, Sedgewick, Stavely, Strathmore, Sundre, Suffield, Sylvan Lake, Taber, Vauxhall, Walsh, Wainwright, Wetaskiwin
Red Deer ElectricHwy 11A
EPCOR41st Ave SW, Ellerslie Road
ENMAXKingsland, Ogden(Capacitor Bank Switching)
APIC 2011 Power & Energy Innovation Forum
U of A Research Findings
University of Alberta
• What is happening in current distribution systems?
• Key research findings
• What needs to be done to manage the situation?
by Wilsun Xu
1. What is happening?
University of Alberta
10 to 15 years ago
• Industrial customers are the main harmonic producers• Interconnection standards have been established to limit harmonics from them• Such loads inject little harmonics into power system nowadays
Utility system
Harmonics filters
Linear & nonlinear loads
Iharmonics
Utilities have establishedlimits on Iharmonicsflowing intotheir systems at the PCCPCC – point of common coupling
Ih<Ilimit
A standard design practices
1. What is happening?
University of Alberta
At present
• More and more home appliances are becoming harmonic sources• Although insignificant individually, their collective impact can be big• Blocks of residential loads have become main harmonic sources
-4
-3
-2
-1
0
1
2
3
4
0 100 200 300 400 500 600
Time step
Cu
rre
nt
[A]
PC 1
PC 3
PC 2
-25
-20
-15
-10
-5
0
5
10
15
20
0 100 200 300 400 500 600
Time step
Cu
rre
nt
[A]
MW 1 on
MW 1 off
MW 2 on
MW 2 off
Desktop PC Microwave
- 1
-0 .8
-0 .6
-0 .4
-0 .2
0
0 .2
0 .4
0 .6
0 .8
1
0 1 0 0 2 0 0 3 0 0 4 0 0 5 0 0 6 0 0
CFL
- 8
- 6
- 4
- 2
0
2
4
6
8
0 1 0 0 2 0 0 3 0 0 4 0 0 5 0 0 6 0 0
T i m e S t e p
Cu
rre
nt
[A]
F i llin g W at er
W a sh i n g
R in s in g
R in s in g o ff
S p in n i n g
F a s t S p in n in g
Washer
1. What is happening?
University of Alberta
Typical spectra of a service transformer load SUB
One neighborhood with 100 servicetransformers (70A)
“PCC”
0
2
4
6
8
10
12
3rd 5th 7th 9th 11th 13th 15th Total
Harmonic order
Cu
rre
nt
Dis
tort
ion
(ID
D, %
)
Residential feeder
Total load of the sample neighborhood is about 3MW. For this block of loads
• The harmonic current at the “PCC” would exceed the limits • The telephone interference level would be close to 1000A, >> 500A limit
Additional Challenges: • The presence of 3rd and 9th harmonics (zero sequence)• No single entity is responsible for it• So utilities “own” the problem
Comparison
2. Key research findings
University of Alberta
• We have done extensive measurements in Edmonton with the help of Epcor• We also conducted field measurements near Beaverlodge (Goodfare sub) with the help of ATCO
IT Index measured at the substation locations
• The design limit for industrial customers is 500!• 4000 is the level where Telus is likely to receive complaints
Telephone interference
University of Alberta
0 2 4 6 8 10 12 140
1000
2000
3000
4000
5000
6000
7000
8000
Power(MW)
IT
12E 2008 23E
M-T1
M-T2
M-T3
P-T1-B1
P-T1-B2
P-T2-B7P-T2-B8
CD-T1-B2
CD-T2-B8
5L4056
21SU
11SU
12SU12E 2011
Simulation: An ideal feeder (loads distributed)Simulation: An ideal feeder (loads concentrated in one location)Simulation: 21SU feederMeasurement results for different feeders
Pow
er I
T L
evel
• The results confirm that the high IT level encountered in today’s distribution system is actually expected and is not caused by some unique feeder conditions.
• All residential feeders with regular load levels are likely to exhibit high IT levels.
Telephone interference2. Key research findings
University of Alberta
Other concerns
• High harmonic voltage and current levels in both primary & secondary systems
• Overloading of service transformer
• Neutral current in the primary feeder
• Penetration of harmonic currents into the transmission system
• Revenue meter errors (potential concern)
• Resonance caused capacitor/cable failure (potential concern)
0.00%1.00%2.00%3.00%4.00%5.00%6.00%7.00%8.00%9.00%
2011 2012 2013 2014 2015
Year
Annual Growth Rate = 15.30%
Voltage THD
12 am2 am 4 am6 am8 am10 am12 pm2 pm4 pm6 pm8 pm10 pm12 am50
100
150
200
250
300
350
Hours
3rd
Vo
ltag
e C
om
po
nent
(V)
SatSun
3rd Harmonic Voltageat a 138kV Bus
2. Key research findings
University of Alberta
3. What needs to be done?
Residential feeders nowadays consists of multiple blocks of “limit-exceeding” loads
SUB
A neighborhood with 100 servicetransformers (70A)
“PCC”
Neighborhood X
Neighborhood YSUB
A neighborhood with 100 servicetransformers (70A)
“PCC”
Neighborhood X
Neighborhood Y
• Ignoring the situation is not a solution. It is also not fair for other types of customers
• One potential solution is to adopt the IEC device level limits (IEC 61000-3-2)
• Another solution is to install filters in the primary feeders
• Other solutions such as distributed filters may also be possible
Filter Filter
4. Conclusions
University of Alberta
• Clusters of residential homes can inject into distribution systems harmonic currents that exceed the limits established for individual industrial customers of comparable MW sizes.
• High telephone interference levels & high level of harmonic penetrations into transmission systems are becoming a new reality
• There are no easy solutions and quick fixes to the problem due to the distributed nature of the harmonic producers
• Utilities shall work together to impose device level limits like what has been done in Europe
• Feeder level harmonic filtering may become a general distribution system design practice in the future
