HARMONIC TREATMENT IN INDUSTRIAL POWER SYSTEMS
Transcript of HARMONIC TREATMENT IN INDUSTRIAL POWER SYSTEMS
IEEE PESC-02 JUNE 20021
HARMONIC TREATMENT IN INDUSTRIAL POWER SYSTEMS
Presented byStefanos Manias
JUNE 2002IEEE PESC-022
CONTACT INFORMATION
Stefanos N. ManiasNational Technical University of AthensPhone: +3010-7723503FAX: +3010-7723593E-mail: [email protected]
Mailing AddressNational Technical University of AthensDepartment of Electrical and Computer Engineering9, Iroon Polytechniou Str, 15773 ZografouAthens, Greece
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PLAN OF PRESENTATION
1. DEFINITIONS2. CATEGORIES OF POWER QUALITY VARIATIONS3. HARMONIC DISTORTION SOURCES IN INDUSTRIAL POWER
SYSTEMS4. EFFECTS OF HARMONICS ON ELECTRICAL EQUIPMENT5. HARMONIC MEASUREMENTS IN INDUSTRIAL POWER SYSTEMS6. HARMONIC STANDARDS7. HARMONIC MITIGATING TECHNIQUES8. GENERAL PASSIVE AND ACTIVE FILTER DESIGN PROCEDURES9. DESIGN EXAMPLES10. CONCLUSIONS
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WHY HARMONIC ANALYSIS ?
When a voltage and/or current waveform is distorted, it causes abnormal operating conditions in a power system such as:
Voltage Harmonics can cause additional heating in induction and synchronous motors and generators.
Voltage Harmonics with high peak values can weaken insulation in cables, windings, and capacitors.
Voltage Harmonics can cause malfunction of different electronic components and circuits that utilize the voltage waveform for synchronization or timing.
Current Harmonics in motor windings can create Electromagnetic Interference (EMI).
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Current Harmonics flowing through cables can cause higher heating over and above the heating that is created from the fundamental component.
Current Harmonics flowing through a transformer can cause higher heating over and above the heating that is created by the fundamental component.
Current Harmonics flowing through circuit breakers and switch-gear can increase their heating losses.
RESONANT CURRENTS which are created by current harmonics and the different filtering topologies of the power system can cause capacitor failures and/or fuse failures in the capacitor or other electrical equipment.
False tripping of circuit breakers ad protective relays.
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a) Current Source nonlinear load
Diode rectifier for ac drives, electronic equipment, etc
HARMONIC SOURCES
Thyristor rectifier for dc drives, heater drives, etc.
Per-phase equivalent circuit of thyristor rectifier
b) Voltage source nonlinear load
Per-phase equivalent circuit of diode rectifier
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0 10 20 30 40-1.0
-0.5
0.0
0.5
1.0
Time (mS)
Cur
rent
0 10 20 30 40-1.0
-0.5
0.0
0.5
1.0
Time (mS)
Cur
rent
0 10 20 30 40-1.0
-0.5
0.0
0.5
1.0
Time (mS)
Cur
rent
TYPE OF
NONLINEAR LOAD
TYPICAL WAREFORM
THD%
1-φ
Uncontrolled Rectifier
80%
(high 3rd component)
1-φSemicontrolled Rectifier Bridge
2nd, 3rd, 4th ,......
harmonic components
6 –Pulse Rectifierwith output voltage filtering and without input reactor filter
80%
5, 7, 11, ……….
INPUT CURRENT OF DIFFERENT NOLINEAR LOADS
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0 10 20 30 40-1.0
-0.5
0.0
0.5
1.0
Time (mS)
Cur
rent
0 10 20 30 40-1.0
-0.5
0.0
0.5
1.0
Time (mS)
Cur
rent
0 10 20 30 40-1.0
-0.5
0.0
0.5
1.0
Time (mS)
Cur
rent
6 - Pulse Rectifierwith large output
inductor
28%5, 7, 11, ………..
6 - Pulse Rectifier
with output voltage filtering and with 3% reactor filter or with
continues output current
40%5, 7, 11, ………..
12 - Pulse Rectifier
15%11, 13, ………..
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CURRENT HARMONICS GENERATED BY 6-PULSE CSI CONVERTERSHARMONIC P.U PULSE
1 1.005 0.27 0.143
11 0.0913 0.07717 0.05919 0.05323 0.04
CURRENT HARMONICS GENERATED BY 12-PULSE CSI CONVERTERS
HARMONIC P.U PULSE IEEE 519 std1 1.00 -5 0.03-0.06 5.6%7 0.02-0.06 5.6%
11 0.05-0.09 2.8%13 0.03-0.08 2.8%
THD 7.5%-14.2% 7.0%
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RECENT CURRENT MEASUREMENTS TAKEN IN ANINDUSTRIAL PLANT WITH 600 KVA, 20 KV/400 V
DISTRIBUTION TRANFORMER
Current waveform and its respective spectrumat the inputs of a motor drive system
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Current waveform and its respective spectrum
at the inputs of a motor drive system
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Current waveform and its respective spectrum
at the secondary of the distribution transformer
( i.e. at the service entrance)
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DEFINITIONS
f (t) = Fourier Series of a periodic function f (t) =
1hhho θtωh cosCC (1)
Too dttf
T1C ,)( (2)
Toh dt)tωhcos()t(f
T2A (3)
Toh dt)tωhsin()t(f
T2B (4)
h = harmonic order
2h
2hh BAC
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% υTHD
100V
V
1
2h
2h
(5)
% iTHD
100I
I
1
2h
2h
(6)
Percentage of the Total Harmonic Distortion of a nonsinusoidal voltage waveform
Percentage of the Total Harmonic Distortion of a nonsinusoidal current waveform
hthVh
hthIh
harmonic component of the voltage
harmonic component of the current
V~H RMS value of the voltage distortion V~
2h
2h
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I~
1h
2hI
~ (7)
V~
V~1h
2h
(8)
100VAk SCkVA DriveHF %υTHD (9)
15h
2h
2 I/Ih
(10)
RMS value of a nonsinusoidal current =
RMS value of a nonsinusoidal voltage =
HF Harmonic Factor =
I~H RMS value of the current distortion I~
2h
2h
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kVA Drive
kVA SC
SINUSOIDAL VOLTAGE NONSINUSOIDAL CURRENT
1i,1 φcosI~ V~P
I~ V~S , φsinI~ V~Q 1i,1
(11)
(12)
(13)
Full load kVA rating of the Drive system
Short Circuit kVA of the distribution system atthe point of connection
222 QPS VA DistortionD
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2h
2h,i
221,i
222 I~V~I~V~SD (14)
SPFactor Power True 1
1,i φcosI
Iλ
(15)
Factorment Displace Factor Distortion
NONSINUSOIDAL VOLTAGE AND NONSINUSOIDAL CURRENT
1h 1hhhh , hhh φsinI~V~QφcosI~V~P (16)
SSSSPower DistortionD
mnm n
*mn
*nm
mnmn
nm
(17)
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2222 DQPS (18)
2 N
21
2HH
21H
2H1
211
1h
2h
2h
SS I~V~
I~V~I~V~I~V~I~V~S
(19)
111 I~V~PowerApparent lFundamenta S
PowerApparent ntalNonfundame SN
2HH2
1H2
H12N I~V~I~V~I~V~S
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Power DistortionCurrent I~V~ H1 (20)
Power Distortion Voltage I~V~ 1H (21)
PowerApparent Harmonic I~V~ HH (22)
Power ActiveNon Harmonic Total Power Active Harmonic Total NP S 2
H2H
2H
(23)
phase32
L-LC VAR/V capacitor theof Reactance X
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Harmonic sequence is the phase rotation relationship with respect to the fundamental component.
Positive sequence harmonics ( 4th, 7th, 10th , ……. (6n+1) th ) have the same phase rotation as the fundamental component. These harmonics circulate between the phases.
Negative sequence harmonics ( 2nd, 5th, 8th ……… (6n-1) th ) have the opposite phase rotation with respect to the fundamental component. These harmonics circulate between the phases.
Zero sequence harmonics ( 3rd, 6th, 9th, ….. (6n-3) th ) do not produce a rotating field. These harmonics circulate between the phase and neutral or ground. These third order or zero sequence harmonics, unlike positive and negative sequence harmonic currents, do not cancel but add up arithmetically at the neutral bus.
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EXAMPLE 1
A periodic, sinusoidal voltage of instantaneous value tωsin2200v Is applied to a nonlinear load impedance. The resulting instantaneous current is
given by: ooo 60tω3sin1060tω2sin1045tωsin202i Calculate the components P, Q, D of the apparent voltamperes and hence calculate the displacement factor, the distortion factor and the power factor.
Solutiontωsin2200v
ooo 60tω3sin1060tω2sin1045tωsin202i The presence of the nonlinearity causes frequency components of current (i.e. thesecond and third harmonic terms) that are not present in the applied voltage.
The rms voltage and current at the supply are:
V200V~ 2222 101020I~
22A106
SINUSOIDAL VOLTAGE-NONSINIMUSOIDAL CURRENT
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The apparent voltamperes at the input is therefore given by
2622222 VA1024106200I~V~S
In this example only the fundamental frequency components are common to both voltage and current. Therefore, the real power P and the apparent power Q are
11 ψcosI~V~P
o45cos20200
W2
4000
11 ψsinI~V~Q o45sin20200
VA2
4000
1ψ = displacement angle between the fundamental of the voltage and the fundamental of the current
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21
222 I~I~V~D
232
2 I~I~V~
26222 VA1081010200 22222 I~V~DQP
Displacement factor 707.02
1ψcos 1
Distortion factor 817.060020
II1
Therefore, the power factor is
577.06
22
1PF
1111 ψcosII~
I~V~ψcosI~V~
SPfactorpower PF
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EXAMPLE 2
A periodic, sinusoidal voltage given by o30tω5sin200tωsin2002v is applied to a series, linear, resistance-inductance load of resistance 4Ω and
fundamental frequency reactance 10Ω. Calculate the degree of power factor improvement realizable by capacitance
Solution. The rms terminal voltage is given by25
21 V~V~V~
Compensation when .HZ50f1
22 200200
V~
Therefore
V283V~
10j4Z1
8.10Z1
o2.684/10tan 11
NONSINUSOIDAL VOLTAGE-RL LOAD
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505 15
50j4Z5
50Z5
o15 4.854/50tan
The instantaneous load current is given by
ooo 4.8530t5sin
502002.68tsin
8.102002i
The rms load current I~ is therefore given by
2
5
5
2
1
125
21
2
ZV~
ZV~I~I~I~
222 A359452.18
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Average power P In this case is
...cosI~V~cosI~V~cosI~V~Pn
1222111Lnn
oo 4.85cos42002.68cos52.18200
W1440
The power factor before compensation is therefore
27.01072.28
1440SP
PF6
26222 VA1072.28I~V~S
Apparent voltamperes S at the load terminals in the absence of capacitance is therefore
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EXAMPLE 3
A periodic, nonsinusoidal voltage with instantaneous value given by
o30-tω2sin200tωsin2002v
Solution.
is applied to a nonlinear impedance.
The resulting current has an instantaneous value given by
oooL 60tω3sin1060tω2sin1045tωsin202i Calculate the components LDLXLR S,S,S of the load apparent voltamperes
and compare thee with the classical values LLL D,Q,P respectively.
o30-tω2sin200tωsin2002v
oooL 60tω3sin1060tω2sin1045tωsin202i
Note that the presence of the load nonlinearity causes a frequency component of load current (I.e. the third harmonic term) that is not present in the supply voltage.
NONSINUSOIDAL VOLTAGE AND NONSINIMUSOIDAL CURRENT
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The rms voltage and current at the supply are given by
24222 V108200200V~ 222222
L A106101020I~ The load apparent voltamperes LS therefore has a value defined in terms V~ and LI
~
262L
22L VA1048I~V~S
Instantaneous expressions of the hypothetical currents DXR i,i,i are given by
o0oR 30t2sin30cos10tsin45cos202i
222o2o2LR A10
41130cos1045cos20I~
o0oX 30tω2cos30sin10tωcos45sin202i
222o2o2LX A10
4930sin1045sin20I~
oD 60t3sin10 2i
222LD A10I~
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Note that current components XR i,i contain only those harmonic terms whichare common to both voltage and current. These are therefore consistent with the
1n terms.
The rms load current components LDLXLR I~,I~,I~ are found, as expected to sum
to the total rms load current LI~
2L
222LD
2LR
2LD I~106
49
411110I~I~I~
Components LDLXLR S,S,S of the apparent voltamperes can now be obtained
26422LR
22LR VA102210810
411I~V~S
26422LX
22LX VA101810810
49I~V~S
26422LD
22LD VA10810810I~V~S
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The component voltamperes are seen to sum to the total apparent voltamperes
8182210SSS 62LD
2LX
2LR
26 VA10482LS
Components LLL D,Q,P of LS are found as follows:2n
11n1n1n
2L ψcosI~V~P
2oo 30cos1020045cos20200
22 310220100
2LR
6626 S108.2064381032210
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2n
11n1n1n
2L ψsinI~V~Q
2oo 30sin1020045sin20200
2LX
66 S106.1412210
2L
2L
2L
2L QPSD
2LD
266 SVA106.12106.148.2048 From the possible compensation viewpoint it is interesting to note that LXSand LQ differ by significant amount.
LXS could be defined as “that component of the load apparent voltamperes that
Is obtained by the combination of supply voltage harmonics with quadratureComponents of corresponding frequency load current harmonics”.
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Similarly the definition of active voltamperes LRS could be given by “that
component of the load apparent voltamperes that is obtained by the combination
of supply voltage harmonics with in-phase components of corresponding
frequency load current harmonics”.
Both LRS and LXS are entirely fictitious and non-physical. The active
voltamperes LRS Is not to be compares in importance with the average power
LP which is a real physical property of the circuit. Term LRS Is merely the
analytical complement of term LXS
Term LXS the energy-storage reactive voltamperes, is that component
of the load apparent voltamperes that can be entirely compensated (for sinusoidal
supply voltage) or minimized (for nonsinusoidal supply voltage) by energy-storage
methods.
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Voltage and current profiles in a commercial building
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HARMONIC STANDARDS International Electrotechnical Commission (IEC) European
Standards.
- EN 61000-3-2 Harmonic Emissions standards were first published as IEC 55-2 1982 and applied only to household appliances. It was revised and reissued in 1987 and 1995 with the applicability expanded to include all equipment with input current 16A per phase. However, until January 1st, 2001 a transition period is in effect for all equipment not covered by the standard prior to 1987.
- The objective of EN 61000-3-2 (harmonics) is to test the equipment under the conditions that will produce the maximum harmonic amplitudes under normal operating conditions for each harmonic component. To establish limits for similar types of harmonics current distortion, equipment under test must be categorized in one of the following four classes.
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CLASS-A: Balanced three-phase equipment and all other equipment
except that stated in one of the remaining three classes. CLASS-B: Portable electrical tools, which are hand held during normal
operation and used for a short time only (few minutes) CLASS-C: Lighting equipment including dimming devices. CLASS-D: Equipment having an input current with special wave shape ( e.g.equipment with off-line capacitor-rectifier AC input circuitry and switch Mode power Supplies) and an active input power 600W.
- Additional harmonic current testing, measurement techniques and instrumentation guidelines for these standards are covered in IEC 1000-4-7.
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• IEEE 519-1992 United States Standards on harmonic limits
- IEEE limits service entrance harmonics.- The IEEE standard 519-1992 limits the level of harmonics at the
customer service entrance or Point of Common Coupling (PCC).- With this approach the costumer’s current distortion is limited based
on relative size of the load and the power supplier’s voltage distortion based on the voltage level.
IEEE 519 and IEC 1000-3-2 apply different philosophies, which effectively limit harmonics at different locations. IEEE 519 limits harmonics primarily at the service entrance while IEC 1000-3-2 is applied at the terminals of end-user equipment. Therefore, IEC limits will tend to reduce harmonic-related losses in an industrial plant wiring, while IEEE harmonic limits are designed to prevent interactions between neighbors and the power system.
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POWER QUALITY STANDARDS – IEEE 519-1992 STANDARDS
TABLE ICURRENT DISTORTION LIMITS FOR GENERAL DISTRIBUTION SYSTEMS
(120-69000 V)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 5.020<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 12.0100<1,000 12.0 5.5 5.0 2.0 1.0 15.0
>1,000 15.0 7.0 6.0 2.5 1.4 20.0Source: IEEE Standard 519-1992.Note: Even harmonics are limited to 25 percent of the odd harmonic limits above.
Current distortions that result in a direct current offset; for example, half wave converters are not allowed.
Table I is for 6-pulse rectifiers. For converters higher than 6 pulse, the limits for characteristic harmonics are increased by a factor o f q/6 , where q is the pule number, provided that the amplitudes of noncharacteristic harmonics are less than 25 percent. *All power generation equipment is limited to these values of current distortion, regardless of actual ISC/IL.Where ISC = Maximum short circuit at PCC.And IL = Average Maximum demand load current (fundamental frequency
component at PCC).
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TABLE IILOW VOLTAGE SYSTEM CLASSIFICATION AND DISTORTION LIMITS
IEEE 519-1992 STANDARTS
Special Applications
General System
Dedicated System
Notch Depth 10% 20% 50%
THD (Voltage) 3% 5% 10%
Notch Area(AN)*
16,400 22,800 36,500
Source: IEEE Standard 519-1992.Note: The value AN for another than 480Volt systems should be multiplied by V/480 .
The notch depth, the total voltage distortion factor (THD) and the notch area limits are specified for line to line voltage.
In the above table, special applications include hospitals and airports. A dedicated system is exclusively dedicated to converter load.*In volt-microseconds at rated voltage and current.
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TABLE III
LIMITS OF THD%
IEEE 519-1992 STANDARDS
SYSTEM Nominal Voltage
Special Application
General Systems
Dedicated Systems
120-600V 3.0 5.0 8.0
69KV and below - 5.0 -
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TABLE IVPROPOSED IEC 555-2 CLASS D STANDARDS for power from 50 to 600W
Harmonic Relative limits Milliamps/Watt
Absolute Limits Amps
3 3.4 2.305 1.9 1.147 1.0 0.779 0.5 0.40
11 0.35 0.3313 linear
extrapolation0.15 (15/n)
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METHODOLOGY FOR COMPUTING DISTORTION
Step 1: Compute the individual current harmonic distortion at each dedicated bus using different Software programs (i.e. SIMULINK, SPICE, e.t.c.) or tables that provide the current distortion of nonlinear loads.
Step 2: Compute the voltage and current harmonic content at the Point of Common Coupling (PCC) which is located at the input of the industrial power system.
- Each individual harmonic current at the PCC is the sum of harmonic current contribution from each dedicated bus.
- The load current at PCC is the sum of the load current contribution from each dedicated bus.
- The maximum demand load current at PCC can be found by computing the load currents for each branch feeder and multiply by a demand factor to obtain feeder demand. Then the sum of all feeder demands is divided by a diversity factor to obtain the maximum demand load current.
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Step 3: Choose a base MVA and base KV for the system use the following equations in order to compute individual and total current and voltage harmonic distortions at PCC and any other point within the power system.
Ib= Base current in Amps Ampsb
3bkV3
10MVA
= System impedance = p.u. MVAMVA
sc
b
MVAb= Base MVA, MVAsc= short circuit MVA at the point of interest
VH= Percent individual harmonic voltage distortion =
Volts 100ZhII
sb
h
(24)
(25)
(26)
sZ
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h = harmonic order
100V
21V
%THD1
2h
2h
υ
100I
I
%THD1
2
2h
2h
i
IH = Percent individual harmonic distortion = 100II
L
h
Isc = Short Circuit current at the point under consideration.
IL = Estimated maximum demand load current
S.C. Ratio = Short circuit Ratio D
sc
L
scMVAMVA
II
MVAD = Demand MVA
(27)
(28)
(29)
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K Factor = Factor useful for transformers design and specifically from transformers that feed Adjustable Speed Drives
1h
2
L
h2IIh
ONCE THE SHORT CIRCUIT RATIO IS KNOWN, THE IEEE CURRENT HARMONIC LIMITS CAN BE FOUND AS SPECIFIED IN TABLE I OF THE IEEE 519-1992 POWER QUALITY STANDARDS
USING THE ABOVE EQUATIONS VALUES OF IDIVINDUAL AND TOTAL VOLTAGE AND CURRENT HARMONIC DISTORTION CAN BE COMPUTED AND COMPARED WITH THE IEEE LIMITS
(30)
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Step 4: If the analysis is being performed for CSI-type drives then the area of the voltage notch AN should also be computed.
- At this point an impedance diagram of the under analysis industrial power system should be available.
- The Notch Area AN at the PCC can be calculated as follows.
AN = AN1 + AN2 + …………. V . microsec
AN1 , AN2 , …… are the notch areas contribution of the different busses
ANDR1 : Notch area at the input of the drive
1NDR1N Adrive the toPCC from sinductance of sum the inductance Source
inductance SourceA
(31)
(32)
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Step 5: Determine preliminary filter design.
Step 6: Compute THDv and THDi magnitudes and impedance versus frequency plots with filters added to the system, one at a time. SIMULINK or PSPICE software programs can be used for final adjustments.
Step 7: Analyze results and specify final filter design.
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EXAMPLE OF A SYSTEM ONE LINEDIAGRAM
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System impedances diagram which can be used to calculate its resonance using PSPICE or SIMULINK
programs
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1) Parallel-passive filter for current-source nonlinear loads
TYPES OF FILTERS
• Harmonic Sinc• Low Impedance• Cheapest• VA ratings = VT (Load Harmonic current + reactive current of the filter)
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2) Series-passive filter for voltage-source nonlinear loads
• Harmonic dam• High-impedance• Cheapest• VA ratings = Load current (Fundamental drop across filter + Load Harmonic Voltage)
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3) Basic parallel-active filter for current source in nonlinear loads
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4) Basic series-active filter for voltage-source in nonlinear loads
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5) Parallel combination of parallel active and parallel passive
6) Series combination of series active and series passive
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7) Hybrid of series active and parallel passive
8) Hybrid of parallel active and series passive
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9) Series combination of parallel-passive and parallel-active
10) Parallel combination of series-passive and series-active
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11) Combined system of series-active and parallel-active
12) Combined system of parallel-active and series-active
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A SIMPLE EXAMPLE OF AN INDUSTRIAL POWER DISTRIBUTION SYSTEM
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HARMONIC LIMITS EVALUATION WHEN POWER-FACTOR-CORRECTION CAPASITORS
ARE USED
- As it can be seen from the power distribution circuit the power-factor-correction capacitor bank, which is connected on the 480 Volts bus, can create a parallel resonance between the capacitors and the system source inductance.
- The single phase equivalent circuit of the distribution system is shown below.
Using the above circuit the following equations hold:
Source AC
totL SI
C
inZ
hI
fI
SV
HarmonicLoad
totR
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,
RXtancos
MVAkVR 1
sc
2LL
sys 2sys
sysα
RR
,
RXtansin
MVAkVX 1
sc
2LL
sys 2sys
sysα
XX
tr
2LL
putr kVAkV1000RR
tr
2LL
putr kVAkV1000XX
α = The turns ratio of the transformer at PCC
(33)
(34)
(35)
(36)
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trsystot XXX
cap
2cap
c kVARkV1000
X
ω
XL tottot
fπ2Xtot
Xω1C
c
Cω1Xc
trsystot RRR (37)
(38)
(39)
(40)
(41)
(42)
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Cω1jLωjR
Cω/jLωjRZtottot
tottotin
, Cω
1Lωo
toto o
o πω21f
The impedance looking into the system from the load, consists of the parallel combination of source impedance and the capacitor impedance tottot jXR
inZ
The equation for can be used to determine the equivalent system impedance for different frequencies. The harmonic producing loads can resonate (parallel resonance), the above equivalent circuit. Designating the parallel resonant frequency by (rad/sec) or (HZ) and equating the inductive and capacitive reactances.
inZ
oω of
(43)
(44)
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- Harmonic current components that are close to the parallel resonant frequency are amplified.- Higher order harmonic currents at the PCC are reduced because the capacitors are low
impedance at these frequencies.- The figure below shows the effect of adding capacitors on the 480 Volts bus for power factor
correction.
This figure shows that by adding some typical sizes of power factor correction capacitors will result in the magnification of the 5th and 7th harmonic components, which in turns makes it even more difficult to meet the IEEE 519-1992 harmonic current standards .
- Power factor correction capacitors should not be used without turning reactors in case the adjustable speed drives are >10% of the plant load.
JUNE 2002IEEE PESC-0263
Let us examine an industrial plant with the following data:- Medium voltage = 20KVLL
- Low voltage = 0.4 KVLL
- Utility three phase short circuit power = 250 MVA- For asymmetrical current, the ratio of system impedance
RX 4.2
The Transformer is rated:
1000 KVA, 20 KV-400 Y/230 VRpu = 1%, Xpu = 7%
- The system frequency is: fsys = 50 HZ.
- For power factor correction capacitors the following cases are examined:a. 200 KVARb. 400 KVARc. 600 KVARd. 800 KVAR
EXAMPLE
JUNE 2002IEEE PESC-0264
The parallel resonant frequencies for every case of power factor correction is calculated as follows:
Ω6154.04.2tancos25020R 1
2sys
Ω4769.14.2tansin25020X 1
2sys
504.0
20α
Ω000246.0506154.0R 2sys
Ω000591.0504769.1X 2sys
Ω00160.01000
4.0100001.0R2
tr
Ω0112.01000
4.0100007.0X2
tr
JUNE 2002IEEE PESC-0265
Ω 001846 . 0 0016 . 0 000246 . 0 Rtot
Ω011791.00112.0000591.0Xtot
H1055.3750π2
011791.0L 6tot
Case a: Ω 8.0
2004.01000X
2c
F1098.38.050π2
1C 3
HZ18.4121098.31050.37π2
1f36o
For 200 KVAR, the harmonic order at which parallel resonance occurs is:
24.85018.412h
JUNE 2002IEEE PESC-0266
Case b: Ω 4.0
4004.01000X
2c
F1096.7C 3
HZ45.291fo
83.5h
Case c:
Ω 267.0600
4.01000X2
c
F1094.11C 3
HZ97.237fo
76.4h
JUNE 2002IEEE PESC-0267
Case d:
Ω 2.0800
4.01000X2
c
F1092.15C 3
HZ08.206fo
12.4h
It is clear for the above system that in the 600 KVAR case, there exists a parallel resonant frequency close to the 5th harmonic.of
JUNE 2002IEEE PESC-0268
POWER FACTOR CORRECTION AND HARMONIC TREATMENT USING TUNED FILTERS
- Basic configuration of a tuned 3-φ capacitor bank for power factor correction and harmonic treatment.
Simple and cheap filter Prevents of current harmonic magnification
JUNE 2002IEEE PESC-0269
- IN ORDER TO AVOID HARMONIC MAGNIFICATION WE CHOOSE A TUNED FREQUENCY < FITH HARMONIC (i.e 4.7)
- The frequency characteristic of the tuned filter at 4.7 is shown below
As it can be seen from the above figure significant reduction of the 5th harmonic is achieved. Moreover, there is some reduction for all the other harmonic components.
JUNE 2002IEEE PESC-0270
The single phase equivalent circuit of the power distribution system with the tuned filter is shown below
Using the above circuit the following equations hold:
JUNE 2002IEEE PESC-0271
0Cω
1LωLωo
fototo
21
ftoto
CLLπ2
1f
Cω1LωLωjRLωjRII
ftottot
tottothf
cap2
os
2cap
2os
c2
osf
kVARfπ2
kV1000f
fπ2Xfπ2
fπ2C1L
(parallel resonance)
= resonance frequency of the equivalent distribution circuit
21
fos
CLπ2
1f
= Resonant frequency of the series filter
The new parallel combination is having resonant frequency when
Also
(45)
(46)
(47)
(48)
JUNE 2002IEEE PESC-0272
Cω1jLωjLωjR
Cω1jLωjLωjR
Zftottot
ftottotin
Cω1LωLω jR
Cω1jLωjLωjR
ftottot
ftottot
tottotsh LωjRIV
Cω1LωLω jR
Cω/1Lω jIIftottot
fhs
(49)
(50)
(51)
JUNE 2002IEEE PESC-0273
As it was discussed before Selecting HZ235fo or 4.7 th harmonic
With KVcap= 0.4 , KVARcap= 600
Hμ45.38H1045.68600235π24.0100050L 6
2
2f
The new parallel combination is having resonant frequency:
CLLπ21f
ftoto
with H1055.37L 6tot
H1045.38L 6
f
F1094.11C 3
we have
HZ16.1671094.111076π2
1f36o
43.350/16.167h (without Lf was 4.76)
JUNE 2002IEEE PESC-0274
The following table shows the variation of Parallel resonant frequencyWith and without resonant inductor
KVAR C(mF)Parallel Resonant f0
Without Lf With Lf
200 3.98 8.80 115.3μH 4.08
400 7.96 6.22 57.7μH 3.66600 11.94 5.08 38.45μH 3.43800 15.92 4.40 29.5μH 3.08
JUNE 2002IEEE PESC-0275
vol tage
motor
+i -
i tot
compens
chock2%5
chock2%3 chock2%1
+- v
Voltage Measurement3
+- v
V1
+- v
V
T1
T
Source1
Source
Series RLC Branch3 Series RLC Branch2
Series RLC Branch1
Series RLC Branch
Scope4
Scope3
Scope2
Scope1
Scope
Ground (output)1
Ground (output)
Ground (input)8
Ground (input)5 Ground (input)4
Ground (input)3 Ground (input)2
Ground (input)1
Ground (input)
Gnd
+ i-
Current Measurement6
+i-
Current Measurement5+
i -Current Measurement4
+ i-
Current Measurement3
+i -Current Measurement1
+ i-
C
Bus Bar (horiz)7
Bus Bar (horiz)6
Bus Bar (horiz)5
Bus Bar (horiz)4
Bus Bar (horiz)3
Bus Bar (horiz)2
Bus Bar (horiz)1
Bus Bar (horiz)
AC Voltage Source
AC Current Source8
AC Current Source7
AC Current Source6
AC Current Source5
AC Current Source4
AC Current Source3
AC Current Source2
AC Current Source1
AC Current Source
50m cable 4x1
380kw/490rpm
200m cable 4x240
.
SIMULATED RESULTS USING MATLAB/SIMULINK
JUNE 2002IEEE PESC-0276
SIMULINK RESULTS
JUNE 2002IEEE PESC-0277
SIMULINK RESULTS
JUNE 2002IEEE PESC-0278
ACTIVE FILTERING
Parallel type Series type
JUNE 2002IEEE PESC-0279
-2500
-1500
-500
500
1500
2500
0 5 10 15 20 25 30 35 40
I[A]
Time [ms]
0
5
10
15
20
25
30
2 5 8 11 14 17 20 23
[% I1
]
Harmonics
-5000
-2500
0
2500
5000
0 10 20 30 40Time [ms]
I Dyn
acom
p [A
]
0%
5%
10%
15%
20%
25%
30%
35%
2 5 8 11 14 17 20 23Harmonics
[%I1
]
RESULTS OF ACTIVE FILTERING
Input current of a 6-pulse Rectifier driving a DC machine without any input filtering
Input current with Active Filtering
JUNE 2002IEEE PESC-0280
-1000
-500
0
500
1000
0 5 10 15 20 25 30 35 40
U [V
]
Time [ms]
0
2
4
6
8
10
12
14
2 5 8 11 14 17 20 23
[% U
1]
Harmonics
-1000
-500
0
500
1000
0 5 10 15 20 25 30 35 40
U [V
]
Time [ms]
0
2
4
6
8
10
12
14
2 5 8 11 14 17 20 23
[% U
]
Harmonics
Typical 6-pulse drive voltage waveform
Voltage source improvement with active filtering
JUNE 2002IEEE PESC-0281
SHUNT ACTIVE FILTERS
By inserting a parallel active filter in a non-linear load location we can inject a harmonic current component with the same amplitude as that of the load in to the AC system.
C
FL
Equivalent circuit
JUNE 2002IEEE PESC-0282
Low implementation cost. Do not create displacement power factor problems and utility loading. Supply inductance LS, does not affect the harmonic compensation of
parallel active filter system. Simple control circuit. Can damp harmonic propagation in a distribution feeder or between
two distribution feeders. Easy to connect in parallel a number of active filter modules in order to
achieve higher power requirements. Easy protection and inexpensive isolation switchgear. Easy to be installed. Provides immunity from ambient harmonic loads.
ADVANTAGES OF THE SHUNT OR PARALLELACTIVE FILTER
JUNE 2002IEEE PESC-0283
WAVEFORMS OF THE PARALLEL ACTIVE FILTER
Source voltage
Load current
Source current
A. F. output current
JUNE 2002IEEE PESC-0284
G1ZZ
VI
G1ZZ
ZIL
S
SLH
LS
LS
G1ZZ
VG1
1I
G1ZZ
G1Z
IL
S
SLH
LS
L
L
hSh
L ZG1
Z
LhC II
0ZVG1IG1I
L
ShLHhSh
(53)
(54)
(55)
(56)
(57)
1G h 0G 1
LC GII (52)
If
Then the above equations become
PARALLEL ACTIVE FILTER EQUATIONS
JUNE 2002IEEE PESC-0285
L
ShLHhLh Z
VII (58)
G1II
LH
S
LHI
LZ
G
= Source impedance
= Is the equivalent harmonic current source
= Equivalent load impedance
= equivalent transfer function of the active filter
For pure current source type of harmonic source SL ZZ
and consequently equations (53) and (55) become
SZ
(59)
1G1 h (60)
Equation (55) is the required condition for the parallel A.F. to cancelthe load harmonic current. Only G can be predesign by the A.F. whileZs and ZL are determined by the system.
Equation (59) shows that the compensation characteristics of the A.F. are not influenced by the source impedance, Zs. This is a major advantage of the A.F. with respect to the passive ones.
JUNE 2002IEEE PESC-0286
• The DC bus nominal voltage, , must be greater than or equal to line voltage peak in order to actively control
• The selection of the interface inductance of the active filter is based on the compromise of keeping the output current ripple of the inverter low and the same time to be able to track the desired source current.
• The required capacitor value is dictated by the maximum acceptable voltage ripple. A good initial guess of C is:
Cmax
t0 C
vΔ
dtimaxC
dtdi
max
VV32
LLφ
nφdCF
dCV.iC
nφV
= peak line-neutral voltage
dCV = DC voltage of the DC bus of the inverter
Lφi = Line phase current
CmaxvΔ = maximum acceptable voltage ripple,
Ci = Phase current of the inverter
dCV
C
Also
JUNE 2002IEEE PESC-0287
For identifying the harmonic currents in general the method of computing instantaneous active and reactive power is used.Transformation of the three-phase voltages and and the three-phase load currents and into α-β orthogonal coordinate.
w
v
u
β
α
vvv
2/3
2/1
2/3
2/101
32
vv
Lw
Lv
Lu
βL
αL
iii
2/3
2/1
2/3
2/101
32
ii
, vu vv wv, iLv Lui Lwi
P-Q THEORY
JUNE 2002IEEE PESC-0288
Then according to theory, the instantaneous real power and the instantaneous imaginary (reactive) power are calculated.
βL
αL
αβ
βα
L
L
ii
vvvv
qp
where
LLLL p~ppp
LLLL q~qqq
DC + low frequency comp. + high freq. comp.
DC + low frequency comp. + high freq. comp.
LpLq
q-p
JUNE 2002IEEE PESC-0289
The conventional active power is corresponding to , the conventional reactive power to and the negative sequence to the 2 f components of and .
The commands of the three-phase compensating currents injected by the shunt active conditioner, , and are given by:
qp
vv-vv
2/3
2/30
2/12/1
1
32
iii 1
αβ
βα
Cw
Cv
Cu
Lp~Lq~ Lp Lq
Cui
Cvi Cwi
p
q
= Instantaneous real power command
= Instantaneous reactive power command
JUNE 2002IEEE PESC-0290
L
L
q~q
p~p
LL
L
q~qq
p~p
LL
LL
q~qq
p~pp
Current Harmonics compensation is achieved
Current Harmonics and low frequency variationComponents of reactive power compensation
Current Harmonics and low frequency variationComponents of active and reactive power compensation
Substituting
JUNE 2002IEEE PESC-0291
HARMONIC DETECTION METHODS
i) Load current detection iAF= iLh It is suitable for shunt active filters which are installed near
one or more non-linear loads.
ii) Supply current detection iAF= KS iSh Is the most basic harmonic detection method for series
active filters acting as a voltage source vAF.
iii) Voltage detection It is suitable for shunt active filters which are used as
Unified Power Quality Conditioners. This type of Active Filter is installed in primary power distribution systems. The Unified Power Quality Conditioner consists of a series and a shunt active filter.
JUNE 2002IEEE PESC-0292
SHUNT ACTIVE FILTER CONTROL
a) Shunt active filter control based on voltage detection
JUNE 2002IEEE PESC-0293
Using this technique the three-phase voltages, which are detected at the point of installation, are transformed to and on the dq coordinates. Then two first order high-pass filters of 5HZ in order to extract the ac components and from and . Next the ac components are applied to the inverse dq transformation circuit, so that the control circuit to provide the three-phase harmonic voltages at the point of installation. Finally, amplifying each harmonic voltage by a gain Kv produces each phase current reference.
dv~ qv~dv qv
dv qv
hVAF vKi
The active filter behaves like a resistor 1/KV ohms to the external circuit for harmonic frequencies without altering the fundamental components.The current control circuit compares the reference current with the actual current of the active filter and amplifies the error by a gain KI . Each phase voltage detected at the point of installation, v is added to each magnified error signal, thus constituting a feed forward compensation in order to improve current controllability. As a result, the current controller yields three-phase voltage references. Then, each reference voltage is compared with a high frequency triangular waveform to generate the gate signals for the power semiconductor devices.
AFi
AFi
iv
JUNE 2002IEEE PESC-0294
b) Reference current calculation scheme using source currents (is), load currents (iL) and voltages at the point of installation (vS).
JUNE 2002IEEE PESC-0295
3-φ HYBRID ACTIVE-PASSIVE FILTER
Compensation of current harmonics and displacement power factor can be achieved simultaneously.
JUNE 2002IEEE PESC-0296
In the current harmonic compensation mode, the active filter improves the filtering characteristic of the passive filter by imposing a voltage harmonic waveform at its terminals with an amplitude
ShCh KIV
JUNE 2002IEEE PESC-0297
• THDi decreases if K increases.• The larger the voltage harmonics generated by the active filter a better filter
compensation is obtained.• A high value of the quality factor defines a large band width of the passive
filter, improving the compensation characteristics of the hybrid topology.• A low value of the quality factor and/or a large value in the tuned factor
increases the required voltage generated by the active filter necessary to keep the same compensation effectiveness, which increases the active filter rated power.
SF
F
Lh
ShZZK
ZII
1S
2h SF
FLh
i I
ZZKZI
THD
If the AC mains voltage is pure sinusoidal, then
JUNE 2002IEEE PESC-0298
Displacement power factor correction is achieved by controlling the voltage drop across the passive filter capacitor.
TC VβV
Displacement power factor control can be achieved since at fundamental frequency the passive filter equivalent impedance is capacitive.
JUNE 2002IEEE PESC-0299
HYBRID ACTIVE-PASSIVE FILTER
Single-phase equivalent circuit Single-phase equivalent circuit for 5th Harmonic
JUNE 2002IEEE PESC-02100
This active filter detects the 5th harmonic current component that flows into the passive filter and amplifies it by a gain K in order to determine its voltage reference which is given by
5FAF iKv
As a result, the active filter acts as a pure resistor of K ohms for the 5 th harmonic voltage and current. The impedance of the hybrid filter at the 5 th harmonic frequency, Z5 is given by
KrCω5j
1Lω5jZ fF
F5
0K The active filter presents a negative resistance to the externalCircuit, thus improving the Q of the filter.
FrK , 0V 5BUS 5ST
5S VLω5j
1I
JUNE 2002IEEE PESC-02101
CONTROL CIRCUIT
The control circuit consists of two parts; a circuit for extracting the 5th current harmonic component from the passive filter iF and a circuit that adjusts automatically the gain K. The reference voltage for the active filter
5FAF iKv
HARMONIC-EXTRACTING CIRCUIT
The extracting circuit detects the three-phase currents that flow into the passive filter using the AC current transformers and then the α-β coordinates are transformed to those on the d-g coordinates by using a unit vector (cos5ωt, sin5ωt) with a rotating frequency of five times as high as the line frequency.
JUNE 2002IEEE PESC-02102
SERIES ACTIVE FILTERS
By inserting a series Active Filter between the AC source and the load where the harmonic source is existing we can force the source current to become sinusoidal. The technique is based on a principle of harmonic isolation by controlling the output voltage of the series active filter.
Equivalent Circuit
JUNE 2002IEEE PESC-02103
- The series active filter exhibits high impedance to harmonic current and consequently blocks harmonic current flow from the load to the source.
SC KGIA.F. theof tageOutput vol V
KGZZV
KGZZIZI
LS
S
LS
LLS
(61)
(62)
= Equivalent transfer function of the detection circuit of harmonic current, including delay time of the control circuit.
G
, 0G1 1G h (63)
JUNE 2002IEEE PESC-02104
K = A gain in pu ohms
The voltage distortion of the input AC source is much smaller than the current distortion.
ShV
If hLZK and hLS ZZK
Then
ShLhLC VIZV
0IS
(64)
(65)
(66)
JUNE 2002IEEE PESC-02105
HYBRID SERIES AND SHUNT ACTIVE FILTER
At the Point of Common Coupling provides:
• Harmonic current isolation between the sub transmission and the distribution system (shunt A.F)
• Voltage regulation (series A.F)• Voltage flicker/imbalance compensation (series A.F)
JUNE 2002IEEE PESC-02106
SELECTION OF AF’ S FOR SPECIFIC APPLICATION CONSIDERATIONSAF Configuration with higher number of * is more preferred
Compensation for Specific Application
Active Filters
Active Series
Active Shunt
Hybrid of Active Series and Passive
Shunt
Hybrid of Active Shunt and Active
SeriesCurrent Harmonics ** *** *
Reactive Power *** ** *Load Balancing *Neutral Current ** *
Voltage Harmonics *** ** *Voltage Regulation *** * ** *Voltage Balancing *** ** *
Voltage Flicker ** *** *Voltage Sag&Dips *** * ** *
JUNE 2002IEEE PESC-02107
CONCLUSIONS
Solid State Power Control results in harmonic pollution above the tolerable limits. Harmonic Pollution increases industrial plant downtimes and power losses. Harmonic measurements should be made in industrial power systems in order (a) aid
in the design of capacitor or filter banks, (b) verify the design and installation of capacitor or filter banks, (c) verify compliance with utility harmonic distortion requirements, and (d) investigate suspected harmonic problems.
Computer software programs such as PSPICE and SIMULINK can be used in order to obtain the harmonic behavior of an industrial power plant.
The series LC passive filter with resonance frequency at 4.7 is the most popular filter. The disadvantages of the the tuned LC filter is its dynamic response because it
cannot predict the load requirements. The most popular Active Filter is the parallel or shunt type. Active Filter technology is slowly used in industrial plants with passive filters as a
hybrid filter. These filters can be used locally at the inputs of different nonlinear loads.
Active Filter Technology is well developed and many manufactures are fabricating Active filters with large capacities.
A large number of Active Filters configurations are available to compensate harmonic current, reactive power, neutral current, unbalance current, and harmonics.
The active filters can predict the load requirements and consequently they exhibit very good dynamic response.
LC tuned filters can be used at PCC and the same time active filters can be used locally at the input of nonlinear loads.
JUNE 2002IEEE PESC-02108
REFERENCES
RECOMMENDED PRACTICES ON HARMONIC TREATMENT[1] IEEE Std. 519-1992, ΄΄IEEE Recommended Practices and
Requirements for Harmonic Control in Electric Power Systems΄΄, 1993.
[2] IEC Sub-Committee 77B report, ΄΄Compatibility Levels in Industrial Plants for Low Frequency Conducted Disturbances΄΄, 1990.
[3] IEC Sub-Committee 77A report, ΄΄Disturbances Caused by Equipment Connected to the Public Low-Voltage Supply System Part 2 : Harmonics ΄΄, 1990 (Revised Draft of IEC 555-2).
[4] UK Engineering Recommendation G.5/3: ΄΄Limits for Harmonics in the UK Electricity Supply System΄΄, 1976.
[5] CIRGE WG 36.05 Report, ΄΄Equipment producing harmonics and Conditions Governing their Connection to the Mains power Supply΄΄, Electra, No. 123, March 1989, pp. 20-37.
[6] Australian Standards AS-2279.1-1991, ΄΄Disturbances in mains Supply Networks-Part 2: Limitation of Harmonics Caused by Industrial Equipment΄΄, 1991.
JUNE 2002IEEE PESC-02109
DEFINITIONS[7] J. Arriilaga, D.A. Bradley, and P.S. Bodger, ΄΄Power System
Harmonics΄΄,New York: Wiley, 1985.[8] N. Shepherd and P. Zand, ΄΄Energy flow and power factor in
nonsinusoidal circuits΄΄, Cambridge University Press, 1979.
EFFECTS OF HARMONICS[9] J.M. Bowyer, ΄΄Three-Part Harmony: System Interactions Leading
to a Divergent Resonant System΄΄, IEEE Trans. on Industry Applications, Vol. 31, No. 6, Nov/Dec 1995, pp. 1341-1349.
[10] R.D. Hondenson and P.J. Rose, ΄΄Harmonics: the Effects on power Quality and Transformers΄΄, IEEE Trans. on Industry Applications, Vol. 30, No.3, May/June 1994, pp. 528-532.
[11] J.S. Subjak and J. S. McQuilkin, ΄΄Harmonics-Causes, effects, Measurements and Analysis: An Update΄΄, IEEE Trans. on Industry Applications, Vol. 26, No. 6, Nov/Dec 1990, pp. 103-1042.
[12] P.Y. Keskar, ΄΄Specification of Variable Frequency Drive Systems to Meet the New IEEE 51 Standard΄΄, IEEE Trans. on Industry Applications, Vol.32, No.2, March/April 1996, pp. 393-402.
JUNE 2002IEEE PESC-02110
[13] T.S. Key, ΄΄Cost and Benefits of Harmonic Current Reduction for Switch-Mode Power Supplies in a Commercial Building΄΄, IEEE Trans. on Industry Applications, Vol. 32, No. 5, September/October 1996, pp. 1017-1025.
PASSIVE HARMONIC TREATMENT TECHNIQUES[14] M.F. McGranaghan and D.R. Mueller, ΄΄Designing Harmonic
Filters for Adjustable-Speed Drives to comply with IEEE-519 Harmonic limits΄΄, IEEE Trans. on Industry Applications, Vol. 35, No 2, March/April 1999, pp. 312-18.
[15] F.Z. Peng, ΄΄Harmonic Sources and filtering Approaches΄΄, IEEE Industry Applications Magazine, July/August 2001, pp. 18-25.
[16] J.K. Phipps, ΄΄A transfer Function Approach to Harmonic Filter Design΄΄, IEEE Industry Applications Magazine March/April 1997.
[17] S.M. Peeran, ΄΄Application, Design, and Specification of Harmonic Filters for Variable frequency Drives΄΄, IEEE Trans. on Industry Applications, Vol. 31, No. 4, July/August 1995, pp. 841-847.
JUNE 2002IEEE PESC-02111
[18] J. Lai and T.S. Key, ΄΄Effectiveness of Harmonic Mitigation Equipment for Commercial Office Buildings΄΄, IEEE Trans. on Industry Applications, Vol. 33, No. 4, July/August 1997, pp. 1104-1110.
[19] D.E. Rice,΄΄A Detailed Analysis of Six-Pulse Converter harmonic Currents΄΄, IEEE Trans. on Industry Applications, Vol. 30, No. 2, March/April 1994, pp. 294-304.
[20] R.L. Almonte and Ashley, ΄΄Harmonics at the Utility Industrial Interface: A Real World Example΄΄, IEEE Trans. on Industry Applications, Vol. 31, No. 6, November/December 1995, pp. 1419-1426.
[21] K. A. Puskarich, W.E. Reid and P. S. Hamer, ΄΄Harmonic Experiments with a large load-Commutated inverter drive΄΄, IEEE Trans. on Industry Applications, Vol. 37, No. 1, Jan/Feb. 2001, pp. 129-136.
[22] L.S. Czarnecki and O. T. Tan, ΄΄Evaluation and Reduction of Harmonic Distortion Caused by Solid State Voltage Controller of Induction Motors΄΄, IEEE Trans. on Energy Conversion, Vol. 9, No. 3, Sept. 1994, pp. 528-421.
JUNE 2002IEEE PESC-02112
[23] R.G. Ellis, ΄΄Harmonic Analysis of Industrial power Systems΄΄, IEEE Trans. on Industry Applications, Vol. 32, No. 2, March/April 1996, pp. 417-421.
[24] D. Adrews et al, ΄΄ Harmonic Measurements, Analysis and Power factor Correction in a Modern Steel Manufacturing Facility΄΄, IEEE Trans. on Industry Applications, Vol. 32, No. 3, May/June 196, pp. 617-624.
[25] D. Shipp and W. S. Vilcheck, ΄΄Power Quality and Line Considerations for Variable Speed AC Drivers΄΄, IEEE Trans. on Industry Applications, Vol.32, No.2, March/April 1996, pp. 403-410.
[26] J. A Bonner et al, ΄΄Selecting ratings for Capacitors and Reactors In Applications Involving Multiple Single-Tuned Filters΄΄, IEEE Trans. on Power Delivery, Vol. 10, No. 1, Jan. 1995, pp. 547-555.
[27] E. J. Currence, J.E Plizga, and H. N. Nelson, ΄΄Harmonic Resonance at a medium-sized Industrial Plant΄΄, IEEE Trans. on Industry Applications, Vol. 31, No. 4, July/August 1995, pp. 682-690.
JUNE 2002IEEE PESC-02113
[28] G. Lemieux, ΄΄Power system harmonic resonance. A document case΄΄, IEEE Trans. on Industry Applications, Vol. 26, No. 3, pp. 483-487, May/June 1990.
[29] D. D. Shipp, ΄΄Harmonic Analysis and Suppression for electrical systems΄΄, ΙEEE Trans. on Industry Applications Vol. 15, No. 5, Sept./Oct. 1979.
ACTIVE HARMONIC TREATMENT TECHNIQUES[30] H. Akagi, ΄΄New trends in active filters for Power conditioning΄΄,
IEEE Trans. on Industry Applications, Vol. 32, Nov/Dec. 1996, pp. 1312-1322.
[31] Bhim Singh et al, ΄΄A Review of Active Filters for Power Quality Improvement΄΄, IEEE Trans. on Industrial Electronics, Vol. 46, No. 5, Oct. 1999, pp. 960-971.
[32] F. Z. Peng, ΄΄Application Issues of Active Power Filters΄΄, IEEE Industry Applications Magazine, Sep./Oct. 1998, pp. 22-30.
[33] S. Bhattacharga et al, ΄΄Active Filter Systems Implementation΄΄, IEEE Industry Applications Magazine, Sep./Oct. 1998, pp. 47-63.
JUNE 2002IEEE PESC-02114
[34] S. Bhattacharya et al, ΄΄Hybrid Solutions for improving Passive Filter Performance in high power Applications΄΄, IEEE, Trans. on Industry Applications, Vol. 33, No. 3, May/June 1997, pp. 732-747.
[35] H. Akagi, ΄΄Control Strategy and site selection of a shunt active filter for damping of harmonies propagation in power distribution systems ΄΄, IEEE Trans. on Power Delivery, Vol. 12, Jan. 1997, pp.354-363.
[36] H. Fujita, T. Yamasaki, and H. Akagi, ΄΄A Hybrid Active Filter for Damping of Harmonic Resonance in Industrial Power Systems΄΄, IEEE Trans. on Power Electronics, Vol. 15, No. 2, March 2000, pp. 215-222.
[37] H. Akagi et al, ΄΄ Α shunt Active Filter Based on Voltage Detection for Harmonic Termination of a Radial power Distribution Line΄΄, IEEE Trans. on Industry Applications, Vol. 35, No. 3, May/June 1999, pp. 638-645.
[38] D. Rivas et al, ΄΄ A simple control scheme for hybrid Active Power Filter΄΄, IEE PESC-00, pp. 991-996.
JUNE 2002IEEE PESC-02115
[39] L. Zhou and Zi Li, ΄΄A Novel Active Power filter Based on the Least compensation Current Control Method΄΄, IEEE Trans. on Power Electronics, Vol. 15, No. 4, July 2000, pp. 655-659.
MODELING[40] IEEE Task Force on Modeling and Simulation, ΄΄Modeling and
Simulation of the propagation of harmonies in electric power networks, Part I: Concepts, models, and simulation techniques΄΄, IEEE Trans. on Power Delivery, Vol. 11, No. 1, Jan. 1996, pp. 452-465.
[41] IEEE Task Force on Modeling and Simulation ΄΄Modeling and Simulation of the propagation of harmonies in electric power networks, Part II: Sample systems and examples΄΄, IEEE Trans. on Power Delivery, Vol. 11, No. 1, Jan. 1996, pp. 466-474.
[42] W. Jewel et al, ΄΄Filtering Dispersed harmonic Sources on Distribution΄΄, IEEE Trans. on Power Delivery, Vol. 15, No. 3, July 2000, pp. 1045-1051.
[43] N.K. Madora and A. Kusko, ΄΄Computer-Aided Design and Analysis of Power-Harmonic Filters΄΄ IEEE Trans. on Industry Applications, Vol. 36, No. 2, March/April 2000, pp.604-613.