Compensation of harmonic currents utilizing AHC by kingsprime

Compensation of Harmonics utilizing AHC 2014
U2009/3015244 Page i
UNIVERSITY OF PORT HARCOURT
FACULTY OF ENGINEERING
DEPARTMENT OF ELECTRICAL/ELECTRONIC ENGINEERING
A
SEMINAR REPORT
ON
COMPENSATION OF HARMONIC CURRENTS
UTILIZING AHC
PRESENTED
BY
KALU KINGSLEY E
U2009/3015244
IN PARTIAL FULFILLMENT OF THE REQUIREMENT FOR THE
AWARD OF B.ENG IN ELECTRICAL/ELECTRONIC
ENGINEERING
JUNE, 2014

U2009/3015244 Page ii
DECLARATION
This is to declare that this seminar work was carried out by KALU KINGSLEY E
under the supervision of Engr. (Dr) B. O. Omijeh and Engr. Mrs. Bukola Akinwole
of the department of Electrical/Electronic Engineering University of Port Harcourt,
2013/2014 academic year; and that to the bestof my knowledge this seminar work
has not been carried out by any other student.
KALU KINGSLEY E ______________ _____________
U2009/3015296 Signature Date

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CERTIFICATION
This is to certify that this seminar work has been read and approved in partial
fulfillment of the requirements for the award of Bachelor of Engineering (B.Eng)
degree, Department of Electrical/Electronic Engineering.
Engr (Dr) B. O. Omijeh ____________ _________
(Seminar co-ordinator) Signature Date
Engr (Dr) RolandUhunmwangho ____________ _________
Head of Department Signature Date
__________________ ____________ _________
Seminar Supervisor Signature Date

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DEDICATION
This work is dedicated to God Almighty who has granted me the zeal and
inspiration to see this seminar research work to its completion.

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ACKNOWLEDGEMENT
I express my gratitude to the Seminar supervisors, Engr. (Dr) B. O. Omijeh
Engr. Mrs Bukola Akinwole who saw to it that this research work was a success
through their constructive and professional advice. I also appreciate the effort and
support of my parents Mr. & Mrs. Fred Chima Kalu for their encouragement.
I finally wish to show my gratitude to all the lecturers of the Department of
Electrical/Electronic Engineering for imparting knowledge to me throughout my
stay in school; and to all my friends and colleagues.

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ABSTRACT
In little more than ten years, electricity power quality has grown from obscurity to
a major issue. Electronic converters and power electronics gave birth to numerous
new applications, offering unmatched comfort, flexibility and efficiency to the
customers. However, their proliferation during the last decade is creating a
growing concern and generates more and more problems: not only these electronic
loads pollute the AC distribution system with harmonic currents, but they also
appearto be very sensitive to the voltage distortion. Then, electricity power quality
is becoming a major issue for utilities and for their customers, and both are
quickly adopting the philosophy and the limits proposed by the new International
Standards (519-1992 IEEE, 61000.3-2/4 IEC). Today, recent advances in power
electronic technology are providing an unprecedented capability for conditioning
and compensating harmonicdistortion generated by the non-linearloads. The case
study presented in this paper demonstrates the role of the power source, the load
and the AC distribution system as regards power quality. The benefit of harmonic
cancellation equipmentis clearly shown. Among the different technical solutions, a
shunt - current injection mode - active harmonic conditioner is evaluated, and
detailed site measurements are presented as confirmation of the unsurpassed
performances. This new innovative active harmonic conditioner appears to be the
easiest of use, the most flexible, the most efficient and cost effective one.

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TABLE OF CONTENT
COVER PAGE....................................................................................................i
DECLARATION................................................................................................ii
CERTIFICATION.............................................................................................iii
DEDICATION ..................................................................................................iv
ACKNOWLEDGEMENT...................................................................................v
ABSTRACT......................................................................................................vi
TABLE OF CONTENT ....................................................................................vii
LIST OF FIGURES ...........................................................................................ix
LIST OF TABLES..............................................................................................x
CHAPTER ONE.................................................................................................1
INTRODUCTION..............................................................................................1
1.1 BACKGROUND OF STUDY .......................................................................1
1.2 STATEMENT OF THE PROBLEM..............................................................1
1.3 OBJECTIVE OF THE STUDY......................................................................1
1.4 SCOPE OF STUDY......................................................................................2
1.5 RESEARCH METHODOLOGY...................................................................2
1.6 SIGNIFICANCE OF STUDY........................................................................2
CHAPTER TWO................................................................................................3
LITERATURE REVIEW....................................................................................3
2.1 THEORETICAL FRAMEWORK...............................................................3
2.2 OVERSIZING OR DERATING OF THE INSTALLATION .......................3
2.3 SPECIALLY CONNECTED TRANSFORMERS .......................................3
2.4 SERIES REACTORS.................................................................................3
2.5 TUNED PASSIVE FILTER .......................................................................4
2.6 TOPOLOGIES OF ACTIVE HARMONIC CONDITIONERS ....................4
2.6.1 Series Conditioners...........................................................................................................4
2.6.2 Parallel Conditioners ........................................................................................................5

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2.6.3 Hybrid Conditioners..........................................................................................................5
2.7 PARALLEL ACTIVE HARMONIC CONDITIONER: SYSTEM
DESCRIPTION..................................................................................................6
2.8 Recording of Real Current For Non-Linear Load.........................................7
CHAPTER 3.....................................................................................................11
METHODOLOGY ...........................................................................................11
3.1 SYSTEM MODEL...................................................................................11
CHAPTER 4.....................................................................................................13
RESULT AND DISCUSSION..........................................................................13
4.1: PRESENTATION OF DATA...................................................................13
4.2 DATA ANALYSIS..................................................................................14
4.3 SITE RESULTS.......................................................................................15
CHAPTER FIVE..............................................................................................21
5.1 SUMMARY ............................................................................................21
5.2 CONCLUSION........................................................................................21
REFERENCES.................................................................................................23

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LIST OF FIGURES
Fig 2.1: Connection of an Innovative AHC in series 5
Fig 2.2: Connection of an Innovative AHC in parallel 5
Fig 2.3: Connection of an Innovative AHC in Hybrid Format 6
Fig 2.4: - Active harmonic compensation principle 6
Fig 2.5: - I load = load current (Graetz bridge), I rms = 82 A THDI = 41% 7
Fig 2.6: I conditioner, I rms = 30 A 8
Fig 2.7: I source= source current, I rms = 75 A, THDI = 3.6% 8
Fig 2.8: Schematic diagram of AHC controlled non linear load 9
Fig 3.1: Schematic single line diagram of the installation 11
Fig 4.1: Points of connection of the active conditioners 16
Fig 4.3: Voltage waveform without active conditioner 17
Fig 4.3: Voltage waveform with active conditioner 17
Fig 4.4: Line (load) current waveform without active conditioner 18
Fig 4.5: Line (source) current waveform with active conditioner 18
Fig 4.6: Line (load) current spectrum (% of H1) without active conditioner 19
Fig 4.7: Line (source) current spectrum (% of H1) with active conditioner 19

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LIST OF TABLES
Table 4.1: Voltage measures onF and G 13
Table 4.2: Detailedmeasures onFeederG 13
Table 4.3: Advantages and Disadvantages ofthe Different Methods of
Compensating Harmonics 14
Table 4.4: ComparisonbetweenAHC and tuned passive filter 20

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CHAPTER ONE
INTRODUCTION
1.1 BACKGROUNDOF STUDY
In industrial low and medium voltage mains, passive filters and PFC capacitors
have traditionally been used to improve the supply quality. However, they cannot
be rated only for the loads being compensated. They are affected by harmonic
currents from other non-linear loads or by harmonics from the power system.
Compared with passive element compensators, an active harmonic compensator
(AHC) can be used to improve the supply quality without worrying about all the
problems associated with applying passive elements.
1.2 STATEMENTOF THE PROBLEM
Today, the situation on low-voltage AC systems has become a serious concern.
The quality of electrical power in commercial and industrial installations is
undeniably decreasing. In addition to external disturbances, such as outages, sags
and spikes due to switching and atmospheric phenomena, there are inherent,
internal causes specific to each site and resulting from the combined use of linear
and non-linear loads. Untimely tripping of protection devices, harmonic overloads,
high levels of voltage and current distortion, temperature rise in conductors and
generators all contribute to reducing the quality and the reliability of a low-voltage
AC system.
1.3 OBJECTIVE OF THE STUDY
The objective of this research work is to see to it that Harmonic currents are
reduced or compensated using Innovative Active Harmonic Conditioner. The first
preliminary requirement thus concerns the power network environment:
implementation of an harmonic compensation technique requires knowledge of the
entire power network (sources, loads, lines, capacitors) and not just a fragmented
view limited merely to the zone concerned.

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1.4 SCOPE OF STUDY
This survey provides a comprehensive discussion of models, algorithms, analysis
and methodologies in this vast and growing literature. It starts with the traditional
methods used in compensating harmonic currents and also the use of Innovative
Active Harmonic Conditioner. The above disturbances are well understood and
directly related to the proliferation of loads consuming non-sinusoidal current,
referred to as "non-linear loads".
1.5 RESEARCH METHODOLOGY
Throughout the survey, I highlight the use of mathematical language and tools in
the study of Harmonics, including nonlinear loads, signals and systems, signal
analyzer, and oscilloscope.
1.6 SIGNIFICANCE OFSTUDY
Compensation of Harmonic currents utilizing AHC is a key degree of freedom for
the reduction of harmonic currents in nonlinear loads. However, the remarkable
progress made by power electronic devices in the recent years, fast IGBT's, makes
it possible to design self-adaptable harmonic suppressors called active harmonic
conditioner, known also as active filters. Active harmonic conditioners are proving
to be viable option for controlling harmonic distortion levels in many applications.

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CHAPTER TWO
LITERATURE REVIEW
2.1 THEORETICALFRAMEWORK
Today, a various panel of harmonic mitigation equipment or solutions is proposed,
but all present some disadvantages. These solutions are listed here after.
2.2 OVERSIZINGOR DERATINGOFTHE INSTALLATION
This solution does not attempt to eliminate the harmonic currents flowing in the
electrical installation, but rather to "make do" by avoiding the consequences. When
designing a new installation, the idea is to oversize all installation elements likely
to transmit harmonic currents, namely the transformers, cables, circuit breakers,
engine generator sets and the distribution switchboards. The most widely
implemented solution is oversizing of the neutral conductor. The result is a major
increase in cost. In existing installations, the most common solution is to derate the
electrical distribution equipment subjected to the harmonic currents. The
consequence is an installation that cannot be used to its full potential.
2.3 SPECIALLYCONNECTEDTRANSFORMERS
This solution inhibits propagation of third-order harmonic currents and their
multiples. It is a centralized solution for a set of single phase loads. However, it
produces no effect on harmonic orders that are not multiples of three (H5, H7) On
the contrary, this solution limits the available power from the source and increases
line impedance. The consequence is an increase in the voltage distortion due to the
other harmonic orders.
2.4 SERIES REACTORS
This solution, used for variable speed drives and three phase rectifiers, consists in
connecting a reactor in series upstream of a non-linear-load. A reactor is not
expensive, but has limited effectiveness. One must be installed for each non-linear
load. Current distortion is divided by a factor of approximately two.

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2.5 TUNEDPASSIVE FILTER
The idea is to "trap" the harmonic currents in L/C circuits tuned to the harmonic
orders requiring filtering. A filter therefore comprises a series of "stages", each
corresponding to an harmonic order. Orders 5 and 7 are the most commonly
filtered. A filter may be installed for one load or a set of loads. Its design requires
in-depth study of the AC system and collaboration with a consulting engineer.
Sizing depends on the harmonic spectrum of the load and the impedance of the
power source. Rating also must be co-ordinate with reactive power requirements of
the loads, and it is often difficult to design the filters to avoid leading power factor
operation for some load conditions. This solution is moderately effective and its
design depends entirely on the given power source and the loads, i.e. it is not
flexible and is virtually impossible to upgrade. Its application may create system
resonances which are dependent on specific system conditions. Note: when
appropriately designed, this type of filter may also be used to eliminate harmonic
distortion already present on the electrical network of the power distributor,
provided a significant overrating for harmonic absorption from the power system.
2.6 TOPOLOGIES OF ACTIVE HARMONIC CONDITIONERS
The idea of active harmonic conditioners, also named active filters, is relatively
old; however the lack of an effective technique at a competitive price slowed its
development for a number of years. Today, the wide-spread use of IGBT
components, mastery of their implementation and the availability of new digital
signal processing (DSP) techniques are paving the way to a much brighter future
for the active harmonic conditioner. The active harmonic conditioner concept uses
power electronics to produce harmonic components which cancel the harmonic
components of the non-linear loads. A number of different topologies are being
proposed, whom some of them are described here after. Within each topology there
are issues of required components ratings and method of rating the overall
conditioner for the loads to be compensated.
2.6.1 Series Conditioners
This type of conditioner, connected in series on the distribution network,
compensates both the harmonic currents generated by the load and the voltage
distortion already present on the AC system. This solution is technically similar to
a line conditioner and must be sized for the total load rating.

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2.6.2 Parallel Conditioners
Also called shunt conditioners they are connected in parallel with the AC line and
need to be sized only for the harmonic power (harmonic current) drawn by the
nonlinear load(s). The parallel topology selected for SineWave is in no way
dependent on the load or electrical AC system characteristics. It is described in
detail in the section 4
2.6.3 Hybrid Conditioners
This solution, combining an active conditioner and a passive filter, may be either
of the series or parallel type. In certain cases, it may be a cost-effective solution.
The passive filter carries out basic filtering (5th order, for example) and the active
conditioner, through its precise and dynamic technique covers the other orders.
Fig 2.1: Connectionof an Innovative Active Harmonic
Conditionerin series
Conditionerin parallel

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2.7 PARALLEL ACTIVE HARMONIC CONDITIONER:SYSTEM
DESCRIPTION
Operating Principle
The active conditioner is connected in-parallel with the AC line, and constantly
injects currents that precisely correspond to the harmonic components drawn by
the load. The result is that the current supplied by the power source remains
sinusoidal.
I load = I fundamental + I harmonic
I conditioner = I harmonic
I load = I source + I conditioner
The normal power source provides the fundamental current, and the harmonic
currents required by the load are supplied by the active harmonic conditioner
(AHC). The entire low-frequency harmonic spectrum (H2 to H25) is covered. If
the harmonic currents drawn by the load are greater than the rating of the active
Conditionerin Hybrid Format
Fig 2.4:- Active harmonic compensationprinciple

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conditioner, the conditioner automatically limits its output current to its rated one.
Easy to implement, an active conditioner may be installed at any point on a low
voltage. AC system to compensate the power drawn by one or several non-linear
loads, thus avoiding the circulation of harmonic currents throughout the low-
voltage AC system.
2.8 Recording ofReal Current For Non-Linear Load
Fig 2.5: - I load = load current (Graetz bridge), I rms = 82 A THDI =
41%
Fig 2.6:I conditioner, I rms = 30 A

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Detailed Description
Fig 2.7:I source = source current, I rms = 75 A, THDI = 3.6%
Fig 2.8:Schematic diagram of AHC controlled non linear load

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The active harmonic conditioner is made up of the following elements:
 FU1: ultra fast protection fuse;
 R1 and contactor K1: precharge system for chemical capacitors C2 & C3;
 Lf & Cf: filter intended to attenuate the effects of chopping;
 L1, DC/ac converter, C2 and C3: PWM inverter leg;
 CT2: sensors for inverter currents;
 control electronics;
 CT1: external sensor for current drawn by the load.
The converter comprises a three phase IGBT current inverter leg that chops at an
average switching frequency of 16 kHz, chemical capacitor C2 and C3 providing
back up power. The conditioner draws from the power source the active power
required for its operation.
The control electronics comprise:
 An harmonic-extraction module which generates a regulation set point
proportional to the harmonic components of the load current;
 A module that regulates inverter currents and the DC voltage;
 A monitoring module which ensures filter protection in the event of overload
or an internal fault;
 A control module which generates the control signals necessary for inverter
operation.
To enhance the compensation capacity at a given point in the installation, it is
possible to connect active conditioners in parallel.
Points of Connection of the Active Conditioner
The active conditioner may be installed at different points on AC distribution
systems:
 Close to the loads generating high level of harmonics to ensure local
compensation of harmonic currents;
 Partial compensation of harmonic currents;
 Centrally, at the PCC level, for global compensation of harmonic currents.
Ideally, compensation of harmonics should take place at their point of origin.
A number of cost and technical criteria are used to make the best selection.

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Mains advantages of the local compensation:
 Avoid dissemination of the harmonic currents in the electrical installation;
 Reduce Joule-effect losses in the cables, and load on the main transformer;
 Reduces size of the cables required in new installations;
 Means installation can meet applicable harmonic standards.

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CHAPTER 3
METHODOLOGY
3.1 SYSTEM MODEL
Case study: ELF AQUITAINE
Description of the l’installation
Fig 3.1:Schematic single line diagram of the installation

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A centralized UPS system supplies two buildings, each one of 4 floors. This UPS
system as a dual feed supply, either the utility power or a generator set. The
distance from the UPS system to the building ranges from 35 m to 150 m. In each
building, distribution is provided through two main feeders; on each floor, a storey
distribution board supplies all the information technology equipment: PC,
workstations servers. AC distribution system is 4 wires (three phases + neutral),
with the neutral conductor sized at 50% of the phase conductor.
Problems Experienced By Elf and Site Audit
Elf experienced several types of disturbances:
 Functional problems in computers;
 Breakdown and failure of very sensitive IT equipment, as well as damages;
 Temperature rise in the neutral conductor, and excessive heat losses;
 Downstream the storey distribution board, voltage distortion non compatible
with the standard compatibility levels, and the computer specifications.

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CHAPTER 4
RESULT AND DISCUSSION
4.1: PRESENTATION OFDATA
Most of the loads is single phase and non-linear. At the basement level, measures
demonstrate a total current harmonic distortion of 86%, and a current harmonic
distortion of 69% for the 3rd order. Then, the circulation of these harmonic
currents in the long cables generates a high voltage distortion at the end of the
cables, where the critical IT equipment are connected. At the point of use, the
voltage distortion is double versus the one at the UPS output: 8.3% vs. 4.2%.
When operating on the generator set and on the static by-pass of the UPS system,
during maintenance or test, voltage distortion up to 15% was noticed. Also, the
neutral current is 140% of the phase current, creating over temperature in the
neutral conductor, and neutral to earth voltage as high as 8 V. The hereafter table
summarizes the voltage measures focused on the feeders F and G:
THDU
phase / neutral
Voltage
neutral / earth
UPS output 4,2% 0 V
feeder G - 4th floor 8% 8,3 V
feeder G - comp. suite 8,3% -
feeder F - 4th floor 5,7% 4 V
feeder C - 4th floor 6% 4,4 V
The following table gives the detailed measures of feeder G, at the basement level:
Total I rms 66 a
Crest factor 2,3
Thdi 86%
Power Factor 0,72
I harmonic rms 42 a
Thdu 7,7%
Neutral / Earth Voltage 7,9 v
I neutral rms 108 a
Table 4.1: Voltage measures onF and G
Table 4.2: Detailedmeasures onFeederG

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4.2 DATA ANALYSIS
Of course, the solution implemented has to eliminate the disturbances experienced
by Elf, but also must guaranty a voltage distortion lower than 5% at the point of
use, i.e. at the input of the computer equipment. Several solutions were proposed
and compared by the consultant who carried out the site audit.
They are listed here after:
 Installation of double wound transformer on each feeder;
 Renewal of the overall distribution, changing also the earthing system;
 Increase of the size of the neutral conductor;
 Installation of active harmonic conditioner(s) at the basement level of each
feeder.
The advantages and disadvantages of each solutions were evaluated carefully, both
on the economical and technical viewpoints. The analysis is summarized in the
following table:
Advantages Disadvantages
Transformer 1. Elimination of voltage
drops due to harmonic
current circulation;
2. Elimination of third
harmonic.
1. high price: derating of
transformer;
2. influence of inrush
current on
UPS.
Renewal 1. Ease of implementation 1. New earthing system
not recommended;
difficulty to master the
circulating currents in the
AC system;
2. No reduction of the
voltage distortion.
Increase of neutral
conductor size
1. No change of the
earthing system and
mastering of circulating
neutral current.
1. No reduction of the
voltage distortion;
2. Slight reduction of the
voltage drop in the neutral
conductor;

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3. A lot of cabling works.
Active harmonic
Conditioner
1. Competitive price;
2. Reduction of the
voltage distortion;
3. Reduction of the
neutral current;
4. Significant decrease of
the rms current.
Need to install 2
conditioners on the same
feeder (F & G).
The active harmonic conditioner solution was selected as it was the most
competitive, and the only one to 100% meet the customer requirements.
Final Solution
To get the best benefit for the customer, one active conditioner will be connected
to each feeder, at the basement level. Forfeeders F & G, whose distance from UPS
system is very long, one additional conditioner will be installed at the 2nd floor
level. Then, harmonic distortion at 4th floor will be as low as possible.
4.3 SITE RESULTS
This section describes the waveform and the characteristics of the power of feeder
G after connection of one 30 A active harmonic conditioner at the basement level.
This is the first step of the implementation of the solution. The measures and
results presented here after gives a good idea of the improvement thanks to the
active harmonic conditioner.
Table 4.3: Advantages and Disadvantages of the Different Methods of
Compensating Harmonics

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Fig 4.1:Points of connectionof the active conditioners

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Voltage waveform at 4th floor
Conclusion:
The total voltage harmonic distortion is reduced from 7.7% to 4.6%, and the
neutral to earth voltage from 7.9 V to 4.4 V.
Fig 4.2
Fig 4.3

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Conclusion:
The benefit of the active conditioner is clearly demonstrated on the current.
 Reduction of 29% of the rms current (from 66 to 47 A);
 Crest factor decreased to 1.92 after compensation (vs 2.3);
 Improvement of the power factor from 0.72 to 0.92.
Fig 4.4
Fig 4.5

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Conclusion:
The graphs show the impact of the Sine Wave active conditioner on the harmonic
currents. Due to the high harmonic current, the active conditioner operates in
limitation mode and compensates partly for the harmonic currents.
 THDI attenuation of 3: 86% down to 28%;
 Reduction of 65% of the neutral current: 108 A down to 38 A;
Fig 4.7
Fig 4.6

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 Reduction by 70% of the harmonic rms current: 42 A down to 13 A.
Comparison between active harmonic conditioner and tuned passive filter
Passive filter Active harmonic
conditioner
Harmonic-current control Requires a filter for each
Frequency (bulky)
Simultaneously monitors
Several frequencies
Influence of a frequency
Variation
Reduced effectiveness No effect
Influence of a
modification in the
impedance
Risk of resonance No effect
Influence of an increase in
Current
Risk of overload and
damage
No risk of overload, but
less effective
Added equipment (load) In certain cases, requires
modifications to the filter
No problem if
i_conditioner >
I_load_harmonics
Harmonic control by
order
Very difficult Possible via parameters
Modification in the
fundamental Frequency
Cannot be modified Possible via
reconfiguration
Dimensions Large Small
Weight High Low
Table 4.4: Comparison between active harmonic conditioner and
tuned passive filter

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CHAPTER FIVE
5.1 SUMMARY
The profusion of non-linear loads makes harmonic distortion of power networks a
phenomenon of increasing amplitude, the effects of which cannot be ignored since
almost all the power network components are in practice affected. Up to now the
most popular solution was passive filtering. However, an attractive alternative to
this complex and non risk-free solution is now commercially available in the form
of active harmonic conditioners. These devices use a structure of the static power
converter type. Consequently, semiconductor progress means that converters,
which are normally harmonic disturbers, now form efficient, self-adaptive
harmonic compensation devices. The easy to use, self-adaptive “shunt- type”
active harmonic conditioner, which requires virtually no preliminary studies prior
to use, is the ideal solution for harmonic compensation on a non-linear load or LV
distribution switchboard. However it does not necessarily replace passive filters
with which it can be combined advantageously in some cases.
5.2 CONCLUSION
5.2.1 A 30 Amp "shunt topology" active harmonic conditioner was
successfully developed, and is being marketed.
5.2.2 All the installations equipped with the Sine Wave active harmonic
conditioner demonstrate excellent performances in a wide range of applications.
5.2.3 Regarding computer type loads, the presented case study is a clear
demonstration of the high level of harmonic current compensation that the
conditioner can achieve.
5.2.4 As a consequence of the compensation of the 3rd harmonic current,
the active conditioner also reduces the neutral (harmonic) current.
5.2.5 These results gives very good reasons to expect in a very short time
the development of active harmonic conditioner to compensate harmonic distortion
in the commercial applications, but also in the industrial sector.
5.3 RECOMMENDATIONS
Electricity is today regarded as a product, especially in Europe. The EN 50160
standard defines the main characteristics at the customer’s point of common
coupling for a low voltage public supply network, and in particular the harmonic

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voltage levels. These are the levels of compatibility in terms of electromagnetic
compatibility. In addition to this European standard, the maximum levels of the
various harmonic orders are defined in IEC 61000 and the recommendations are
thus:
 For low voltage public supply networks: IEC 61000-2-2 and CIGRE
recommendations.
 For medium and high voltage public supply networks: IEC draft standard
for medium voltage and CIGRErecommendations.
 For low voltage and medium voltage industrial installations: IEC 61000-
2-4.
By way of illustration, the table taken from this standard gives the harmonic levels
of compatibility in three standard situations (classes).

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Compensation of harmonic currents utilizing AHC by kingsprime

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Compensation of harmonic currents utilizing AHC by kingsprime