This document discusses the various sources of harmonics in power systems. It defines harmonics as multiples of the fundamental power system frequency that distort voltages and currents. The main sources described include transformers, rotating machines, power converters such as large and medium power converters and variable frequency drives, fluorescent lamps, and arcing devices like electric arc furnaces. Power converters are identified as the most widespread source due to their use of electronic switching to rectify and vary AC power frequencies and voltages. The impacts of increasing non-linear loads on power quality are also noted.
The project focuses on the harmonic analysis of transformer during the switching transient period. Measuring fundamental and second harmonics of differential current, an algorithm based on the Discrete Fourier Transform and an amplitude estimator are used to simulate and list various harmonic components of current and flux. Generalized functions for describing the relationships between resultant flux and harmonic components are derived. This is important to find these relations for further use in detecting non-linearity and elimination of harmonic components.
The transformers are an integral part of the power system. In transformers, the main consequence of harmonic
currents is an increase in losses, mainly in windings, because of the deformation of the leakage fields. Higher losses mean that
more heat is generated in the transformer so that the operating temperature increases, leading to deterioration of the insulation
and a potential reduction in lifetime. Due to the non-linear loads, the transformers are much affected by the distorted currents
and supply voltages which largely reduce its efficiency due to overheating. Nonlinear loads cause harmonics to flow in the power
lines which can overload wiring and many desktops, personal computers present nonlinear loads to the AC supply because of
their power supplies design (capacitor input power supply). In power transformers, the main consequence of harmonic currents
is an increase in losses, mainly in windings, because of the deformation of the leakage fields. Higher losses mean that more heat
is generated in the transformer so that the operating temperature increases, leading to deterioration of the insulation and a
potential reduction in lifetime. As a result, it is necessary to reduce the maximum power load on the transformer, a practice
referred to as de-rating, or to take extra care in the design of the transformer to reduce these losses. To estimate the de-rating of
the transformer, the load’s K Factor may be used. Thus analysing this problem and reducing the losses of the transformer has
become a major area of research in today’s scenario. This report includes the effects of non-sinusoidal supply voltage on the
transformer excitation current and the core losses which includes eddy current and hysteresis losses.
Definition of power Quality, power quality terminology, power quality issues, Susceptibility Criteria, Responsibility of supplier and users of elect power, Standards.
The project focuses on the harmonic analysis of transformer during the switching transient period. Measuring fundamental and second harmonics of differential current, an algorithm based on the Discrete Fourier Transform and an amplitude estimator are used to simulate and list various harmonic components of current and flux. Generalized functions for describing the relationships between resultant flux and harmonic components are derived. This is important to find these relations for further use in detecting non-linearity and elimination of harmonic components.
The transformers are an integral part of the power system. In transformers, the main consequence of harmonic
currents is an increase in losses, mainly in windings, because of the deformation of the leakage fields. Higher losses mean that
more heat is generated in the transformer so that the operating temperature increases, leading to deterioration of the insulation
and a potential reduction in lifetime. Due to the non-linear loads, the transformers are much affected by the distorted currents
and supply voltages which largely reduce its efficiency due to overheating. Nonlinear loads cause harmonics to flow in the power
lines which can overload wiring and many desktops, personal computers present nonlinear loads to the AC supply because of
their power supplies design (capacitor input power supply). In power transformers, the main consequence of harmonic currents
is an increase in losses, mainly in windings, because of the deformation of the leakage fields. Higher losses mean that more heat
is generated in the transformer so that the operating temperature increases, leading to deterioration of the insulation and a
potential reduction in lifetime. As a result, it is necessary to reduce the maximum power load on the transformer, a practice
referred to as de-rating, or to take extra care in the design of the transformer to reduce these losses. To estimate the de-rating of
the transformer, the load’s K Factor may be used. Thus analysing this problem and reducing the losses of the transformer has
become a major area of research in today’s scenario. This report includes the effects of non-sinusoidal supply voltage on the
transformer excitation current and the core losses which includes eddy current and hysteresis losses.
Definition of power Quality, power quality terminology, power quality issues, Susceptibility Criteria, Responsibility of supplier and users of elect power, Standards.
This presentation gives detailed information about power quality i.e. how poor power quality is caused? what are the parameters on which we measure power quality? how can we solve the problem of poor power quality? this presentation will give you all the answers.
- This study presents the evaluation and
parametric modeling of voltage drop in power distribution
networks. The issues of voltage drop in power distribution
networks has become a recurrent decimal in power distribution
sector, which has avert effects on electronics appliances, which
result in incessant fire out in offices and residential buildings.
Benin Electricity Distribution Company (BEDC) injection
substation both in Ekpoma and Benin City were investigated for
a period of three months (1ST February to 30TH April, 2014). Data
were obtained from both technical staff and prospect power
consumers in that area with the help of questionnaires. Causes of
various voltages drop in six power distribution injection
substation sectors were obtained from both residential and
industrial areas with the corresponding time (hour).
Mathematical modeling was developed for voltage drop. Firstly,
it was observed from BEDC power system that there were no
technical reports recorded on voltage drop cases and due to lack
of technical record, this aspect has witnessed a low response time
from the technical sector to eradicate. It is observed that voltage
drop occurrences and response time before repairs has similar
exponential pattern, which justify the neglect of voltage drop.
Voltage drop in both residential and industrial areas were
considered
Identification and minimization of HarmonicsMayur Hiwale
In this ppt we will get to know about basic idea of harmonics, types of harmonics , measuring devices and minimizing techniques and also covering the there impact on power system and impact on consumer equipment's.
Voltage Flicker Analysis and its Mitigation by STATCOM for Power Quality Impr...IJMTST Journal
Voltage flicker is considered as one of the most severe power quality problems (especially in loads like electrical arc furnaces) and much attention has been paid to it lately. The reason for this disturbance is mainly due to the large nonlinear loads such as electric arc furnaces. Due to the latest achievements in the semiconductors industry and consequently the emergence of the compensators based on voltage source converters, FACTS devices have been gradually noticed to be used for voltage flicker compensation. This paper covers the contrasting approaches; dealing with the voltage flicker mitigation in three stages and assessing the related results in details. Initially, the voltage flicker mitigation, using FCTCR (Fixed Capacitor Thyristor Controlled Reactor), was simulated. Secondly, the compensation for the Static Synchronous Compensator (STATCOM) has been performed. The voltage flicker compensation by 8– pulse as well as 12 – pulse static synchronous compensator (STATCOM) has been performed. This paper deals with the voltage flicker mitigation and reduction in total harmonic distortion (THD) and compared the results in detail. The obtained results show that STATCOM is very efficient and effective for the compensation and mitigation of voltage flicker and harmonics all the simulation results have been performed on the MATLAB Software.
ANALYSIS OF SOLID STATE TRANSFORMER WITH PERMANENT MAGNET SYNCHRONOUS GENERATOREditor IJMTER
In recent years the complexity of the grid systems has grown due to the increased
penetration of renewable energy and distributed generation sources. The increased complexity
requires new methods to quickly manage the changing sources and loads. This research focuses
on one of such technologies, called the SST. A SST uses power electronic devices to achieve
voltage conversion from one level to another. Several SST topologies have been proposed by
different research groups, without a clear idea on which is most suited for grid applications.To
ensure a proper choice of topology,a separate literature review is presented in this paper. The final
choice of topology is extremely modular. In this, conventional dc-dc converter of solid state transformer is replaced by SEPIC converter and the analysis is done using PMSG.
The summary of the research, first is to introduce the harmonics in power system, by explains the meanings of the harmonic, causes and sources. Then the effects of the harmonics in power system. Second to analysis the harmonics during the fourier analysis, how we can calculate and analysis the harmonics. Third, the experiment part which is the results form lab work to inform the harmonics effects in power system. Fourth, which is explain how to eliminate the harmonics in power system, then the finally the conculation which is try to concluote the all parts of the research.
This is the third slide set in series of Introductory course on Power Quality for undergraduates. This deals with transient over-voltages, Ferro Resonance, Over Voltage Protection, Switching Transients, Shielding
Here This is the different between Smart and digital Transformer.And the definition of Smart transformer that may helpful for Student for nice presentation.
This presentation gives detailed information about power quality i.e. how poor power quality is caused? what are the parameters on which we measure power quality? how can we solve the problem of poor power quality? this presentation will give you all the answers.
- This study presents the evaluation and
parametric modeling of voltage drop in power distribution
networks. The issues of voltage drop in power distribution
networks has become a recurrent decimal in power distribution
sector, which has avert effects on electronics appliances, which
result in incessant fire out in offices and residential buildings.
Benin Electricity Distribution Company (BEDC) injection
substation both in Ekpoma and Benin City were investigated for
a period of three months (1ST February to 30TH April, 2014). Data
were obtained from both technical staff and prospect power
consumers in that area with the help of questionnaires. Causes of
various voltages drop in six power distribution injection
substation sectors were obtained from both residential and
industrial areas with the corresponding time (hour).
Mathematical modeling was developed for voltage drop. Firstly,
it was observed from BEDC power system that there were no
technical reports recorded on voltage drop cases and due to lack
of technical record, this aspect has witnessed a low response time
from the technical sector to eradicate. It is observed that voltage
drop occurrences and response time before repairs has similar
exponential pattern, which justify the neglect of voltage drop.
Voltage drop in both residential and industrial areas were
considered
Identification and minimization of HarmonicsMayur Hiwale
In this ppt we will get to know about basic idea of harmonics, types of harmonics , measuring devices and minimizing techniques and also covering the there impact on power system and impact on consumer equipment's.
Voltage Flicker Analysis and its Mitigation by STATCOM for Power Quality Impr...IJMTST Journal
Voltage flicker is considered as one of the most severe power quality problems (especially in loads like electrical arc furnaces) and much attention has been paid to it lately. The reason for this disturbance is mainly due to the large nonlinear loads such as electric arc furnaces. Due to the latest achievements in the semiconductors industry and consequently the emergence of the compensators based on voltage source converters, FACTS devices have been gradually noticed to be used for voltage flicker compensation. This paper covers the contrasting approaches; dealing with the voltage flicker mitigation in three stages and assessing the related results in details. Initially, the voltage flicker mitigation, using FCTCR (Fixed Capacitor Thyristor Controlled Reactor), was simulated. Secondly, the compensation for the Static Synchronous Compensator (STATCOM) has been performed. The voltage flicker compensation by 8– pulse as well as 12 – pulse static synchronous compensator (STATCOM) has been performed. This paper deals with the voltage flicker mitigation and reduction in total harmonic distortion (THD) and compared the results in detail. The obtained results show that STATCOM is very efficient and effective for the compensation and mitigation of voltage flicker and harmonics all the simulation results have been performed on the MATLAB Software.
ANALYSIS OF SOLID STATE TRANSFORMER WITH PERMANENT MAGNET SYNCHRONOUS GENERATOREditor IJMTER
In recent years the complexity of the grid systems has grown due to the increased
penetration of renewable energy and distributed generation sources. The increased complexity
requires new methods to quickly manage the changing sources and loads. This research focuses
on one of such technologies, called the SST. A SST uses power electronic devices to achieve
voltage conversion from one level to another. Several SST topologies have been proposed by
different research groups, without a clear idea on which is most suited for grid applications.To
ensure a proper choice of topology,a separate literature review is presented in this paper. The final
choice of topology is extremely modular. In this, conventional dc-dc converter of solid state transformer is replaced by SEPIC converter and the analysis is done using PMSG.
The summary of the research, first is to introduce the harmonics in power system, by explains the meanings of the harmonic, causes and sources. Then the effects of the harmonics in power system. Second to analysis the harmonics during the fourier analysis, how we can calculate and analysis the harmonics. Third, the experiment part which is the results form lab work to inform the harmonics effects in power system. Fourth, which is explain how to eliminate the harmonics in power system, then the finally the conculation which is try to concluote the all parts of the research.
This is the third slide set in series of Introductory course on Power Quality for undergraduates. This deals with transient over-voltages, Ferro Resonance, Over Voltage Protection, Switching Transients, Shielding
Here This is the different between Smart and digital Transformer.And the definition of Smart transformer that may helpful for Student for nice presentation.
IOSR Journal of Pharmacy and Biological Sciences(IOSR-JPBS) is an open access international journal that provides rapid publication (within a month) of articles in all areas of Pharmacy and Biological Science. The journal welcomes publications of high quality papers on theoretical developments and practical applications in Pharmacy and Biological Science. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
IOSR Journal of Pharmacy and Biological Sciences(IOSR-JPBS) is an open access international journal that provides rapid publication (within a month) of articles in all areas of Pharmacy and Biological Science. The journal welcomes publications of high quality papers on theoretical developments and practical applications in Pharmacy and Biological Science. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
A Novel Approach of Harmonic Reduction with Transformer Connected 3-Phase Mul...IJMER
This paper proposes a multilevel inverter arrangement employing a series connected transformer to suppress 5th,7th,11th &13th order harmonics(generated by non-linear loads).In the proposed scheme sinusoidal pwm signal generation technique is used for three phase multilevel VSI in conjunction with series connected transformer .The proposed model eliminates the need of output filter inductor. With this control strategy harmonic components of output voltage and switching losses can be
minimized considerably. Simulation results verify the proposed concept and indicates that the transformer is capable of reducing the harmonics in the line
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
A Voltage Controlled Dstatcom for Power Quality Improvementiosrjce
Due to increasing complexity in the power system, voltage sag is becoming one of the most significant
power quality problems. Voltage sag is a short reduction voltage from nominal voltage, occurs in a short time.
If the voltage sags exceed two to three cycles, then manufacturing systems making use of sensitive electronic
equipments are likely to be affected leading to major problems. It ultimately leads to wastage of resources (both
material and human) as well as financial losses. This is possible only by ensuring that uninterrupted flow of
power is maintained at proper voltage levels. This project tends look at the solving the sag problems by using
custom power devices such as Distribution Static compensator (D-STATCOM).Proposed scheme follows a new
algorithm to generate reference voltage for a distribution static compensator (DSTATCOM) operating in
voltage-control mode. The proposed scheme ensures that unity power factor (UPF) is achieved at the load
terminal during nominal operation, which is not possible in the traditional method. Also, the compensator
injects lower currents therefore, reduces losses in the feeder and voltage-source inverter. Further, a saving in
the rating of DSTATCOM is achieved which increases its capacity to mitigate voltage sag. Nearly UPF is
maintained, while regulating voltage at the load terminal, during load change. The state-space model of
DSTATCOM is incorporated with the deadbeat predictive controller for fast load voltage regulation during
voltage disturbances. With these features, this scheme allows DSTATCOM to tackle power-quality issues by
providing power factor correction, harmonic elimination, load balancing, and voltage regulation based on the
load requirement.
Estimation of Harmonics in Three-phase and Six-phase (Multi- phase) Load Circ...IAES-IJPEDS
The Harmonics are very harmful within an electrical system and can have serious consequences such as reducing the life of apparatus, stress on cable and equipment etc. This paper cites extensive analytical study of harmonic characteristics of multiphase (six- phase) and three-phase system equipped with two & three level inverters for non-linear loads. Multilevel inverter has elevated voltage capability with voltage limited devices; low harmonic distortion; abridged switching losses. Multiphase technology also pays a promising role in harmonic reduction. Matlab simulation is carried out to compare the advantage of multi-phase over three phase systems equipped with two or three level inverters for non-linear load harmonic reduction.The extensive simulation results are presented based on case studies.
Automobile Management System Project Report.pdfKamal Acharya
The proposed project is developed to manage the automobile in the automobile dealer company. The main module in this project is login, automobile management, customer management, sales, complaints and reports. The first module is the login. The automobile showroom owner should login to the project for usage. The username and password are verified and if it is correct, next form opens. If the username and password are not correct, it shows the error message.
When a customer search for a automobile, if the automobile is available, they will be taken to a page that shows the details of the automobile including automobile name, automobile ID, quantity, price etc. “Automobile Management System” is useful for maintaining automobiles, customers effectively and hence helps for establishing good relation between customer and automobile organization. It contains various customized modules for effectively maintaining automobiles and stock information accurately and safely.
When the automobile is sold to the customer, stock will be reduced automatically. When a new purchase is made, stock will be increased automatically. While selecting automobiles for sale, the proposed software will automatically check for total number of available stock of that particular item, if the total stock of that particular item is less than 5, software will notify the user to purchase the particular item.
Also when the user tries to sale items which are not in stock, the system will prompt the user that the stock is not enough. Customers of this system can search for a automobile; can purchase a automobile easily by selecting fast. On the other hand the stock of automobiles can be maintained perfectly by the automobile shop manager overcoming the drawbacks of existing system.
Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
Instead of buying and hoping for the best, we can use data science to help us predict which products may be good fits for us. It includes various function programs to do the above mentioned tasks.
Data file handling has been effectively used in the program.
The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
Quality defects in TMT Bars, Possible causes and Potential Solutions.PrashantGoswami42
Maintaining high-quality standards in the production of TMT bars is crucial for ensuring structural integrity in construction. Addressing common defects through careful monitoring, standardized processes, and advanced technology can significantly improve the quality of TMT bars. Continuous training and adherence to quality control measures will also play a pivotal role in minimizing these defects.
Industrial Training at Shahjalal Fertilizer Company Limited (SFCL)MdTanvirMahtab2
This presentation is about the working procedure of Shahjalal Fertilizer Company Limited (SFCL). A Govt. owned Company of Bangladesh Chemical Industries Corporation under Ministry of Industries.
TECHNICAL TRAINING MANUAL GENERAL FAMILIARIZATION COURSEDuvanRamosGarzon1
AIRCRAFT GENERAL
The Single Aisle is the most advanced family aircraft in service today, with fly-by-wire flight controls.
The A318, A319, A320 and A321 are twin-engine subsonic medium range aircraft.
The family offers a choice of engines
About
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
Courier management system project report.pdfKamal Acharya
It is now-a-days very important for the people to send or receive articles like imported furniture, electronic items, gifts, business goods and the like. People depend vastly on different transport systems which mostly use the manual way of receiving and delivering the articles. There is no way to track the articles till they are received and there is no way to let the customer know what happened in transit, once he booked some articles. In such a situation, we need a system which completely computerizes the cargo activities including time to time tracking of the articles sent. This need is fulfilled by Courier Management System software which is online software for the cargo management people that enables them to receive the goods from a source and send them to a required destination and track their status from time to time.
1. IOSR Journal of Electrical and Electronics Engineering (IOSR-JEEE)
e-ISSN: 2278-1676,p-ISSN: 2320-3331, Volume 7, Issue 3 (Sep. - Oct. 2013), PP 01-03
www.iosrjournals.org
www.iosrjournals.org 1 | Page
An Overview of Harmonic Sources in Power System
Imtiaz Ahmed1
, Mir Zayed Shames1
, Md. Muksudul Alam1
1
(Department of Electrical and Electronic Engineering, Ahsanullah University of Science and Technology,
Dhaka, Bangladesh)
Abstract : Harmonics are multiples of the fundamental frequency of power system. These harmonics are
creating distorted voltages and currents in the power system. Distortion of voltages and currents can affect the
power quality. This article covers Harmonics sources in power system. Different Sources of harmonics in power
system have been discussed.
Keywords: Current, Distortion, Frequency, Harmonics, Power System, Source, Voltage
I. INTRODUCTION
Harmonic waveform distortion is just one of many different disturbances that perturb the operation of
electrical systems. It is also a unique problem in light of an increasing use of power electronics that basically
operate through electronic switching. Different nonlinear loads produce different but identifiable harmonic
spectra. This makes the task of pinpointing possible culprits of harmonic distortion more tangible. Utilities and
users of electric power have to become familiar with the signatures of different waveform distortions produced
by specific harmonic sources. This will facilitate the establishment of better methods to confine and remove
them at the sites where they are produced. In doing this, their penetration in the electrical system affecting
adjacent installations will be reduced [1], [2].
The presence of non-linear loads and the increasing number of distributed generation power systems
(DGPS) in electrical grids contribute to change the characteristics of voltage and current waveforms in power
systems, which differ from pure sinusoidal constant amplitude signals. Under these conditions advanced signal
processing techniques are required for accurate measurement of electrical power quantities. The impact of non-
linear loads in electrical power systems has been increasing during the last decades. Such electrical loads, which
introduce non-sinusoidal current consumption patterns (current harmonics), can be found in rectification front-
ends in motor drives, electronic ballasts for discharge lamps, personal computers or electrical appliances.
Harmonics in power systems mean the existence of signals, superimposed on the fundamental signal, whose
frequencies are integer numbers of the fundamental frequency. The electric utility companies should supply
their customers with a supply having a constant frequency equal to the fundamental frequency, 50/60 Hz, and
having a constant magnitude. The presence of harmonics in the voltage or current waveform leads to a distorted
signal for voltage or current, and the signal becomes non-sinusoidal signal which it should not be [3].
II. HARMONIC SOURCES
The main source of the harmonics is any non-linear loads that produce the voltage harmonics and
current harmonics. This occurs because the resistance of the device is not a constant. The resistance in fact,
changes during each sine wave. So, non linear device is one in which the current is not proportional to the
applied voltage.
2.1 Transformers
A transformer can incur in core saturation conditions in either of the following cases: When operating
above rated power when operating above rated voltage the first situation can arise during peak demand periods,
and the second case can occur during light load conditions, especially if utility capacitor banks are not
disconnected accordingly and the feeder voltage rises above nominal values. Distorted current under transformer
saturation conditions is shown in fig 1. From the fig, it is evident that a transformer operating on the saturation
region will show a nonlinear magnetizing current, which contains a variety of odd harmonics, with the third
dominant. The effect will become more evident with increasing loading. No hysteresis losses are produced in an
ideal lossless core. The magnetic flux and the current needed to produce them are related through the
magnetizing current of the steel sheet material used in the core construction. Even under this condition, if we
plot the magnetizing current vs. time for every flux value considered, the resultant current waveform would be
far from sinusoidal. Sinusoidal magnetizing current is not symmetrical with respect to its maximum value
because of hysteresis effect is considered. The distortion is typically due to triplen harmonics (odd multiples of
three, namely, the 3rd, 9th, 15th, etc.), but mainly due to the third harmonic. This spectral component can be
confined within the transformer using delta transformer connections. This will help maintain a supply voltage
2. An Overview of Harmonic Sources in Power System
www.iosrjournals.org 2 | Page
with a reasonable sinusoidal waveform [4].
2.2 Rotating Machines
Due to rotor slots or slight irregularities in the winding patterns of a three-phase winding of a rotating
machine or small asymmetries on the machine, harmonic currents can develop. These harmonics induce an
electromotive force (emf) on the stator windings at a frequency equal to the ratio of speed/wavelength. The
resultant distribution of magneto motive forces (mmf) in the machine produces harmonics, which is the function
of speed. Additional harmonic currents can be created upon magnetic core saturation. However, these harmonic
currents are usually smaller than those developed when the machines are fed through variable frequency drives
(VFDs).
2.3 Power Converters
The increasing use of the parameters like voltage and frequency are varied to adapt to specific
industrial and commercial processes has made power converters the most widespread source of harmonics in
distribution systems. Electronic switching helps the task to rectify 50/60 Hz AC into DC power. In DC
applications, the voltage is varied through adjusting the firing angle of the electronic switching device.
Basically, in the rectifying process, current is allowed to pass through semiconductor devices during only a
fraction of the fundamental frequency cycle, for which power converters are often regarded as energy-saving
devices. If energy is to be used as AC but at a different frequency, the DC output from the converter is passed
through an electronic switching inverter that brings the DC power back to AC.
Converters can be grouped into the following categories:
Large Power Converters
Medium-Size Power Converters
Low-Power Converters
Variable Frequency Drives
2.3.1 Large Power Converters
Large Power Converters is a converter which large blocks of energy are transformed from AC to DC.
These are used in electric utility applications. Their nominal power is in the mega-volt-ampere range. Generally,
they present a much higher inductance on the DC than on the AC side. Therefore, the DC current is practically
constant and the converter acts as a harmonic voltage source on the DC side and as a harmonic current source on
the AC side. Furthermore, all resultant currents are the same in all phases in a perfectly balanced system.
2.3.2 Medium-Size Power Converters
Medium-Size Power Converters’ range is Kilo-volt-ampere size. These are found in increasing numbers
in industry. The first applications in the industry were for DC motor speed control that still represents the major
market for these types of converters. However, they are increasingly used in AC induction motor speed control.
Similar to large-size power converters, the fifth harmonic can reach amplitudes that range from one fifth to one
third the fundamental rated current.
2.3.3 Low-Power Converters
UPS (Uninterruptible Power Supply) units, discharge lamps, television sets, computers, fax machines
are among these low kilo-volt-ampere– size power converter applications. If they are additionally provided with
UPSs to handle voltage sags and power supply interruptions, the amounts of harmonic currents can substantially
increase [5].
Fig. 1 Distorted current under transformer saturation
conditions [1]
3. An Overview of Harmonic Sources in Power System
www.iosrjournals.org 3 | Page
2.3.4 Variable Frequency Drives
Variable frequency drive (VFD) usage has increased dramatically in HVAC applications. The VFDs are
now commonly applied to air handlers, pumps, chillers and tower fans. A better understanding of VFDs will
lead to improved application and selection of both equipment and HVAC systems.
VFDs draw current from the line only when the line voltage is greater than the DC Bus voltage inside
the drive. This occurs only near the peaks of the sine wave. As a result, all of the current is drawn in short
intervals (i.e., at higher frequencies). Variation in VFD design affects the harmonics produced [6].
2.4 Fluorescent Lamps
For pure and stable sinusoidal voltages, electric power systems are designed. Due to the incessantly
growing demand for electricity, the levels of harmonic distortions of voltage and current waveforms in power
systems have steadily increased. Harmonic distortions affect sensitive equipment connected to the power
networks and are especially problematic for compact fluorescent lamps.
Fluorescent Lamps are highly nonlinear in their operation. It gives rise to odd harmonic currents of
important magnitude. In fluorescent lamp, magnetic core inductors or chokes contained inside the start ballasts
function to limit the current to the tube. Likewise, they use a capacitor to increase the efficiency of the ballast by
increasing its power factor. Electronic ballasts operate at higher frequency, which permits the use of smaller
reactors and capacitors. The use of higher frequencies allows them to create more light for the same power
input. This is used to reduce the input power [1].
2.5 Arcing Devices
The voltage-current characteristics of electric arcs are highly non-linear. Following arc ignition the
voltage decreases due to the short-circuit current, the value of which is only limited by the power system
impedance. The main harmonic sources in this category are the electric arc furnace. It discharges type lighting
with magnetic ballasts.
The harmonics produced by electric arc furnaces are not definitely predicted due to variation of the arc
feed material. The arc current is highly nonlinear and reveals a continuous spectrum of harmonic frequencies of
both integer and non integer order. Due to the physical Phenomenon of the melting with a moving electrode and
molten material, the arc furnace load gives the worst distortion. The arc current wave may not be same from
cycle to cycle.
III. FUTURE SOURCES OF HARMONICS
The sources of harmonics in the electrical system of the future will be various and numerous. Due to
increasing use of sensitive electronics in personal computers, multimedia, digital communications and industrial
automated processes, the problem grows complicated.
Generally, which are not regarded as large generators of harmonics, may be lining up to join current
harmonic producers. Photovoltaic, wind, natural gas, carbonate full cells and even hydrogen are expected to
play increasingly important roles in managing the electricity needs of the future.
IV. CONCLUSION
This paper discussed different sources of harmonic in power system. Transformers, rotating machines,
power converters, fluorescent lamps and Arcing Devices are the main source of harmonic in power system.
Harmonic current is produced by harmonic. Harmonic currents can cause overload in wiring and transformers,
can produce heat, and in extreme cases, fire.
V. ACRONYMS
DGPS - Distributed Generation Power Systems
EMF - Electromotive Force
MMF - Magneto Motive Forces
UPS - Uninterruptible Power Supply
VFD - Variable Frequency Drives
REFERENCES
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