/
A seminar tcport on
POWER QUALITY
Submitted in partial fulfillment of the requirement for the avard
of the degree of
BACHELOR OF TECHNOLOGY
(ELECTRICAL ENGINEERING)
GOVERNMENT ENGINEERING COLLEGESHEIKHPURA
BAZIDPUR (BIHAR)
Submitted by
SWATI PRIYA
Reg. No: 21103157902
GINEERINGCOLLEG
SMEIKHA
Under the guidance of
Mr.Kamal Kant & Mr. Abhishek Kumar
(Assistant Professor )
DEPARTMENT OFELECTRICAL ENGINEERING
GOVERNMENT ENGINEERING COLLEGE SHEIKHPURA
BAZIDPUR(BIHAR), INDIA 811105
January 2024
yERNMENT
cOL E
a re
Government Engineering College, Sheikhpura
Department of Electrical Engineering
CERTIFICATE
This is to certify that seminar on power quality is delivered and report is submittcd by Swati
Priya, Reg. No. 21103157902 of Seventh Semester for partial fulfillment of requiremcnt for the
degree of BACHELOR OF TECHNOLOGY (Electrical Engineering) of Government
Engineering College, Sheikhpura during the academic year 2023- 2024.
Signature of Supervisor/s Islozy Signature of HOD
Signature of External Examiner
ACKNOWLEDGEMENT
We would like to express our gratitude towards all the people who
have contributed their precious time and effort during the course.
Firstly, we would thank almighty God, our parents and all the
tcachers without whom we would not be what we are now. We
would like to thank Asst. Prof. Kamal Kant for his invaluable
support, guidance, motivation, and encouragement throughout the
very short but precious period that he gave during this work was
carried out. His deep understanding of subject and life that he shares
with me is invaluable and we are deeply indebted to him.
Swati Priya
21103157902
TABLE OF CONTENTS
SI. No
Page No.
1. Acknowledgement 1
2. Abstract
3. List of Table 1V
4. List of Figure 1V
5. Introduction
2
6. Increasing Interest in Power Quality
7. Power Quality 3
8. Scope 3
9. Events 4
10. Description,Cause and Consequences 5-8
11. Mitigation techniques 9
12. Mitigating Devices 9-11
13. Issues & challenges of RES-Grid integration 12
14. IEEE Power Quality Standards 13
15. Impact On Society and Environment 14
16. Conclusion 15
17. Reference 16
ABSTRACT
The report gives an overview of POWER QUALITY. The aim of the
power system has always been to supply electrical energy to customers.
Earlier the consumers of electrical energy were mere acceptors.
Interruptions and other voltage disturbances were part of the deal. But
today electric power is viewed as a product with certain characteristics
which can be measured, predicted, guaranteed, improved etc.
Moreover, it has become an integral part of our life. The term 'power
quality' emerged because of this new emphasis placed on the customer
utility relationship.
The fact that power quality has become an issue recently does not mean
that it was not important in the past. Utilities all over the world have for
decades worked on the improvement of what is now known as power
quality. In recent years, users of electric power have detected an
increasing number of drawbacks caused by electric power quality
variations. These variations already existed on the electrical system but
only recently they are causing serious problems. This is because end
user equipment has becomne more sensitive to disturbances that arise both
on thesupplier as well as the utility side.
End user equipments are more interconnected in networks and industrial
processes, so that the impact of a problem with any piece of equipment
is much more severe. To improve power quality with adequate solutions,
it is necessary to know what kinds of disturbances occurred. Apower
quality monitoring system that can automatically detect, characterize,
and classifydisturbances on electrical lines is therefore required.
List of Table
Table 1IEEEpower quality standards--. 13
List of Figure
Figure 1Event of various voltage- 4
Figure 2 Different mitigation techniques and their solution-------9
Figure 3 DVR and their V-I Characteristics-- 10
Figure 4 Distribution Static Compensators 10
Figure 5 SVCand their V-I Characteristics 11
Figure 6 Transient Voltage Surge Suppressor- 11
Figure 7 Pyramid of power quality--- 14
INTRODUCTION
Electric power quality, or simply power quality, involves voltage,
frequency, and waveform.Good power quality can be defincd as asteady
supply voltage that stays within the prescribed range. stcady A.C.
fiequency close to the rated value, and smooth voltage curve wavefom
(resembles a sine wave). In general, it is useful to consider power quality
as the compatibility between what comes out of an electric outlet and the
load that is plugged into it.
The term is used to describe electric power that drives an electrical load
and the load's ability to function properly. Without the proper power, an
electrical device (or load) may malfunction, fail prematurely or not
operate at all. There are many ways in which electric power can be of
poor quality and many more causes of such poor-quality power.
> Power Quality means quality of the normal voltage supplied to
facility.
> Thegrowing use of microprocessors and electronic equipments has
made us focus on power supply.
Sometimes equipments and machinery can be damaged or even fail
due to bad power quality.
The voltage provided should be as close as possible to nominal
voltage and the waveform must be pure sine wave free from any
harmonics and other disturbances.
1
INCREASING INTEREST IN POWER QUALITY
Power quality is an increasingly important issue for all business. A
recent study by IBM showed that power quality problems cost US
business more than $15 billion a year. The increased interest in power
quality has resulted in significant advances in monitoring equipments
that can be used to characterize disturbances and power quality
variations. The recent increased interest in power quality can be
explained in several ways.
+Equipments have become more sensitive to voltage
disturbances.
The electronic and power electronic equipments have become much
more sensitive to voltage disturbances than their counterparts 10 or
20years ago.
+ Equipments cause voltage disturbances
Modern electronic and power electronic equipments are not only
sensitive to voltage disturbances but also cause disturbances for other
customers. E.g., Non-sinusoidal current drawn by rectifiers and
inverters.
+Technical challenge taken up by utilities.
Designing a system with a high reliability of supply at a limited cost is a
technical challenge which appealed to many in the power industry and
hopefully still does in the future.
+Power quality can be measured.
The availability of electronic equipments to measure and show wave
forms has certainly contributed to the interest in power quality.
2
DEFINITION:
Asper IEEE. Power Quality is *The concept of powering and grounding
sensitive equipment in a manner that is suitable to the operation of that
cquipment."
PQ Dealswith
1. Continuity of the supply
2. "Quality" of the voltage
SCOPE
> For Economic operation of power system, the level of power
quality should be properly maintained.
> Power system design
> Future growth
>For optimization and reliable operation
> To meet the growing needs for standardization and performance
criteria.
>The effects due to over-voltages, also the losses incurred due to
under-voltages, must be seriously dealt with.
Also, non-linear loads introduce harmonics in the system which have
their own effects incuding power factor reduction.
Hence, PQ provides a goodplatform to deal with all these problems.
3
EVENTs
The major problem in the power sector that a need to treatment of quality
up-gradation are termed as power quality events.
VVoltage Surges
VVoltageSwell
Voltage Sag
Voltage Unbalance
Voltage Spike
Voltage Flickering
Harmonics Distortion
Noise
Short Interruption
VLong Interruption
(s)
Normal Sag Swel Outage
Figure 1 Event of various voltage
Power quality provides the solutions to all these problems in a very
efficient and optimizes way.
4
Description, Cause and Consequences
Voltage Surges
It isa voltage risethat endangers the insulation of electric cquipment.
Causes:
Shutdown of heavilyloaded circuits.
Switching events such as the connection or disconnection of a
current and short-circuiting to ground.
Effects:
Computers and other sensitive electronic equipment can seriously
be damaged by such an over-voltage surge.
Temporal fluctuations produce parity errors and interrupts
protection systems.
Voltage Swell
Momentary increase of the voltage, at the power frequency, outside the
normaltolerances, with the duration of more than one cycle and typically
less than few seconds
Causes:
Start/stop of heavy loads.
Badly dimensioned power sources
Badly regulated transformers (mainly during off-peak hours).
Effects:
Data loss, flickering of lighting and screens, stoppage, or damage
of sensitive equipment, if the voltage values are too high.
Voltage Sag (Dip)
The decrease of nominal voltage level between 10-90 percent of the
nominal rms voltage for the duration of 0.5 cycles to l minute
Causes:
Faults in the transmission or distribution network
Connection of heavy loads and start-up of large motors
Effects:
Disconnection and loss of efficiency in electric rotating machines
Tripping of contactors and electro-magnetic relays
5
Voltage Unbalance
Avoltagevariation in athree-phase system in which thethree
voltage nagnitudes or the phasc angle differences between them
are not equal.
Causes:
Large single-phase loads (induction furnaces, traction loads)
" Incorrect distribution of allsingle-phase loads (this may be also
due to a fault).
Effects:
Unbalanced systems imply the existence of anegative sequence
that is harmful to all three phase loads. The most affected loads
are three-phase induction machines.
VoltageSpikes
In electrical engineering, spikes are fast, short duration electrical
transients in voltage.
Causes:
Lightning strikes
Power outages
Tripped circuit breakers
Short circuits
Effects:
voltage spikes may be created by a rapid buildup or decay of a
magnetic field, which may be induced into another circuit.
Voltage Fluctuation & Flickering
Fluctuation is oscillation of voltage value. And flickering is a visible
change in brightness of lamp.
Causes:
Arc furnaces
frequent start/ stop of electric motors.
Oscillating loads.
6
Effects:
Most conscquences arc common to under-voltages.
" Filament of can be damaged.
AAAReduction in life of electrical equipment
HARMONIC DISTORTION
Voltage or current waveforms assume non- sinusoidal shape. The
waveform corresponds to the sum of different sine waves with different
magnitude and phase, having frequencies that are multiples of power
system frequency.
Causes:
. Classic sources: arc furnaces, welding machines, rectifiers and DC
brush motors.
Modcrn sources; all non-linear loads
Effects:
Increased probability in occurrence of resonance, overheating of
allcables and equipment, loss of efficiency in electric machines,
electromagnetic interference with communication systems.
Noise
Superimposing of high frequency signals on the waveform of the power
system frequency
Causes:
" Electromagnetic interferences.
" Improper grounding
Effects:
. Disturbances on sensitive electronic equipment usually not
destructive.
May cause data loss and data processing errors.
7
SHORT INTERRUPTIONS
Interaption of clectrical supply for a duration of few milli seconds to
One or two seconds
Causes:
Mainly due to opcning and automatic enclosure of protection
devices
" Insulation failure, lightning, and insulation flash-over
Effects:
Tripping of protection devices, loss of information and
malfunction of data processing equipment
Stoppage of sensitive equipment, such as PCs, PLCs, if they are
not prepared to deal with this situation.
LONG INTERRUPTIONS
Total interruption of clectrical supply for duration greater than 1to 2
seconds
Causes:
Equipment failure in the power system network,storms and objects
striking lines or poles, fire, human error, bad coordination, or
failure of protection devices.
Effects:
Stoppage of all the equipment
MITIGATION TECHNIQUES
Power Ouaity
Events
Distrbuted
Power End- Use
Transmission Distrbution Quality Devikes
Resources Interface
Assize Grid
Devclop
Advanced Develop Develop Sohut ions
Codes ad Enhanced Make End Lise
Adequncy Distributed Interface Devices Less
Resources Standards Sensitive
Devioes
Figure 2 Different mitigation techniques and their solution
MITIGATING DEVICES
Dynamic voltage restorer
Distribution static compensators
V Static VAR compensators
Harmonic filters
V Noise filters
Transient voltage suppressors
V Unified power quality conditioning
9
Dynamic voltage restorer
Dynamic voltage restorers (DVR) are complicated static devices
which work by adding the 'missing' voltage during a voltage sag.
Useto mitigate Voltage based power quality problem.
V Voltage Swell
VVoltage Sag
Voltage Unbalance
Harmonics Distortion
By-pass Switches
LNE VovR S
Almag
V
Injection
Transformer
Source
Vload=gri
Passive Load
Filter
Energy VSI
Storage HH
Voc DVR Reul
Control
Unit
Ioad
Figure3 DVR and their V-ICharacteristics
Distribution Static Compensators
It injects the pulseswhich are exactly 180 degrees out of phase of
the unwanted harmonics, thus cancelling out the unwanted
harmonics and yielding the output wave, very closc in nature to
the fundamental wave.
non linear load1
DC to AC converter
(injects anti harmonie
pulse1)
Figure 4 Distribution Static Compensators 10
Static VAR compensators
Static VAR compensators (SVR) use a combination of capacitors and
rcactors to regulate the voltage quickly.
Solid-state switches control the insertion of the capacitors and reactors
at the right magnitude to prevent voltage from fluctuating.
Transrmission Line
Stepdown ww
Transformer m
AVma
Bus
AVCma Vret
Capacitor
Inductor nauetor
0 kw
Capacity Inductive
Figure 5 SVCand their V-I Characteristics
Transient Voltage Surgé Suppressor
Transient voltage surge suppressors are used as interface between the
power source and sensitive loads,so that the transient voltage is clamped
by the TVSS before it reaches the load.
It has a component with a nonlinear resistance that limits excessive line
voltage and conducts any excess impulse energy to ground.
Transiernt
Voltage
Clamped
Transient
Protected
Transien4 Load
Gurrent
Figure 5 Transient Voltage Surge Suppressor
11
HARMONICS
The dynamic power system loads produce a time varying amplitude in
current waveforms depending on the load characteristics which consists
of the fundamental and harmonics components.
For assessing power quality, it is important to know the total harmonic
distortion i.e. the voltage and current distortion factors VTHD &I THD
Vk= Voltage of Kth harmonic,
Ik = Current of Kth harmonic
Issues &challenges of RES-Grid integration
Renewable energy resources are intermittent in nature hence, it is
therefore a challenging task to integrate renewable energy resources into
the power grid.
Further, these challenges are classified into technical and non-technical
and described below:
(a) Technical issues:
The following are the technical issues are described as
(1) Power quality
+ Harmonics
+ Frequency and voltage fluctuation
(2) Power fluctuation
+ Small time power fluctuations
+Long time power fluctuations
(3) Storage
(4) Protection issues
(5) Optimal placement of RES
(6) Islanding
(b) Non-technical issues:
(1) Due to scarcity of technical skilled workers.
(2)Less availability of transmission line to accommodate RES. (3)RES
technologies are excluded from the competition which discourages the
installation of new power plant for reserve purpose.
12
IEEEPOWER OUALITY STANDARDS
IEEE SCC-22: Power Quality Standards Coordinating Committee
IEEE 1159: Monitoring Electric Power Quality
IEEE 1159.1: Guide for Recorder and Data Acquisition
IEEE1159,2: Power Quality Event Characterization Requirements
IEEE1159.3: Data File Format for Power Quality Data Interchange
IEEE P1564: Voltage Sag Indiccs
IEEE 1346; Power System Compatibility with Process Equipment
IEEE PLI00: Power and Grounding Electronic Equipment (Emerald Book)
IEEE1433: Power Quality Definitions
IEFFP1453: Voltage flicker
IEEE 519: Harmonic Control in Electrical Power Systems
IEEE Harmonics Working Group
Single-phase Harmonics Task Force
IEEE PSI2A: Guide for Applying Harmonic Limits on Power Systems
Inter Harmonics Task Force
Harmonics Modeling and Simulation Task Force
Probabilistic Aspects of Harmonics Task Force
Surge Protective Devices Committee
(Seventeen sub-committee links can be found at the "sub-committee pages" link)
IEEE P446: Emergency and standby power
IEEEPI409: Distribution Custom Power
IEEE P1547: Distributed Resources and Electric Power Systems Interconnection
Table 1IEEE power quality standards
13
IMPACT ONSOCIETY AND ENVIRONMENT
The mitigation of all the power quality related issucs leads to the
cconomic operation of the power system.
A technically sound quality of powcr will be supplied to the
equipments, thereby leading to their smooth operation, and
ensuring a long life for them.
>The elimination of harmonics and other issues leads to the proper
operation of the system, thereby eliminating the unwanted
vibrations and keeping the system stable.
} The reactive power is compensated at an acceptable and affordable
cost and thus, the system efficiency improves.
>The power factor is improved: this leads to a heavy savage in the
costs of electricity bills.
True Power Quality Perceived Power Quality
Grounding
UPS Bonding
IMPROVED Wiring
UPTIME
Voltage
Regulator Surge Protertive
Devices (SPDTYSS)
Transient Noise
Surge Pt otective Filters
Ievices (SPD/TVSS)
Iransient Noise
HARDWARE Aters voltage
DAMAGE Regslatos
PREVENTION
Wiring
\UPS
Bonding
Grounding
Figure 7 Pyramid of power quality
Above all, the problem of power pollution is eliminated.
14
CONCLUSION
POWER QUALITY maintenance is an important aspect in the
economic operation of a system.
Various PQproblems may lead to another undesirable problems.
Proper mitigation devices can be used to maintain the level of
power quality as desired.
15
REFERENCES
1171:E. "IEEE Recommended Practicesond Requirements for
T7urmomic Controlin Electrical Power Systens, " IEEE Std. 519
1992, revision of IEEE SId. 519-198/
127 IEEE. "IEEE Guide for Service toEquipment Sensitive to
Momentary Volage Disturbances" IEEE Sd. I250-1995.
15/ 1EEE, "IEEE Recommended Practice for EvaluatingElectric
P'ower System Compatibility with Electronic Process
Equipment," IEEE Std. 1346-1998.
14] IEEE Sd 446-1987, "IEEE Recommended Practice for
Emergency and Standby Power Systems for Industrial and
Commercial Applications," (IEEE Orange Book). [5] IEEE Std
1250-1995, "IEEE Guide for Service to Equipment Sensitive to
Momentary Voltage Disturbanc
(6] IEEE 100, The Authoritative Dictionary of IEEE Sandard
Terms, seventh edition, 2000, p.234.
[7]Bhim Singh, Kamal Al-Haddad, Ambrish Chandra, Areview
of active filters for power quality improvement, IEEE Trans. on
industrial electronics, Vol.46, No. 5,pp. 960-971l, October 1999.
16
