Cannabis Indica

thcscience_admin
Page 1
Analysis of DVR in Distribution during
Voltage Sags & Voltage Swells
A
DISSERTATION
Submitted in partial fulfillment of the requirement for the award of
Degree of Master of Technology in Power System.
Submitted To
[RAJIV GANDHI PROUDYOGIKI VISHWAVIDYALAYA, BHOPAL (M.P.)]
Submitted By:
SHREYA JAIN
Enroll. No: 0121EE13MT16
Under The Supervision of:
Asst. Prof. Tushar Kumar
Department of Electrical & Electronics Engineering
SCOPE COLLEGE OF ENGINEERING, BHOPAL
APRIL - 2016
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
SCOPE COLLEGE OF ENGINEERING,
BHOPAL (M.P.) 462021
CERTIFICATE
This is to certify that the “Analysis of DVR in Distribution during Voltage Sags &
Voltage Swells” being submitted by Shreya Jain in partial fulfillment of the requirement for
the award of Master of Technology Degree in Power Systems to Rajiv Gandhi
Proudyogiki Vishwavidyalaya, Bhopal (MP) is a record of bonafide work done by her
under my supervision.
APPROVED AND SUPERVISED BY:
Asst.Prof. Tushar Kumar
Guide, Dept. Of (EX)
SCE BHOPAL
FORWARDED BY :
Dr. R.P. Gupta
Sr. Director
Dr. D.S. Raghav
SCE BHOPAL
Principal
SCE BHOPAL
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
CERTIFICATE OF APPROVAL
The Dissertation entitled “Analysis of DVR in Distribution during Voltage Sags &
Voltage Swells” being submitted by Miss. Shreya Jain has been examined by us and is
hereby approved for the award of degree “Master of Technology in Power Systems ”, for
which it has been submitted. It is understood that by this approval the undersigned do not
necessarily endorse or approve any statement made, opinion expressed or conclusion drawn
therein, but approve the dissertation only for the purpose for which it has been submitted.
(Internal Examiner)
(External Examiner)
Name:
Name:
Date:
Date:
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
SCOPE COLLEGE OF ENGINEERING, BHOPAL (M.P.)
DEPARTMENT OF ELECTRICAL & ELECTRONICS
ENGINEERING
CANDIDATE’S DECLARATION
I hereby declare that the Dissertation entitled “Analysis of DVR in Distribution during Voltage
Sags & Voltage Swells” is my own work conducted under the supervision of Asst. Prof. Tushar
Kumar, Department of Electrical & Electronics Engineering at Scope College of Engineering,
Bhopal.
I further declare that to the best of my knowledge this report does not contain any part of work that
has been submitted for the award of any degree either in this university or in other university
/Deemed University without proper citation.
I also declare that “A check for plagiarism has been carried out on the dissertation and is found
within the acceptable limit and report of which is enclosed herewith”.
This is to certify that the above statement is made by the candidate is correct to the best of my
knowledge.
Date :
Shreya Jain
(0121EE13MT16)
Signature of Guide
PRINCIPAL
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
ACKNOWLEDGEMENT
This Dissertation is the result of guidance and support of various people at SCOPE
COLLEGE OF ENGINEERING without whom all my effort would have been directionless and
fruitless. I sincerely thank all of them, for assisting me in completing the dissertation. I express
my ardent and earnest gratitude to my guide Asst. Prof. Tushar Kumar Department of Electrical
& Electronics Engineering, SCOPE COLLEGE OF ENGINEERING BHOPAL for their help and
encouragement at all the stages of my dissertation improve. Their guidance and motivation helped
me to be fruitful in my effort.
I would like to extend my deepest gratitude to Dr. R. P. Gupta Sr. Director, SCOPE
COLLEGE OF ENGINEERING BHOPAL for providing all the necessary facilities, support,
encouragement and inspirational environment to bring out the best of my endeavors.
I also express my heartfelt and profound gratitude to our Principal, Dr. D. S. RAGHAV
for his valuable suggestion and ample resources at all stages of the research work.
Finally, I would like to say that I am indebted to my parents and my husband for everything that
they have done for me. All of this would have been impossible without their constant support. I
also thank God for being kind to me and blessing me through this journey.
Shreya Jain
(0121EE13MT16)
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
ABSTRACT
Now days Power quality is a premier fact by which the high-tech devices are getting affected. Power
quality problem is quite natural and is often occurs, such as non-sinusoidal voltage, frequency
of current which in turn results in the failure of end use equipments.
Main problem is voltage perturbation during voltage sags & voltage swells. To figure out these
difficulties, custom power devices can be used. These problems can be solved up to a greater extent.
Power Distribution systems ideally should provide their customers with an incessant flow of energy
at smooth sinusoidal voltage at the slender magnitude level and frequency.
The DVR has a higher energy capacity compared to the SMES and UPS devices. Moreover, the
DVR is smaller in size and economical as compared to the DSTATCOM and other custom power
devices. The DVR is fast , flexible and efficient .In addition to voltage sags and swells
compensation ,DVR having one more quality of harmonic s correction .DVR eliminates or mitigates
the voltage sag/ swell and power quality problem when unnatural condition occur in distribution
system.
This article focuses on the performance of DVR for voltage compensation which is done by using
MATLAB Software to explain PI Controller & discrete PWM Pulse Generator Module have been
used
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
LIST OF FIGURES
Figure
Description about the figure
Page
no.
No.
2.1
Presentation of Voltage Sags
13
2.2
Presentation of Voltage Swell
13
2.3
Presentation of voltage Imbalance
14
2.4
Presentation of Harmonics
15
2.5
Presentation of Voltage Fluctuation
16
2.6
Duration of Sag
18
3.1
Flow chart of DVR distribution
21
3.2
Schematic diagram of DVR
22
3.3
Equivalent circuit of DVR
23
3.4
Protection mode
24
3.5
Standby mode
25
3.6
Pre-Sag Compensation
26
3.7
Vector diagram of In Phase Compensation
27
3.8
Vector diagram of Voltage tolerance method for minimum energy
28
injection
4.1
PI Controller Block Representation
31
4.2
Phase Modulation of the Control Angle δ
32
4.3
Phase Sequence Analyzer
33
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
4.4
Single Line Representation
36
4.5
Simulation Circuit of Sag generation and compensation using DVR 37
4.6
Simulation Circuit of Swell generation and compensation using DVR 39
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
CONTENTS
Chapter 1.
Introduction
1 - 5
1.1 Product Perspective
1.2 Objective
1.3 Application of DVR
1.4 Problem Domain
1.5 Organization of the Dissertation
Chapter 2.
Literature Survey
6 - 17
2.1 Power Quality
2.2 Power Quality Issues
2.3 Characteristics of Voltage Sags & Voltage Swells
2.4 Solution of Power Quality Issues
Chapter 3.
DVR Analysis –Proposed Work
18 - 25
3.1 Introduction to DVR
3.2 Classification of DVR
3.3 Equation of DVR
3.4 Operational Modes
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
3.5 Formulation
Chapter 4.
Conclusion and Future Enhancement
26 - 39
4.1 Discrete PWM
4.2 Phase Modulation
4.3 Phase Sequence Analyzer
4.4 Single Line Representation of DVR
4.5 Discussion of Test System Of Sag & Swell
4.6 Simulation Result
4.7 Rating of Components
4.8 Screen Shots
Chapter 5.
Conclusion and Future Enhancement
49 - 51
5.1 Conclusion
5.2 Limitations
5.3 Future Enhancement
Chapter 6.
References
49 - 51
6.1 References
6.2 List of Publication
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
CHAPTER 1
INTRODUCTION
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
CHAPTER 1
INTRODUCTION
1.1 Product Perspective
Electrical energy is the most Efficient and enormous of energy and all of us are desperately dependent
on the electric supply. We cannot imagine the life without supply of electricity. At the same time the
quality and persistence of electric power supplied is also very important for the efficient functioning
of the end user equipment. Most of the commercial and industrial loads demand high quality
uninterrupted power. Thus maintaining the qualitative power is of important.
Power quality is one of the leading concerns in the era of power system. Power quality measures the
fitness of electric power transmitted from utilities. The high quality sinusoidal waveform produced at
power stations. The well-known applications of power electronics based non linear devices and faults
cause deviation from uncontaminated sinusoidal waveform. These situations facing electricity
customers and suppliers have increased the popularity and development of power quality studies.
Power quality is becoming an increasingly important topic in the performance of many industrial
applications such as information technology devices related to communication, advanced control,
automation, precise manufacturing technique and online service.
Power Distribution systems ideally should provide their customers with an incessant flow of energy
at smooth sinusoidal voltage at the slender magnitude level and frequency. However in practice power
systems especially the distribution system has many nonlinear loads which substantially impact the
quality of power supplies. As a result of nonlinear loads, the pureness of the waveform of supplies is
lost. This fetch up producing many power quality problems. Aside from nonlinear loads some system
events both usual (e.g. capacitor switching motor starting) and unusual (e.g. fault) could also bring
down power quality issue.
Power Quality disturbance can be defined as the deviation of the voltage and the current from its
perfect waveform. So many methods are used to extenuate/palliate voltage sags and swells, but we use
the most efficient method of a custom power devices, e.g. FACTS for transmission systems which
makes the power transfer capabilities and stability margin better. The custom power concern to the use
of power electronics controller in a distribution system.
Particularly, to deal with different power quality problems. Different approaches exist to limit the
caused by voltage dips and ones interesting approach considered here is to use of custom power devices
used in electrical network to improve power quality problems. Each device has its own pros and cons.
These are as follows: The SVC pre-dates the DVR, but still the preferences are given to DVR because
the SVC has no ability to control active power flow.
The DVR has a higher energy capacity compared to the SMES and UPS devices. Moreover, the DVR
is smaller in size and economical as compared to the DSTATCOM and other custom power devices.
The DVR is fast , flexible and efficient .In addition to voltage sags and swells compensation ,DVR
having one more quality of harmonic s correction .DVR eliminates or mitigates the voltage sag/ swell
and power quality problem when unnatural condition occur in distribution system. Even it can restores
the load voltage within a few milliseconds and avoid any power system disruption to that load. Among
the disturbances voltage sag is considered the most severe since the sensitive loads are very susceptible
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
to temporary changes in the voltage. The main aim of DVR is to detect the voltage sag or swell and
injecting the required voltage in series to the bus by using injection transformer.
1.2 Application of DVR
There are many applications of DVR are as follows:
•
DVR can be used to Compensate load Voltage
•
They improves the Power Quality
•
DVR can be used under system Frequency variation to provide Real Power by the load which
is done by connecting a uncontrolled rectifier at the input of the VSC.
•
They protect the system from Voltage Sags and Swells.
•
. DVR acts as an additional energy source.
•
The dynamic performance ability of DVR leads to improving supply quality for future and
allows us more complex device to use.
1.3 Objective
Voltage Sag: Voltage sag is a momentary decrease in the rms voltage magnitude lasting between half
a cycle and several seconds. Disruptive voltages sags are usually caused by fault conditions on the
utility side or customer side. Voltage sag is generally described by two essential characteristics such
as Magnitude and duration. Balanced voltage sags are due to the three phase faults.
Voltage Swell: The increase of voltage magnitude between 1- 2 and 1-8 p.u. is called voltage swell.
The most accepted duration of a swell is from 0.5 cycles to 1 minute. They appear on the switching
off of a large load; energizing a capacitor bank or voltage increase of the un-faulted phases during a
single line to ground fault. The possible effects of voltage swell are stress on computer components
and they shorten their life. Also swell can upset electronic control and electric motor drives.
1.4 Problem Domain
Power quality means the fitness of electrical power and its stabilized disposition to power consumer
device. PQ problem is defined as any problem manifested in voltage, current or a frequency
deviation that leads to the failure or disoperation of consumer equipment. Power quality is not a
single unit measurement it is a collection of several type which includes Capacitor switching,
lightning surge (Transient), Interruptions, Sags/Swells (Disturbance), Harmonics, Flicker, Voltage
regulation, Reliability, Power factor (Steady-state).
There are several types of power quality problems that a customer may encounter and may classified
according or depending on how the voltage waveform is being distorted. There are transients, short
duration of variations (sags, swells, and interruption), long duration variations (sustained
interruptions, under voltages, over voltages), and voltage imbalance, waveform distortion (dc offset,
harmonics, inter harmonics, notching, and noise), voltage fluctuations and power frequency
variations.
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
A.
Voltage Sags
Voltage sag is defined as the reduction of RMS voltage between 0.1 p.u. and 0.9 p.u. and lasting
between 0.5 cycles to 1 minute. Voltage sag are mostly caused by system fault and last for duration
ranging from 3 cycles to 30 cycles depending on the fault clearing time.
B.
Voltage Swells
A voltage swells is defined as a rise in RMS voltage which is between 1.1 p.u and 1.8p.u for period
stuck between 0.5 cycles to 1 minute. A voltage swell is characterized by its magnitude (RMS) and
duration.
1.5 Organization of Dissertation
The content of the thesis is as follows:
After the introduction chapter, chapter 2 contains the Power quality problems and custom power
concept along this thesis. Voltage sags and swells are analyzed and compensation technique is
discussed.
Chapter 3, deals with the Dynamic Voltage Restorer (DVR) which we have explained in detailed by
circuit diagram, working, modes of operation and its equivalent diagram are presented.
Chapter 4 defines a new control method for DVR is shown by using Sequence Analyzer And Phase
Modulator with PWM inverter.
Chapter 5, Explains the modeling and simulation of Voltage sags/swell compensation by DVR.
Chapter 6, Discusses the Conclusion and future works.
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
CHAPTER 2
LITERATURE SURVEY AND
BACKGROUND
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
CHAPTER 2
LITERATURE SURVEY AND BACKGROUND
2.1 Power Quality
The quality of power delivered to the end user is most important as performance of the Consumer’s
equipment is heavily dependent on it. Dynamic Voltage restorer’s first unit installed in 1996 so many
configurations compensating unit and controller have been presented; In these paper we presented the
most important contribution.
[1] O. Anaya Lara Et Presents The Simulation of Dynamic Voltage Restorer & Suggests four different
methods to inject the voltage using DVR which are In Phase Compensation Phase Advance
Compensation Voltage Tolerance method And In Phase Voltage Compensation.
[2] S.F Torebi presents Modelling & Simulation Technique of DVR which protects from voltage
sags and swells to sensitive load. This can be used to protect a group of medium voltage or low voltage
consumers by using improved d-q-0 controller technique.
[3] Frede Blaabjerg deals with four different topologies to provide DC supply and compare all
these which can be realised with minimum amount of energy storage . Firstly DVR performed without
energy storage and Passive convertor is used. In other case DVR performed with energy storage system
as DC link capacitor.
[4] Jose M Lozano represents the use of matrix convertor which contains nine bidirectional
switches arranged in three groups associated with an output line Matrix Convertor used in DVR to
mitigate voltage fluctuation. DSVPWM Direct Space Vector Pulse Width Modulation technique is
used for Unbalanced & distorted Voltage supply. In this method various different types of switching
power converters have been employed.
[5] Mahmoud A El-Gammal gives an overview of the DVR its configurations, components,
compensating strategies control methods and its capabilities and limitations . The DVR is designed for
Protection Purpose
[6] John Godask Nielsen deals with the Power Quality issues i.e. Voltage Dip By inserting the
DVR in either the medium voltage distribution system or in low voltage distribution system. Michael
john Newman presented that the series connected inverter of a DVR could also be used to compensate
for steady state load voltage harmonics which increases the Power Quality value. Compensation is
done by using Narrow bend resonant based controllers for each harmonics.
[7] D MhindaVilathgamuwa gives new concept of two or more DVR connection to common DC
link. In which One DVR is used to compensate Voltage Sag & another DVR replenish the DC link
energy storage which depends on load power factor.
[8] Shazl A. Mohammed says Voltage sag is a common method and desirable power quality
phenomenon in the distribution system which put sensitive loads under danger. In this DVR can
provide the solution to mitigate voltage sag by injection voltage as well as power into the system. This
thesis presents and gives overview of DVR its function configuration components compensating
strategies and control method.
[9] Meera Annie Varghese presents one of the modern devices which are used to guard consumers
against sudden changes in voltage amplitude known as Dynamic Voltage Restorer. It is used in
distribution system network to protect consumers from sudden change in voltage magnitude. DVR is
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
a custom power device. In this paper Resonant Controller and Charged regulator is proposed in order
to eliminate the steady state error in DVR response and stabilize the system. The current limitation
protects the DVR and restores the point of common coupling (PCC) voltage. Here the DVR with the
15 level inverter systems protects the PCC voltage without any real power injection into the DVR
during voltage sag condition. And the simulation results show how the DVR controls the emergency
conditions of distribution systems.
[10] S.Masoud Barakati deals with a DVR as a solution to compensate the fault and protects
sensitive load. DVR is connected across distribution system with voltage in range of kilovolts; series
converter is a component of DVR which should be implemented based on the multilevel converter.
Multilevel converter has a capability to handle voltage in range of kilovolts.and power of several
megawatts. So this paper proposes a configuration of Dynamic Voltage Restorer based on
asymmetrical cascade multi-cell converter. The asymmetrical CM converter increases number of
output voltage levels with reduced number of switches. Also other methods which are adopted as the
control system. In this system PSCAD/EMTDC is using and simulation results are presented to valid
date its effectiveness.
[11] Mehmet Tumay presents modeling and simulation of a dynamic voltage restorer with
sinusoidal Pulse Width modulation based controller by using simu-link. These methods are simple to
design and allow flexibility in cost and robust in nature.
[12] T. Sundar presents Simulation and investigation of archetype DVR for power flow control
DVR is used in the distribution systems to protect consumers against sudden changes in voltage
amplitude. This paper analyzes the emergency control in distribution systems proposed by
multifuntioning DVR control strategy. Also the multiloop controller using the posicast and P-Resonant
controller are proposed to improve the transient response and eliminate the steady state error in DVR
response. The proposed algorithm is applied to disturbances in load voltage caused by induction
motors, and a three-phase short circuit fault. Also capability of proposed DVR has been tested to limit
the downstream fault current.
[13] Hadi Ezoli presents Hysteresis Voltage Control of DVR based on unipolar PWM. Power
Quality Problems are like voltage sag, voltage swell and harmonics are major concern of the industrial
and commercial electrical consumers due to enormous failure in expressions of time and money. This
is due to the advent of a large numbers of sophisticated electrical and electronic equipment, such as
computers, programmable logic controllers, variable speed drives and so forth. The use of the
equipment often requires power supplies of high quality. Some special equipment is sensitive to
voltage disturbance, especially if these take up to several periods, the circuit does not work. Therefore
these adverse effects of voltage changes require the subsistence of effective mitigating devices. There
are various solutions to these problems. One of the most effective solutions is the installation of a
dynamic voltage restorer.
Now after these all researches we conclude and gave the new method of Dynamic voltage Restorer
with pulse width Modulation technique by using MATLAB. The planned method has become an
efficient effective fast flexible & simple in design under both Sag and Swell condition .In these DVR
works in three modes of operation: Protection mode, Standby mode and injection mode.
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
2.2 Power Quality Issues
The basic measures for power quality are constant rms value, constant frequency, symmetrical three-
phases, pure sinusoidal wave shape and limited THD. This power quality disturbance makes the
malfunctioning of equipment and also makes it inefficient. Power quality problems embrace a wide
range of disturbances and they are voltage sags, voltage swell, harmonic distortion, impulse transient
and interruptions.
The main reasons to concern with Power Quality are given as:
Due to many microprocessor based controls end user device becomes more sensitive.
Complexity of industrial processes : the restart up is very costly
Large computer systems in many businesses facilities
Power electronics equipment used for enhancing system stability, operation &
efficiency. They are major source of bad PQ and are defenseless to bad PQ as well.
Deregulation of the power industry
Complex interconnection of system which results in more severe consequence if any
one component fails
Continuous development of high performance equipment. Such equipment is more
susceptible to power disturbances. Voltage Sags : It is short duration decrease in rms
voltage value from 0.1 to 0.9 pu.
Causes of Voltage sags:
•
A voltage sag generated when the rms voltage decreases between 10% -90% of nominal
voltage ,
•
Equipment failure
•
Power system failure,
•
Customer load additions and large load additions in the utility service area.
Outcomes:
•
Failure of contractors and switchgear
•
Malfunctioning of Adjustable Speed Drives
Fig.2.1 Presentation of Voltage Sags
Voltage Swells: Voltage Swell is opposite of Voltage Sag and less common in nature. And it is
defined as short duration increase in voltage values level 110% - 180% of nominal voltage for
duration of ½ cycles to one minute.
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
Fig.2.2 Presentation of Voltage Swell
Causes of voltage Swell:
•
Voltage Swell is always caused by an abrupt diminution in load.
•
Although they can also be caused by loose neutral connection,
•
By capacitor bank load and power line switching.
•
Change in ground reference on ungrounded phases
Outcomes:
•Due to over voltage electronic parts get damaged
•Insulation breakdown
•Overheating
Voltage Imbalance: The percentage of maximum deviation from the average of three phase voltage or
currents means magnitude & phase angle between the voltages signals are of different phase.
Causes of Voltage Imbalance:
•
Existence of Large Single Phase Loads.
•
Faults Arising in the system
Outcomes:
•
Presence of Harmonics
•
Reduction in System Efficiency
•
Power Loss Increases Equipment life decreases
Fig.2.3 Presentation of voltage Imbalance
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
Waveform Distortion: The power system networks try to generate and pass on sinusoidal voltage and
current signals. But the sinusoidal nature is not maintained and distorted occur in the signal.
Causes: The causes of waveform distortion are as follows:
•
DC offset: The signal which presents in DC voltage is called DC offset. Due to presence of
DC offset, the signals shift by certain level from its actual reference level.
•
Harmonics: When voltage and current signals are at frequency which are integral multiples of
the fundamental frequency so it is called Harmonics. The reason of harmonics generation is due to
non linear loads in power system network.
Fig.2.4 Presentation of Harmonics
•
Inter Harmonics: These harmonics are that harmonics at frequency which are not the integral
multiple of fundamental frequency.
•
Notching: The transfer of current from one phase to another phase during commutation process
of a power electronics device, a periodic disturbance is occur which is called notching.
•
Noise: The presence of unwanted signal cause noise due to interference with
communication network.
Voltage Fluctuation: It occurs due to random voltage change. But they did not increase up to 0.9 to
1.13pu.
Causes of Voltage Fluctuation:
•
Frequency Start/ discontinue of Electric Ballasts
•
Oscillating Loads
•
Electric Arc furnace
Outcomes:
•
Flickering of lights
•
Ricketiest in the visuals
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
Fig.2.5 Presentation of Voltage Fluctuation
Transients: The momentary change in voltage and current signals in power system over a short
period of time cause transients. Transient are categorized into two types impulsive and oscillatory.
•
Impulsive: The impulsive transients are unidirectional in nature.
•
Oscillatory: Oscillatory transient have swings with rapid change of polarity.
Causes: There are many causes due to
•
Arching between the contacts of the switches
•
unexpected switching of loads
•
Poor or loose connection
•
Lightening strokes
Outcomes:
•
Electronic devices are affected and show wrong results
•
Motor run with higher temperature
•
Failure of ballasts in the fluorescent lights
•
Reduce the efficiency and lifetime of equipment
2.2 Characteristics of voltage sags
Voltage sags is characterized by its magnitude, duration and phase angle jump. These all are
explained as
•
Magnitude of sag: Magnitude of sag is defined as the minimum voltage leftovers during the
event. And magnitude is fundamental rms voltage or peak voltage. So sag is considered as the
residual/ remaining voltage during the event. And in case of three phase system where dip is used to
characterize sag.
The magnitude of voltage at a certain points depends on
•
Type of fault
•
Fault impedance
•
System configuration
•
Distance of the fault from the point of consideration
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
•
Duration of sag:
Type of sag
Duration
Magnitude
Instantaneous
0.5-30 cycles
0.1-0.9 pu
Momentary
30cycle – 3s
0.1-0.9 pu
Temporary
3s- 1min
0.1-0.9 pu
Fig.2.6 Duration of Sag
The duration of sag is the time for which the voltage is below at threshold value. It is determined by
fault clearing time. In three phase system all three rms voltages should be considered to calculate the
duration of sag. Sag starts from when one of the phase rms voltages is less than the threshold and
continues until all the three phase voltage.
•
Phase angle jump: Short circuit in a power system causes dip in voltage as well as changes the
phase angle of the system. The change from normal to other phase angle is called phase angle jump. It
causes the shift in zero crossing of instantaneous voltage which affects the power electronics convertor
because they use phase angle information for firing.
2.3 Solution of Power Quality Issue
Power electronic based device offers protection of industrial and commercial customers from power
quality problems basically sags, swells, and harmonics, interruption and unbalance voltages. To reduce
all this effects the devices are as follows:-
•
Line voltage regulator: These are special transformers connected in series with the transmission
line designed to regulate the voltage in accordance with the changes in the system. Examples of line
voltage regulators are- tap changing transformers, CVT’s, buck- boost regulators etc.
•
M-G sets (Motor -Generator sets): These M-G sets are installed at the load side in order to
supply power to critical loads during the interruptions from the power supply company. In this
maintenance and safety are main concern.
•
Magnetic Synthesizers: These employ resonant circuits made of inductors and capacitors.
They are used to filter the harmonics from affecting the loads. But these are bulky and noisy.
•
SVC (Static VAR Compensator): These also use passive elements like inductors and
capacitors. But the use of solid state switches to control the voltage injection increases their
efficiency. The switches are controlled such that correct magnitude of voltage is injected at correct
point of time so that voltage fluctuations are reduced. But these are expensive.
•
UPS (Uninterrupted Power Supplies): It provides a constant voltage during both voltage sags
and outages from a battery or super conducting material. The main parts of an UPS are battery,
rectifier and an inverter.
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
•
SMES (Superconducting Magnetic Energy Storage): SMES stores electrical energy within a
superconducting magnet. It provides a large amount of power (750 KVA to 500 MVA) within a short
time.
•
Custom Power Device: All the above mentioned conventional devices are not suitable to
mitigate voltage disturbances effectively. Therefore, there is a need to use new type of devices known
as Custom Power Devices. These are power electronic equipment aimed to help in mitigating power
quality problems. These are of many types like- Dynamic Voltage Regulator (DVR), D-STATCOM,
auto transformer, UPQC etc. In this thesis the DVR (Dynamic Voltage Restorer) carried out for
improving the power quality.
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
CHAPTER 3
PROPOSED RESEARCH
METHODLOGY
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
CHAPTER 3
PROPOSED METHODOLOGY
3.1 Introduction of Proposed Methodology
Power quality means the fitness of electrical power system. And if any disturbances generated in
system then it causes damage. To solve this problem the concept of custom power device is introduced.
One of them device is dynamic voltage restorer. Which is the most efficient & effective device. It is
series connected solid state device that injects voltage into the system in order to modulate the load
side voltage.
Fig 3.1 Flow chart of DVR distribution
3.2 Classification of DVR
The DVR can be classified as follows:
i.
An Injection Transformer / Booster transformer
ii.
Filter
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
iii. Storage Device
iv.
Voltage source Converter (VSC)
v.
Control unit
Fig 3.2 Schematic diagram of DVR
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
3.3 EQUATION OF DVR
Fig 3.3 Equivalent circuit of DVR
Above diagram represents the equivalent circuit of DVR, The fault of a load bus depends on the system
impedance Zth . When source voltage is dip or increases (VTH), then the DVR injects a series voltage
( Vinj ) through injection transformer. So the load voltage magnitude which we look for VL is set up.
Now the equation is written as:
VDVR = VL + ZTH IL – VTH
Where
VL = Magnitude of load voltage
ZTH = Load Impedance
IL = Load Current
VTH =System voltage during fault
The load current IL is ,
IL = [PL + jQL] / V
When VL is considered as a reference equation can be rewritten as ,
VDVR = VL < 0 + ZTH <( β- θ) – VTH < δ
∝, β, δ are angles of VDVR , VTH & ZTH ,respectively and θ is load power angle.
1
2
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
θ = tan-1 ( QL / PL)
The complex power angle of DVR can be
SDVR = VDVR I*L
It requires only reactive power injection and DVR itself generates reactive power.
3.4 Modes of operation
The role of DVR is to inject an energetically controlled missing voltage in series generated by a voltage
source convertor which is connected in series to the bus/ line voltage by using injection transformer.
The phase angle & magnitude of voltage are variable during sag. The DVR has three modes of
operation i.e. Protection mode , Standby mode (during steady state) & Injection Mode (during sag).
3.4.1. Protection mode
If the system parameters exceeds from its reference or preset value on load side so system will be
isolated. When the system observes any disturbance or detects any fault or abnormal condition bypass
switch removes the DVR from the system to protects from damages and It protects from over current
also and provide different path to current.
Fig 3.4 Protection mode
3
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
3.4.2 Standby mode (VDVR =0)
In Standby mode the DVR may either go into short circuit operation or inject small voltage to
compensate voltage sag. The injection transformer’s low voltage winding is shorted through the
voltage source converter. There is no switching of semiconductor occurs full load current pass through
the primary winding. Solid state bypass switches are used to perform short circuit operation.
Fig 3.5 Standby mode
3.4.3 Injection Mode (VDVR < 0)
In injection mode DVR injects a compensating voltage through injection / booster transformer after
disturbance of required phase and magnitude. The primary function of DVR is compensating voltage
disturbances on distribution system. To attain compensation , three phase ac voltages are injected in
series with required magnitude ,phase angle and wave shape. The types of voltage sags , load
conditions and power rating of DVR will determines the possibility of compensating voltage sag.
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
3.5 Compensation Method
Voltage injection methods depend upon DVR rating, load condition, types of voltage sags. The
methods of voltage injection are as follows:
i.
Pre sag compensation
ii.
In phase compensation
iii. In phase advanced compensation
iv.
Voltage tolerance method with minimum energy injection
3.5.1 Pre Sag/ Dip Compensation
The pre sag compensation method observes the supply voltage continuously and when the fault or any
disturbances occurs, it will inject the difference voltage between the sag or pre set value. So load
voltage can be restored back to pre fault value.
VDVR = Vprefault – VL
VDVR is the injected voltage.
Vprefault is the pre fault load voltage vector.
VL is the load voltage
Fig 3.6 Pre-Sag Compensation
4
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
3.5.2 In Phase Compensation
In this method injected voltage & supply voltage are in same phase.But the magnitude of injected
voltage is minimum and it can cause phase shift between remaining voltage vector at PCC and pre sag
value.
VL = VPrefault
Fig 3.7 Vector diagram of In Phase Compensation
3.5.3 In Phase Advance Compensation
In Phase Advance Compensation method, the energy storage size is reduced. Active power dependent
on the angle between the sag voltage & load current. When sag is generated, phase of load voltage
jump’s too few steps that cause difficulties for load. Active power is injected only during fault. So
active power supply is limited stored energy in DC links and this is more expensive.
Active power component should be zero to minimize the injected energy. In this method we can change
only the phase of sag voltage because the value of load current & voltages are fixed. This method use
only reactive power and all the sag are not mitigated without real power.
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
3.5.4. Voltage Tolerance Method with Minimum Energy Injection
The load can tolerate the small drop in voltage & small jump in phase angle. The voltage magnitude
lies between 90% to 110% of nominal voltage and 5% to 10% of nominal state which did not disturb
the load. Both magnitude and phase are control parameter by this method by minimum energy
injection.
Fig 3.8 Vector diagram of Voltage tolerance method for minimum energy injection
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
CHAPTER 4
SIMULATION
AND
RESULT ANALYSIS
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
CHAPTER 4
SIMULATION AND RESULT ANALYSIS
4.1 DISCRETE PWM
To compensation the sag voltage in realistic application , a discrete PWM (Pulse Width Modulation)
technique is used. It is extremely popular method of high switching frequency in industrial application.
The main function of PWM is to keep a constant voltage magnitude of sensitive load under system
disturbance. They only measures rms voltage. When there is voltage sag then an error occurs which is
observed by PI controller and based on error value PWM generates pulses to the IGBT switch in VSI.
PI Controller observes the error produced by the difference between the fault voltage & the supply
voltage. Then it generates a required δ angle to drive the error to zero. With this phase angle a control
voltage is generated. The magnitude of control voltage is depends on phase angle δ. The phase angle
is proportional to the degree of disturbance. The generated voltage is called the controlled voltage.
The advantages of using PWM technique are, it is less in cost. No energy storage device is used and
less number of switches required.
Fig. 4.1 PI Controller Block Representation
4.2 PHASE MODULATION
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
Phase modulation used in many application to carry both analogue and digital signals. Maintain the
amplitude of the signal constant the phase is varied to bring the required information or signal. The
modulation angle δ is generated by phase modulation. And δ angle is applied to PWM generators in
phase A , where as the angle for phase B & C are shifted by 240° or -120° & 120° respectively
VA = sin (ωt + δ )
VB = sin (ωt + δ-2 π/3 )
VC = sin (ωt + δ +2 π/3)
Fig. 4.2 Phase Modulation of the Control Angle δ
4.3 PHASE SEQUENCE ANALYSER
The three phase sequence analyser Blocks outputs the magnitude and segment of positive ,negative
and zero balance & unstable signals. Discrete form of this block specifies the magnitude and phase.
5
6
7
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
Fig. 4.3 Phase Sequence Analyser
Sequence Impedance: This are classified and explained below
Positive sequence: Positive Sequence is defined as the impedance offered by the system
to the flow of positive sequence current.
Negative Sequence: Negative sequence is defined as the impedance to the flow of negative
sequence current.
Zero Sequence: Zero Sequence Impedance is defined as the impedance offered by the system to the
flow of zero sequence current.
The positive, negative and zero sequence signals are as follows:
Positive sequence:
Negative Sequence:
Zero Sequence:
8
9
10
11
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
The sequence impedance varies with the type of power system equipment. In Static and balanced
power system components like transformer and power lines the positive and negative sequence
currents are same.
4.4 SINGLE LINE REPRESENTATION OF DVR
Fig. 4.4 Single Line Representation
Single line diagram of dvr system comprises by a 13kV , 40 Hz generating system where it fed two
transmission line through three winding transformer which is star/delta/delta, 13/114/114kv. They
distributed in two network in which transformer of star/delta, 114/11kV is connected. From this two
distribution, one is affected by fault where fault resistance is 0.66. And DVR is work only during fault
condition either generated sag voltage or swell voltage.
4.5 DISCUSSION OF TEST SYSTEM OF SAG & SWELL
DVR system connected to the distribution system which presents both with DVR & without DVR
condition for sags/swells.
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
Fig. 4.5Simulation Circuit of Sag generation and compensation using DVR
This figure represents the sag generation which is compensated by DVR. When fault occurs in the
system then circuit breaker is open circuited and protect the system from damage and connect the DVR
through injection transformer to the bus. The required voltage is generated by PWM generator which
is energized by DC source. Now the injected voltage is inserted to the load by injection transformer to
protect from damages.
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
If three phase fault is generated which affects the system efficiency so to protects from this a circuit
breaker is connected across the load. So when circuited breaker sense the fault it gets open and
disconnected the load to protects from damage.
Now DVR a solid state power electronic device is used as a protecting device which is
connected between the distribution networks via injection transformer. After these the faulty voltage
i.e. sags voltage is sensed by phase sequence analyzer which converts the three phase rms voltage
into per unit voltage.
Sequence analyzer contains magnitude and phase both , but we terminate the phase
because we use only magnitude of voltage. A summer and constant is used which calculated the error
voltage and send to the PI controller.
PI controller is a used to find the difference in voltage i.e. sag value. The modulation
angle δ is generated by phase modulation. And δ angle is applied to PWM generators in phase A ,
where as the angle for phase B & C are shifted by 240° or -120° & 120° respectively. Then with the
help of PWM gate pulse is provided to VSC and according to the required voltage VSC generated a
missing voltage. Now generated voltage is given to the faulty system via injection transformer and
voltage is modified.
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
Fig. 4.6 Simulation Circuit of Swell generation and compensation using DVR
This figure represents the swell generation which is compensated by DVR. When fault occurs because
of capacitor bank in the system then circuit breaker is open circuited and protect the system from
damage and connect the DVR through injection transformer to the bus. Now in swell there is a
momentary increase in voltage so it can be stored by capacitor. The stored voltage is analysed by error
detection of PI controller. The LC filter is connected across the circuit to reduce the harmonics of the
system. Now the whole circuit explains below.
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
If three phases L-G fault is generated cause the swell in voltage which affects the
system efficiency so to protect from this a circuit breaker is connected across the load. The fault is
generated because of capacitive load in this circuit. So when circuited breaker sense the fault it gets
open and disconnected the load to protects from damage otherwise the device or load is overheated.
DVR is used as a protecting device which is connected between the distribution
networks via injection transformer. After these the faulty voltage i.e. swell voltage is sensed by
phase sequence analyser which converts the three phase rms voltage into per unit voltage.
Sequence analyser contains magnitude and phases both, but we terminate the phase
because we use only magnitude of voltage. A summer and constant is used which calculated the error
voltage and send to the PI controller.
PI controller is a used to find the difference in voltage i.e. sag value. The modulation angle
δ is generated by phase modulation. And δ angle is applied to PWM generators in phase A , where as
the angle for phase B & C are shifted by 240° or -120° & 120° respectively. Then with the help of
PWM gate pulse is provided to VSC and according to the required voltage VSC generated a missing
voltage. A LC filter is connected in series to reduce the harmonics produced by PWM. And the error
excess voltage is stored in battery which use for further purpose also. Now the voltage becomes as
desired.
4.5 SIMULATION RESULT
1. Voltage Sag With & Without DVR
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
2. Voltage Swells With & Without DVR
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
4.7 RATING OF COMPONENTS
S.NO.
COMPONENTS
RATING
1.
Three Phase source
Frequency
Source Resistance
Phase to phase rms voltage
25e3 V
50Hz
0.1Ω
13e3
2.
Three phase transformer (3winding)
Power
100e6 VA
Frequency
50Hz
Winding 1 Parameter
Voltage
13e3V
Resistance
0.002PU
Inductance
0.08PU
Winding 2 Parameter
Voltage
115e3V
Resistance
0.002PU
Inductance
0.08PU
Winding 3 Parameter
Voltage
115e3V
Resistance
0.002PU
Inductance
0.08PU
Magnetizing Resistance
500PU
Magnetizing Inductance
500PU
3.
Line 1 Parameter
Line Resistance
0.05Ω
Line Inductance
0.04806H
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
Line 2 Parameter
Line Resistance
0.001Ω
Line Inductance
0.0005H
4.
Three phase transformer (2winding)
Power
250e6 VA
Frequency
50Hz
Winding 1 Parameter
Voltage
115e3V
Resistance
0.002PU
Inductance
0.08PU
Winding 2 Parameter
Voltage
11e3V
Resistance
0.002PU
Inductance
0.08PU
Winding 3 Parameter
Voltage
115e3V
Resistance
0.002PU
Inductance
0.08PU
Magnetizing Resistance
500PU
Magnetizing Inductance
500PU
5.
Fault Parameter
Fault resistance
0.66
Ground resistance
0.005
6.
Three Phase Circuit Breaker
Breaker Resistance
0.001Ω
7.
Capacitor
750e-6
8.
Linear Transformer
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
Power
250e6 VA
Frequency
50Hz
Winding 1 Parameter
Voltage
15e3V
Resistance
0.002PU
Inductance
0.08PU
Winding 2 Parameter
Voltage
11e3V
Resistance
0.002PU
Inductance
0.08PU
9.
Filter Parameter
Capacitor
2.2e-6F
Inductor
0.01H
10.
DC Voltage
5e3V
11.
Inverter
Parameter
Carrier frequency= 1080 Hz ,
Sample time = 50 μs
IGBT based 3arms bridge
Carrier Frequency
1080Hz
Sample Time
50 µsec
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
CHAPTER 5
CONCLUSIONS AND FUTURE SCOPE
5.1 Conclusion
This paper has presented the power quality problems of voltage sags and swells. Compensation
technique of DVR is presented to solve the problem of distortion. The design & simulation of DVR
was presented. The aim of this paper is to compensate the voltage sag and swell problem. Modeling &
Simulation was done by using MATLAB. This simulation shows DVR provides better regulation. In
this PI controller is used to composite the error.
This report had presented the power quality problems such as voltage sag with the compensation
techniques of custom power electronics device DVR. This research work presents comprehensive
results for the design and application of DVR for voltage sag. A controller utilizes the error signal
which is actually the difference between the reference signal and the actual signal. Voltage source
convertor (VSC) was implemented with the help of pulse width modulation. Modeling and Simulation
of DVR is done through MATLAB/SIMULINK computer software. The simulation carried out here
shows that DVR provide better voltage regulation capabilities. Based on analysis of test system, it is
suggested that percentage sag and operating voltage are major factors in estimating the requirement of
DC storage capacity. The effectiveness of a DVR system mainly depends upon the amount and
stiffness of DC energy storage device.
Investigations were carried out for various cases of voltage sags at different transmission voltage
levels. Result show that any increase in transmission voltage and voltage sag demands sufficient
increase in DC storage capacity. An expression is developed to estimate the required DC storage
voltage for specified transmission voltage and percentage sag. In the test system, it is observed that
after a particular amount of increases in the load on feeders, the voltage levels at the load terminal
decreases.
5.2 Limitations
Every system has its own limitations, though in this they are very less but those are as follows:
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
1. Dynamic voltage restorer using in manufacturing area requiring significant power to run tools
equipment and utility plants.
2. It is also use in transmission and distribution coz it is series compensation devices.
3. The utility companies can add dynamic voltage restorers, static condensers, fault current limiters,
and/or high-energy surge arresters. Since these are beyond the control of the end user of the electricity,
the following concentrates on "in-the-facility" solution.
5.3 Future Enhancements.
1. The DVR should be tested examine by connecting the DVR into a real network where the efficiency
& accuracy can be better evaluated.
2. The performance comparison of DVR done by comparing fuzzy controlled DVR, neural network
controller DVR, ANN based controller of DVR , Particle Spam Optimization (PSO) based DVR
controller.
3. Multi level DVR can be looked for future work.
4. For interconnecting the renewable source to grid DVR should be used.
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
REFERENCES
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
REFERENCES
[1] Sanjay Haribhai chaudhary ,Mr.Gaurav Gangali “Mitigation of voltage sags and swell using
DVR”.IOSR,vol 8,issue 4 (Nov-dec 2013).
[2] Mr.Y.Prakash,Dr. S.Sanskar “power quality improvement Using DVR in power
system”.IEEE spectrum 2014.
[3] Shakti Prashad mishra “Simulation and analysis of DVR voltage sags and
swells”ELESVIESR procedia engg.64 -2013
[4] Chandrakant L.Bhattar “mitigation of voltage sags and swells using DVR”IJR vol.2 issue 3 march
2013.
[5] F.B. Ajaei ,S .Afsharnia ,A.Kahrobaeian & S .Farhangi, “ A Fast & Effective control scheme for
the dynamic voltage restorer,” IEEE Trans. On power delivery, Vol. 26 ,no. 4 ,pp. 2398-2404, oct
2011.
[6] Ding Ning, Cai Wei ,Suo Jaun, Wang Jianwei & Xu Yonghai, “ Voltage sag disturbance detection
based on rms voltage method, ” IEEE power and energy engeeniring Conference , pp. 1-4 ,march 2009.
[7] Ravilla Madhusudan “Modelling and Simulation of Dynamic Voltage Restorer for Power Quality
Problems Voltage Sags and Swells” IEEE Trans power delivery, vol.17 no. march 30,31 2012
[8] Raunak Jangid,Kapil Parakh “Reducing the voltage sags and swells problem in distribution system
using Dynamic voltage restorer With PI ControIJller” IJSCE vol.3 issue 6 January 2014.
[9] N.Hingorini ,”Introducing custom power”,IEEE Spectrum ,vol.32,no.6, June 1995.
[10] P. Roncero- Sanchez, E. Acha, J.E. Ortega calderon, “A versatile control scheme for a dynamic
voltage restorer for power quality improvement” IEEE Trans, power del., vol 24, no.1 jan 2009.
[11] M I Marie, E.F EI- Saandany, and M M A Salama, “A new approach to control dvr based on
symmetrical components estimation”, IEEE Trans, power del., vol 22, no. 4 oct 2012”
[12] N.G. Jayanti, M.Basu, I. Axente, K.Gaughan, & M.F.Conlon, “ Sequence analysis based DSP
controller for dynamic voltage restorer” IEEE Power Electronics specialist conference , pp.3986-3991,
june 2008.
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
[13] S.S.Choi ,B.H.Li, and D.M. Vilathgamuwa, “Comparative study of inverter and line side filtering
schemes in the dynamic voltage restorer,” IEEE power engineering society winter meeting , Vol.4,
pp. 2967-2972, Jan 2000.
[14] A.O .AI-Mathmani, M.A. Hannan , M.AL-Dabbagh ,M.A. Mohd Ali ,and A.Mohamed, “
Development of new control strategy for voltage sag mitigation,” 2nd IEEE international power and
energy conference .pp.318-323,Dec.2008.
[15] Chi-Seng Lam, Man-Chung Wong ,and Ying-Duo Han, “Voltage swell and overvoltage
compensation with unidirectional power flow controlled dynamic voltage restorer,” IEEE transaction.
[16] Saripalli Ragesh , Mahesh K Mishra and Shridhar K, “Design and simulation of dynamic voltage
restorer using pulse width modulation” 16th national power system conference ,AndhraPradesh,
India.pp. 317-322, Dec 2010.
[17] C. Zhan , M. barnes, V.K. Ramachandramurthy, N.jenkis, “Dynamic voltage restorer with battery
energy storeage for voltage dip mitigation” Power Electronics and variable speed drives, 18-19 ,
Conference publication No. 475, IEE September 2000.
[18] Brice j. Quirel, Braink Johnson and Herb L Hess, “Mitigation of voltage sag with phase jump
using a Dynamic voltage restorer” IEEE2006.
[19] Sasitharan S. Mahesh K Mishra, B.Kalyan and jayashankar, “Rating and design issues of DVR
injection transformer” IEEE 2008.
[20] Chris Fitzer , Mike Barnes , Member, IEEE and Peter green, “Voltage sag detection technique for
a dynamic voltage restorer ” in IEEE transaction on industry application. Vol. 40, no.1, January –
february 2004.
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
PAPER PUBLICATION
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
PAPER PUBLICATION
[1] Shreya Jain, Mr. Tushar , “Analysis of DVR in Distribution during voltage sags & voltage
swells.” International Journal for Applied Research, Volume: 6, Issue 2, pp 55-
ANALYSIS OF DVR IN DISTRIBUTION DURING VOLTAGE SAGS & VOLTAGE SWELLS
Guided by: Dr. Ashad Ullah Qureshi
Contact: 6260651575, 9179357477
APPENDIX – B
LIST OF PUBLICATION
[1] “Analysis of DVR in Distribution during voltage sags & voltage swells”, International
Journal for Applied Research, Volume: 6, Issue 2, pp 55-57, February 2016.

Leave a Reply