This document provides an overview of a research project on custom power devices. It outlines the objective to mitigate various power quality issues. It then reviews different custom power devices like DSTATCOM, DVR, UPQC, etc. and discusses their topologies and control attributes. The document identifies issues with existing interline dynamic voltage restorers (IDVR) compensating long duration voltage sags. It proposes a generalized unified power quality conditioner (GUPQC) with three voltage source converters to address this issue. It outlines the work to be done, including simulation and comparative studies. Finally, it provides references for literature on custom power devices and related topics.

1. Contents
Objective
Overview of custom power devices
Literature survey
Identified problems
Work to be done
Course work
References

2. Objective
• To Mitigate Voltage sag, Voltage swell,
Overvoltage, Under voltage, voltage
imbalance and current imbalance, Transient,
Voltage flicker and Different types of
Harmonics

3. Control attributes of FACTS controllers
• Active and reactive power control
• voltage control
• VAR compensation
• damping oscillations
• transient and dynamic stability
• voltage stability
• fault current limiting

5. Overview of Custom Power Devices
• DSTATCOM
• DVR
• UPQC
• IUPQC
• IDVR
• GUPQC

6. Basic DSTATCOM topology

7. Basic DVR topology

8. Detailed configuration of the UPQC

9. Existing Method: A simplistic IDVR
system with two DVRs connected to dc
link.

10. Typical IUPQC connected in a distribution system

11. Typical MC-UPQC used in a distribution system.

12. Proposed Method: Shunt and series
compensators of GUPQC

13. Energy Storage Unit:
It is responsible for energy storage
in DC form.
Flywheels
batteries
superconducting magnetic
energy storage (SMES)
supercapacitors

14. LITERATURE SURVEY
Bahr Eldin. S. M, K. S. Rama Rao, Rosdiazli Ibrahim, N. Perumal
Department of Electrical and Electronics Engineering University
Technology PETRONAS “Cascade Multi-level Converter Based Generalized
Unified Power Quality Conditioner”, IEEE 4th International Conference on
Intelligent and Advanced Systems, 2012
• In a multi-bus, three independent feeders distribution system,
the load reactive power and current harmonics of one feeder
are compensated by shunt compensator,
• while in the other two feeders the voltage harmonics, voltage
sag/swell and interruptions are compensated by two three-
level CMCs as series compensators.
• The simulation and compensation performance analysis are
based on PSCAD/EMTDC.

15. • Ahmed Elserougi, Ahmed M. Massoud, Ayman S. Abdel-Khalik, Shehab Ahmed,
and Ahmed Abdalla Hossam-Eldin “An Interline Dynamic Voltage Restoring and
Displacement Factor Controlling Device (IVDFC)” IEEE Transactions On Power
Electronics, VOL. 29, NO. 6, June 2014
 An interline dynamic voltage restorer (IDVR) is invariably employed
in distribution systems to mitigate voltage sag/swell problems.
 An IDVR merely consists of several dynamic voltage restorers (DVRs)
sharing a common dc link connecting independent feeders to
secure electric power to critical loads.
 While one of the DVRs compensates for the local voltage sag in its feeder,
the other DVRs replenish the common dc-link voltage. For
normal voltage levels, the DVRs should be bypassed.
 Instead of bypassing the DVRs in normal conditions, this paper proposes
operating the DVRs, if needed, to improve the displacement factor (DF) of
one of the involved feeders. DF improvement can be achieved via
active and reactive power exchange (PQ sharing) between different
feeders.

16. • A. Elnady , A. Massoud , A. Noureldin “Recursive implementation of
MUSIC algorithm to minimize power system disturbances”, Electrical
Power and Energy Systems 56 (2014) 9–18, 2013 Elsevier
 This paper exhibits new recursive implementation of the root-MUSIC
algorithm in power system applications in order to extract the
instantaneous power disturbances, which emanate from the arc furnace.
 The MUSIC algorithm is selected because it has an outstanding capability
to estimate and track the frequencies of all types of distortion such as
harmonics and interharmonics.
 The utilized algorithm has been newly developed so as to recursively track
the instantaneous disturbances in the arc furnace current and
consequently mitigate them.
 The suggested development of the recursive root-MUSIC is compared with
the ESPRIT in order to prove that the adopted technique outperforms the
high-resolution common techniques in a noisy or non-noisy environment.
 The instantaneous disturbance is formed by an innovative formulation of
the recursive notch filter. Moreover, the experimental results are given to
prove the practicality of the proposed concepts and techniques.

17. • Voltage sag is one of the most severe power quality
disturbances to be dealt with by the industrial sector,
as it can cause severe process disruptions and result in
substantial economic loss.
• One of the main factors which limit capabilities of
Dynamic Voltage Restorer (DVR) in compensating long-
duration voltage sags is the amount of stored energy
within the restorer.
• In order to overcome this limitation, Inter-line Dynamic
Voltage Restorer (IDVR) has been proposed where two
DVRs each compensating a transmission line by series
voltage injection, connected with common dc-link.
• When one DVR compensates voltage sag, the other
DVR of the IDVR replenish the dc-link energy storage.
Identified Problem

18. • This IDVR works efficiently when the lines under
consideration are connected with two different grid
substations, as it is reasonable to assume that voltage
sag in one line would have lesser impact on the other
line. But in case when the lines are connected with
same grid substation and feeding two different
sensitive loads in an industrial park, voltage sag in one
line affects the voltage profile of other lines.
• Under the above circumstances, long duration voltage
sags cannot be mitigated by IDVR due to insufficient
energy storage in dc-link.
• This study proposes a voltage sag compensator based
on Generalized Unified Power Quality Conditioners
(GUPQC), which comprises of three voltage-sourced
converter modules sharing a common dc link.

19. • Two voltage-sourced converter modules
connected in series with the lines, which
compensates voltage sag and a third shunt
converter module maintains bus voltage and
replenish the common dc-link energy storage.
• The control strategy for power flow control of
shunt converter and sag compensation control of
series converters. Adjustable carrier PWM is used
for generating switching pulses.
• The salient advantages of the proposed method
are compensating long duration deeper voltage
sags, reduction in size of dc-link capacitor and
simultaneous voltage sag compensation in all
lines.

20. WORK to be done
• Design and simulation of Distribution Lines, different
Types Of Load, DSTATCOM, DVR, UPQC, IUPQC, IDVR,
and GUPQC USING MATLAB/SIMULINK
• Comparative Studies Of Different Algorithm Using
GUPQC.

21. References
[1] Ahmed Elserougi, Ahmed M. Massoud, Ayman S.
Abdel-Khalik, Shehab Ahmed, and Ahmed Abdalla
Hossam-Eldin “An Interline Dynamic Voltage
Restoring and Displacement Factor Controlling
Device (IVDFC)” IEEE Transactions On Power
Electronics, VOL. 29, NO. 6, June 2014
[2] T. Ruban Deva Prakash and N. Kesavan Nair ,
“Voltage Sag Mitigation in Multi-Line Transmission
System Using GUPFC” International Journal of
Electrical and Power Engineering, 1: 517-523. 2007
[3] Bahr Eldin S. M, K. S. Rama Rao, and N. Perumal
“Three-Level Converters based Generalized Unified
Power Quality Conditioner” World Academy of
Science, Engineering and Technology Vol:6 2012-02-
23

22. [4] Payal Deshpande, Amit Shrivastava, Anula Khare
“Different Modeling Aspects and Energy Systems of
Unified Power Quality Conditioner (UPQC): An
Overview Unified Power Quality Conditioner”
International Journal Of Renewable Energy Research
Payal Deshpande et al., Vol.3, No.2, 2013
[5] D. Mahinda Vilathgamuwa, Senior Member, IEEE, H.
M. Wijekoon, Student Member, IEEE, and S. S. Choi,
Member, IEEE Interline Dynamic Voltage Restorer: A
Novel and Economical Approach for Multiline Power
Quality Compensation IEEE Transactions on industry
applications, vol. 40, no. 6, november/december
2004

23. [6]Hamid Reza Mohammadi, Ali Yazdian Varjani, and
Hossein Mokhtari, Member, IEEE “Multiconverter
Unified Power-Quality Conditioning System: MC-
UPQC” IEEE Transactions on power delivery, vol. 24,
no. 3, july 2009
[7]Ewald F. Fuchs and Mohammad A.S. Masoum
“Power quality in power systems and Electrical
machines”
[8] Hamid Reza Mohammadi, Ali Yazdian Varjani, and
Hossein Mokhtari, Multiconverter Unified Power-
Quality Conditioning System: MC-UPQC IEEE
Transactions On Power Delivery, Vol. 24, NO. 3, July
2009

24. [9] Sunil Kumar Gupta and H. P. Tiwari, “Suitable
Capacitor Requirements for Dynamic Desired Voltage
Sag Compensation on Distribution Network Using
DVR” International Journal of Information and
Electronics Engineering, Vol. 2, No. 2, March 2012
[10] A. Elnady , A. Massoud , A. Noureldin “Recursive
implementation of MUSIC algorithm to minimize
power system disturbances” Electrical Power and
Energy Systems 56 (2014) 9–18, 2013 Elsevier

25. Thank you

27. • Eduardo Espinosa, Jos6 Espinoza Member,
IEEE, Luis Moran Fellow, IEEE “A Multi-Cell
Unified Power Quality Conditioner that
Operates with Asymmetrical DC Links
Voltages for Minimum THD”
• Bahr Eldin S. M, K. S. Rama Rao and N.
Perumal “Generalized Unified Power Quality
Conditioner for Compensating Current and
Voltage Imperfections” IEEE PEDS 2011,
Singapore, 5 - 8 December 2011

28. • Unified Power Quality Conditioner for Power
Quality Improvement with Advanced Control
Strategy Swapnil Y. Kamble, Madhukar M.
Waware

29. Sl.No. Title of the Paper Journal / Conference Month & Year Volume & Page Nos.
1 Role of PI and Fuzzy Based Three Phase
Distribution Static Synchronous
Compensator
2nd International Conference on
Intelligent Information Systems
and Management (IISM'11)
July 14-16,
2011
ISBN 978-1-4507-6434-6 ©
2011 Published by the
Coimbatore Institute of
Information Technology
2 Modelling and Simulation of Fuzzy Based
Power Flow Control using UPFC
International Conference on
Computation of Power, Energy,
Information and Communication
(ICCPEIC-2012),
18th & 19th,
April 2012
ISBN 978-1-4675-2243-4 ©
2012 Published by
Coimbatore Institute of
Information Technology
3 Artificial Intelligence Based Three Phase
Unified Power Flow Controller
Proceedings of National
Conference on Emerging
Technologies in Electrical
Engineering
( NCEEE-12)
11-12, April
2012
Pg.No.196-200
Department of Electrical &
Electronics Engineering,
Valliammai Engineering
College, Kattankulathur,
Chennai
4 Performance Analysis Of The STATCOM
With PI Controller In IEEE14 Bus.
Proceeding of the International
Conference of Electrical
Engineering and Technology on
April 20-21, 2012
April 20-21,
2012
Pg.No. 56-60
5 Power Quality Improvement using Three
Phase Unified Power Flow Controller
(PI-Fuzzy-ANN)
Proceedings of National
Conference on Emerging
Technologies in Electrical
Engineering
( NCEEE-12)
11-12, April
2012
Department of Electrical &
Electronics Engineering,
Valliammai Engineering
College, Kattankulathur,
Chennai

30. 6 Mitigation of voltage Sag and Swell
using UPQC
Proceedings on national
conference on advances in
electrical and electronics
engineering NCAEE-2012
2012 Department of
electrical and
electronics engineering
Bharath institute of
science and technology
Chennai-600073
7 Comparative Analysis of Fuzzy
Logic and Integral Controller for
Load Frequency Control in Southern
Regional Grid, India
Proceedings of National
Conference on Emerging
Technologies in Electrical
Engineering
( NCEEE-12)
11-12, April
2012.
Pg. 152-156
8 Mitigation of Voltage Sag and Swell
in Multi-Line Transmission System
using Three Level Converter Based
GUPFC
Proceedings of National
Conference on Emerging
Technologies in Electrical
Engineering
( NCEEE-12)
11-12, April
2012
Pg. 137-141
9 Mitigation of Voltage Sag and Swell
Using Interline Unified Power
Quality Conditioner
International Conference
on Computation of Power,
Energy, Information and
Communication (ICCPEIC-
2013)
17th &
18th , April
2013
ISBN: 978-1-4673-6405-
8/13/$31.00©2013IEEE
10 Harmonic Elimination Using
Generalized Unified Power Quality
Conditioner
International Conference
on Computation of Power,
Energy, Information and
Communication (ICCPEIC-
17th &
18th , April
2013
ISBN: 978-1-4673-6406-
5/13/$31.00©2013IEEE
Pg. 1-6

31. 11 Power Quality Improvement by Using
Diode-Clamped Multilevel Inverter for
Renewable Energy System
National Conference on Methods
Enriching Power and Energy
Developments – MEPED’13
April 2013 Vol. 1, Issue 2,
Pg.334-338
12 Harmonics Elimination Using Interline
Unified Power Quality Conditioner
Proceeding of National Level
Conference – NCRTEST’ 13
15
FEBRUARY
2013
Pg. No. 4
13 A semi automatic continuity test kit for
travelling cable assembly
3rd Edition of National
Conference on Modeling,
simulation, Design and
Experimental study of Electrical
system. MOSDES 2013
April 25-
26,2013
Pg.No. 20-24
14 TO LIMIT THE FAULT CURRENT USING
UNIFIED POWER QUALITY CONDITIONER
Journal of Engineering Research
and Studies
October-
December,
2011/1-8
JERS/Vol.II/ Issue IV/pg. 1-8

32. 15 Implementation of single
phase UPFC using fuzzy
logic controller
CiiT International
Journal of Fuzzy
Systems
June
2012
Print: ISSN 0974 –
9721 & Online:
ISSN 0974 – 9608
16 Mitigation of voltage sag
and Swell using
Distribution Static
Synchronous
Compensator
CiitT International
Journal of Digital
Signal Processing.
Novemb
er 2011
Vol.3, No 10,
Pg.No. 481-487
17 MODELLING AND
SIMULATION OF SOFT-
SWITCHING DC/DC
CONVERTER WITH HIGH
VOLTAGE GAIN
Journal of
Engineering
Research and
Studies
July-
Septem
ber,201
1
JERS/Vol.II/ Issue
III

36. Raphael J. Millnitz dos Santos, Jean C. da Cunha, and Marcello Mezaroba “A
Simplified Control Technique For A Dual Unified Power Quality
Conditioner” IEEE Transactions On Industrial Electronics (Volume:PP
, Issue:99) 27 March 2014
• This paper presents a simplified control technique for a dual three-phase
topology of a unified power quality conditioner - iUPQC.
• The iUPQC is composed of two active filters, a series active filter (SAF)
and a shunt active filter (PAF) used to eliminate harmonics and
unbalances.
• Different from a conventional UPQC, the iUPQC has the series filter
controlled as a sinusoidal current source and the shunt filter controlled as
a sinusoidal voltage source.
• Therefore, the PWM controls of the iUPQC deal with a well-known
frequency spectrum, since it is controlled using voltage and current
sinusoidal references, different from the conventional UPQC which is
controlled using non-sinusoidal references.
• In this paper, the proposed design control, power flow analysis and
experimental results of the developed prototype are presented.

37. • M.Farsadi 1, A.Gara shahrak 1, S.Dabbage Tabrizi DVR With Fuzzy Logic
Controller and Photovoltaic for Improving the Operation of wind farm,
Department of electrical engineering, faculty of engineering, university of
Urmia, Urmia, Iran
• Wind power is one of the most important kind of renewable energies.
Wind farm as a device which receives this energy needs some special
conditions to work properly. The most common type of wind turbine is the
variable-speed directly connected to the grid. Faults in the power system
can originate the disconnection of wind farms. Dynamic voltage restore
(DVR) is a custom power device used for eliminating voltage sages and
swells which is the result of the faults. This paper presents a simulation
model of a 12-pulse DVR using photovoltaic (PV) as a mean of providing an
alternative energy source for the DVR. In this study, the design of a fuzzy
logic (FL) controlled DVR are presented and extended to perform fast fault
detection. A new control method for DVR is proposed by combining FL
with a carrier modulated PWM inverter. Simulations were carried out
using the MATLAB SIMULINK. The simulation results proved the capability
of PV-based DVR in eliminating voltage sag and swell distributed system.
Improving the operation of wind farm as a energy generator and
stabilizing its voltage is the main result of this work.

38. • R.Vijayakumar, R.Subramanian “Compensation Of Voltage Variations In
Distribution System By Using DVR Based Separate Energy Storage Devices”
International Electrical Engineering Journal (IEEJ) Vol. 4 (2013)
• The Separate Energy Storage Device (SESD) based Dynamic Voltage
Restorer (DVR) used to protect consumers from the grid voltage
fluctuations like Long and Short-Duration Voltage Variations.
• This paper analyses the operation principle of the SESD based DVR and its
design is based on simple PI control method and decision making switch to
compensate Long and Short-Duration Voltage Variations.
• During short-duration voltage variation super capacitor and fuel cell
hybrid system is used to compensate the fault.
• In the same way during long-duration voltage variation photovoltaic (PV)
system or backup battery or other grid is used to compensate the fault
based on the availability.
• Using MATLAB/SIMULINK, the models of the SESD based DVR is establish,
and the simulation tests are performed to evaluate the system
performances.

39. P.Prasad , Md. Khaja Jainuddin, Y.Rambabu, V.K.R.Mohan Rao Unified Power Quality
Conditioner (UPQC) With Storage Device for Power Quality Problems , Research
Inventy: International Journal Of Engineering And Science Vol.3, Issue 8 (September
2013)
 The quality of the Electrical power is effected by many factors like harmonic
contamination, due to non-linear loads, such as large thyristor power converters,
rectifiers, voltage and current flickering due to arc in arc furnaces, sag and swell
due to the switching of the loads etc.
 One of the many solutions is the use of a combined system of shunt and active
series filters like unified power quality conditioner (UPQC).
 This device combines a shunt active filter together with a series active filter in a
back to back configuration, to simultaneously compensate the supply voltage and
the load current or to mitigate any type of voltage and current fluctuations and
power factor correction in a power distribution network.
 In this paper a novel design of UPQS is proposed which is composed of the DC/DC
converter and the storage device connected to the DC link of UPQS for balancing
the voltage interruption.
 Computer simulation by MATLAB/ SIMULINK has been used to support the
developed concept.

40. • Siyu Leng, Student Member, IEEE, II-Yop Chung, Member, IEEE, Chris S. Edrington, Senior Member, IEEE, and David A. Cartes,
Senior Member, IEEE”A New Harmonic Distortion Measurement Algorithm for Power Quality Evaluation and Compensation”,
2011 IEEE
• A new algorithm is proposed to measure the
harmonic distortion without calculating individual
harmonic components. This feature can greatly
reduce the computational burden on many harmonic
detection methods when it comes to power quality
evaluation. In addition, the proposed algorithm can
also facilitate power quality compensation such as
shunt active filter control or active front-end
coordination. Therefore, the proposed harmonic
distortion measurement algorithm can provide a
flexible and economical solution for many power
quality problems. Simulation results verify the
performance of the proposed algorithm.

41. • Mostafa I. Marei, Member, IEEE, Ehab F. El-Saadany, Senior Member, IEEE,
and Magdy M. A. Salama, Fellow, IEEE ”A Flexible DG Interface Based on a
New RLS Algorithm for Power Quality Improvement” IEEE SYSTEMS
JOURNAL, VOL. 6, NO. 1, MARCH 2012
• Distributed generation (DG) exists in distribution systems and is installed
by either the utility or the customers. This paper proposes a novel
utilization of the existing DG interface to not only control the active power
flow, but also to mitigate unbalance, harmonics and voltage flicker, and
manage the reactive power of the system. The proposed flexible
distributed generation (FDG) is similar in functionality to FACTS, but works
at the distribution level. Moreover, a novel recursive least square (RLS)
structure is presented. The new structure is applied to multi-output (MO)
systems for parameter tracking/estimation, and is called MO-RLS. It is
dedicated to symmetrical components estimation. An innovative
processing unit-based RLS is investigated to deal with unbalance,
harmonics, and reactive power compensation. In addition, this paper
portrays a technique for flicker mitigation based on the RLS algorithm for
instantaneous tracking of the measured voltage envelope. One advantage
of the proposed control system is its insensitivity to parameter variation, a
necessity for distribution system applications. Simulations of the
suggested FDG based control algorithm are conducted to evaluate the
performance of the proposed system.

42. • Seyed Abbas Taher, Seyed Ahmadreza Afsari “Optimal location and sizing
of DSTATCOM in distribution systems by immune algorithm” Electrical
Power and Energy Systems, 2014 Elsevier Ltd
• In this paper, optimal location and sizing of DSTATCOM for the sake of
power loss reduction, and improvement of current and voltage profile in
distribution networks are investigated. An effective biologically inspired
algorithm (Immune Algorithm) is used to search the best location and
determine the size of DSTATCOM. By keeping voltage and current profile
improvements in mind, minimum cost of installation of DSTATCOM and
maximum power loss reduction are integrated into an objective function
through appropriate weighting factors. Comparative results are obtained
on two standard distribution systems (IEEE 33-bus and IEEE 69-bus) with
encouraging optimization as far as location and size of DSTATCOM and
objective function minimization are concerned.

43. • Raphael J. Millnitz dos Santos, Jean C. da Cunha, and Marcello Mezaroba,
Member, IEEE “A Simplified Control Technique for a Dual Unified Power
Quality Conditioner” 2013 IEEE TRANSACTIONS ON INDUSTRIAL
ELECTRONICS
• This paper presents a simplified control technique for a dual three-phase
topology of a unified power quality conditioner - iUPQC. The iUPQC is
composed of two active filters, a series active filter (SAF) and a shunt
active filter (PAF) used to eliminate harmonics and unbalances. Different
from a conventional UPQC, the iUPQC has the series filter controlled as a
sinusoidal current source and the shunt filter controlled as a sinusoidal
voltage source. Therefore, the PWM controls of the iUPQC deal with a
well-known frequency spectrum, since it is controlled using voltage and
current sinusoidal references, different from the conventional UPQC which
is controlled using non-sinusoidal references. In this paper, the proposed
design control, power flow analysis and experimental results of the
developed prototype are presented.

44. • A. Jeraldine Viji a, T. Aruldoss Albert Victoire “Enhanced PLL based SRF control
method for UPQC with fault protection under unbalanced load conditions”
Electrical Power and Energy Systems, 2014 Elsevier
• This paper presents novel control strategy of a three-phase four-wire unified
power quality conditioner (UPQC). It is used to improve power quality in
distribution system. The UPQC is realized by the integration of series and parallel
active power filter (SAPF and PAPF) sharing a common dc bus capacitor. The
realization of parallel APF and series APF are carried out using a three-phase, three
legs voltage source inverter (VSI) with split capacitor. In both APFs the fundamental
source voltages and currents are extracted by synchronous reference frame
technique. SAPF connected with the supply by series transformer. The secondary
of series transformer is affected by load side short circuits. This paper also explains
the control circuit for protection of series transformer against over voltage and
over current. PAPF connected with the system by series inductance. The
performance of the applied control algorithm of shunt active filter with series
active filter is evaluated in terms of power-factor correction, load balancing, and
mitigation of voltage and current harmonics in a three-phase four-wire distribution
system for non-linear load, unbalanced supply and load conditions . Sinusoidal
PWM current controller, modulated hysteresis current controller are used for
generation of switching pulses to series and parallel APFs. The two control
algorithm is simulated by use of MATLAB/Simulink-based environment and the
obtained results validated through experimental study with the UPQC hardware
prototype

45. • Aziz Tashackori, Seyed Hossein Hosseini, Mehran Sabahi, and Tohid Nouri
“A Three-Phase Four-leg DVR Using Three Dimensional Space Vector
Modulation, 2013 IEEE
In this paper a three-phase four-wire Dynamic Voltage Restorer (DVR) is
proposed to inject required compensating series voltage to the electric
power system in such a way that continuous sinusoidal voltage is seen at
load side ever at heavy fault occurrences at utility side. The proposed DVR
is composed of a three-phase four-leg inverter and a three-phase high
frequency harmonic filter that are connected to the utility by three single-
phase power transformers. Three dimensional space vector modulation
(3DSVM) is applied to the proposed DVR to generate switching pulses for
power switches. Fourth added wire enables the DVR to compensate
unbalance voltage sag and swell that are custom power quality problems
in electrical utility. The performance of the structure and applied switching
scheme under both balanced and unbalanced sag and swell are validated
by simulations in PSCAD-EMTDC software.

46. • Hamid Reza Mohammadi, Ali Yazdian Varjani, and
Hossein Mokhtari, Member, IEEE “Multiconverter
Unified Power-Quality Conditioning System: MC-
UPQC” IEEE TRANSACTIONS ON POWER
DELIVERY, VOL. 24, NO. 3, JULY 2009
In the proposed configuration, all converters
are connected back to back on the dc side and
share a common dc-link capacitor. Therefore,
power can be transferred from one feeder to
adjacent feeders to compensate for sag/swell and
interruption.
Software used: PSCAD/EMTDC

47. • Eduardo Espinosa, Jos6 Espinoza Member, IEEE, Luis Moran
Fellow, IEEE “A Multi-Cell Unified Power Quality
Conditioner that Operates with Asymmetrical DC Links
Voltages for Minimum THD”
A UPQC based on power cells that operate with
different DC link voltages has been presented. The DC link
voltages levels are found in order to operate each power
cell at the inverter side with the minimum switching
frequency possible while assuring the minimum THD at the
load total voltage waveform. The voltage results in a
modified square waveform where the angles and
amplitudes are calculated off-line. The results are
presented for a UPQC based on 4 power cells per phase
and the expressions are derived for an arbitrary number of
power cells n,. For instance, for nc. = 8 a parallel voltage
THD of just 4.6 % is achieved.
Software used: PSCAD/EMTDC

48. • Ali Reza Reisi a,Mohammad H. Moradi b, Hemen Showkati “Combined photovoltaic and
unified power quality controller to improve power quality, Solar Energy 88 (2013) 2012
Elsevier Ltd
• Rapid growth of nonlinear loads leads to lots of power quality problems such as harmonics,
unbalance operation and excessive source-end neutral current in three-phase supplying
networks. This paper proposes an combined Photovoltaic (PV) Unified Power Quality
Controller (UPQC) for compensation of source voltage deficiencies (e.g. sag and swell).
Meanwhile, considering the Advanced Generalized Theory of Instantaneous Power (A-GTIP)
algorithm, the proposed UPQC leads to suppress grid-end current harmonics caused by the
distorted–unbalanced load-terminal voltages. Hence, the grid-end currents could remain
purely sinusoidal. Additionally, using combined UPQC and PV system there will be capital
investment savings since one less converter will be used in comparison with separated UPQC
and PV. In this paper a new Maximum Power Point Tracking (MPPT) algorithm is also
proposed to efficiently improve the performance of the solar panels. The proposed algorithm
is composed of two parts, set point calculation and fine tuning. The set point calculation part,
based on the short circuit current method, first approximates maximum power. Second, exact
amount of the maximum power will be tracked by the fine tuning part which is based on the
perturbation and observation method (P&O). Then, output of the MPPT circuit would be
connected to the DC side of the AUPQC. Matlab/Simulink simulations verify the performance
of the proposed PV–UPQC performance.

49. • D. Mahinda Vilathgamuwa, Senior Member, IEEE, H. M. Wijekoon,
Student Member, IEEE, and S. S. Choi, Member, IEEE Interline
Dynamic Voltage Restorer: A Novel and Economical Approach for
Multiline Power Quality Compensation IEEE TRANSACTIONS ON
INDUSTRY APPLICATIONS, VOL. 40, NO. 6, NOVEMBER/DECEMBER
2004
The dynamic voltage restorer (DVR), a custom power device,
has been proposed to protect sensitive loads from the effects of
voltage sags on the distribution feeder. One of the main factors
which limits capabilities of a particular DVR in compensating long-
duration voltage sags is the amount of stored energy within the
restorer. This paper proposes a new concept of interline dynamic
voltage restoration (IDVR) where two or more DVRs in different
feeders are connected to a common dc link. While one of the
DVRs compensates for a voltage sag, the other DVRs connected to
a common dc Link replenish the dc-link energy storage

50. Parametric equations of power quality
events

52. Linear Voltage / Current
No Harmonic Content
voltage
current

53. Non-Linear Voltage / Current
Harmonic Content
voltage
current

54. Types and Sources of Power System
Harmonics

56. • Voltage harmonics are mostly caused by
current harmonics. A non-linear load will not
directly cause voltage harmonics unless it is
injecting power. However, the voltage
provided by the voltage source will be
distorted by current harmonics due to source
impedance. If the source impedance of the
voltage source is small, current harmonics will
cause only a small voltage harmonics.

57. • In a normal alternating current power system, the current varies sinusoidally at a
specific frequency, usually 50 or 60 hertz. When a linear electrical load is
connected to the system, it draws a sinusoidal current at the same frequency as
the voltage (though usually not in phase with the voltage).
• Current harmonics are caused by non-linear loads. When a non-linear load, such
as a rectifier, is connected to the system, it draws a current that is not necessarily
sinusoidal. The current waveform can become quite complex, depending on the
type of load and its interaction with other components of the system. Regardless
of how complex the current waveform becomes, as described through Fourier
series analysis, it is possible to decompose it into a series of simple sinusoids,
which start at the power system fundamental frequency and occur at integer
multiples of the fundamental frequency.
• Further examples of non-linear loads include common office equipment such as
computers and printers, Fluorescent lighting, battery chargers and also variable-
speed drives.