Bonfring International Journal of Power Systems and Integrated Circuits, Vol. 9, No. 1, March 2019
1
Power Quality Improvement Using Dynamic
Voltage Restorer
K. Sureshkumar, S. Vasanthamani, M. Mariammal, S. Raj,
R.L. Vinodkumar
Abstract--- One of the important in a power system study
is a power quality improvement. It will be important now due
to preface the discrete industrial devices and sensitive loads.
The main issues in a power quality are voltage sags and swells
at the distribution side. There are many different methods
available to defect voltage sags and swells; the most popular
methods is DVR (Dynamic Voltage Restorer). The DVR is a
series compensating device, it is mainly used in low voltage
and medium voltage application. The new configuration of
DVR has been proposed using PI (Proportional Integral) controller and PID (Proportional Integral Derivative) controller and also THD values of PI (Proportional Integral)
and PID (Proportional Integral Derivative) controllers are
compared and it is conclude that total THD in PID
(Proportional Integral Derivative) controller is better than PI
(Proportional Integral) controller, which compensates voltage
sags and swells during a single phase fault. Simulation results
are carried out with MATLAB/SIMULINK to verify the
performance of the proposed model.
Keywords--- DVR, Single-Phase Faults, Voltage Sags,
Voltage Swells.
I.
INTRODUCTION
W
E know the quality of power is facing discrete problems
such as voltage sags, swells, surges, flicker, voltage
imbalance, interruption and harmonic distortion. Among that
voltage sags and swells are more frequent and acute than
others. The DVR is one of the most custom power devices
used for the progress of power quality performance. The DVR
maintains the load side voltage at a real magnitude and phase
by compensating the voltage sags and swells. Therefore any
variety of voltage unbalance at the point of common coupling
(PCC) can be eliminated. The DVR compensates voltage sags
by increasing voltage in series with the supply side, hence
overcomes the losses of power. The DVR injects sufficient
amount of voltage to restore the voltage to its real value. The
amount of power injection by the DVR can be decided by
choosing an appropriate amplitude and phase angle.The SVC
pre-dates the DVR, but the DVR is still favored because the
SVC has no capability to control the active power flow. The
DVR is small in size and price is less compared to
DSTATCOM and other custom power devices.Most of the
HVDC systems in operation today are based on linecommutated converters. With line commutated converters, the
converter has only one degree of freedom – the firing angle,
which represents the time delay between the voltage across a
valve becoming positive (at which point the valve would start
to conduct) and the thyristors being turned on.PID
(Proportional Integral Derivative) is not heavy on hardware,
therefore it can be implemented on cheap hardware also. For
e.g. arduino Uno can run a couple of PID (Proportional
Integral Derivative) loops very efficiently.PID(Proportional
Integral Derivative) controller once designed, then its further
tuning doesn't require a skilled personnel.
According to IEEE 519 1992 and IEEE 1159 1995
standards voltage sag generally ranges from 10%-90% of the
real operating voltage and lasts for a duration of half cycle to
1minute. On the other hand voltage swells are defined as an
increase in RMS voltage for durations 0.5 cycles to 1 minute
with magnitude 1.1pu to 1.8pu. The Fig.1 below shows the
voltage sags and swells of IEEE 1159 1995 standard.
As voltage swells are less common in distribution side so
they do not need much more attention as voltage sags. Voltage
sags and swells can create large current unbalance, causes
shutdown or failure to sensitive equipments.
Figure 1: Voltage Reduction
II.
K. Sureshkumar, UG Student, Department of Electrical and Electronics
Engineering, SCAD Institute of Technology.
S. Vasanthamani, UG Student, Department of Electrical and Electronics
Engineering, SCAD Institute of Technology.
M. Mariammal, UG Student, Department of Electrical and Electronics
Engineering, SCAD Institute of Technology.
S. Raj, UG Student, Department of Electrical and Electronics
Engineering, SCAD Institute of Technology.
R.L. Vinodkumar, Asst Professor, Department of Electrical and
Electronics Engineering, SCAD Institute of Technology.
DOI:10.9756/BIJPSIC.9002
LITERATURE SURVEY
In 2016, R.Kalaivani, Voltage sag disturbances are the
most frequently occurring Power Quality problems in the
distribution system. This concept explains modeling and
simulation of a dynamic voltage restorer as a voltage sag and
swell mitigation device in electrical power distribution
networks. A Dynamic Voltage Restorer (DVR) is proposed to
handle deep voltage sags, swells and outages on a low voltage
single phase residential distribution system.
ISSN 2277-5072 | © 2019 Bonfring
Bonfring International Journal of Power Systems and Integrated Circuits, Vol. 9, No. 1, March 2019
In 2015, S.Manmadha Rao, S.V.R.LakshmiKumari,
B.Srinivasa Rao,
Power quality is the most important aspect in the present
power system environment. Among all the power quality
problems most frequently occurring disturbances, affecting the
quality of power are voltage sags and swells. Custom power
device, Dynamic Voltage Restorer (DVR) connected in series
with a goal to protect the loads from source side voltage
disturbances. Here single phase DVR is adopted for each
phase instead of using three phase DVR to compensate
unbalanced sags/swells.
2
The change in phase angle is obtained by comparing the
per-unit faulted voltage with the reference voltage 1P.U. Then
the error signal so obtain is given to PI (Proportional
Integral)controller and PID (Proportional Integral Derivative)
controller, which generates the required change in phase
angle. Then the reference voltage is generated by using new
changed phase angle which are summarized in equation.
The MATLAB representation of the control strategy of
DVR is shown in Fig.4.
DYNAMIC VOLTAGE RESTORE
III.
L. Gyugyi in 1994 proposed a methodology for dynamic
voltage restoration at the distribution end. This method
enables the use of real power to be injected at the faulted
supply voltage side and is known as dynamic voltage restorer.
In this study, the DVR structure basically consists of a voltage
source converter (VSC), a line injection transformer between
the supply AC voltage side and the sensitive load, a dc energy
source in parallel with a DC link capacitor and a control
technique as shown in Fig.2.
Figure 4: Simulink Model for the Control Strategy of DVR
The flow chart for the control strategy of DVR for
injecting the voltage to a test system during fault condition is
shown in Fig.5.
As the DVR is a series compensating device, so it is
connected in series between the source voltage side and the
sensitive load through the line injection transformer. In order
to inject active and reactive power several types of energy
storage are used. Such as battery bank, DC link capacitor,
super conductors. For the switching action of the DVR during
fault duration controller is an important part. The VSI converts
DC to AC and makes it sure that only the sag and swell
voltage will be injected through the line transformer at the
PCC.
Figure 2: Basic Topology of a DVR
IV.
CONTROL STRATEGY
For fast response action the control strategy of the DVR
plays an important role. When the voltage sags and swells are
detected, the DVR should react as fast as possible. It can be
implemented using SPWM control technique per unit
reference voltage and instantaneous value of load voltage in
per unit.
The basic rules of control strategy are as follows:detection of voltage sags and swells, calculating the amount of
compensation required, generating pulses through SPWM
generator and stop the pulse triggering after passing of fault
duration.
Figure 5: Flow Chart for the Control Strategy of DVR
It is then given to SPWM generator to produce singlephase pulse that controls the switching of VSI and hence the
DVR. The Fig.6 below shows the control strategy for
generating reference voltage.
ISSN 2277-5072 | © 2019 Bonfring
Bonfring International Journal of Power Systems and Integrated Circuits, Vol. 9, No. 1, March 2019
Figure 6: Control Strategy for Reference Voltage Generator
The complete schematic diagram of DVR with proposed
system is shown in Fig.7.
Figure 7: Simulation of DVR Connected System
V.
SIMULATION RESULTS
3
Figure 8 (b): Load side voltage after sagCompensation with PI
controller
Figure 8 (c): Load Voltage after sag Compensation with PID
Controller
The Fig.8 (a) represents the duration of three-phase voltage
sag. The result shows about 80% drop in voltage during the
sag duration within the interval 0.1sec to 0.2sec. With a total
sag duration for 0.1sec.
(b)Shows the line voltage after sag compensation with PI
(Proportional Integral) controller. Shows the line voltage after
sag compensation with PID (Proportional Integral
Derivative)controller.
Figure 8(d): THD with PI Controller
Figure 8 (a): Load Bus Voltage During Sag
Figure 8(e): THD with PID Controller
ISSN 2277-5072 | © 2019 Bonfring
Bonfring International Journal of Power Systems and Integrated Circuits, Vol. 9, No. 1, March 2019
The THD for PI controller in DVR having 1% with the
fundamental frequency 50HZ as shown in figure-8(d).
The THD for PID controller in DVR having 0.9% with the
fundamental frequency 50HZ as shown in figure-8(e).
[14] R. Mihalic, P. Zunko and D. Povh, “Improvement of transient stability
using unified power flow controller power delivery”, IEEE Transactions,
Vol. 11, Pp. 485–492, 1996.
[15] A.A. Edris, “Proposed terms and definitions for flexible AC
transmission systems (FACTS)”, IEEE Transactions, Vol. 2, Pp. 1848–
1853, 1997.
The THD for PID controller is better than PI controller.
VI.
CONCLUSION
A comprehensive study of a DVR as a powerful custom
power device has been studied with use of
MATLAB/SIMULINK. The main advantages of DVR are low
cost, simpler implementation; require less computational
efforts and its control is simple as compared to other methods.
The control system is based on PI(Proportional Integral) and
PID(Proportional Integral Derivative) based SPWM technique
which scaled error between load side of the test system and its
reference for compensating sags and swells. The simulation
results show that the DVR performance is efficient in
mitigation ofvoltage sags and swells. The DVR handles both
overvoltage and under voltage situations without any
difficulties. It injects an appropriate voltage component to
correct any abnormality rapidly in the voltage waveform; in
addition, it keeps the load voltage balanced and constant at the
nominal value.
REFERENCES
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12]
[13]
4
R. Pal and S. Gupta, “Simulation of Dynamic Voltage Restorer (DVR)
to Mitigate Voltage Sag During Three-Phase Fault”, International
Conference on Electrical Power and Energy Systems (ICEPES), 2016.
Y. Prakash and S. Sankar, “Mitigation of Voltage SAG Problem Using
Dynamic Voltage Restorer (DVR)”, International Journal of Advanced
Research in Electrical, Electronics and Instrumentation Engineering,
Vol. 4, No. 10, 2015.
D. Francis, “Mitigation of Voltage Sag and Swell Using Dynamic
Voltage Restorer”, International Conference on Magnetics, Machines &
Drives, AICERA, 2014.
M. Venmathi and L. Ramesh, “The Impact of Dynamic Voltage Restorer
on Voltage Sag Mitigation”, IET Chennai 3rd International on
Sustainable Energy and Intelligent Systems (SEISCON 2012), Pp. 1-7,
2012.
C. Benachaiba and B. Ferdi, “Power Quality Improvement Using DVR”,
American Journal of Applied Sciences, Vol. 6, No. 3, Pp. 396-400,
2009.
H. Kim, S.J. Lee and S.K. Sul, “Reference wave generation in dynamic
voltage restorers by use of PQR power theory”, IEEE Applied Power
Electr. Conf. and Exposition, Vol, 3, Pp.1452-1457, 2004.
H.J. Jung, I.Y. Suh, B.S. Kim, R.Y. Kim, S.Y. Choi and J.H. Song, “A
study on DVR control for unbalanced voltage compensation”, IEEE
Applied Electronics Conference and Expositions, Vol. 2, Pp.1068-1073,
2002 .
K.C. Bayindir, A. Teke and M. Tumay, “A robust control of dynamic
voltage restorer using fuzzy logic”, Electrical Machines and Power
Electronics, International Aegean Conf., Pp. 55-60, 2007.
P. Ruilin and Z. Yuegen, “Sliding mode control strategy of dynamic
voltage restorer”, International Conference on Industrial Electronics and
Control Applications, 2005.
F. Jurado, “Neural network control for dynamic voltage restorer”, IEEE
Trans on Industrial Electronics, Vol. 51, 2004.
K. Iyer, “Dynamic Voltage restorer three dimensional space vector
PWM control algorithm”, 9 th International, Conference Electrical
Power Quality and Utilization, 2007.
L. Sarıbulut, “Performance analysis of unified power flow controller
(UPFC) by using different controllers”, M.Sc. thesis, Department of
Electrical and Electronic Engineering, Cukurova University, 2008.
Y.H. Song and A.T. Johns, Flexible AC Transmission Systems
(FACTS), IEE Power and Energy Series, 1999.
ISSN 2277-5072 | © 2019 Bonfring
Keep reading this paper — and 50 million others — with a free Academia account
Used by leading Academics
Galal Nadim
Fayoum University
Hossein Sadegh Lafmejani
Sotirios Xydis
National Technical University of Athens
Marjorie Skubic
University of Missouri Columbia
