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http://www.iaeme.com/IJEET/index.asp 1 [email protected]
International Journal of Electrical Engineering & Technology (IJEET)
Volume 7, Issue 3, May–June, 2016, pp.01–13, Article ID: IJEET_07_03_001
Available online at
http://www.iaeme.com/ijeet/issues.asp?JType=IJEET&VType=7&IType=3
ISSN Print: 0976-6545 and ISSN Online: 0976-6553
Journal Impact Factor (2016): 8.1891 (Calculated by GISI) www.jifactor.com
© IAEME Publication
SHORT DURATION VOLTAGE
DISTURBANCE IDENTIFICATION USING
RMS ALGORITHM IN DISTRIBUTION
SYSTEM
S. Vijaya Laxmi
Research Scholar, University College of Engg & Tech,
Acharya Nagarjuna University, Andhra Pradesh–India
Dr. P. V. Ramana Rao
Professor & H.O.D/E.E.E, University College of Engg & Tech,
Acharya Nagarjuna University, Andhra Pradesh–India
ABSTRACT
Delivering good quality of power is the main agenda for distribution
system to the loads. But maintain power quality is not so easy due to the load
variations in the system. Sag and swell are the main factors that affect power
quality. In this paper, multiple sag conditions and swell conditions were tested
by producing the condition in different phases of the system. A simple
algorithm called RMS algorithm was developed and tested for the said
conditions. Sag and swell were generated on single phase and multiple phases
for testing the algorithm. The algorithm and the results were obtained using
Matlab.
Key words: RMS, Algorithm, Sag, Swell, Power Quality
Cite this Article: S. Vijaya laxmi and Dr. P. V. Ramana Rao, Short Duration
Voltage Disturbance Identification Using RMS Algorithm in Distribution
System. International Journal of Electrical Engineering & Technology, 7(3),
2016, pp. 01–13.
http://www.iaeme.com/ijeet/issues.asp?JType=IJEET&VType=7&IType=3
1. INTRODUCTION
Power quality determines the quality of electric power to load devices. Maintaining
frequency, voltage and power factor within nominal values makes load to function
properly without stress on the devices. This maintenance of power quality also
reduces the losses in the system increasing the life of the equipment connected. The
paper and also the technology on that are mostly driven by the able quality problems.
S. Vijaya laxmi and Dr. P. V. Ramana Rao
http://www.iaeme.com/IJEET/index.asp 2 [email protected]
The term power quality [1-4] is very general conception. Broadly, it should be
outlined as provision of voltages and system style in order that user electrical power
will use electric energy from the distribution system successfully, while not
interference on interruption. Power quality is outlined within the IEEE one hundred
Authoritative lexicon of IEEE normal terms because the conception of powering and
grounding instrumentation in a very manner that's appropriate to the operation of that
instrumentality and compatible with the premise wiring system and alternative
connected equipment utilities might want to outline power quality as responsible.
From the able quality market or trade perspective, it's any product or service that's
equipped to users or utilities to live, treat, remedy, educate engineers or forestall
Power Quality problems, issues and connected things. This paper critically discusses
concerning the able quality of power issues, problems and connected standards,
assessment of power quality problems and strategies for its correction [5-8].
Power quality issues like transients, sags, swells and alternative to the curving
wave shape of the availability voltage have an effect on the performance of those
instrumentality items. Voltage sags and swell in an electrical grid aren't forever
attainable to avoid as a result of the finite clearing time of the faults that cause the
voltage sags, swells and therefore the propagation of sags and swells from the
transmission and distribution systems to the low-tension hundreds [9-10]. Voltage
sags and swells are the common reasons for interruption in production plants and for
end instrumentality malfunctions generally, specifically, in economical identification
will cause disruption and vital prices attributable to loss of production. One solution
to the present downside is to create the instrumentality itself additional tolerant to
sags, either by intelligent management or by storing energy within the instrumentality.
The main objective of the paper is to generate sag and swell in different phases of
the system and analyze them. A simple RMS algorithm was generated to analyze the
condition of the system, whether the sag/swell exists in the system. If yes, in which
phase of the system. This algorithm developed is very simple.
2. POWER QUALITY DISTURBANCES
Figure 1 Power Quality Issues
Short Duration Voltage Disturbance Identification Using RMS Algorithm In Distribution
System
http://www.iaeme.com/IJEET/index.asp 3 [email protected]
Figure 2 Power System Network that can Produce Sag/Swell
Power quality issues are shown diagrammatically in figure 1 and figure 2 shows
the power system network that creates sag/swell for observation and analysis. Power
system disturbances can occur as general phenomenon and these disturbances are of
two types-long term duration and short duration disturbances. Long duration
disturbances are the disturbances that persist for the duration more than 1 minute. If
the duration of the fault is less than 1 minute, the fault is termed as short duration
fault. Long duration voltage raise is called over voltage and short duration voltage
raise is called swell. Similarly, long duration voltage drop is termed as under-voltage
and short duration voltage drop is termed as sag. Sag is a general phenomenon that
occurs due to energizing heavy loads or starting of large motors. Swell is another kind
which might be produced due to energizing capacitor banks or sudden release in
loads.
Voltage sag might cause poor efficiency and decreases the life time of the device
connected. Swell might cause the device to be damaged. This causes the power
system to poor power quality. Poor power quality can cause unexpected power supply
failures, equipment failure or malfunctioning, equipment overheating and might lead
to reduction in lifetime of the device, increased system losses and production of EMI.
Long term sustained voltage variation if when the supply voltage is zero for more
than 1 minute, the long term voltage disturbance is termed as sustained interruption.
This sustained interruption cannot be cleared automatically and needs human
intervention. Short term variations can be designated as instantaneous, momentary or
temporary. Instantaneous variations in voltage vary from time duration 0-30 cycles,
momentary variations vary from 30 cycles to 30 seconds and temporary variations
vary from 30 seconds to 1 minute in time. Sag is termed as the variation in voltage
from 90% to 10% of its final value for short duration. Swell is raise in voltage value
from 110% to 180% if its final value. Interruption occurs when voltage or current falls
to 0.1 pu in less than 1 minute. When current commutation occurs in power electronic
devices, a periodic voltage disturbance is caused which is called notching.
Instantaneous rapid change in voltage is called transient. Depending on the type of
transient nature, transients are classified into two types- oscillatory and impulsive.
Harmonics are power frequency disturbances having frequency which is integral
multiples of power frequency. These power frequency disturbances can be
decomposed to sum of fundamental quantity and harmonic content. These are mainly
produced due to the presence of non-linear loads in the system.
S. Vijaya laxmi and Dr. P. V. Ramana Rao
http://www.iaeme.com/IJEET/index.asp 4 [email protected]
3. RMS ALGORITHM
A simple algorithm called RMS algorithm was developed to detect the sag/swell in
the system. Sag or swell can cause unusual operation of the system. Thus the sag and
swell should be avoided. But in the power system due to load variations these sag and
swell cannot be avoided and these are very general phenomenon as per the power
system is concerned. But measures should be taken to reduce the sag/swell. To take
any action the first step needed is to identify the parameter. Here the identification of
sag/swell is much important to take necessary action against to reduce the quantity of
sag/swell and bring the voltage level to nominal value. Also the identification is
required in how many phases sag/swell are present in the system. So a simple RMS
algorithm was developed for identification.
Table I RMS Algorithm test cases for identification of sag/swell
Voltage Sag Voltage Swell
Output Phase -
A
Phase -
B
Phase -
C
Phase -
A
Phase -
B
Phase –
C
Case 1 0 0 0 0 0 0 No sag exists
No swell exists
Case 2 1 0 0 0 0 0 Sag exists in 1 phase
Case 3 0 0 0 1 0 0 Swell exists in 1 phase
Case 4 1 1 0 0 0 0 Sag exists in 2 phases
Case 5 0 0 0 1 1 0 Swell exists in 2 phases
Case 6 1 1 1 0 0 0 Sag exists in 3 phases
Case 7 0 0 0 1 1 1 Swell exists in 3 phases
Case 8 1 0 0 1 0 0 Sag exists in 1 phase
Swell exists in 1 phase
Case 9 1 0 0 1 1 0 Sag exists in 1 phase
Swell exists in 2 phase
Case 10 1 0 0 1 1 1 Sag exists in 1 phase
Swell exists in 3 phase
Case 11 1 1 0 1 0 0 Sag exists in 2 phase
Swell exists in 1 phase
Case 12 1 1 0 1 1 0 Sag exists in 2 phase
Swell exists in 2 phase
Case 13 1 1 0 1 1 1 Sag exists in 2 phase
Swell exists in 3 phase
Case 14 1 1 1 1 0 0 Sag exists in 3 phase
Swell exists in 1 phase
Case 15 1 1 1 1 1 0 Sag exists in 3 phase
Swell exists in 2 phase
Case 16 1 1 1 1 1 1 Sag exists in 3 phase
Swell exists in 3 phase
The test conditions were considered as 1 for ON and 0 for OFF. As shown in table
1, the sag and swell were generated for different phases of the power system. Fourier
analysis provides a set of mathematical tools which can be used to break down a
signal into its various magnitude components.
Short Duration Voltage Disturbance Identification Using RMS Algorithm In Distribution
System
http://www.iaeme.com/IJEET/index.asp 5 [email protected]
The identified voltage magnitude from the algorithm will send to the MATLAB
file for evaluation of voltage magnitudes for the given reference signal. In Matlab file
multiple conditional operators have been included for identification type of fault. In
the Matlab file, the identified voltages have been compared to the specified reference
voltages with the use of logical operators, if the identified voltage is less the specified
voltage given as fault identified as sag, if it is greater it is considered as swell.
If the Sag/Swell have been identified in the pre process then it have to identify
whether symmetrical fault or asymmetrical fault. Analysis for identification of fault in
the phases has taken here.The end of the identification process is displaying the
results, these results can further utilized for fault reducing devices a like DVR,
SFCL...Etc.
4. MATLAB RESULT ANALYSIS
Matlab results were obtained by considering different cases producing sag and swell
in different phases of power system.
Case 1: analysis when no sag and no swell are present in the system
Figure 3 Result showing no sag/swell present in the system
Case 2: analysis when only sag exists in 1 phase of the system
Figure 4 result showing sag present in 1 phase of the system
S. Vijaya laxmi and Dr. P. V. Ramana Rao
http://www.iaeme.com/IJEET/index.asp 6 [email protected]
Case 3: analysis when only swell exists in 1 phase of the system
Figure 5 Result showing swell present in 1 phase of the system
Case 4: analysis when sag exists in 2 phase of the system
Figure 6 result showing sag present in 2 phase of the system
Case 5: analysis when swell exists in 2 phase of the system
Figure 7 Result showing swell present in 2 phase of the system
Short Duration Voltage Disturbance Identification Using RMS Algorithm In Distribution
System
http://www.iaeme.com/IJEET/index.asp 7 [email protected]
Case 6: analysis when only sag exists in 3 phase of the system
Figure 8 Result showing sag present in 3 phase of the system
Case 7: analysis when swell exists in 3 phase of the system
Figure 9 Result showing swell present in 3 phase of the system
Figure 3 shows the result window noting that no sag or no swell is present in the
system. Figure 4 shows that sag is present in 1 phase of the system while no swell is
present in the system. Figure 5 shows the swell present in 1 phase with no sag in the
system. Figure 6 shows sag present in 2 phases with no swell and figure 7 shows the
swell in 2 phases with no sag. Figure 8 shows sag present in 3 phases with no swell
while figure 9 shows swell in 3 phases of the system with no sag.
Case 8: analysis when sag exists in 1 phase and swell in 1 phase of the system
S. Vijaya laxmi and Dr. P. V. Ramana Rao
http://www.iaeme.com/IJEET/index.asp 8 [email protected]
Figure 10 Result showing sag present in 1 phase and swell exists in 1 phase of the system
Case 9: analysis when sag exists in 1 phase and swell in 2 phases of the system
Figure 11 Result showing sag present in 1 phase and swell exists in 2 phases of the system
Case 10: analysis when sag exists in 1 phase and swell in 3phases of the system
Figure 12 Result showing sag present in 1 phase and swell exists in 3 phase of the system
Figure 10 shows the window noting sag is present in 1 phase with swell also in 1
phase of the system. Figure 11 shows sag present in 1 phase with swell in 2 phases of
the system. Figure 12 shows the presence of sag in 1 phase with swell in 3 phases of
the system.
Short Duration Voltage Disturbance Identification Using RMS Algorithm In Distribution
System
http://www.iaeme.com/IJEET/index.asp 9 [email protected]
Case 11: analysis when sag exists in 2 phases and swells in 1 phase of the system
Figure 13 Result showing sag present in 2 phase and swell exists in 1 phase of the system
Case 12: analysis when sag exists in 2 phases and swells in 2 phases of the system
Figure 14 Result showing sag present in 2 phase and swell exists in 2 phase of the system
Case 13: analysis when sag exists in 2 phases and swells in 3 phases of the system
S. Vijaya laxmi and Dr. P. V. Ramana Rao
http://www.iaeme.com/IJEET/index.asp 10 [email protected]
Figure 15 Result showing sag present in 2 phase and swell exists in 3 phase of the system
Figure 13 shows the window noting sag is present in 2 phases with swell also in 1
phase of the system. Figure 14 shows sag present in 2 phases with swell in 2 phases of
the system. Figure 15 shows the presence of sag in 2 phases with swell in 3 phases of
the system.
Case 14: analysis when only sag exists in 3 phases and swells in 1 phase of the
system
Figure 16 Result showing sag present in 3 phases and swell exists in 1 phase of the system
Case 15: Analysis when only sag exists in 3 phases and swells in 2 phases of the
system
Short Duration Voltage Disturbance Identification Using RMS Algorithm In Distribution
System
http://www.iaeme.com/IJEET/index.asp 11 [email protected]
Figure 17 Result showing sag present in 3 phase and swell exists in 2 phase of the system
Case 16: analysis when sag exists in 3 phases and swells in 3 phases of the system
Figure 18 Result showing sag present in 3 phase and swell exists in 3 phase of the system
Figure 16 shows the window noting sag is present in 3 phases with swell also in 1
phase of the system. Figure 17 shows sag present in 3 phases with swell in 2 phases of
the system. Figure 18 shows the presence of sag in 3 phases with swell in 3 phases of
the system.
5. CONCLUSION
A Novel sag/swell detection algorithm has been proposed and compared and
implemented by using Matlab algorithms. The simulation study of algorithm has been
presented in this paper for extracting voltage component of source voltage under
sag/swell conditions. The function of in Matlab is a powerful tool for doing that even
with noisy signals. The identification process is very accurate. The simulation results
shows that sag/swell have been identified with what phase swell or sag exists. This
algorithm explained is very simple and can effectively detect the presence of
sag/swell in the system. Different cases have been considered for the production of
sag/swell and the results were shown.
REFERENCES
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S. Vijaya laxmi and Dr. P. V. Ramana Rao
http://www.iaeme.com/IJEET/index.asp 12 [email protected]
[3] A. O. Al-Mathnani, M. A. Hannan, M. Al-Dabbagh, M. A. Mohd Ali, and A.
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Short Duration Voltage Disturbance Identification Using RMS Algorithm In Distribution
System
http://www.iaeme.com/IJEET/index.asp 13 [email protected]
AUTHORS PROFILE
S.VIJAYA LAXMI was born in India in 1975; She received the
B. Tech degree in Electrical and Electronics Engineering from
V.R.S. Engineering College, Vijayawada, Nagarjuna University
in 1997 and M. Tech degree from S.V.U College of Engineering
in 2005 S.V.U Tirupati and Andra Pradesh, India. Currently she
is pursuing Ph.D in Electrical Engineering, as a Research
Scholar in University college of Engineering and Technology,
Acharya Nagarjuna University, Andhra Pradesh India. Her areas
of Interest are Voltage Quality Identification and Mitigation in
Power systems and Application of Intelligent control techniques
to Power systems.
P.V. RAMANA RAO was born in India in 1946; He received
the B. Tech degree in Electrical and Electronics Engineering
from IIT Madras, India in 1967 and M. Tech degree from IIT
Kharagpur, India in 1969. He received Ph. D from R.E.C
Warangal in 1980. Total teaching experience 41 years at NIT
Warangal out of which 12 years as Professor of Electrical
Department. Currently Professor of Electrical Department in
University college of Engineering and Technology, Acharya
Nagarjuna University, Andhra Pradesh, India. His fields of
interests are Power system operation and control, Power System
Stability, HVDC and FACTS, Power System Protection,
Application of DSP techniques and Application of Intelligent
control techniques to Power systems.