1. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –
6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 2, March – April (2013), © IAEME
330
MONITORING AND ANALYSIS OF RELIAIBILITY OF
ELECTRICAL DISTRIBUTION SYSTEM
USING MATLAB – A CASE STUDY
Shubhangi Arbale* and Rajesh M Holmukhe**
*Post graduate student (ME Electrical)
**Associate Professor in Electrical Engineering
Electrical Engineering Department,
Bharati Vidyapeeth Deemed University College of Engineering
Pune, India
ABSTRACT
Electrical Power distribution reliability and quality are the key challenges faced by the
electrical utility industry in current scenario. Technology alone cannot provide a solution to
power reliability and quality problems and there exists a variety of procedures and programs
that can be put in place to ensure reliable, high quality electric supply. Due to its high impact
on the cost of electricity and its direct correlation with consumer, distribution reliability
continues to be one of the most important topic in the electric power industry. This study
presents new method of assessing and improving reliability along with the factors that affect
it. A reliability analysis program of a sample model using MATLAB software is developed.
Also algorithm and flowcharts which generate reports and graphs are specified.
Keywords- Power quality, Distribution reliability, MATLAB
1. INTRODUCTION
The primary objective of any electric utility company in the new competitive
environment would be to increase the market value of the services it provides with the right
amount of reliability and at the same time lower its costs for operation, maintenance, and
construction of new facilities in order to provide lower rates for consumers. At present, the
electric power industry is undergoing considerable change with respect to structure,
INTERNATIONAL JOURNAL OF ELECTRICAL ENGINEERING
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ISSN 0976 – 6545(Print)
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2. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –
6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 2, March – April (2013), © IAEME
331
operation, and regulation. The various electric utility acts introduced in India have initiated
the restructuring process and the traditional vertically integrated utility structure consisting of
generation, transmission and distribution functions has been dismantled. Instead, distinct
generation, transmission, and distribution companies have been established in which each
company performs a single function in the overall electricity supply task. As a result, the
overall responsibility of serving the individual customer needs does no longer reside in a
single electric utility, as was the case in the vertically integrated utility structure. In order to
appreciate the reliability issues arising in the present electric power industry environment, it
is necessary to recognize the many faces and actions that are shaping the environment. The
deregulation legislations establish the many new entities to facilitate system operations and
market functions independent of owners of facilities. As consumers will increasingly demand
lower rates and higher reliability in the new competitive environment, the challenging task of
an electric utility company will be to minimize the capital investments and operation and
maintenance expenditures to hold down electricity rates. If, however, the cost is cut too far, it
may endanger the system’s ability to supply reliable power to its consumers. The movement
toward deregulation will therefore introduce a wide range of reliability issues that will require
system reliability criteria and tools that can incorporate the residual risks and uncertainties in
system.
2. NEED, RESEARCH PROBLEM, STUDY AREA AND OBJECTIVES OF THE
STUDY
The distribution reforms have been identified as the key area for putting the power
sector on the right track. The strategies identified are aimed at improving financial viability,
reduction of T&D losses, improving customer satisfaction, increasing reliability and quality
of power supply. The power system is vulnerable to system abnormalities such as control
failures, protection or communication system failures, and disturbances, such as lightning,
and human operational errors. Therefore, maintaining a reliable power supply is a very
important issue for power systems design and operation. The economic and social effects of
loss of electric service have significant impacts on both the utility supplying electric energy
and the end users of electric service. The cost of a major power outage confined to one state
can be on the order of tens of millions of rupees. If a major power outage affects multiple
states, then the cost could exceed @Rs 100 million. Reliability overall can be improved by
lowering either the frequency or the duration of interruptions. Preventive Maintenance
activities could impact on the frequency by preventing the actual cause of the failure.
Consequently, preventive measures are cost-effective when the reliability benefit outweighs
the cost of implementing the preventive measures. There is, therefore, a need for utilities to
incorporate systematic methods which relate maintenance of system assets to the
improvement in system reliability. This is part of the wider concept of asset management.
Asset management involves making decisions to allow the network business to maximize
long term profits. While delivering high service, maintenance planning techniques have
separately been well developed, with reliability assessment starting in the 1930s .However;
few techniques relate system reliability to component maintenance. Furthermore, the
available techniques are not generally put into practice. The reason for this is the lack of
suitable input data and a reluctance to use theoretical tools to address the practical problem of
maintenance planning

3. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –
6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 2, March – April (2013), © IAEME
332
STATEMENT OF RESEARCH PROBLEM
Reliable electric power supply is essential for modern society. The extensive use of
electricity has led to a high susceptibility to power failures. In this way, reliability of supply
has gained focus and it is considered increasingly important for electric power system
planning and operation. In this paper, an overview of the state of the art of power system
reliability analysis using MATLAB is studied. The paper is addressed to readers with interest
in using different software for reliability analysis methods. The motivation behind this paper
is to establish a comprehensive overview of the field of power system reliability assessment
techniques and to serve as input for further research and development in the area of
applicability.
STUDY AREA
The area of study for this analysis is a small distribution substation region where
numbers of consumers are within one lakh and type of consumers are is either residential,
commercial or Industrial (i.e. LT and HT consumers both ).This system can be used for
any type of distribution system with certain modifications.
OBJECTIVES
The objective of reliability monitoring is manifold and is as follows:
1. Furnish management with performance data regarding the reliability and quality of
electrical system as a whole and for each voltage level and operating area.
2. Provide data for comparison of electrical system performance among consenting
companies.
3. Provide data for analysis of reliability of service in a given area (geographical,
political, operating, etc) to determine how factors such as design differences,
environment or maintenance methods, and operating practices affect performance.
4. Maintenance scheduling and Resource allocation
3. SIGNIFICANCE OF THE STUDY
Electric power distribution systems constitute the greatest risk to the interruption of
power supply. Earlier distribution systems have received less attention than generation and
transmission systems .Presently, focus is moving toward distribution as the electrical
distribution companies business focus changes from consumers to customers. Deregulation of
the power system market has led to a shift from technical to economic driving factors. The
utilities that own and operate the power distribution systems now face various market
requirements. On the one hand, customers are paying for a service (delivered energy) and the
authorities are imposing regulation, supervision, and compensation depending on the degree
to which contractual and other obligations are fulfilled. On the other hand, utilities must
ensure that their expenditure is cost-effective. This means that electricity utilities must satisfy
quantitative reliability requirements while at the same time minimizing their costs. One
predominant expense for a utility is the cost of maintaining system assets, for example
through adopting preventive measures, collectively called preventive maintenance (PM).PM
measures can impact on reliability by either improving the condition, or prolonging the
lifetime of an asset.

4. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –
6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 2, March – April (2013), © IAEME
333
METHODOLOGY ADOPTED FOR THE STUDY
The researchers have done field visits to distribution substation in Solapur and Pune
cities located in state of Maharashtra (India).Informal discussions were conducted with
engineers and officers from these distribution companies/Utilities.
DIFFERENCE BETWEEN CMS (Consumer monitoring System i.e. presently used in
electrical distribution companies/ utilities e.g. MAHADISCOM / MSEB) AND
RELIABILITY ANALYSIS system USING MATLAB(studied and developed by
researchers)
Table 1
Sr.
No.
CMS MATLAB
1 Problem of consumer
mapping.
As this system is operated
online, therefore no consumer
mapping problem
2 Possibilities of human
error are more.
No possibility of human error, as
all the data is fed automatically
to the system.
3 Cannot be interfaced
with SCADA and/or
SAMRTGRID
Easily interfaced with SCADA
and SAMRTGRID by using
processors
4 Input data is fed to the
system manually.
Input data is fed to the system
automatically
4. SAMPLE MODEL FOR ANALYSIS
Fig. 1 Sample Model for Analysis
This circuit diagram is for distribution system which distributes power to Industrial
area and residential area 1 and 2.It consists of three phase voltage source in series with RL
branch. This source is connected to two winding transformer through three phase VI
measurement link. Then the connection is given to different consumers (i.e. residential,

5. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –
6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 2, March – April (2013), © IAEME
334
industrial etc ) through 25KV feeder which is a transmission line with a single PI section. The
model consists of one set of RL series elements connected between input and output
terminals and two sets of shunt capacitance lumped at both ends of the line. The scope is used
to check the output.
5. POWER GENERATION UNIT- SUBSYSTEM:
This is a subsystem of generating unit It consists of three phase synchronous machine with
three phase parallel RLC load. Further through the step down transformer (13.8KV/120 KV),
the supply is given to lines via connection 1, 2, 3.as shown in the following block.
Fig.2 Power Generation Unit: Subsystem
Fig.3 Flow chart for analysis of Reliability Indices
Start
Prepare sample model in
Simulink
Insert Fault
Add interruption time
Run Model for 8.64
sec.
Analyze the model which
calculate SAIFI,
SAIDI,CAIDI values
Generate report in table
format and in the form of
graph.
Running directly
power distribution GUI
End
End

6. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –
6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 2, March – April (2013), © IAEME
335
FAULT PATTERN FOR INDUSTRIAL AREA AND RESIDENTIAL AREA
Fig.4 Simulation Result: Output for Fig 5. Simulation Result: Output for
Industrial Area Residential Area
This graph gives fault current with respect to time(i.e. fault pattern) for industrial area (fig
4)and residential area(fig 5) .During fault when current drops below 100A, then the
magnitude of current in all three phases for each interruption is seen.
OUTPUT
Table 2. Annual Overall Performance Indices

7. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –
6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 2, March – April (2013), © IAEME
336
Fig.6 Overall Performance Indices Fig.7 Overall Performance Indices
The overall performance indices (Fig 6 and 7)gives pictorial presentation of
magnitude of SAIFI, SAIDI, CAIFI which helps to find out the area with poor reliability and
determine the places where modification, maintenance and renovation is required in power
distribution system. In month of May SAIDI is 241.022 minutes, it means that the average
customer was out for 241.022 minutes on month of May. CAIDI is 12463.5 minutes, it
means, on average, any customer who experienced an outage in May was out of service for
12463.5 minutes. SAIFI is 10, this means that in month of May , the customers at this utility
had 10 probability of experiencing a power outage. SAIFI can also be found by dividing the
SAIDI value by the CAIDI value,
6. CONCLUSION
In this study, a simple and efficient reliability monitoring and analysis method has
been proposed for determining reliability Indices. This MATLAB Software oriented analysis
can be applied for any type of configuration of the distribution system and on line assessment
is also possible with certain modifications and additional processors. Reliability monitoring
provides data for analysis to determine reliability of service in a given area (geographical,
political, operating, etc) to determine how factors such as design differences, environment or
maintenance methods, and operating practices affect performance. This will help to obtain the
optimum improvement in reliability per rupee spent for design, maintenance and operating
programs and in addition, use this information to predict the performance of future
transmission and distribution system arrangements. The system studied and developed here
can be integrated with SCADA and /or Smart Grid. In present system used by distribution
utilities in Maharashtra (India), the main difficulty is consumer mapping of large number of
consumers. Presently there are different steps used by distribution utilities e.g. fixing source
of supply to consumer from distribution transformer centre, carrying out pole to pole survey,
thus determining the consumer location with pole number to feed input from DTC
(distribution transformer) , billing ,tally of billed consumption for energy audit etc .The
MATLAB system studied and developed by researchers will provides solution to consumer
mapping problem as this system automatically operates such that correct Indices are
calculated with proper consumer mapping.
0
5000
10000
15000
20000
25000
30000
January
February
March
April
May
June
July
August
Septem…
Octomber
November
December
SAIDI(Min) SAIFI(No) CAIDI(Min)
0
5000
10000
15000
20000
25000
30000
January
February
March
April
May
June
July
August
September
Octomber
November
December
SAIDI(Min) SAIFI(No) CAIDI(Min)

8. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –
6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 2, March – April (2013), © IAEME
337
ACKNOWLEDEMENT
Bharati Vidyapeeth Deemed University College of Engineering, Pune, Maharashtra
state (India) for providing lab for experimentation, library for journals/books and MATLAB
software facilities. Maharashtra State Electricity Distribution Co. Ltd, Pune and solapur,
Maharashtra state (India) for necessary information.
REFERENCES
[1] Reliability of Electric Utility Distribution Systems: EPRI White Paper, EPRI, Palo Alto,
CA.
[2] Brown R. E., Electric Distribution System Reliability, Marcel Dekker, New York, 2002.
[3] Gaver D.P., Montmeat F.E,. Patton A.D, Power system reliability: I—Measures of
reliability and methods of calculation. IEEE Trans. Power Apparatus Syst., Vol. 83,
pp. 727-737, July, 1964.
[4] Patton D., "Determination and Analysis of Data for Reliability Studies," IEEE
Transactions on Power Apparatus and Systems, PAS-87, January 1968.
[5] Broadwater R P., Shaalan H E., Distribution system reliability and restoration analysis,
Electric Power System Research, 29 (1994) pp. 203-211
[6] Montmeat C. E, Patton A.D., Zemkowski J., Cumming D. J., Power system reliability
II—Applications and a computer program, IEEE Trans. Power Apparatus Syst., Vol. PAS-87,
pp. 636-643, July, 1965.
[7] Dr C.K.Panigrahi, P.K.Mohanty, A.Nimje, N.Soren, A.Sahu and R.K.Pati, “Enhancing
Power Quality and Reliability in Deregulated Environment”, International Journal of
Electrical Engineering & Technology (IJEET), Volume 2, Issue 2, 2011, pp. 1 - 11,
ISSN Print : 0976-6545, ISSN Online: 0976-6553.
[8] Dr. V.Balaji and E.Maheswari, “Model Predictive Control Techniques for CSTR using
MATLAB”, International Journal of Electrical Engineering & Technology (IJEET), Volume
3, Issue 3, 2012, pp. 121 - 129, ISSN Print : 0976-6545, ISSN Online: 0976-6553.
[9] Flt Lt Dinesh Kumar Gupta, “Linear Programming in MATLAB” International Journal of
Industrial Engineering Research and Development (IJIERD), Volume 4, Issue 1, 2013,
pp. 19 - 24, ISSN Online: 0976 - 6979, ISSN Print: 0976 - 6987.
FIELD VISITS
Various electricity distribution substations in Pune and solapur city in state of
Maharashtra (India).
WEBSITES
1) www.cumminspower.com/ Accessed in year 2012
2) www.mahdiscom.com/ Accessed in year 2012
3) www.matlab.com/ Accessed in year 2010
4) www.merc.com/ Accessed in year 2013