Monitoring and analysis of reliaibility of electrical distribution system

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  • 1. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 2, March – April (2013), © IAEME330MONITORING AND ANALYSIS OF RELIAIBILITY OFELECTRICAL DISTRIBUTION SYSTEMUSING MATLAB – A CASE STUDYShubhangi Arbale* and Rajesh M Holmukhe***Post graduate student (ME Electrical)**Associate Professor in Electrical EngineeringElectrical Engineering Department,Bharati Vidyapeeth Deemed University College of EngineeringPune, IndiaABSTRACTElectrical Power distribution reliability and quality are the key challenges faced by theelectrical utility industry in current scenario. Technology alone cannot provide a solution topower reliability and quality problems and there exists a variety of procedures and programsthat can be put in place to ensure reliable, high quality electric supply. Due to its high impacton the cost of electricity and its direct correlation with consumer, distribution reliabilitycontinues to be one of the most important topic in the electric power industry. This studypresents new method of assessing and improving reliability along with the factors that affectit. 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, MATLAB1. INTRODUCTIONThe primary objective of any electric utility company in the new competitiveenvironment would be to increase the market value of the services it provides with the rightamount of reliability and at the same time lower its costs for operation, maintenance, andconstruction of new facilities in order to provide lower rates for consumers. At present, theelectric power industry is undergoing considerable change with respect to structure,INTERNATIONAL JOURNAL OF ELECTRICAL ENGINEERING& TECHNOLOGY (IJEET)ISSN 0976 – 6545(Print)ISSN 0976 – 6553(Online)Volume 4, Issue 2, March – April (2013), pp. 330-337© IAEME: www.iaeme.com/ijeet.aspJournal Impact Factor (2013): 5.5028 (Calculated by GISI)www.jifactor.comIJEET© I A E M E
  • 2. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 2, March – April (2013), © IAEME331operation, and regulation. The various electric utility acts introduced in India have initiatedthe restructuring process and the traditional vertically integrated utility structure consisting ofgeneration, transmission and distribution functions has been dismantled. Instead, distinctgeneration, transmission, and distribution companies have been established in which eachcompany performs a single function in the overall electricity supply task. As a result, theoverall responsibility of serving the individual customer needs does no longer reside in asingle electric utility, as was the case in the vertically integrated utility structure. In order toappreciate the reliability issues arising in the present electric power industry environment, itis necessary to recognize the many faces and actions that are shaping the environment. Thederegulation legislations establish the many new entities to facilitate system operations andmarket functions independent of owners of facilities. As consumers will increasingly demandlower rates and higher reliability in the new competitive environment, the challenging task ofan electric utility company will be to minimize the capital investments and operation andmaintenance expenditures to hold down electricity rates. If, however, the cost is cut too far, itmay endanger the system’s ability to supply reliable power to its consumers. The movementtoward deregulation will therefore introduce a wide range of reliability issues that will requiresystem reliability criteria and tools that can incorporate the residual risks and uncertainties insystem.2. NEED, RESEARCH PROBLEM, STUDY AREA AND OBJECTIVES OF THESTUDYThe distribution reforms have been identified as the key area for putting the powersector on the right track. The strategies identified are aimed at improving financial viability,reduction of T&D losses, improving customer satisfaction, increasing reliability and qualityof power supply. The power system is vulnerable to system abnormalities such as controlfailures, protection or communication system failures, and disturbances, such as lightning,and human operational errors. Therefore, maintaining a reliable power supply is a veryimportant issue for power systems design and operation. The economic and social effects ofloss of electric service have significant impacts on both the utility supplying electric energyand the end users of electric service. The cost of a major power outage confined to one statecan be on the order of tens of millions of rupees. If a major power outage affects multiplestates, then the cost could exceed @Rs 100 million. Reliability overall can be improved bylowering either the frequency or the duration of interruptions. Preventive Maintenanceactivities could impact on the frequency by preventing the actual cause of the failure.Consequently, preventive measures are cost-effective when the reliability benefit outweighsthe cost of implementing the preventive measures. There is, therefore, a need for utilities toincorporate systematic methods which relate maintenance of system assets to theimprovement in system reliability. This is part of the wider concept of asset management.Asset management involves making decisions to allow the network business to maximizelong term profits. While delivering high service, maintenance planning techniques haveseparately been well developed, with reliability assessment starting in the 1930s .However;few techniques relate system reliability to component maintenance. Furthermore, theavailable techniques are not generally put into practice. The reason for this is the lack ofsuitable input data and a reluctance to use theoretical tools to address the practical problem ofmaintenance 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), © IAEME332STATEMENT OF RESEARCH PROBLEMReliable electric power supply is essential for modern society. The extensive use ofelectricity has led to a high susceptibility to power failures. In this way, reliability of supplyhas gained focus and it is considered increasingly important for electric power systemplanning and operation. In this paper, an overview of the state of the art of power systemreliability analysis using MATLAB is studied. The paper is addressed to readers with interestin using different software for reliability analysis methods. The motivation behind this paperis to establish a comprehensive overview of the field of power system reliability assessmenttechniques and to serve as input for further research and development in the area ofapplicability.STUDY AREAThe area of study for this analysis is a small distribution substation region wherenumbers 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 forany type of distribution system with certain modifications.OBJECTIVESThe objective of reliability monitoring is manifold and is as follows:1. Furnish management with performance data regarding the reliability and quality ofelectrical system as a whole and for each voltage level and operating area.2. Provide data for comparison of electrical system performance among consentingcompanies.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 allocation3. SIGNIFICANCE OF THE STUDYElectric power distribution systems constitute the greatest risk to the interruption ofpower supply. Earlier distribution systems have received less attention than generation andtransmission systems .Presently, focus is moving toward distribution as the electricaldistribution companies business focus changes from consumers to customers. Deregulation ofthe power system market has led to a shift from technical to economic driving factors. Theutilities that own and operate the power distribution systems now face various marketrequirements. On the one hand, customers are paying for a service (delivered energy) and theauthorities are imposing regulation, supervision, and compensation depending on the degreeto which contractual and other obligations are fulfilled. On the other hand, utilities mustensure that their expenditure is cost-effective. This means that electricity utilities must satisfyquantitative reliability requirements while at the same time minimizing their costs. Onepredominant expense for a utility is the cost of maintaining system assets, for examplethrough adopting preventive measures, collectively called preventive maintenance (PM).PMmeasures can impact on reliability by either improving the condition, or prolonging thelifetime 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), © IAEME333METHODOLOGY ADOPTED FOR THE STUDYThe researchers have done field visits to distribution substation in Solapur and Punecities located in state of Maharashtra (India).Informal discussions were conducted withengineers and officers from these distribution companies/Utilities.DIFFERENCE BETWEEN CMS (Consumer monitoring System i.e. presently used inelectrical distribution companies/ utilities e.g. MAHADISCOM / MSEB) ANDRELIABILITY ANALYSIS system USING MATLAB(studied and developed byresearchers)Table 1Sr.No.CMS MATLAB1 Problem of consumermapping.As this system is operatedonline, therefore no consumermapping problem2 Possibilities of humanerror are more.No possibility of human error, asall the data is fed automaticallyto the system.3 Cannot be interfacedwith SCADA and/orSAMRTGRIDEasily interfaced with SCADAand SAMRTGRID by usingprocessors4 Input data is fed to thesystem manually.Input data is fed to the systemautomatically4. SAMPLE MODEL FOR ANALYSISFig. 1 Sample Model for AnalysisThis circuit diagram is for distribution system which distributes power to Industrialarea and residential area 1 and 2.It consists of three phase voltage source in series with RLbranch. This source is connected to two winding transformer through three phase VImeasurement 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), © IAEME334industrial etc ) through 25KV feeder which is a transmission line with a single PI section. Themodel consists of one set of RL series elements connected between input and outputterminals and two sets of shunt capacitance lumped at both ends of the line. The scope is usedto check the output.5. POWER GENERATION UNIT- SUBSYSTEM:This is a subsystem of generating unit It consists of three phase synchronous machine withthree 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: SubsystemFig.3 Flow chart for analysis of Reliability IndicesStartPrepare sample model inSimulinkInsert FaultAdd interruption timeRun Model for 8.64sec.Analyze the model whichcalculate SAIFI,SAIDI,CAIDI valuesGenerate report in tableformat and in the form ofgraph.Running directlypower distribution GUIEndEnd
  • 6. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 2, March – April (2013), © IAEME335FAULT PATTERN FOR INDUSTRIAL AREA AND RESIDENTIAL AREAFig.4 Simulation Result: Output for Fig 5. Simulation Result: Output forIndustrial Area Residential AreaThis graph gives fault current with respect to time(i.e. fault pattern) for industrial area (fig4)and residential area(fig 5) .During fault when current drops below 100A, then themagnitude of current in all three phases for each interruption is seen.OUTPUTTable 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), © IAEME336Fig.6 Overall Performance Indices Fig.7 Overall Performance IndicesThe overall performance indices (Fig 6 and 7)gives pictorial presentation ofmagnitude of SAIFI, SAIDI, CAIFI which helps to find out the area with poor reliability anddetermine the places where modification, maintenance and renovation is required in powerdistribution system. In month of May SAIDI is 241.022 minutes, it means that the averagecustomer was out for 241.022 minutes on month of May. CAIDI is 12463.5 minutes, itmeans, on average, any customer who experienced an outage in May was out of service for12463.5 minutes. SAIFI is 10, this means that in month of May , the customers at this utilityhad 10 probability of experiencing a power outage. SAIFI can also be found by dividing theSAIDI value by the CAIDI value,6. CONCLUSIONIn this study, a simple and efficient reliability monitoring and analysis method hasbeen proposed for determining reliability Indices. This MATLAB Software oriented analysiscan be applied for any type of configuration of the distribution system and on line assessmentis also possible with certain modifications and additional processors. Reliability monitoringprovides 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 ormaintenance methods, and operating practices affect performance. This will help to obtain theoptimum improvement in reliability per rupee spent for design, maintenance and operatingprograms and in addition, use this information to predict the performance of futuretransmission and distribution system arrangements. The system studied and developed herecan be integrated with SCADA and /or Smart Grid. In present system used by distributionutilities in Maharashtra (India), the main difficulty is consumer mapping of large number ofconsumers. Presently there are different steps used by distribution utilities e.g. fixing sourceof 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 .TheMATLAB system studied and developed by researchers will provides solution to consumermapping problem as this system automatically operates such that correct Indices arecalculated with proper consumer mapping.050001000015000200002500030000JanuaryFebruaryMarchAprilMayJuneJulyAugustSeptem…OctomberNovemberDecemberSAIDI(Min) SAIFI(No) CAIDI(Min)050001000015000200002500030000JanuaryFebruaryMarchAprilMayJuneJulyAugustSeptemberOctomberNovemberDecemberSAIDI(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), © IAEME337ACKNOWLEDEMENTBharati Vidyapeeth Deemed University College of Engineering, Pune, Maharashtrastate (India) for providing lab for experimentation, library for journals/books and MATLABsoftware 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 ofreliability 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," IEEETransactions 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 reliabilityII—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, “EnhancingPower Quality and Reliability in Deregulated Environment”, International Journal ofElectrical 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 usingMATLAB”, International Journal of Electrical Engineering & Technology (IJEET), Volume3, 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 ofIndustrial Engineering Research and Development (IJIERD), Volume 4, Issue 1, 2013,pp. 19 - 24, ISSN Online: 0976 - 6979, ISSN Print: 0976 - 6987.FIELD VISITSVarious electricity distribution substations in Pune and solapur city in state ofMaharashtra (India).WEBSITES1) www.cumminspower.com/ Accessed in year 20122) www.mahdiscom.com/ Accessed in year 20123) www.matlab.com/ Accessed in year 20104) www.merc.com/ Accessed in year 2013