The institute of electrical and electronics engineers standards association ieeesa is an organization within ieee that develops global standards in a broad range of industries, including. The operational profile is a quantitative characterization of how a system will be used that shows how to increase productivity and reliability and speed development by allocating development resources to function on the basis of use. The ieee distribution reliability working group is heavily vested in the use and proper application of the reliability indices. Pdf reliability analysis of distribution system using etap. Ieee xplore, delivering full text access to the worlds highest quality technical literature in engineering and technology. Probability distributions of saifi and saidi for the ieeerts. Using the historic data number of failures per year for every failure data 50 cus oh ss ss oh failure data 0. Germanys value on the saidi is much lower today than it was in 2006. The statistics are all inclusive for all types of outages. As an example, a saidi of 100 means the average customer on the electric system over a period of a year would experience a total of 100 minutes of power interruption. Avista discovered a software coding error that has been within the omt system since 2002.
It is usually measured over the course of a year, and according to ieee standard 661998 the median value for north american utilities is. Ieee standard 66 classifying saidi, saifi, caidi into. It applies the attributes that are helpful for achieving the reliability and it focus on metrics. As per national electricity policy 2005, nep 200516 and.
Methods to analyze software failure modes and include software in a system fault tree analysis. This presentation will cover the key features of the ieee 1633 recommended practices for software reliability. Saifi indicates how often the average customer experiences a sustained interruption over a predefined period of time, typically a year. The most common indices are saifi, saidi, caidi, and asai. Perform a software reliability goal setting by defining systemlevel software reliability goals. Schneidewind, reliability modeling for safety critical software, ieee transactions on reliability, vol. Calculate asai, asui, saifi and saidi for the system. Major event day as defined by ieee standard 66, a day in which the daily saidi exceeds. A country like germany in the midst of an energy transition can therefore counter the argument that renewable energies create instability in the grid by referring to a trend in recent years that shows the opposite. Article pdf available in ieee transactions on power delivery 191. The ieee reliability test system rts developed by the application of probability method subcommittee has been used to compare and test a wide range of generating capacity and composite system. Based on 1 typical percentage of saidi that is caused by incidents occurring on lv, and 2 austrian data which includes both asidi and saidi, it is likely that countries which provide such a mv indicator underestimate their interruption time by about 520%, compared to countries which use saidi. Exercises on reliability assessment of electric power systems. Pdf saifi reliability calculation for the distribution line.
This standard is intended to aid the electric power industry in reporting and evaluating electric generating unit reliability, availability, and productivity. For the purpose of calculating daily system saidi, any interruption that spans multiple calendar days is accrued to the day on which the interruption began. Revised ieee 1633 recommended practices for software. Saidi, saifi, and caidi measure the overall reliability of the. The most common measurement indices which distribution utilities follow and share are those defined by the system average interruption duration index saidi and. Standards address a range of issues, including but not limited to various protocols to help maximize product functionality and compatibility, facilitate. The system average interruption duration index saidi is commonly used as a reliability. The reliability society provides a professional home for specialty engineering communities or disciplines covering not only reliability engineering, but also integrity, system safety, prognostics and health management phm testability, system security, human system interface his, human factors hf, maintainability, and supportability engineering disciplines, software engineering with a. Tracking the reliability of the us electric power system electricity. A variety of online tools and calculators for system reliability engineering, including redundancy calculators, mtbf calculators, reliability prediction for electrical and mechanical components, simulation tools, sparing analysis tools, reliability growth planning and tracking, reliability calculators for probability distributions, weibull analysis and maintainability analysis calculations. Trivedi, fellow, ieee abstract perhaps the most stringent restriction in most software reliability models is the assumption of statistical independence among successive software failures. Ieee in computing is widely popular for the development of standards for computer networking and its suite of services. The predictive and historical reliability assessment module of the cyme power engineering software computes reliability indices for the overall system and their corresponding protection zones, as well as customer point indices. Failure correlation in software reliability models.
Leading topics such as research on the fundamental sciences that underpin risk and reliability technologies, challenges in reliability of ultracomplex systems of interacting hardware and software, utilization and processing of large data and machine learning algorithms. For our members, the boston reliability chapter web site is the focal point of interaction among the membership and the advisory committee, providing updates and interconnectivity. Structure of california reliability incentive mechanisms saidi and saifi. Definition must be understandable by all and easy to apply. Definition must be specific and calculated using the same process for all utilities. Comparison of the effect of the distributed generators vs. Power distribution reliability indices, ieeesa standards. Standard definitions of reliability have focused on the frequency, duration, and extent of power outages. The envelope of acceptable supply for relation between reliability indices is defined and evaluated for power. Saidi and saifi indices guiding towards more reliable. Ieee and aiaa commissioned the development of a new standard called, the recommended practice on software reliability, ieee p1633 iee08. Caidi, saidi, ens, aens, reliability, distributed generators, disconnects 1. A systematic approach to organizing the process of determining the operational profile for guiding software development is presented.
Electricity transmission reliability measures aemc. One utility might report saifi and saidi, while others report saifi and caidi. Saidi saidi is defined as the average duration of interruptions for customers served during a specified time period. Institute of electrical and electronics engineers wikipedia. Distribution reliability indices calculation and utilize. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. Software design for reliability accendo reliability. Exhibit g reliability indices for substation components. The reliability of power distribution systems is promised to witness major benefits under the concept of the modernized electrical infrastructure, simply referred to as the smart grid. These goals become part of the overall software reliability program plan. The reliability of the electric system underpins virtually every sector of the modern u. Standards are published documents that establish specifications and procedures designed to maximize the reliability of the materials, products, methods, andor services people use every day. The purposes of task 32308, hardware and software reliability, are to examine reliability engineering in general and its impact on software reliability measurement, to develop improvements to existing software reliability modeling, and to identify the potential usefulness. Ieee std 66 reliability indices determining the expected.
The definition of homogeneous used here is that the ratio of the total. System average interruption duration index saidi, customer. Saidi was chosen as the indicator because it is size independent and it. The predictive model can be calibrated based on historical data.
Avista utilities report on electric system service reliability for 2018. Reliability of the grid is a growing and essential component of national security. The distributed generators dgs, although dated back to the late 1970s, are considered among those applications that attribute to the definition of smart grids. For the purpose of calculating daily system saidi, any interruption. Finding the reliability expression of different substation configurations. Iv ensuring electricity system reliability, security, and.
Members and guests may use the web site to get periodic news, read publications from our monthly meetings, conduct research and register for events. The power system continuity of supply level is controlled through system indices. This software tool is capable of handling and modeling a large, repairable system. Schneidewind, software metrics model for integrating quality control and prediction, proceedings of the international symposium on software reliability engineering. Ieee defines reliability as the ability of a system or component to perform its required functions under stated. Members support ieees mission to advance technology for humanity and the profession, while memberships build a platform to introduce careers in technology to students around the world. The customer average interruption duration index caidi is a reliability index commonly used by electric power utilities. To be effective, the reliability standards adopted must identify feeders that. For this they use international standards called saidi and saifi created by institute of electrical electronics engineers ieee. Ieee distribution reliability working group benchmark results 2005 to 2015, oliver wyman analysis exhibit 5. Software engineering stack exchange is a question and answer site for professionals, academics, and students working within the systems development life cycle. Saidi system average interruption duration index a system index of average duration of interruption in the power supply indicated in minutes per customer. Pdf predicting distribution system performance against.
The institute of electrical and electronics engineers ieee is a professional association for electronic engineering and electrical engineering and associated disciplines with its corporate office in new york city and its operations center in piscataway, new jersey. Lyu published by ieee computer society press and mcgrawhill book company the book content here is free for use or link. Statistically, days having a daily system saidi greater than t. Aiaa recommended practice on software reliability applied. Evaluation and improvement of reliability indices of electrical.
Distribution reliability analysis wichita state university. Operational profiles in softwarereliability engineering. Please cite the book properly in resulted publications. Malaiya, senior member, ieee, michael naixin li, james m. S risk assessment of software projects using fuzzy inference system. Ability of a computer program to perform its intended functions and operations in a systems environment, without experiencing failure system crash. Software reliability is the probability of failurefree software operation for a specified period of time in a specified environment. Although similar to caidi, the average number of customers served is. Saifi system average interruption frequency index, saidi system average interruption duration index, caidi customer average interruption duration. It views the output of this study as an important tool for utilities to use in their individual reliability analysis. It is worth noting that the ieee 66 guide defines a number of other similar and related.
Unified reliability index development for utility performance. It was formed in 1963 from the amalgamation of the american institute of electrical engineers and the institute of radio engineers. It was developed to overcome present difficulties in the interpretation of electric generating unit performance data from various systems and to facilitate comparisons among different systems. Introduction the power system is vulnerable to system abnormalities such as control failures, protection. It is related to saidi and saifi, and is calculated as. Some days, reliability r i is a whole lot worse than other days r i is saidi day, actually unreliabilty usual cause is severe weather. Reliability is often measured by the outage indices defined in one international standard called ieee 66. Tsaiditsaifisari, which are similar measures associated with transmission. In this exercise, you shall find out how large approximations reasonably could be made in a few different situations. While the focus of the ieee p1633 standard is software reliability, software and hardware do not operate independent of one another, therefore, both software and hardware are addressed in this tutorial in an.
Problem understanding the ieee definition of software. It differs from hardware reliability in that it reflects the design. Ieee membership offers access to technical innovation, cuttingedge information, networking opportunities, and exclusive member benefits. Approaches to setting electric distribution reliability standards and. Software reliability integration in the design phase.
Ieee develops many different standards, such as ieee 802 and ieee 802. Ieee 829 is also known as the ieee standard for software and system test documentation. Reliability indices determining the expected saifi and saidi. Electrical and electronics engineers ieee have proposed statistical. Failure correlation in software reliability models katerina go. The most widely used reliability indices are saifi, saidi and caidi ieee std. Ieee benchmark year 2016 results for 2015 data follow up. Bieman, senior member, ieee, and rick karcich abstract software testcoverage measures quantify the degree of thoroughness of testing. Ieee 829 defines the standards for software analysis and citations. Evaluation and improvement of reliability indices of. Software reliability is also an important factor affecting system reliability. Trends and perspective in risk and reliability engineering. Saidi was chosen as the indicator because it is size independent and it is the best indicator of system stresses.
In the design phase, there are six main software reliability techniques. Major event day as defined by ieee standard 66, a day in which the daily saidi exceeds a threshold value, t med. Software reliability testing helps discover many problems in the software design and functionality. Distribution reliability indices ieee std 662012 has been developed 20. Software reliability testing is a field of software testing that relates to testing a softwares ability to function, given environmental conditions, for a particular amount of time.
Reliability assessment of power distribution systems using disjoint. Use of ieee standard 662003 does not appear to bias saidi or saifi values compared to using prior definitions of major events. Ability to assess the reliability of cots, foss, and contractor or subcontractor delivered software. It differs from hardware reliability in that it reflects the design perfection, rather than manufacturing perfection. Software reliability is the key task for achieving the high reliability of any software industry. This talk will highlight current and promising directions in the fields of reliability engineering and risk assessment. Ieee 829 is a standard for software testing by the institute of electrical and electronics engineers ieee that specifies all the stages of software testing and documentation at each stage. Cyme international software, predictive and historical. System average outage duration index saidi by feeder. Problem understanding the ieee definition of software engineering. Change in customer average interruption duration index caidi for benchmarked utilities, 2005 vs.
18 431 1018 264 546 969 162 932 1559 176 1027 164 437 864 1189 1065 495 420 225 267 117 931 585 446 1440 1534 470 1295 123 109 637 1290 994 104 1269 676 506 1402 145