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This paper focuses on material that is required for the practical application of fuzzy reliability; impacts of repair and data uncertainty. For this purpose, a holistic solution is presented to measure and manage the degree of uncertainty in the reliability indices of repairable systems. First, a flexible form of Markov Processes (MPs) namely Equivalent Transition Rate (ETR) is introduced in order to obtain an analytical formalism. Second, we delve deeply into the issues of fuzzy arithmetic by providing an intuitive, methodic and computational discussion of feasible approaches; Standard Fuzzy Arithmetic (SFA), Intermediate Variables (IMVs) and Taylor Series (TS). Specific emphasis is then placed upon Fuzzy Transformation Method (FTM). Third, we evaluate the performance of proposed techniques in case of a reliability problem involving fuzzy complexity. Consequently, the reader is given useful insights into the nature of fuzzy computations and practical impediments when measuring uncertain data. Given materials and methods, current paper provides a broad perspective by evaluating the reliability characteristics of a repairable Substation Automation System (SAS) that is one of the fundamental elements in Smart Grids (SGs). In this regard, quantitative results and diagrammatic outputs are supported by a detailed analysis under different assumptions. Our findings demonstrate that fuzzy outputs are computationally tractable and properly estimated. Besides, this investigation shows how the objective SAS can respond to the variations in reliability data. The framework proposed here encourages the continuation of the work towards more applications in electric power components and systems. As far as we know, there are no studies on these techniques, results and remarks. [ABSTRACT FROM AUTHOR]

This paper presents a new technique for the determination of minimal cut sets in substation reliability evaluation. The proposed technique detects events including the malfunction of circuit breakers referred to as stuck-breaker conditions. These selections are important steps in substation reliability evaluation. The effectiveness of the proposed technique is examined by it being applied to breaker-and-a-half, ring bus and radial configurations. The proposed technique can be easily used in the expansion of computer programs in order to obtain the substation reliability indices. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper sheds new lights on data uncertainty in fuzzy reliability computations to achieve the best possible accuracy using minimum data. To the best of our knowledge, there are major drawbacks to implement Conventional Fuzzy Arithmetic (CFA): catastrophic overestimation, non-applicability to real-world systems and complex computations based on impractical optimizations. A novel approach namely Fuzzy Transformation Method (FTM) has recently been put forward that eliminates the core problems of CFA. The present paper aims to validate the applicability of FTM to the reliability issues. Few researchers have addressed the issues of both symmetric and asymmetric uncertainty distributions in Fuzzy Failure Rates and how a fuzzy result can profoundly come under the influence of them. Hence, a comprehensive investigation is launched to evaluate the uncertainties and some beneficial observations are provided as well as sensitivity analysis and component importance measure in fuzzy frameworks. An interesting correlation between the component importance and input-output uncertainties is observed. Additionally, pictorial representations, results and remarks are numerically discussed. We opted for All-Digital Protection Systems (ADPSs) due to novelty of them and their impacts on substation reliability. Until now, there has not been provided a fuzzy perspective concerning reliability of ADPSs. [ABSTRACT FROM AUTHOR]

Highlights: [•] We propose a set of composite reliability evaluation models. [•] We assess the role of automated substations on the distribution system reliability. [•] SAS plays a vital role in the enhancement of the distribution system reliability. [•] System reliability is significantly improved by implementing the DA schemes. [•] We rank various automated distribution systems based on their reliability. [ABSTRACT FROM AUTHOR]

Abstract: This paper aims to present a comprehensive technique to quantitatively assess the reliability of substation automation systems. The technique is based on the tie-sets methodology. In order to demonstrate the application of the proposed technique, a variety of substation automation architectures is first introduced. The associated reliability block diagrams as well as the exact system reliability are then given. The impacts and the degree of importance of various components on the reliability of substation automation systems are presented. Two suitable measures of importance are selected. The first is the Birnbaum’s measure used to determine the bottleneck of the system reliability. The second measure uses criticality importance to diagnose failures and generating repair or inspection checklists. [Copyright &y& Elsevier]

This study aims at quantitatively assessing the availability indices of various substation automation systems. In order to illustrate the proposed technique, first, nine types of substation automation architectures are reviewed. The reliability block diagrams of various substation automation architectures are then developed. Subsequently, comparative studies are performed to demonstrate the most reliable architectures in comparison with the others. The results obtained by the proposed approach show the impact of repair on availability indices of the automation system. Finally, different sensitivity analyses are conducted for all architectures, where the impact of varying availability of all components on reliability indices of the automation system is illustrated. [ABSTRACT FROM PUBLISHER]

Considering six common types of substation automation systems (SASs), this paper not only performs a quantitative reliability evaluation of different automated industrial substations, but also assesses the impacts of various automated substations on the distribution system reliability. The technique is based on the event-tree methodology, reliability block diagram approach, and the concept-of-expectation method. The proposed approach is applied to the eight basic industrial substation configurations, and quantitative assessment of reliability benefits from the utilization of substation automation is conducted through a range of studies. The results show the value of using a systematic quantitative approach for investigating the effects of automation systems on substation reliability. The main contributions of this paper are: 1) to give explicit formulas for reliability evaluations of the automated industrial substation with arbitrary time duration of the automatic switching operation; 2) to prove the SAS with a faster automatic switching operation has a higher degree of improvement in the substation reliability indices; 3) to provide an effective tool for ranking the most reliable industrial substation configurations in the presence of various SASs; and 4) to quantitatively evaluate the effects of the automated substation with various SASs on distribution reliability indices. [ABSTRACT FROM AUTHOR]

Due to the fact that repair plays a vital role in the reliability modeling, this paper investigates the effects of component repair on the availability, reliability, and component importance analyses of various four substation automation systems (SASs). For this purpose, some explicit expressions are derived for the steady-state availability, mean time to failure, mean time to first failure (MTTF^1), and repair rate regarding a repairable SAS. Then, some numerical results are presented and are accompanied by detailed descriptions of how much increase in the reliability and availability indices of SASs can take place with component repair. Besides, for the repairable model, the results obtained demonstrate the most reliable SAS in comparison with the others. Then, different sensitivity analyses have been carried out for the repairable and the nonrepairable SAS. Finally, some suitable measures of importance are selected and used, thereby knowing which components of a repairable SAS are the most important and how much they can improve the system performance. The results calculated by importance measures can be informative to guide the designers when trying to enhance the performance of a repairable SAS. [ABSTRACT FROM AUTHOR]

Automation can significantly enhance substation reliability by speeding up service restoration. Although much research works has been done in reliability assessment of substation control systems, there are still several aspects that need to be considered in automated substation reliability evaluation. The impacts of automation system on substation reliability indices have not been comprehensively covered in the literature so far. This paper aims at presenting a comprehensive technique to quantitatively assess the reliability of the automated substations. The technique is based on the event tree methodology and the concepts of conditional probability technique. A step by step evaluation procedure is presented using a typical substation automation architecture known as simple star. The proposed technique is applied to some conventional substation configurations to examine the effectiveness of the technique and also to examine the level of reliability improvement achieved by automation. Furthermore, different sensitivity analyses have been carried out for both automatic switching action and a specific automated substation. The proposed strategy is easy to implement and suitable to analyze for an automated substation reliability with arbitrary automation architectures. Also, automated substation reliability assessment tools can be developed in detail, and can be catered to the specific needs of substation design. [ABSTRACT FROM AUTHOR]

This paper is concerned with a fuzzy analysis of power-flow (PF) involving uncertainties of load demands and network parameters. The crux of this paper is to propose an advanced fuzzy arithmetic. Fuzzy transformation method merges with backward–forward sweep in order to evaluate the contribution and propagation of uncertainty in IEEE 33-bus and 69-bus distribution systems. Results are validated by true intervals and random ranges. To determine true intervals, Global Optimization Problems (GOPs) are defined and solved through derivative-based and free techniques. To estimate random ranges, Monte-Carlo Simulations (MCSs) are employed. Our findings confirm that the sharpness of fuzzy intervals, tractability of computations, and applicability of possibility distributions. Following scenario-based evaluations, this paper discusses new implications of power losses, voltage profiles, optimal re-configuration, feeder extension, and reactive power compensation so that results would be beneficial to system planners and operators. Altogether, this paper provides a blueprint for a new way to handle uncertainties in a wide variety of power system problems without global optimization, linearization, and randomized simulations. [ABSTRACT FROM AUTHOR]

Highlights: [•] Different components of TCR–FC type SVC are introduced. [•] Using Markov process, a reliability Markov model for TCR–FC type SVC is obtained. [•] An equivalent three-state model for TCR–FC type SVC is proposed. [•] A sensitivity analysis for the availability of the equivalent model is carried out. [Copyright &y& Elsevier]