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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]

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 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]