Papers by Keyword: Reliability Evaluation

Abstract: A survey of methods for characterizing threshold voltage (VT) drift when applied to commercial SiC DMOSFETs was conducted to explore how results can vary from one test to another. Typical linear-with-log-stress-time VT drift was observed with a rate of increase near 50–60 mV/dec for all methods. However, the magnitude of the drift varied greatly depending on the time delay between stress and measurement. A power law recovery ( ) common to all methods results in much smaller VT drifts when using slower methods, meaning long delays between stress and measurement can lead to tests that are unable to adequately discriminate bad devices from good.

Abstract: This paper proposes a method for electrical substation expansion by considering reliability indices of various types of bus configuration in electrical substation. The reliability indices LOLF, LOLP, and EENS are evaluated by using Newton-Raphson power flow calculation with minimal cut sets. The yearly load growth, together with power capacity of components (capacity limit of components), and the operation of protective components are also taken into account. Two types of failures, i.e. active failure and passive failure, are considered. Finally, the reliability of all bus configuration types in electrical substation is compared by the reliability indices.

Abstract: To solve the reliability assessment challenge of protection channels caused by elements multiplexing. The paper build a weighted-undirected graph of optical fiber protection channels, whose nodes measurement is SDH reliability and reliability of optical fiber as edge weights. Start from the information provided by the actual grid, encode the data according to the most close to the actual data format, developed an algorithm for channels and services reliability assessment based on logical "or" and "exclusive or". The result is verified in a 9-node and 19-channel network in central China Grid, showing that the proposed encoding method and model have good practicability and operability, which can offer grid reference to network optimization, scientific channels arrangement and the maintenance of the protection channels.

Abstract: The implement of direct load control can reduce power system load at peak times by restricting the given load at the required time straightforwardly. These actions also have a positive influence on the distribution system reliability along with the increase of load rate. Thus, in order to make further research on the impact of DLC on distribution system reliability, a mathematical model of DLC on the basis of linear programming method should be set up firstly. Then, according to the change of load rate, establishing a cubic spline interpolation function represents the reliability index changing with load rate. Finally, the validity of above model and the method are studied through numerical tests on modified RBTS BUS 6 test system. As the result shows, the effectively direct load control can improve the distribution system reliability.

Abstract: The construction and operating mode of distribution network have changed due to the access of distributed generations (DGs), which has a deep influence on reliability evaluation. A new approach and the related analytical formulation is proposed in this paper to get a better evaluation for distribution network connected to DGs, after considering the fault reconstruction, switch type, DGs types and access locations, islands abundance probabilities and other factors. We propose a classification that includes various cases defined by the relative position of load points (LPs), faults, and switches, in networks with and without DGs. Taking IEEE RBTS BUS6 distribution system for example, the simulation results in the proposed method indicate that DGs improved the reliability for distribution network effectively.

Abstract: For the field data of 10 sets of machining center from Shiyan Yixing Industrial Development Co., Ltd. application of statistical methods, the typical domestic machining centers are conducted a comprehensive analysis of reliability. By applying fault frequency and fault proportion primary-and-secondary Diagram, the fault parts and priority are classified and solved.

Abstract: Laser Initiation System is a type of high value initiating explosive device. The reliability of LIS can't be verified through mass of system firing tests. With the problem in hand, this paper combined with reliability characteristics of both F/S work type devices and repeatedly work type devices in LIS, presented an method of reliability evaluation for LIS. The practical verification shows that the evaluation method is effective and feasible, and it also can be a reference for the research on reliability evaluation of other high value initiation systems in the future.

Abstract: The failure data of the electromechanical product satisfies a certain law that a batch of failure data usually meet a variety of distributions at the same time. As to this phenomenon, an optimization method of evaluation model of reliability which is combined with the concept of entropy was put forward in this work. In the optimization process, several empirical models and multiple evaluation indexes were proposed for selecting a best model of reliability evaluation model, and entropy weight was defined to show the importance of evaluation indexes.

Abstract: To introduce a kind of method of fuzzy modeling based on the accuracy of data sources and accessibility of the interface which can predict the future system reliability. Data sources are from Reliability management system, distribution network planning detail and projects of overhaul, capital construction, technical transformation, business expansion. There is little reports of the reliability evaluation algorithm by now. This paper is based on the correlation analysis method of load forecasting to forecast the reliability index.

Abstract: The basic mathematical method for power system reliability evaluation was indicated, the simple and complex system was respectively introduced, several methods of reliability analysis of simple was given in this paper, and the reliability evaluation indexes system and methods of composite generation and transmission system was analyzed, then focused on state enumeration method applied in the reliability assessment of system, the detailed example analysis was given and the adequacy reliability indexes were computed in detail. Finally, the current reliability evaluation and status of composite generation and transmission system was summarized simply and its reliability evaluation algorithm steps applied in current actual engineering projects was given.