System Reliability Goal Research Articles

Optimal configuration of multi microgrid electric hydrogen hybrid energy storage capacity based on distributed robustness

The combination of energy storage and microgrids is an important technical path to address the uncertainty of distributed wind and solar resources and reduce their impact on the safety and stability of large power grids. With the increasing penetration rate of distributed wind and solar power generation, how to optimize capacity configuration of hybrid energy storage capacity to improve system economy and reliability has become a research hotspot. This article establishes a multi microgrid interaction system with electric‑hydrogen hybrid energy storage. The microgrid system uses distributed wind and solar power as the power source. Then, considering the uncertainty of wind and solar power, a distributed robust model with the goal of system operation economy and reliability was established. This model is used to optimize the configuration of energy storage capacity for electric‑hydrogen hybrid energy storage multi microgrid system and compare the economic costs of the system under different energy storage plans. Finally, the article analyzes the impact of key factors such as hydrogen energy storage investment cost, hydrogen price, and system loss rate on energy storage capacity. The results indicate that reducing the investment cost of hydrogen energy storage is the key to reduce operating cost of multi microgrid hybrid energy storage system.

Dynamic fault tree analysis of auxiliary feedwater system in a pressurized water reactor

Abstract The safe and secure designs of any nuclear power plant together with its cost-effective operation without accidents are leading the future of nuclear energy. As a result, the Reliability, Availability, Maintainability, and Safety analysis of NPP systems is the main concern for the nuclear industry. But the ability to assure that the safety-related system, structure, and components could meet the safety functions in different events to prevent the reactor core damage requires new reliability analysis methods and techniques. The Fault Tree Analysis (FTA) is one of the most widely used logic and probabilistic techniques in system reliability assessment nowadays. The Dynamic fault tree technique extends the conventional static fault tree (SFT) by considering the time requirements to model and evaluate the nuclear power plant safety systems. Thus this paper focuses on developing a new Dynamic Fault Tree for the Auxiliary Feed-water System (AFWS) in a pressurized water reactor. The proposed dynamic model achieves a more realistic and accurate representation of the AFWS safety analysis by illustrating the complex failure mechanisms including interrelated dependencies and Common Cause Failure (CCF). A Simulation tool is used to simulate the proposed dynamic fault tree model of the AFWS for the quantitative analysis. The more realistic results are useful to establish reliability cantered maintenance program in which the maintenance requirements are determined based on the achievement of system reliability goals in the most cost-effective manner.

Reliability analysis and optimization of production system for production scheduling

Production planning and scheduling mainly solve the problems of multi-process, multi-resource scheduling and sequence optimization in the workshop. Existing production scheduling methods focus on how to minimize the production period, but production system reliability is seldom considered in the actual production scheduling strategy. Production system reliability is closely related to the state change of equipment in production system, the production stability and efficiency. Therefore, in order to ensure the reliability of the production system when planning production tasks, this paper proposes a new strategy for production scheduling. Firstly, the model of production system is conducted to analyses its reliability. Secondly, a reliability evaluation method is proposed by analysing the status of equipment in the production system. Moreover, the optimization goal of production system reliability is added to the original production scheduling goal. Finally, the optimization method is put forward and verified by an example.

Reliability Allocation Procedures in Complex Redundant Systems

In the last two decades, the reliability assessment acquired a fundamental role in many advanced technology applications where environment, personnel, and system safety are mandatory features. This study deals with reliability allocation (RA) procedures that are top-down techniques that allow apportioning of the system reliability goal between its components. This apportionment of reliability values among the various items making up the whole system is based on estimated achievable reliability, criticality, complexity, or any other relevant factors in the allocation process. In the first part, this paper analyzed the main allocation methods shown in the literature in order to enlarge the range of applicability of these allocation techniques, from series architectures to redundant architectures. In the second section, the RA methods were tested on two case studies in order to extend their applicability in the presence of very complex redundant architectures.

A fuzzy multi-objective genetic algorithm for system reliability optimisation

The problem of optimising system reliability is often confronted with imprecise goals concerned with reduction of system costs and improvement of system reliability. Due to the presence of imprecise parameters, the impact of the decision is fuzzy and multi-objective. The present paper models the problem as a fuzzy multi-objective nonlinear program. To effectively handle the fuzzy goals and constraints of the multi-objective decision problem, a fuzzy multi-objective genetic algorithm approach (FMGA) is proposed. The proposed approach is flexible; it allows for generation of intermediate solutions, which eventually lead to high quality solutions. By using fuzzy membership functions, FMGA incorporates the decision maker's preferences and choices that influence system costs and reliability goals. Computations based on benchmark problems demonstrate the utility of the approach.

A new method for reliability allocation of avionics connected via an airborne network

Avionics are connected via an airborne network, and the realization of their functions depends on successful data transmission through the network. Once the system reliability goal has been defined, reliability allocation must be performed to the subsystems and components. However, the widely used reliability allocation methods are not capable of dealing with complex connections between avionic subsystems. In this paper, an improved Advisory Group on the Reliability of Electronic Equipment (AGREE) allocation method is proposed for multi-mission networked avionics. In the proposed procedure, both the complexity and the importance of components are explicitly considered. Analytic algorithms and Monte Carlo simulation are applied to calculate the reliability of such a complex network structure. To determine the reliability allocation values, a heuristic algorithm is proposed, and an allocation adjustment procedure is provided to avoid inconsistent allocations caused by the same category of components involved in multiple missions of avionics. Our numerical study on A380 avionics, whose data are transmitted through Avionics Full Duplex Switched Ethernet (AFDX), shows that the proposed method is practical and quite efficient in handling such complex reliability allocation problems.

Incorporating energy efficiency into electric power transmission planning: A western United States case study

Driven by system reliability goals and the need to integrate significantly increased renewable power generation, long-range, bulk-power transmission planning processes in the United States are undergoing major changes. At the same time, energy efficiency is an increasing share of the electricity resource mix in many regions, and has become a centerpiece of many utility resource plans and state policies as a means of meeting electricity demand, complementing supply-side sources, and reducing carbon dioxide emissions from the electric power system. The paper describes an innovative project in the western United States to explicitly incorporate end-use efficiency into load forecasts – projections of electricity consumption and demand – that are a critical input into transmission planning and transmission planning studies. Institutional and regulatory background and context are reviewed, along with a detailed discussion of data sources and analytical procedures used to integrate efficiency into load forecasts. The analysis is intended as a practical example to illustrate the kinds of technical and institutional issues that must be addressed in order to incorporate energy efficiency into regional transmission planning activities.

Water management institutions for more resilient societies

The management of water resources under conditions of uncertainty and scarcity is a fundamental determinant of the ability of societies to withstand unexpected shocks and extreme events. Conventional approaches to water resource planning aim to create reliable supplies. Practitioners often fail to identify their contribution to the broader goal of achieving social resilience rather than just technical system reliability. Recent work on understanding resilience in socio-ecological systems as well as on the management of ‘common pool’ natural resources such as water suggests that the contribution of planning processes to social resilience may in its turn contribute to the achievement of the narrow goal of system reliability. To illustrate this, the development of the water resource infrastructure system that underpins the South African economy is described with particular attention to the institutional processes that guide project selection and system operation.

An architecture for handwritten text recognition systems

This paper presents an end-to-end system for reading handwritten page images. Five functional modules included in the system are introduced in this paper: (i) pre-processing, which concerns introducing an image representation for easy manipulation of large page images and image handling procedures using the image representation; (ii) line separation, concerning text line detection and extracting images of lines of text from a page image; (iii) word segmentation, which concerns locating word gaps and isolating words from a line of text image obtained efficiently and in an intelligent manner; (iv) word recognition, concerning handwritten word recognition algorithms; and (v) linguistic post-pro- cessing, which concerns the use of linguistic constraints to intelligently parse and recognize text. Key ideas employed in each functional module, which have been developed for dealing with the diversity of handwriting in its various aspects with a goal of system reliability and robustness, are described in this paper. Preliminary experiments show promising results in terms of speed and accuracy.

Planning models for software reliability and cost

This paper presents modeling frameworks for distributing development effort among software components to facilitate cost-effective progress toward a system reliability goal. Emphasis on components means that the frameworks can be used, for example, in cleanroom processes and to set certification criteria. The approach, based on reliability allocation, uses the operational profile to quantify the usage environment and a utilization matrix to link usage with system structure. Two approaches for reliability and cost planning are introduced: Reliability-Constrained Cost-Minimization (RCCM) and Budget-Constrained Reliability-Maximization (BCRM). Efficient solutions are presented corresponding to three general functions for measuring cost-to-attain failure intensity. One of the functions is shown to be a generalization of the basic COCOMO form. Planning within budget, adaptation for other cost functions and validation issues are also discussed. Analysis capabilities are illustrated using a software system consisting of 26 developed modules and one procured module. The example also illustrates how to specify a reliability certification level, and minimum purchase price, for the procured module.

System-Based Component-Test Plans and Operating Characteristics: Binomial Data

Component-test plans are often designed by allocating system reliability among the system's components, then choosing individual component plans suitable for demonstrating achievcment of each component's reliability goal. This approach does not consider how much information relative to the system reliability goal is provided by the ensemble of component tests. We consider the notion of system reliability operating characteristic (OC) curves, based on the component tests, and illustrate their use in designing or evaluating an overall test program. By specifying OC values (akin to producer's and consumer's risks), optimum, system-ortented component-test plans can be derived. These ideas are illustrated for a series system, and for a simple series-parallel system, with binomial data.

System-Based Component-Test Plans and Operating Characteristics: Binomial Data

Component-test plans are often designed by allocating system reliability among the system's components, then choosing individual component plans suitable for demonstrating achievcment of each component's reliability goal. This approach does not consider how much information relative to the system reliability goal is provided by the ensemble of component tests. We consider the notion of system reliability operating characteristic (OC) curves, based on the component tests, and illustrate their use in designing or evaluating an overall test program. By specifying OC values (akin to producer's and consumer's risks), optimum, system-ortented component-test plans can be derived. These ideas are illustrated for a series system, and for a simple series-parallel system, with binomial data.

JBW Redundancy-Allocation Algorithm

A very simple heuristic redundancy-allocation algorithm for serial-parallel configurations is presented which: 1. Yields near-optimal system reliability under multiple resource system constraints. 2. Economically achieves a given redundant system reliability goal. 3. Accommodates both linear and nonlinear resource complexity functions. 4. Allows relative weighting of system resources. 5. Allows heterogeneous stages; ie. each stage is treated as a k-out-of-n:G model. The algorithm is conceptually and computationally simple and can be implemented with pencil-paper procedures and operations. Computational simplicity is demonstrated through the application of a TI-59 hand-held calculator program used to solve 12 previously published problems. The results obtained with the algorithm compares favorably with previous results. The TI-59 program is available in a separately available supplement.

Frequency and Duration Methods for Power System Reliability Calculations: I - Generation System Model

As a goal, the evaluation and computation of electric power system reliability requires that a consistent technique be used for all portions?generation, transmission, and distribution. At present, a number of different methods are used for the generation system, while the frequency and duration of outages seems to be developing as a standard measure for the analysis of the distribution system. This paper and a subsequent one will present a reliability calculation method for the generation system that incorporates the frequency and duration of unit outages and includes consideration of the loads. This method leads to calculated generation reliability measures which are the availability, frequency of occurence, and mean duration of reserve states. These are cumulative states in that they specify system reserve conditions of a given magnitude or less. This paper is concerned with the procedure for calculating the availability, frequency, and outage duration for a number of generating units connected in parallel to form a single system. Numerical data are used to illustrate the technique and make comparisons with other methods.