Reliability Parameters Of Components Research Articles

Reliability Analysis of Nuclear Power Plant Electrical System Considering Common Cause Failure Based on GO-FLOW

The reliability of nuclear power plant electrical systems is an important guarantee of nuclear safety, and the common fault failure problem arising from redundant design and intelligent control may greatly affect reliability assessment results. Combined with the features of repairability, multi-state characteristics, and common fault failure of nuclear power plant electrical systems, a reliability analysis method of nuclear power plant electrical systems based on the GO-FLOW method considering common fault failure is proposed. This study firstly constructs the algorithmic model of combining operators of repairable components and the equivalent model of reliability parameters of multi-mode repairable components, then establishes a probability calculation model of common fault failure for repairable systems by considering the quantitative computation of the common signaling system model, and finally, quantitatively calculates the reliability of nuclear power plant electrical systems and their influencing factors. The example simulation calculates the reliability of the external power supply system and the electrical system of the nuclear power plant, analyzes the influence of the common signal processing and the common fault failure factors on the reliability of the electrical system of the nuclear power plant, and verifies the validity of the proposed method. The results show that the common fault failure factors have a large impact on the system reliability analysis; the common fault failure of the standby diesel generator set will seriously reduce the reliability of the electrical system, which can be improved by installing additional standby diesel generators.

Component Reliability of a Class of Regular Networks and Its Applications

With the continuous attention to the parallel computing system, the reliability of the system, which is mainly measured by two parameters, connectivity and diagnosability, needs to be constantly studied and improved. At present, the component connectivities of some networks have been extensively studied, while the component diagnosabilities of these networks have rarely involved in. In this article, some networks with common characteristics are summarized as a class of regular networks. The definition of this kind of networks is given, and its reliability based on component failures is determined. To be specific, we prove that <inline-formula><tex-math notation="LaTeX">$c\kappa _{m+1}(G)=m(k-1)-\binom{m}{2}+1$</tex-math></inline-formula> for <inline-formula><tex-math notation="LaTeX">$1\leq m\leq k-2$</tex-math></inline-formula> and <inline-formula><tex-math notation="LaTeX">$ct_{m+1}(G)=(m+1)k-\binom{m}{2}-2\ m$</tex-math></inline-formula> for <inline-formula><tex-math notation="LaTeX">$1\leq m\leq k-2$</tex-math></inline-formula> under the PMC model, where <inline-formula><tex-math notation="LaTeX">$c\kappa _{m+1}(G)$</tex-math></inline-formula> and <inline-formula><tex-math notation="LaTeX">$ct_{m+1}(G)$</tex-math></inline-formula> represent the <inline-formula><tex-math notation="LaTeX">$(m+1)$</tex-math></inline-formula>-component connectivity and the <inline-formula><tex-math notation="LaTeX">$(m+1)$</tex-math></inline-formula>-component diagnosability of such networks <inline-formula><tex-math notation="LaTeX">$G$</tex-math></inline-formula>, respectively. Based on this, we design a low time complexity component diagnosis algorithm for this kind of networks. As applications, the above two component reliability parameters of many famous networks are explored. Furthermore, the proposed diagnosis algorithm is simulated on these networks, and the results show that the algorithm has high diagnosis accuracy for various networks.

Methods for the reliability optimization of district-distributed heating systems with prosumers

District-distributed heating systems are considered as the result of the development of existing district heating systems, in which various energy technologies are integrated to achieve maximum efficiency of the heating to consumers. The distributed sector in these systems is associated, first of all, with the implementation of prosumers. The problem statement is determining such values of reliability parameters of components (in particular, failure rates) of studied system that provide the required level of reliability of heating to consumers at the minimum cost for ensuring this level of reliability taking into account the redundancy of prosumers. A methodology is based on the nodal probability of failure-free operation index, the Markov random process, the laws of heat transfer processes in heat supply, and some other methods. A case example is considered, an analysis of the results obtained is carried out, and directions for further research are formulated.

Evaluation of the Useful and Residual Life of a Class of Relay-Based Centralised Traffic Control

Currently in Bulgaria, the main railway lines (corridors) are being modernised to increase train speed up to 160/200 km/h, which necessitates adoption of modern European traffic control systems (ERTMS/ETCS, classified as so-called class A systems). The remaining sections continue to operate mainly relay-based systems for ensuring safety of train traffic (the so-called class B systems). These systems include, first, station centralised traffic control systems, most of which are currently route relay-based ones. On the railways of Bulgaria, two classes of route relay-based centralised traffic control systems (RRCTCS) are operated, using respectively, the relays of so called «first class of reliability», and the relays of the so called «not first class of reliability». The inevitable increase in the age of RRCTCSs makes it necessary to assess their technical condition and technical suitability to clarify strategies for their further operation. Such an assessment is difficult due to the lack, first, of statistical data on the failures and reliability parameters during operation as per types of systems and their constituent elements and, second, of manufacturers’ recommendations on the service life of RRCTCS. The service life and residual service life, as well as the useful and residual life of RRCTCSs could, in the author’s opinion, be assessed according to the following criteria: • Electrical and mechanical useful life/wear of the components. • Reliability parameters of the relay components. • Electrical and mechanical useful life or the condition of the external and internal cabling. • Operating costs required to maintain RRCTCS within the range of predefined technical parameters. The article analyses and evaluates the average useful life and the average residual life of RRCTCS based on the first two criteria. It is concluded that neither electrical nor mechanical wear resistance of components is among leading characteristics for assessing useful and residual life. Two approaches are used to consider some of reliability parameters of the relay components: deterministic and probabilistic one, which are based on the «intensity of dangerous failures» characteristic of the relay of the first reliability class. Based on that characteristic, the probability of a dangerous failure of the first-class relays in operation was calculated for 58 Bulgarian RRCTCSs of N-68 type with non-routed manoeuvres, as well as the probability of their safe operation; the latter probability is proposed to be used to calculate the average residual life of the relay, and based on that, to calculate the average residual life of RRCTCSs of that type. By early 2021, the estimated maximum of the latter is 11 years. The consequences of implementing two strategies in subsequent years are considered: a) «nothing is done» and b) «RRCTCS useful life/age management» (based on the program of gradual decommissioning of N-68 type RRCTCSs and of re-equipment of relevant stations). This is also a prerequisite for safety management of train traffic. It is argued that an average useful life of RRCTCS could be estimated as no more than 60 years in operation. Considering additional factors, this period should be understood as a predicted value of the expected time after which the corresponding RRCTCS will reach the limit state and will be decommissioned. The average useful life and the average residual life should be considered the best guideline for the expected age limit for this type of RRCTCS.

Research on the Inverse Problem of Reliability Evaluation–Model and Algorithm

Due to the high dependence of economic and social development on power systems, the demand for reliable operation of power systems is increasing. Considering the popularity and widespread installation of smart meters, accurate system/node reliability indexes can be obtained. The inverse problem of reliability evaluation (IPRE) refers to the use of known system/node reliability indexes to obtain component reliability parameters. In this paper, a novel method of solving the IPRE is proposed. First, based on a nonsequential Monte Carlo (NSMC) method, analytical expressions for system reliability indexes in terms of component reliability parameters are derived, and then, the nonlinear equations of the IPRE are constructed. Second, a high-order polynomial approximation based on the conjugate gradient algorithm is used to calculate the unknown component reliability parameters, and the results are compared with those obtained using traditional neural networks method. Finally, a continuation method is used to correct the errors of the obtained component reliability parameters. Three cases, namely, the IEEE 1979 Reliability Test System (IEEE RTS-79), the Roy Billinton Test System (RBTS) and the Chuanyu power system in Southwest China, are used to test the method proposed in this paper to verify its feasibility and accuracy.

EVALUATING RELIABILITY OF ELECTRONIC COMPONENTS IN VEHICLES BY ACCELERATED RELIABILITY TESTING

This paper presents an accelerated reliability testing method for evaluating the reliability of electronic components. Due to their gradually common applications in vehicles, lightemitting diodes are used to conduct experiments. In these tests, temperature and humidity are the two genres of environmental stress considered. While the former type is the accelerated stress (at 70°C, 90°C and 100°C), the later is kept under normal operating conditions (80% RH). The research indicates that accelerated reliability testing is a suitable method to quickly obtain reliability parameters of electronic components. Besides, for electronic components that show degradation characteristics during the test, test duration, as well as expenditure, can be lower by testing obtaining degradation parameters instead of testing until the component is completely broken (test duration has been reduced from over 9400 hours to 2668 hours).

Effects of On-Site PV Generation and Residential Demand Response on Distribution System Reliability

In the last few decades, there has been a strong trend towards integrating renewable-based distributed generation systems into the power grid, and advanced management strategies have been developed in order to provide a reliable, resilient, economic, and sustainable operation. Moreover, demand response (DR) programs, by taking the advantage of flexible loads’ energy reduction capabilities, have presented as a promising solution considering reliability issues. Therefore, the impacts of combined system architecture with on-site photovoltaic (PV) generation units and residential demand reduction strategies were taken into consideration on distribution system reliability indices in this study. The load model of this study was created by using load data of the distribution feeder provided by Bosphorus Electric Distribution Corporation (BEDAS). Additionally, the reliability parameters of the feeder components were determined based on these provided data. The calculated load point and feeder side indicators were analyzed comprehensively from technical and economic perspectives. In order to validate the effectiveness of the proposed structure, four case studies were carried out in both DigSILENT PowerFactory and MATLAB environments.

Search the optimal ratio of system’s component reliability parameters and the heat capacity of prosumers in the district heating system

The paper presents a methodology for ensuring the reliability of heat supply to prosumer connected to a district heating system, by using the heat capacity of its own heat source and optimization of failure rates of system components. To solve this problem, a mathematical formalization is developed, within which a markov random process, a flow distribution model of the theory of hydraulic circuits, nodal reliability indices, and simplified models of heat transfer processes in heat supply to consumers are used. A case study is considered based on a test scheme of district heating system with prosumer, an analysis of the results obtained is carried out, conclusions and directions for the further research on the subject are formulated.

A risk analysis model for underground gas storage well integrity failure

Loss of underground gas storage (UGS) well integrity can result in serious consequences. Risk analysis is critical to maintaining the integrity of a UGS well and reducing potential accidents. This study proposes a risk analysis model for UGS well integrity failure. First, we employ the bow-tie (BT) approach to establish a systematic well integrity failure model, qualitatively depicting the causal relationship between well integrity failure and potential consequences. Subsequently, hierarchical Bayes analysis (HBA) is used to model source-to-source uncertainty among the aggregated reliability data and provide reasonable estimates for the reliability parameters of components (i.e., well components and safety barriers). This process allows us to consider UGS well attributes using collected data. Furthermore, to address the issues of the BT approach in risk quantification, the developed BT model is mapped to a corresponding Bayesian network (BN). Predictive analysis is performed to estimate the occurrence probabilities of well integrity failure and potential consequences. Probability updating is performed to identify the key contributing factors given the observation of an undesired event. Finally, to obtain a more case-specific result, risk updating is conducted by using probability adapting of the BN and the new information accumulated over time. The results show that the proposed model can effectively handle uncertainty in risk calculation and provide more accurate results. This study has practical value for improving UGS safety.

Reliability Evaluation and Sensitivity Analysis to AC/UHVDC Systems Based on Sequential Monte Carlo Simulation

With the sequential Monte Carlo simulation (sMCs), the duration of the system state is obtained by the difference of the state sequences of related equipment. The state probability is not the explicit function of the reliability parameters. Therefore, it is difficult to derive the sensitivity directly. A new sensitivity model for the sMCs is proposed in this paper, which is based on the derivative of the state duration to the reliability parameters, and the sensitivity model is applied to the AC/UHVDC system. The states and durations of the related equipment from the beginning of the simulated years to the generated time of the system state are considered and differentiated to describe the derivative. To obtain the sequence of the UHVDC line, the possible reached state, mean duration, and probability for each state transition are considered. By combining the sensitivity model of the UHVDC line itself, the equivalent transition rates are applied to connect the system state duration and reliability parameters of the UHVDC components. The numerical results based on a provincial system in China are provided to validate the feasibility and accuracy of the proposed model.

Analytical model for fast reliability evaluation of composite generation and transmission system based on sequential Monte Carlo simulation

This paper proposes an analytical reliability evaluation (RE) model for composite generation and transmission system (CGTS) based on the sequential Monte Carlo simulation (MCS) method. The main idea is to partition the chronological system state sequence produced by sequential MCS into a set of mutually exclusive events based on the law of total probability. An analytical model is developed by extracting the component reliability parameters (CRPs) from system reliability index calculation formula of each mutually exclusive event. Once the proposed model is established, system reliability indices with variable CRPs can be obtained directly, rather than repeatedly performing the time-consuming sequential MCS process. In addition, sensitivity coefficients of system reliability indices with respect to CRPs can be obtained using the developed analytical model. A 4-unit generation system, the CGTS of IEEE-RTS system and a 91-bus power system are used for case study to validate the correctness and effectiveness of the proposed analytical RE model.

Inverse Problem of Power System Reliability Evaluation: Analytical Model and Solution Method

Power system reliability evaluation (PSRE) typically involves with finding the system (or bus) reliability index from known component reliability parameters. In this paper, we consider the case of using the system (or bus) reliability index to obtain the unknown component reliability parameter (UCRP). This problem is called the inverse PSRE problem. Analytical model of the inverse PSRE problem is constructed and formulated as the nonlinear algebraic equations. In particular, analytical models for the composite generation and transmission system and the generating system are developed based on the state enumeration method. Solution method using the interval analysis is developed by transforming the nonlinear algebraic equations into the interval nonlinear equations with UCRPs represented by the interval numbers. A modified Krawczyk-operator algorithm based on interval bisection elimination scheme is developed to overcome the difficulty of selecting the appropriate initial interval in the problem-solving process. The RBTS, IEEE-RTS, and a 91-bus system are used for the case study to verify the effectiveness of the proposed model and the solution method. In addition, an application to power system planning is investigated to examine how the component reliability parameters can be modified quantitatively to achieve the desired system reliability improvement.

Quantification of initiating event frequencies and component reliability data in level 1 probabilistic safety assessment at Puspati TRIGA research reactor

Prior to developing level-I probabilistic safety assessment in Puspati TRIGA Reactor (RTP), collecting and analyzing data is the cornerstone of the probabilistic safety assessment processes. This paper provides on how data quantification is made available for both initial initiating events frequency and components reliability. Taking into consideration on the availability of data, it was decided that generic data to be used in combination with plant-specific data. Methods for estimating the parameters used in quantifying is also presented in this paper. This includes, data treatment by applying Bayesian updates in forming a better refine posterior data. It was found out that, result with the presence of plant-specific data history tends to have high value, loss of offsite power (LOOP) with 1.27E-03. Meanwhile, for other IEs that used generic data, shown lower result with maximum value of 2.68E-06 (loss of flow accident at secondary pump: LOSC-P). As for components data, basic event, No signal from fission chamber 1 (fail to function) is the highest value with 4.07E-01, followed with Manual valve SV1A fail to close (2.75E-01). This publication is perhaps one of the first publically available document providing information on generic and plant specific data for initiating event and components reliability parameters that were used in a Level-1 PSA study for a nuclear research reactor. In addition, this information can be used by PSA technical staff in how to analyze and treat initial incident event data, including, type and what data need to be collected.

Failure Analysis of Current and Future Electricity Meters and their Components in Relation to the Costs of Ownership

Among other aspects, the reliability of electricity meters is important for securing energy supply and other Smart Grid (SG) functions and services. This paper analyses the reliability of functions and services provided by electricity meters in relation to reliability of individual electricity meters and their components. The increasing reliability requirements lead to higher complexity and manufacturing cost of electricity meter. On the other hand, purchase price pressure may cause increased failure rate of an individual meter, drop in overall reliability of SG environment, and finally can increase operating costs. Thus, Total Cost of smart meter Ownership (TCO) is associated with the failure rate (reliability). While seeking optimal TCO/reliability ratio, a contribution of each individual component to the overall failure rate of an electricity meter was investigated. Expected development of selected components reliability parameters and its influence on failure rate of meter and metering system was also estimated.

A mathematical model and an algorithm for sampling sets of components on the Assembly enterprises of space technology

The article considers the problem of determining the rational plans of the input sampling reliability and technical parameters of components of space technology, the totality of which is supplied to the Assembly plants for the manufacture of complex products of space technology. Problem statement and mathematical model based on the minimization of the economic costs of control and losses related to the risks of taking wrong decisions, are given in the article. The properties of the mathematical models are investigated, the algorithm for its optimization is developed. The result is an optimal plan for the sampling of sets of components, which includes: an optimal product mix subject to mandatory control of the aggregate and optimum risks of first and second kind, when acceptance number of statistical plan is zero. The latter circumstance is due to the high requirements of reliability and technical parameters of products of space technology.

Reliability Equivalence to Symmetrical UHVDC Transmission Systems Considering Redundant Structure Configuration

In recent years, the ultra-high voltage direct current (UHVDC) transmission system has been developed rapidly for its significant long-distance, high-capacity and low-loss properties. Equipment failures and overall outages of the UHVDC system have increasingly vital influence on the power supply of the receiving end grid. To improve the reliability level of UHVDC systems, a quantitative selection and configuration approach of redundant structures is proposed in this paper, which is based on multi-state reliability equivalence. Specifically, considering the symmetry characteristic of an UHVDC system, a state space model is established as a monopole rather than a bipole, which effectively reduces the state space dimensions to be considered by deducing the reliability merging operator of two poles. Considering the standby effect of AC filters and the recovery effect of converter units, the number of available converter units and corresponding probability are expressed with in universal generating function (UGF) form. Then, a sensitivity analysis is performed to quantify the impact of component reliability parameters on system reliability and determine the most specific devices that should be configured in the redundant structure. Finally, a cost-benefit analysis is utilized to help determine the optimal scheme of redundant devices. Case studies are conducted to demonstrate the effectiveness and accuracy of the proposed method. Based on the numerical results, configuring a set of redundant transformers is indicated to be of the greatest significance to improve the reliability level of UHVDC transmission systems.

Markov Chain model for solar farm generation and its application to generation performance evaluation

Abstract Solar profile and component outage create considerable impact on solar generation. This paper proposes a Markov chain model that incorporates both factors into solar generation. This model considers the solar farm as a generating unit with multiple generation states, where each state is characterized by generating photovoltaic arrays, ambient temperature, and solar radiation. The probability, frequency, and transition rate between generation states are obtained from collected solar profile samples and component reliability parameters. Three generation performance indices that describe the solar generation from the perspective of energy, time, and frequency are defined and estimated from the proposed model. The accuracy and efficiency of the proposed model is verified by a sequential Monte Carlo simulation approach using collected solar profile samples from six distinctive sites in North Dakota, USA. Influence of component reliability parameters, seasonal solar profile pattern, and photovoltaic module type on solar generation is investigated in details.

Optimization of reliability parameters structure for district heating systems

The problem of reliability parameters distribution on the district heating system's scheme is considered. This is one of important part of the general problem of optimal synthesis of district heating systems and is urgent for both the systems under design and the existing insufficiently reliable systems. The concept of solving the problem is based on the average reliability parameters of components (failure and restoration rates) which determine the first approximation to the optimal solution. This parameters needs for the further distribution its average values among system components. Algorithm and mathematical models for determine of optimal reliability parameters of system components with provide the required level of heat supply reliability and minimal total costs on ensuring this level are developed. The methodology of solving the stated problem is based on the methods of the theory of hydraulic circuits, nodal reliability, indices models of Markov random process and general regularities of heat transfer processes. The methodology also takes into account changes in thermal loads during the heating period and time redundancy of consumers related to heat storage.

Variance-based importance analysis measure for mission reliability of phased mission system

ABSTRACTImportance measures are used to estimate the relative importance of components to system reliability. Phased mission systems (PMS) have many components working in several phases with different success criteria, and their component structural importance is distinct in different phases. Additionally, reliability parameters of components in PMS always have uncertainty in practice. Therefore, existing component importance measures based on either the partial derivative of system structure function or component structural importance may have difficulties in PMS importance analysis. This paper presents a simulation method to evaluate the component global importance for PMS based on the variance-based method and the Monte-Carlo method. To facilitate the practical use, we further discuss the correlation relationship between the component global importance and its possible influence factors, and present here a fitting model for evaluating component global importance. Finally, two examples are given to show that the fitting model displays quite reasonable component importance.

Methodology for optimization of component reliability of heat supply systems

The paper suggests a methodology to determine optimal reliability parameters (failure and restoration rates) of heat supply system components, which provide the required level of heat supply reliability. The methodological approach consists in the economically rational distribution of the total effect of reliability improvement among the system components, which is calculated using the average reliability parameters of the components. This task, along with the task to ensure structural reliability, is one of the key reliability tasks within a more general problem of optimal synthesis of heat supply systems and is urgent for both the systems under design and the existing insufficiently reliable systems.The methodology of solving the stated problem is based on the methods of the theory of hydraulic circuits, nodal reliability indices of heat supply, models of Markov random process and general regularities of cogeneration and heat transfer processes. The methodology also takes into account changes in thermal loads during the heating period and time redundancy of consumers related to heat storage. The results of the practical research based on the calculation experiment that confirms the viability of the presented methodology for the schemes of real heat supply systems are presented.The advantages of the proposed methodology compared to the existing approaches to solving this problem consist in joint optimization of the component reliability of heat source and heat network schemes, integration of procedures for the reduction in failure rates and the improvement in restoration rates of the components in one calculation pattern of search for the optimal system reliability, the absence of the need to conduct iterative calculations when using the average reliability parameters of components, considering the required levels of reliability indices.