Cool the Generators: System Reliability and Fault Tree Analysis of Hydrogen Cooling Systems
TL;DR: In this article, a comprehensive hydrogen cooling system (H2) is presented for the cooling of n # 250-MW generators of fossil-fuel power plants, which is validated using RS-View32 Works, a real-time automation platform.
Abstract: A comprehensive hydrogen (H2) cooling system (HCS) is presented for the cooling of n # 250-MW generators of fossil-fuel power plants. A novel six stage hot redundant structure (S2HRS)-based HCS clubbed with highly reliable and efficient process control and instrumentation system is proposed for the cooling of large generators in integrated gasification combined cycle power plants (CCPPs). This article provides a comparison between the proposed and the existing systems in terms of system reliability and fault tree analysis (FTA). The effectiveness of real-time featured proposed HCS is validated by computer simulation using RS-View32 Works, a real-time automation platform.
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31 Dec 2016
TL;DR: In this article, the main life-limiting factors of power electronics for grid-connected photovoltaic (PV) systems are discussed, where how the power converters are stressed considering real-field mission profiles.
Abstract: Power electronics is the enabling technology for optimizing energy harvesting from renewable systems like Photovoltaic (PV) and wind power systems, and also for interfacing grid-friendly energy systems. Advancements in the power semiconductor technology (e.g., wide band-gap devices) have pushed the conversion efficiency of power electronics to above 98%, where however the reliability of power electronics is becoming of high concern. Therefore, it is important to design for reliable power electronic systems to lower the risks of many failures during operation; otherwise will increase the cost for maintenance and reputation, thus affecting the cost of PV energy. Today’s PV power conversion applications require the power electronic systems with low failure rates during a service life of 20 years or even more. To achieve so, it is vital to know the main life-limiting factors of power electronic systems as well as to design for high reliability at an early stage. Knowhow of the loading in power electronics in harsh operating environments (e.g., fluctuating ambient temperature and solar irradiance) is important for life-time prediction, as the prerequisite of Design for Reliability (DfR). Hence, in this paper, the technological challenges in DfR of power electronics for grid-connected PV systems will be addressed, where how the power converters are stressed considering real-field mission profiles. Furthermore, the DfR technology will be systematically exemplified on practical power electronic systems (i.e., gridconnected PV systems).
69 citations
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01 Jan 2006
TL;DR: This work develops the explicit expressions for the mean time-to-failure, MTTF, and the steady-state availability, A T (∞), for four configurations of warm standby components and standby switching failures based on their reliability and availability.
Abstract: Abstract Four different system configurations with warm standby components and standby switching failures are compared based on their reliability and availability. The time-to-repair and the time-to-failure for each of the primary and warm standby components are assumed to follow the negative exponential distribution. We develop the explicit expressions for the mean time-to-failure, MTTF, and the steady-state availability, A T (∞), for four configurations. For all four configurations, comparisons are made for specific values of distribution parameters and of the cost of the components. The configurations are ranked based on MTTF, A T (∞), and cost/benefit where benefit is either MTTF or A T (∞).
62 citations
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TL;DR: In this paper, a reliability model for the combined cycle power plants (CCPP) is proposed to evaluate the reliability of the overall CCPP from an engineering system perspective, and sensitivity indices are proposed to identify the plant critical components, i.e., those with the most considerable influences on the system reliability and availability targets.
Abstract: Power plant successful operation is always a function of its constituent sub-systems and components. Due to the current financial constraints in power industry, power plant operators are continuously facing a wide range of challenges when dealing with maintenance scheduling and asset management practices of the plant sub-systems. Knowledge on the roles and criticality of the constituent components on the plant overall performance will help in establishing the plans for its smooth, safe, and economic operation. To ensure making the techno-economical decisions on the maintenance of power plant equipment, this paper focuses on the reliability modeling of the combined cycle power plants (CCPP). Reliability models are first developed for the gas turbine power plants (GTPP) and steam turbine power plants (STPP) which provides the input to evaluate the reliability of the overall CCPP from an engineering system perspective. Reliability-oriented sensitivity indices are proposed the aforementioned types of power plants to identify the plant critical components, i.e., those with the most considerable influences on the system reliability and availability targets. Having the system critical components recognized, one can then decide on the efficient maintenance strategies for the power plant components so that the available resources can be well planned and allocated techno-economically.
56 citations
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TL;DR: In this paper, an analytical reliability model for run-of-the-river (ROR) power plants was developed with the intention of being used in adequacy studies of power systems, and the well-known technique of fuzzy c-means clustering was employed to find the optimal states of the resultant multistate reliability model.
Abstract: Deployment of renewable energies for the electricity generation is on the rise around the world, among which is the run-of-the-river (ROR) power plant whose output power is variable throughout the year depending on the water flow of the respective river. The inherent uncertainty associated with renewable energy resources calls for new stochastic modeling approaches to measure the impacts of using these energies on the power system performance. This paper develops an analytical reliability model for ROR power plants. The model is based on the state-space analysis and is devised with the intention of being used in adequacy studies of power systems. Failure of related components and the intermittent nature of water flow are concurrently accommodated in the proposed model. The well-known technique of fuzzy c-means clustering is employed to find the optimal states of the resultant multistate reliability model. Two reliability test systems, i.e., Roy Billinton Test System (RBTS) and IEEE Reliability Test System (IEEE-RTS), are examined to demonstrate the effectiveness of the proposed reliability model. The water-flow data of Sheshpir River in Pars province of Iran are used.
13 citations
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TL;DR: In this paper, a novel methodology is presented for condensate extraction pump (CEP) of the surface condenser, which is the main intersection of heat loss, typically 40% of the thermal efficiency of a power plant.
Abstract: This paper presents a study on designing next generation integrated automation for condenser section of the power-plants. The paper formulates the integration of Level II and Level III in terms of SCADA system. A novel methodology is presented for condensate extraction pump (CEP) of the surface condenser, which is the main intersection of heat loss, typically 40% of the thermal efficiency of a power plant. CEP of condense is proposed to integrate with the high-pressure cycles to attain the improved electrical efficiency, which affects the heat transfer capability of surface condenser. This paper is proposed a Control and Instrumentation of Condensate-Extraction System (CES), dedicated for cooling of 30-MW-and-above size generation capacity. The paper is dedicated for the design and development of an effective CES, analyzing its impact over other contributions in terms of system reliability optimization. In addition, a methodology is presented to enhance the performance supervision of the CES in real-time.
2 citations
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References
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TL;DR: The first recorded usage of the word reliability dates back to the 1800s, albeit referred to a person and not a technical system as discussed by the authors, and since then, the concept of reliability has become a pervasive attribute worth of both qualitative and quantitative connotations.
Abstract: The first recorded usage of the word reliability dates back to the 1800s, albeit referred to a person and not a technical system. Since then, the concept of reliability has become a pervasive attribute worth of both qualitative and quantitative connotations. In particular, the revolutionary social, cultural and technological changes that have occurred from the 1800s to the 2000s have contributed to the need for a rational framework and quantitative treatment of the reliability of engineered systems and plants. This has led to the rise of reliability engineering as a scientific discipline. In this paper, some considerations are shared with respect to a number of problems and challenges which researchers and practitioners in reliability engineering are facing when analyzing today's complex systems. The focus will be on the contribution of reliability to system safety and on its role within system risk analysis.
645 citations
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TL;DR: This paper outlines the basic ideas within the e-maintenance concept and then provides an overview of the current research and challenges in this emerging field.
Abstract: The importance of the maintenance function has increased because of its role in keeping and improving system availability and safety, as well as product quality. To support this role, the development of the communication and information technologies has allowed the emergence of the concept of e-maintenance. Within the era of e-manufacturing and e-business, e-maintenance provides the opportunity for a new maintenance generation. As we will discuss later in this paper, e-maintenance integrates existing telemaintenance principles, with Web services and modern e-collaboration principles. Collaboration allows to share and exchange not only information but also knowledge and (e)-intelligence. By means of a collaborative environment, pertinent knowledge and intelligence become available and usable at the right place and time, in order to facilitate reaching the best maintenance decisions. This paper outlines the basic ideas within the e-maintenance concept and then provides an overview of the current research and challenges in this emerging field. An underlying objective is to identify the industrial/academic actors involved in the technological, organizational or management issues related to the development of e-maintenance. Today, this heterogeneous community has to be federated in order to bring up e-maintenance as a new scientific discipline.
399 citations
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TL;DR: This paper focuses on a sub-class of Dynamic Fault trees, called Priority Dynamic Fault Trees (PDFTs), containing only static gates, and Priority Dynamic Gates (Priority-AND, and Functional Dependency) for which a priority relation among the input nodes completely determines the output behavior.
Abstract: This paper focuses on a sub-class of Dynamic Fault Trees (DFTs), called Priority Dynamic Fault Trees (PDFTs), containing only static gates, and Priority Dynamic Gates (Priority-AND, and Functional Dependency) for which a priority relation among the input nodes completely determines the output behavior. We define events as temporal variables, and we show that, by adding to the usual Boolean operators new temporal operators denoted BEFORE and SIMULTANEOUS, it is possible to derive the structure function of the Top Event with any cascade of Priority Dynamic Gates, and repetition of basic events. A set of theorems are provided to express the structure function in a sum-of-product canonical form, where each product represents a set of cut sequences for the system. We finally show through some examples that the canonical form can be exploited to determine directly and algebraically the failure probability of the Top Event of the PDFT without resorting to the corresponding Markov model. The advantage of the approach is that it provides a complete qualitative description of the system, and that any failure distribution can be accommodated.
114 citations
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TL;DR: How process automation system architectures have evolved and discusses future trends are reviewed, drawing an analogy between the synergistic new technologies being developed today and the technology landscape of the early 1970s that resulted in the first DCS systems.
Abstract: New developments in information technologies are radically transforming process automation. Their impact and benefit derive both from these technologies individually and from their convergence in new system architecture concepts. This paper reviews how process automation system architectures have evolved and discusses future trends. We draw an analogy between the synergistic new technologies being developed today and the technology landscape of the early 1970s—characterized by the near-simultaneous appearance of microprocessors, communication networks, CRT displays—that resulted in the first DCS systems (in particular, the Honeywell TDC2000). Emerging technologies highlighted include wireless, embedded devices, service-oriented architecture, and application infrastructures.
82 citations
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TL;DR: This paper introduces a new real-time reliability prediction method for dynamic systems which incorporates an on-line fault prediction algorithm and shows that the effects of the system, and measurement noises on the fault estimates are greatly reduced by exponential smoothing, which indicates that the comparatively high accuracy of the fault Estimates & predictions is guaranteed.
Abstract: While a specific system is in use, its reliability will decrease gradually after the infant mortality period because of the components' degradation, or external attacks. Thus, reliability is a natural characteristic of a system's health, and can be used for condition monitoring & predictive maintenance. This paper introduces a new real-time reliability prediction method for dynamic systems which incorporates an on-line fault prediction algorithm. The factors that may reduce a system's reliability are modeled as an additive fault input to the system, and the fault is assumed to be varying linearly with time, approximately. The time-varying fault is roughly estimated based on a modified particle filtering algorithm at first. Then, as a time series, the fault estimate sequence is smoothed, and predicted by an exponential smoothing method. Mathematical analysis shows that the effects of the system, and measurement noises on the fault estimates are greatly reduced by exponential smoothing, which indicates that the comparatively high accuracy of the fault estimates & predictions is guaranteed. Based on the particle filtering & fault prediction results, the whole system's predictive reliability is computed through a Monte Carlo simulation strategy. The effectiveness of the proposed real-time reliability prediction method is validated by a computer simulation of a three-vessel water tank system.
80 citations
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