A novel methodology for forecasting gas supply reliability of natural gas pipeline systems

In this paper, a novel systematic and integrated methodology to assess gas supply reliability is proposed based on the Monte Carlo method, statistical analysis, mathematical-probabilistic analysis, and hydraulic simulation. The method proposed has two stages. In the first stage, typical scenarios are determined. In the second stage, hydraulic simulation is conducted to calculate the flow rate in each typical scenario. The result of the gas pipeline system calculated is the average gas supply reliability in each typical scenario. To verify the feasibility, the method proposed is applied for a real natural gas pipelines network system. The comparison of the results calculated and the actual gas supply reliability based on the filed data in the evaluation period suggests the assessment results of the method proposed agree well with the filed data. Besides, the effect of different components on gas supply reliability is investigated, and the most critical component is identified. For example, the 48th unit is the most critical component for the SH terminal station, while the 119th typical scenario results in the most severe consequence which causes the loss of 175.61×10⁴ m³ gas when the 119th scenario happens. This paper provides a set of scientific and reasonable gas supply reliability indexes which can evaluate the gas supply reliability from two dimensions of quantity and time.     

大容量电站锅炉受热面管子的可靠性设计与寿命评定

以传统的设计方法为基础，提出了大容量电站锅炉受热面管子的振动和强度可靠性设计方法以及寿命的评定方法。在振动可靠性设计方面，把卡门漩涡频率和声学驻波频率处理为随机变量，使用概率设计法确定锅炉尾部受热面振动设计的可靠度。在强度可靠性设计方面，把锅炉受热面管子的外径、壁厚、管内压力、材料强度等设计量根据实际处理为随机变量，使用可靠性分析技术确定锅炉受热面管子强度设计的可靠度。在寿命评定方面，对锅炉受热面管子的寿命数据进行统计分析，确定锅炉受热面管子的平均寿命。通过对锅炉受热面管子壁厚的监测和跟踪，确定锅炉受热面管子的剩余寿命。给出了水冷壁、过热器、再热器和省煤器管子强度可靠性设计的实例、管式空气预热器管束振动的可靠性设计实例和锅炉过热器管子寿命评定的实例。表1参9     

Optimal electricity supply reliability using customer shortage costs

This paper describes an economic cost-benefit method for determining the optimal power system capacity and reliability of electricity supply using customer shortage costs. The approach is based upon identifying a system plan that simultaneously considers cost-of-service as well as value-of-service, and maximizes the net economic benefits taking into account the interdependence between electricity reliability, price, and demand. In contrast to the existing literature on this subject, which considers only customer outage costs, this paper argues that it is the related but considerably broader notion of customer shortage cost that is more relevant in the context of optimizing the reliability of electricity supply. The paper develops a method for estimating shortage costs and sketches an integrated framework for optimizing reliability using such costs.     

Market modeling for assessment of demand side programs using the marginal cost

Demand side management is nowadays considered as a fundamental step in the energy planning process. The criteria proposed for the assessment of the demand side programs (DSPs) are usually based on the balance between the marginal supply cost and the mean DSP cost. These criteria could not support the allotting of the invested capital to incentives for the consumers and advertising. This paper presents a methodology to support the utility planning at this point with more reliability. It proposes the expansion of the assessment criteria with the use of the marginal cost of the DSP. For the calculation of the DSP marginal cost, a dynamic model is developed and it is used for the simulation of the penetration of a DS Program. Using the ‘least‐cost’ criterion as the decision rule for the simulation, the planner has a distribution of the available investment capital throughout the whole planning period. The use of the ‘most‐value’ criterion supports the separation of the invested capital between incentives for the consumers and supportive expenses, e.g. advertising, marketing costs, etc. Copyright © 2000 John Wiley & Sons, Ltd.     

Life Cycle Assessment,ExternE and Comprehensive Analysis for an integrated evaluation of the environmental impact of anthropogenic activities

The implementation of resource management strategies aimed at reducing the impacts of the anthropogenic activities system requires a comprehensive approach to evaluate on the whole the environmental burdens of productive processes and to identify the best recovery strategies from both an environmental and an economic point of view.In this framework, an analytical methodology based on the integration of Life Cycle Assessment (LCA), ExternE and Comprehensive Analysis was developed to perform an in-depth investigation of energy systems. The LCA methodology, largely utilised by the international scientific community for the assessment of the environmental performances of technologies, combined with Comprehensive Analysis allows modelling the overall system of anthropogenic activities, as well as sub-systems, the economic consequences of the whole set of environmental damages. Moreover, internalising external costs into partial equilibrium models, as those utilised by Comprehensive Analysis, can be useful to identify the best paths for implementing technology innovation and strategies aimed to a more sustainable energy supply and use.This paper presents an integrated application of these three methodologies to a local scale case study (the Val D’Agri area in Basilicata, Southern Italy), aimed to better characterise the environmental impacts of the energy system, with particular reference to extraction activities. The innovative methodological approach utilised takes advantage from the strength points of each methodology with an added value coming from their integration as emphasised by the main results obtained by the scenario analysis.     

采暖锅炉计算机监控_管理系统

本监控系统具有方便快捷的运行平台和良好的人机界面;采暖锅炉 集散控制系统,控制系统创新地采用了布风调节,变频调节,模糊控制等手段,提高了锅炉的效率,稳定性和可靠性;建立了供水热网的预估模型,使锅炉和热网有机地连为一个整体,统一进行调节,改善了用户的供热品质,收到了良好的效果。     

利用工业低品位余热的高温热泵供暖系统

实现建筑节能目标任重道远,传统的燃烧矿物质燃料的锅炉供暖方式不仅浪费能源,而且严重污染环境.这里介绍一种全新的利用工业低温余热的高温热泵供暖方案.它不仅使供暖环境实现零污染,而且运行费用是目前各供暖费用中最低的.这种方式必将是我国北方城市热网的最有效的补充.     

考虑配电网馈线可用容量的负荷点可靠性区间分析

针对配网系统可靠性和负荷变化的不确定性,提出了一种以负荷点可靠性指标为核心的基于最小路法的可靠性区间分析法。该算法利用最小路法,将配网系统元件进行分类,使其既能够快速求取负荷点的可靠性指标,又能得出系统可靠性指标。同时还引入了可用容量的概念及详细定义,并在进行负荷点可靠性指标分析时,考虑馈线可用容量约束条件。算例计算验证了该方法的有效性和实用性。     

基于网架结构综合分析的开关布点优化规划

传统的配电网开关位置及数量的优化规划是将系统整体的可靠性指标及成本作为目标函数,对分段开关与联络开关的位置及数量进行优化,并没有通过寻找薄弱环节而达到快速有效提升系统可靠性的目的。将网架结构对可靠性的影响划分为“环节、联络和相互影响”3个方面,量化计算3个方面对不同负荷点可靠性的影响程度。将计算结果与分枝定界法相结合,得出基于网架结构综合分析的开关布点优化方法。针对供电可靠性的薄弱环节开展分析应用,结果表明,该方法使得开关的布点规划方案更贴近用户,更实用。     

Evaluation of the introduction of a hydrogen supply chain using a conventional gas pipeline–A case study of the Qinghai–Shanghai hydrogen supply chain

A large-scale hydrogen supply chain is an alternative for the transportation of energy generated from a renewable energy source. Utilizing this technology would drastically improve the generation of clean energy. Therefore, an analysis method to estimate the economic and environmental benefits of the introduction of a hydrogen supply chain using an existing pipeline is developed. The proposed method first estimates the energy and exergy flows in the system to calculate the overall efficiency of these quantities. Afterward, the payback period is estimated based on the overall energy efficiency using the discounted cash flow (DCF) method. The overall efficiency of the system, based on the energy analysis presented, would seem to be the final delivered electrical, fuel and useable heat energy delivered to end use divided by the input solar and wind energy. Furthermore, the environmental effects due to the introduction of the systems are evaluated considering the reduction of global warming and air pollution gases, such as CO₂ and PM2.5. The proposed analysis method was applied considering a natural gas pipeline that connects Qinghai and Shanghai. As a result, conversion ratios of 24.9% for electricity and 17.5% for heat were achieved, with the overall efficiency of the system of 42.4% based on the electricity obtained from photovoltaics. 3.02 Gt of CO₂, 104 kt of SO_x, and 134 kt of NO_x, which represent 3.3%, 0.5%, and 0.6% of the annual discharge in China, respectively, and 8.66 kt of PM2.5 would be reduced every year. Furthermore, a reduction of 953 Mt in coal consumption is expected. The payback period of the proposed system using the DCF method is 4.17 and 2.28 years for the two alternatives evaluated in this work. The cash flow of the DCF is influenced by installation cost and operation cost of equipment.     

A heuristic-based approach for reliability importance assessment of energy producers

Reliability of energy supply is one of the most important issues of service quality. On one hand, customers usually have different expectations for service reliability and price. On the other hand, providing different level of reliability at load points is a challenge for system operators. In order to take reasonable decisions and obviate reliability implementation difficulties, market players need to know impacts of their assets on system and load-point reliabilities. One tool to specify reliability impacts of assets is the criticality or reliability importance measure by which system components can be ranked based on their effect on reliability. Conventional methods for determination of reliability importance are essentially on the basis of risk sensitivity analysis and hence, impose prohibitive calculation burden in large power systems. An approach is proposed in this paper to determine reliability importance of energy producers from perspective of consumers or distribution companies in a composite generation and transmission system. In the presented method, while avoiding immense computational burden, the energy producers are ranked based on their rating, unavailability and impact on power flows in the lines connecting to the considered load points. Study results on the IEEE reliability test system show successful application of the proposed method.     

Assessing reliability in energy supply systems

Reliability has always been a concern in the energy sector, but concerns are escalating as energy demand increases and the political stability of many energy supply regions becomes more questionable. But how does one define and measure reliability? We introduce a method to assess reliability in energy supply systems in terms of adequacy and security. It derives from reliability assessment frameworks developed for the electricity sector, which are extended to include qualitative considerations and to be applicable to new energy systems by incorporating decision-making processes based on expert opinion and multi-attribute utility theory. The method presented here is flexible and can be applied to any energy system. To illustrate its use, we apply the method to two hydrogen pathways: (1) centralized steam reforming of imported liquefied natural gas with pipeline distribution of hydrogen, and (2) on-site electrolysis of water using renewable electricity produced independently from the electricity grid.     

Value-based system facility planning - a rational response to conflicting customer and regulatory demands

In a competitive energy market in which power supply reliability influence customer's purchasing decisions, utilities throughout the world are rapidly recognizing that they cannot ignore customer preferences. Reliability of electric service should be based on balancing the costs to a utility and the value of the benefits received by its customers. The customer survey approach is based on the assumption that customers are in the best position to understand how interruptions impact their activities that depend on electricity supply. A challenge to electric utilities is to increase the market value of the services they provide with the right amount of reliability and to lower its costs of operation, maintenance, and construction to provide lower rates for customers. Lastly, the value-based reliability cost-benefit assessment helps electric utilities to achieve the goal of providing reliable energy service at the lowest possible cost, which their customer values.     

Multi-objective optimization of the hybrid wind/solar/fuel cell distributed generation system using Hammersley Sequence Sampling

As the development of China's economy, environmental problems in China become more and more serious. Solar energy and wind energy are considered as ones of the best choices to solve the environmental problems in China and the hybrid wind/solar distributed generation (DG) system has received increasing attention recently. However, the instability and intermittency of the wind and solar energy throw a huge challenge on designing of the hybrid system. In order to ensure the continuous and stable power supply, optimal unit sizing of the hybrid wind/solar DG system should be taken into consideration in the design of the hybrid system. This paper establishes a multi-objective optimization framework based on cost, electricity efficiency and energy supply reliability models of the hybrid DG system, which is composed of wind, solar and fuel cell generation systems. Detailed models of each unit for the hybrid wind/solar/fuel cell system were established. Advanced ε-constraints method based on Hammersley Sequence Sampling was employed in the multi-objective optimization of the hybrid DG system. The approximate Pareto surface of the multi-objective optimization problems with a range of possible design solutions and a logical procedure for searching the global optimum solution for decision makers were presented. In this way, this work provided an efficient method for decision makers in the design of the hybrid wind/solar/fuel cell system.     

Intelligent optimization of renewable resource mixes incorporating the effect of fuel risk,fuel cost and CO2 emission

Power system planning is a capital intensive investment-decision problem. The majority of the conventional planning conducted since the last half a century has been based on the least cost approach, keeping in view the optimization of cost and reliability of power supply. Recently, renewable energy sources have found a niche in power system planning owing to concerns arising from fast depletion of fossil fuels, fuel price volatility as well as global climatic changes. Thus, power system planning is under-going a paradigm shift to incorporate such recent technologies. This paper assesses the impact of renewable sources using the portfolio theory to incorporate the effects of fuel price volatility as well as CO₂ emissions. An optimization framework using a robust multi-objective evolutionary algorithm, namely NSGA-II, is developed to obtain Pareto optimal solutions. The performance of the proposed approach is assessed and illustrated using the Indian power system considering real-time design practices. The case study for Indian power system validates the efficacy of the proposed methodology as developing countries are also increasing the investment in green energy to increase awareness about clean energy technologies.     

东汽330MW双抽供热凝汽式汽轮机设计技术

对供热抽汽汽轮机的设计技术进行了论述,结合东汽330MW双抽供热机组,对汽轮机通流设计、配汽方法、调节控制及本体结构等进行了分析,分析结果表明,东汽330MW双抽供热汽轮机采用先进通流技术和结构技术设计,具有较高的经济性和可靠性.     

Reliability assessment of generation and transmission systems using fault-tree analysis

This paper presents a method that integrates deterministic approach with fault-tree analysis for reliability assessment of a composite system (generation and transmission in power systems). The contingency screening is conducted in the first step. The results are further classified into three clusters in the second step: normal, local trouble and system trouble. The fault-tree analysis is used to assess the reliability of the composite system in the third step. Finally, Risk Reduction Worth is adopted as a measure of importance for identifying the crucial element that has significant impact on the reliability. In this paper, a composite system in Taiwan serves as an example for illustrating the simulation results attained by the proposed method. The simulation results, verified by Siemens PTI PSS/E TPLAN software package, show that the proposed method is applicable for large scale power systems.     

Solid oxide fuel cell micro combined heat and power system operating strategy: Options for provision of residential space and water heating

Solid oxide fuel cell (SOFC) based micro combined heat and power (micro-CHP) systems exhibit fundamentally different characteristics from other common micro-CHP technologies. Of particular relevance to this article is that they have a low heat-to-power ratio and may benefit from avoidance of thermal cycling. Existing patterns of residential heat demand in the UK, often characterised by morning and evening heating periods, do not necessarily complement the characteristics of SOFC based micro-CHP in an economic and technical sense because of difficulties in responding to large rapid heat demands (low heat-to-power ratio) and preference for continuous operation (avoidance of thermal cycling). In order to investigate modes of heat delivery that complement SOFC based micro-CHP a number of different heat demand profiles for a typical UK residential dwelling are considered along with a detailed model of SOFC based micro-CHP technical characteristics. Economic and environmental outcomes are modelled for each heat demand profile. A thermal energy store is then added to the analysis and comment is made on changes in economic and environmental parameters, and on the constraints of this option. We find that SOFC-based micro-CHP is best suited to slow space heating demands, where the heating system is on constantly during virtually all of the winter period. Thermal energy storage is less useful where heat demands are slow, but is better suited to cases where decoupling of heat demand and heat supply can result in efficiencies.     

A Monte-Carlo Simulation Method for the Economic Assessment of the Contribution of Wind Energy to Power Systems

A method for determining the costeffectiveness of wind energy and the economic limitations of penetration into electrical power systems is presented. It is based on a Monte-Carlo approach which simulates the hour-by-hour operation of the power system. The hourly random variations in wind and load are modeled in addition to the operating constraints inherent in conventional generation. The economic assessment is based on a selected one-year simulation period, Two examples of the application of this method are given.