极端冰雪灾害条件下边坡可靠度分析

以极端冰雪灾害为例,选取对边坡稳定影响最明显的几种因素,通过正交试验,并采用简化的Bishop法计算边坡安全系数,通过线性回归获得计算边坡可靠度的极限状态方程的显式表达式,计算并分析了边坡在不同工况下的可靠度.所得结论可为灾害预防提供参考.     

气象灾害信息在输电线路运行维护中的应用分析

针对目前因各种气象灾害所频频引发的电网事故,详细介绍了我国主要的气象灾害,以及不同气象灾害对电力系统尤其是输电线路的安全运行所造成的危害及影响;对如何有效利用已有的气象预报信息以及输电线路状态监测技术,在实现输电线路的防灾减灾能力提高以及进一步建立相应的预警机制等方面进行了总结归纳,为进一步研究输电线路的防灾减灾技术方面提供了参考。     

极端天气事件对新能源发电和电网运行影响研究

风电和光伏发电极易受极端天气的影响而出现大规模停机和出力损失,严重时可能威胁电网安全稳定运行。针对极端天气事件对新能源发电和电网运行的影响开展研究。首先从新能源发电的角度阐述了极端天气影响新能源的机理。然后基于海量风电机组和光伏发电单元的运行数据,对寒潮、大风、降雪、沙尘等几类极端天气条件下新能源发电和电网运行情况进行深入分析。最后从电网调度运行的角度提出保障极端天气条件下电网安全稳定运行的建议。     

极端天气下计及气温影响的架空线路 荷载风险建模方法

摘要： 基于结构可靠性原理和线路设计基本理论,根据线路荷载-强度的随机特性与干涉理论,建立考虑气温影响的架空线路荷载风险分析模型,提出将极端天气下温差变化对线路的影响折算为等值荷载的方法,采用最小二乘法进行温差折算荷载建模。以一条实际运行的架空输电线路为例验证线路失效概率模型的有效性,研究结果表明,在分析极端天气下线路可靠性指标时计及气温变化的影响不可忽视。     

冬季极端天气状况下空气源热泵运行实验研究

对夏热冬冷地区某住宅的空气源热泵空调器在降雪天气状况下的运行性能进行了实测研究。结果表明:制热量平均值较额定值下降约15%,瞬时值最大下降约30%;制热工况平均COP值为2.66,较额定值下降11.3%,包含除霜在内的运行周期平均COP值为2.37,较额定值下降20.9%,除霜耗电量为总耗电量的9.2%;不受结霜影响的瞬时制热量最大值达到额定值的94%～98%;室内机风速变化引起的制热量变化幅度约为4%。分析表明,室外机在结霜状况下工作是导致制热量及COP值下降的主要原因,先进的除霜方式是降低结霜对制热量的影响与提高运行能效的关键。     

电网极端天气区划图智能绘制系统的建设

以数据库技术和可视化技术为支撑,以国家电网关于极端天气分布图(雷区、冰区、舞动区)的相关规范标准为依据,采用计算机软件集成技术和地理信息系统开发技术,建设电网极端天气区划图智能绘制系统,实现极端天气专题图的智能成图、编辑、审批、发布、分析、评价等多项功能,为电网规划和电网防灾减灾提供决策依据。     

机车走行部运行可靠性研究

通过对机车走行部部件的分类,分析了走行部主要部件故障发生的原因。利用可靠性的基本原理,分析机车走行部的故障模式及其影响,总结出提高走行部主要部件运行可靠性的管理方法和维修体制。     

极端天气下含小水电的弱区域配电网风险模式研究

为充分发挥区域内小水电等分布式电源支撑潜力,提高弱区域配电网抵御极端天气的能力,文章提出了弱电网极端天气风险运行模式。首先通过内部分布式小水电出力、主网联络线输送功率和负荷的多时间尺度的联合优化调度,在系统发生风险时确保区内重要负荷可靠持续供电;然后,根据不同时间尺度下风险来临概率和水电站来水预测,自适应调整各水电站蓄水量可接受的最小目标值,提高了小水电站的经济性。最后以海南乐东电网为算例,验证了所提模式的可行性和有效性。     

200MW自然循环锅炉运行可靠性分析

本文对配200MW的670t/h锅炉进行了可靠性分析.并提出了改进措施.     

计及台风极端天气影响的城市能源规划

气候变化导致极端天气事件频发,给城市能源供应带来了前所未有的挑战.但现有的城市能源规划研究较少考虑极端天气事件对城市能源系统的影响.基于天气历史数据与极端天气条件下系统运行情况生成极端天气情景,提出融合常规情景与极端天气情景的城市能源规划模型架构,并以厦门市的城市电源规划为案例展开研究.结果表明,当考虑以"十年一遇"或...     

牵引电机故障分析及提高运用可靠性的办法

分析了机车牵引电动机发生故障的原因,归纳为4个方面。提出了提高机车牵引电动机可靠性的7项措施。     

Offshore wind turbine reliability and operational simulation under uncertainties

The fast‐growing offshore wind energy sector brings opportunities to provide a sustainable energy resource but also challenges in offshore wind turbine (OWT) operation and maintenance management. Existing operational simulation models assume deterministic input reliability and failure cost data, whereas OWT reliability and failure costs vary depending on several factors, and it is often not possible to specify them with certainty. This paper focuses on modelling reliability and failure cost uncertainties and their impacts on OWT operational and economic performance. First, we present a probabilistic method for modelling reliability data uncertainty with a quantitative parameter estimation from available reliability data resources. Then, failure cost uncertainty is modelled using fuzzy logic that relates a component's failure cost to its capital cost and downtime. A time‐sequential Monte Carlo simulation is presented to simulate operational sequences of OWT components. This operation profile is later fed into a fuzzy cost assessment and coupled with a wind power curve model to evaluate OWT availability, energy production, operational expenditures and levelised cost of energy. A case study with different sets of reliability data is presented, and the results show that impacts of uncertainty on OWT performance are magnified in databases with low components' reliability. In addition, both reliability and cost uncertainties can contribute to more than 10% of the cost of energy variation. This research can provide practitioners with methods to handle data uncertainties in reliability and operational simulation of OWTs and help them to quantify the variability and dependence of wind power performance on data uncertainties.     

基于认知分析的变电站人为可靠性分析方法

叙述了变电站设备可靠性分析方法和其他工业领域的人为可靠性分析研究历史,分析了变电站运行人员的操作行为和操作票制度,并指出了智能电网战略下数字化、无人值守变电站的发展趋势,以及程序化操作和远动执行装置的推广运用对运行人员具体操作的影响.结合电力操作独有的特点,修改基本的认知可靠性和误差分析模型,使其符合电力系统实际,提出了一种基于认知可靠性和误差分析模型的变电站人为操作可靠性分析方法.通过某变电站倒闸操作的案例分析,验证了模型的正确性,并指出模型的应用方向.     

提高DF4C型机车增压器运用可靠性的措施

1问题的提出DF4C型机车装用的是天津机车车辆机械厂生产的ZN290型增压器或江津增压器厂生产的VTC254-13型增压器。该增压器的高增压比使机车柴油机功率得到了很好的发挥,但在运用过程中暴露出部件损坏程度大、吊修率高的质量问题。2003年以前,我段每年因增压器质量问题造成的机     

A multi-point univariate decomposition method for structural reliability analysis

A new multi-point univariate decomposition method is presented for structural reliability analysis involving multiple most probable points (MPPs). The method involves a novel function decomposition at all MPPs that facilitates local univariate approximations of a performance function in the rotated Gaussian space, Lagrange interpolation for univariate component functions and return mapping to the standard Gaussian space, and Monte Carlo simulation. In addition to the effort in identifying all MPPs, the computational effort in the multi-point univariate method can be viewed as performing deterministic response analysis at user-selected input defined by sample points. Compared with the existing multi-point FORM/SORM, the multi-point univariate method developed provides a higher-order approximation of the boundary of the failure domain. Both the point-fitted SORM and the univariate method entail linearly varying cost with respect to the number of variables. However, the univariate method with less than nine sample points requires fewer calculations of the performance function than the point-fitted SORM. Numerical results indicate that the proposed method consistently generates an accurate and computationally efficient estimate of the probability of failure.     

Digital tuft analysis of stall on operational wind turbines

Operational wind turbines are exposed to dynamic inflow conditions because of, for instance, atmospheric turbulence and wind shear. In order to understand the resulting three‐dimensional and transient aerodynamics effects at a site, a 10m stall‐regulated upwind two‐bladed wind turbine was instrumented for a novel digital tuft flow visualization study. High definition video of a tufted blade was acquired during wind turbine operation in the field, and a novel digital image processing algorithm calculated the blade stall directly from the video. After processing O(10⁵) sequential images, the algorithm achieved a ?5% bias error compared with previous manual analysis methods. With increasing wind speed (5m/s to 20m/s) the fraction of tufts exhibiting stalled flow increased from 5% to 40% on the outboard 40% of the blade. The independently measured instantaneous turbine power production correlates highly with the stall fraction. Some azimuthal variation in the stall fraction associated with dynamic stall induced by vertical wind shear was seen with a maximum in the 45–90° azimuthal location. The high detail, quantitative image processing method demonstrated good agreement with the expected behaviour for a stall‐regulated wind turbine and revealed azimuthal variation because of shear‐induced dynamic stall. The amount of reliable blade stall data to be obtained from digital tuft visualization has hereby been vastly increased. Copyright © 2015 John Wiley & Sons, Ltd.     

Exergy and reliability analysis of wind turbine systems: A case study

The present study undertakes an exergy and reliability analysis of wind turbine systems and applies to a local one in Turkey: the exergy performance and reliability of the small wind turbine generator have been evaluated in a demonstration (1.5 kW) in Solar Energy Institute of Ege University (latitude 38.24 N, longitude 27.50 E), Izmir, Turkey. In order to extract the maximum possible power, it is important that the blades of small wind turbines start rotating at the lowest possible wind speed. The starting performance of a three-bladed, 3 m diameter horizontal axis wind turbine was measured in field tests. The average technical availability, real availability, capacity factor and exergy efficiency value have been analyzed from September 2002 to November 2003 and they are found to be 94.20%, 51.67%, 11.58%, and 0–48.72%, respectively. The reliability analysis has also been done for the small wind turbine generator. The failure rate is high to an extent of 2.28×10⁻⁴ h⁻¹ and the factor of reliability is found to be 0.37 at 4380 h. If failure rate can be decreased, not only this system but also other wind turbine systems of real availability, capacity factor and exergy efficiency will be improved.     

A comparative institutional analysis of the Fukushima nuclear disaster: Lessons and policy implications

This paper analyzes the causes, responses, and consequences of the Fukushima nuclear power plant accident (March 2011) by comparing these with Three Mile Island (March 1979) and Chernobyl (April 1986). We identify three generic modes of organizational coordination: modular, vertical, and horizontal. By relying on comparative institutional analysis, we compare the modes' performance characteristics in terms of short-term and long-term coordination, preparedness for shocks, and responsiveness to shocks. We derive general lessons, including the identification of three shortcomings of integrated Japanese electric utilities: (1) decision instability that can lead to system failure after a large shock, (2) poor incentives to innovate, and (3) the lack of defense-in-depth strategies for accidents. Our suggested policy response is to introduce an independent Nuclear Safety Commission, and an Independent System Operator to coordinate buyers and sellers on publicly owned transmission grids. Without an independent safety regulator, or a very well established “safety culture,” profit-maximizing behavior by an entrenched electricity monopoly will not necessarily lead to a social optimum with regard to nuclear power plant safety. All countries considering continued operation or expansion of their nuclear power industries must strive to establish independent, competent, and respected safety regulators, or prepare for nuclear power plant accidents.     

A comparison of the accuracy of building energy analysis in Bahrain using data from different weather periods

Weather data are important in building design and energy analysis. In Bahrain, the weather data currently used are based on far past climatic information. Climate variability during the last few decades has raised concern over the ability of these data to provide accurate results when analysing the energy performance of buildings. This study discusses issues related to climate variability and evaluates its impact on the performance of weather data used in building simulation. An evaluation was performed using two methods: firstly, a comparison of measured climatic elements and secondly, a comparison of the thermal performance of two statistically based weather data files. With respect to their impact on typical Bahraini building thermal systems, the comparison was carried out between simulation results and the actual energy consumption of two case studies. This paper shows a 14.5% difference between simulation results based on far past data and present electricity consumption and concludes that the prediction of present and future performance based on recent updated data gives better results.     

An end-use approach to reliability investment analysis

Reliability investments occuring on the customer side of the meter are becoming increasingly important, and warrant consideration when planning utility efforts to improve electricity reliability. This paper presents an end-use approach to the analysis of reliability investments, and suggests that from an economic efficiency perspective, society might prefer a greater emphasis on customer-side reliability investments. The feasibility of this approach is demonstrated using utility-supplied end-use data.