Classification of wintertime large-scale tilted ridges over the Eurasian continent and their influences on surface air temperature

This study investigates the major patterns of large-scale tilted ridges(LSTRS)over the Eurasian continent and their connections with large-scale surface air temperature during boreal winter.A total number of 134 LSTR events with zonal extent exceeding 90°of longitude on the peak day are identified.Using self-organizing map(SOM),the LSTRs are classified into five clusters that are characterized by different spatial distributions and orientations.The leading two clusters are closely associated with extensive and persistent cold events over different places.Considering the first cluster,LSTRs extend from the Ural Mountains to Northeast Asia and are favorable for the amplification and southeastward extension of the Siberian high.Therefore,this cluster is closely associated with the occurrence of extensive and persistent cold events in china.In comparison with the first cluster,the LSTRs of second group are situated to the west,with starting points from the Kola Peninsula,and cause extensive and persistent cold events over Eastern Europe,central Asia,and central Siberia.The results suggest that the vertical coupling between LSTRs and the corresponding anomalous sea level pressure is crucial for the persistent cold temperature events associated with the leading two SOM clusters.

Spatiotemporal Variability in Extreme Temperature Events in an Arid-Semiarid Region of China and Their Teleconnections with Large-Scale Atmospheric Circulation

With a warming climate,temperature extremes have been a main global issue in recent decades due to their potential influence on the sustainable development of human life and natural ecosystems.In this study,12 indicators of extreme temperature events are used to evaluate the spatiotemporal distribution,periodic structure and teleconnections with large-scale atmospheric circulation in Xinjiang,Northwest China by combining wavelet coherence(WTC) analysis based on continuous wavelet transform(CWT) analysis with the sequential Mann-Kendall test.We find that over the past six decades,the climate in Xinjiang has become warmer and has suffered from increases in the frequency of warm extremes and decreases in the frequency of cold extremes.Warm extremes have mainly occurred in the southern Tianshan Mountains surrounding the Tarim Basin and western part of the Taklamakan Desert,and cold extremes have primarily occurred in the southwestern Altai Mountains and northern foot of the Tianshan Mountains.Extreme temperature events,including warm extremes,cold extremes,and other temperature indices,have significant interannual variability,with the main oscillation periods at smaller(2–4-year band),intermediate(4–7-year band),and greater time scales in recent decades.Furthermore,cold-extreme indices,including frost days,cool days,and cool nights all show a clear changepoint during 1990–1997 at the 95% confidence level,and both ice days and cold spell duration indicator have a potential changepoint during 1981–1986.However,the changing points for warmextreme indices are detected during 1992–1998.The temperature variables are significantly correlated with the EI Ni?o-Southern Oscillation(ENSO) and Arctic Oscillation(AO),but less well correlated with the Pacific Decadal Oscillation(PDO).The phase difference in the WTC spectra is not uniform between temperature extremes and climatic oscillations.Our findings will have important implications for local governments in taking effective measures to mitigate the potential effects of regional climate warming due to human activities in Xinjiang.

Main Energy Paths and Energy Cascade Processes of the Two Types of Persistent Heavy Rainfall Events over the Yangtze River–Huaihe River Basin

Two types of persistent heavy rainfall events （PHREs） over the Yangtze River-Huaihe River Basin were determined in a recent statistical study： type A, whose precipitation is mainly located to the south of the Yangtze River; and type B, whose precipitation is mainly located to the north of the river. The present study investigated these two PHRE types using a newly derived set of energy equations to show the scale interaction and main energy paths contributing to the persistence of the precipitation. The main results were as follows. The available potential energy （APE） and kinetic energy （KE） associated with both PHRE types generally increased upward in the troposphere, with the energy of the type-A PHREs stronger than that of the type-B PHREs （except for in the middle troposphere）. There were two main common and universal energy paths of the two PHRE types： （1） the baroclinic energy conversion from APE to KE was the dominant energy source for the evolution of large-scale background circulations; and （2） the downscaled energy cascade processes of KE and APE were vital for sustaining the eddy flow, which directly caused the PHREs. The significant differences between the two PHRE types mainly appeared in the lower troposphere, where the baroclinic energy conversion associated with the eddy flow in type-A PHREs was from KE to APE, which reduced the intensity of the precipitation-related eddy flow; whereas, the conversion in type-B PHREs was from APE to KE, which enhanced the eddy flow.

Extensive Cold-Precipitation-Freezing Events in Southern China and Their Circulation Characteristics

Concurrence of low temperature,precipitation and freezing weather in an extensive area would cause devastating impacts on local economy and society.We call such a combination of concurrent disastrous weather“extensive coldprecipitation-freezing”events(ECPFEs).In this study,the ECPFEs in southern China(15°−35°N,102°−123°E)are objectively defined by using daily surface observational data for the period 1951−2013.An ECPFE in southern China is defined if the low temperature area,precipitation area and freezing area concurrently exceed their respective thresholds for at least three consecutive days.The identified ECPFEs are shown to be reasonable and reliable,compared with those in previous studies.The circulation anomalies in ECPFEs are characterized by a large-scale tilted ridge and trough pairing over mid-and high-latitude Eurasia,and the intensified subtropical westerlies along the southern foot of the Tibetan Plateau and the anomalous anticyclonic circulation over the subtropical western Pacific.Comparative analysis reveals that the stable cold air from the north and the warm and moist air from the south converge,facilitating a favorable environment for the concurrence of extensive low-temperature,precipitation and freezing weather.

Comparison of two types of persistent heavy rainfall events during sixteen warm seasons in the Sichuan Basin

Based on hourly precipitation from national surface stations,persistent heavy rainfall events(PHREs)over the Sichuan Basin(SCB)are explored during the warm season(May to September)from 2000 to 2015 to compare synoptic circulations and maintenance mechanisms between different PHRE types.There are two main types of PHREs:one is characterized by a rain belt west of 106°E over the SCB(WSB-PHREs),and the other features a rain belt east of 106°E over the SCB(ESB-PHREs).In total,there are 18 ESB-PHREs and 10 WSB-PHREs during the study period.Overall,the rain belts of WSB-PHREs are along the terrain distribution east of the Tibetan Plateau,while the precipitation intensity of ESB-PHREs is stronger.For the two types of PHREs,the shortwave trough over the SCB and the western Pacific subtropical high act as their favorable background environments,particularly for ESB-PHREs.The water vapor of WSB-PHREs is mainly transported from the South China Sea,whereas for ESB-PHREs the South China Sea and Bay of Bengal are their main moisture sources.The composite vorticity budgets of southwest vortices during their mature stage indicate that the convergence effect is a dominant factor for maintaining the two types of PHREs,and the strong vertical vorticity advection is also favorable,but the relative contribution of vertical advection is larger for WSB-PHREs.

Zone 3 Relay Blocking Scheme to Prevent Cascaded Events

Defense systems are needed to prevent catastrophic failures of a power grid due to cascaded events. Cascaded events can be attributed to improper operations of protective relays. The most challenging problem for the design and implementation of a defense system is the performance in accuracy and speed in a real time environment. Protective devices are normally designed to operate fast in order to isolate the fault（s）. This paper proposes a new methodology to distinguish line overloads from actual faults for distance relays. In order to distinguish between line flow transfers from a line outage and an actual fault, the line outage distribution factor （LQDF） and generation shift factor （GSF） based power flow estimation method, and a secure peer to peer （P2P） communication structure are adopted. Computer simulations of cascaded events for a 6-bus system and the Korean power grid have been performed to establish the feasibility of the proposed scheme.

Energy Security Planning for Hydrogen Fuel Cell Vehicles in Large-Scale Events:A Case Study of Beijing 2022 Winter Olympics

Energy security planning is fundamental to safeguarding the traffic operation in large-scale events.To guarantee the promo-tion of green,zero-carbon,and environmental-friendly hydrogen fuel cell vehicles(HFCVs)in large-scale events,a five-stage planning method is proposed considering the demand and supply potential of hydrogen energy.Specifically,to meet the requirements of the large-scale events’demand,a new calculation approach is proposed to calculate the hydrogen amount and the distribution of hydrogen stations.In addition,energy supply is guaranteed from four aspects,namely hydrogen produc-tion,hydrogen storage,hydrogen delivery,and hydrogen refueling.The emergency plan is established based on the overall support plan,which can realize multi-dimensional energy security.Furthermore,the planning method is demonstrative as it powers the Beijing 2022 Winter Olympics as the first“green”Olympic,providing both theoretical and practical evidence for the energy security planning of large-scale events.This study provides suggestions about ensuring the energy demand after the race,broadening the application scenarios,and accelerating the application of HFCVs.

Understanding the Dynamics Location of Very Large Populations Interacted with Service Points

This paper offers preliminary work on system dynamics and Data mining tools. It tries to understand the dynamics of carrying out large-scale events, such as Hajj. The study looks at a large, recurring problem as a variable to consider, such as how the flow of people changes over time as well as how location interacts with placement. The predicted data is analyzed using Vensim PLE 32 modeling software, GIS Arc Map 10.2.1, and AnyLogic 7.3.1 software regarding the potential placement of temporal service points, taking into consideration the three dynamic constraints and behavioral aspects: a large population, limitation in time, and space. This research proposes appropriate data analyses to ensure the optimal positioning of the service points with limited time and space for large-scale events. The conceptual framework would be the output of this study. Knowledge may be added to the insights based on the technique.

“Approach” and “Threshold” Effects of Large-scale Urban Events on Heritage Conservation:A Study on Heritage Conservation from Standpoint of Cultural Anthropology

Large-scale urban events like the Olympic Games,the World Expo,etc.,have brought about an "approach" leading to renewed conservation measures for old city areas.While they make many heritages receive better protection,they also create new problem of "threshold" to heritage conservation;thus,ideas about the effects of large-scale urban events on cultural heritage preservation are polarized into two opposite directions.Using cultural anthropology as the basis of analysis,this article interprets how these conflicting concepts came to be.As large-scale urban events accelerate and strengthen urban development,they also often cause the abandonment of specific cultural elements during the process of heritage conservation for the oldest city areas.This leads to a general loss of direction in cultural protection efforts.A potential solution is to unearth the cultural spirit of the old cities and preserve it through practical technologies,in considering the specific function of large-scale urban events.In so doing,it is possible to explore new directions and approaches to conserve the heritages of the old city under the guide of urban cultural development strategies.

城市电网应对突发事件保障供电安全的对策研究

该文从预防和应对城市突发事件和灾害造成大停电事故的角度,分析当前城市电网存在的主要问题。在此基础上,从加强系统规划设计,城市供电应急系统建设和城市电网运行控制研究等三个方面,提出了保障城市电网供电安全的工作重点和建议,以期建设坚强的城市电网,降低城市电网的运行风险,加快事故后的抢修重建和供电恢复工作,提高应对突发事件和重大灾害、保障供电安全的能力。

小型压水堆严重事故序列的筛选及模拟分析研究

根据某小型压水堆的特点和运行经验,筛选给出可能引起严重事故的始发事件清单,然后基于SCDAP/RELAP5程序建立了反应堆严重事故分析平台,模拟确认了反应堆严重事故的响应序列。以反应堆全部电源丧失事故为例,根据稳压器安全阀响应情况将事故细分为两类断电事故,并分别分析了反应堆系统的热工水力响应行为及特征参数与后果,为评估装置薄弱环节、严重事故管理导则的开发奠定了基础。

大型核电站全厂断电事故的失效模式分析

运用故障树分析方法，对核电站全厂断电事故进行分析。建造了全厂断电事故即厂用电力系统Ａ、Ｂ两列６．６ｋＶ交流应急母线ＬＨＡ和ＬＨＢ同时失电故障树。利用ＳＥＴＳ程序及法国标准９０万千瓦压水堆核电站２００堆年运行经验反馈的可靠性数据，对全厂断电故障树作了定性、定量分析，得到了全厂断电事故的发生概率。给出了全厂断电事故的主要失效模式及发生的概率和事件的重要度。

类比沙堆模型的电网危害性事件序列展示模型

为了给大面积停电和自组织临界性问题的研究提供一种基础技术手段,根据沙堆模型与电力系统危机演变展示模型间存在一定类比性,建立了类比沙堆模型的电力系统危害性事件展示模型,大面积停电危机演变过程中,经常出现的危害性事件有两种:一种是事故跳闸或连锁跳闸,另一种是电压失稳或崩溃。与沙堆模型中沙粒总是不断地下落相对应,类比沙堆模型的电力系统危害性事件展示模型中,负荷需求不断地增长着,模型从初始状态出发,在负荷需求不断增长的条件下,不同的危害性事件将依次呈现出来,展示危机演变的进程。

基于情景要素的电网大面积停电事件情景序列构建方法研究

为了进一步做好电网大面积停电事件应对工作,针对电网大面积停电事件外部致因条件与事件内部演化规律不清的问题,采用"情景-构建"方法梳理事件情景要素,并在历史事故案例数据以及大量应急演练数据的基础上,综合运用数据挖掘方法,建立相关事件情景的逻辑与时间序列,为电网大面积停电事件的应急响应与决策指挥等工作提供科学、合理的理论支持,相关研究思路与方法也可为电力企业其它类型突发事件的应急管理工作提供参考。

全球大停电的经验教训

根据国际能源机构的预测，在未来20多年里，发展中国家和新兴国家的耗电量将增加220%，而工业化国家则仅增加37％。现有电力系统负荷的大幅度增加将产生瓶颈效应和可靠性问题。历年发生的欧美州大停电清楚地表明，相邻系统间的紧密电气耦合对于重负荷互联系统而言，可能存在无法控制的级联事故风险。介绍美加大停电和欧洲大停电事件，讨论大停电的经验教训。对避免环流、防止电压崩溃等解决大型电力系统稳定性问题的措施及“防火墙”的实施进行了说明。阐述涉及系统改善的高压直流输电（HVDC）和灵活交流输电（FACTS）技术的优点。

大型电网连锁故障分析技术及大停电智能预警系统

连锁故障引发的大停电事故在全球范围内时有发生,对社会和经济造成了巨大损失。为了理解连锁故障的演变特征并进一步构建有效的大停电预防系统,回顾近年来国内外发生的8次大停电事故,研究大停电事故的故障演化过程;对现有连锁故障研究模型和方法进行评述,分析其适用性及模型优缺点;提出基于事件校核和连续时域仿真的连锁故障时序事件搜索方法;最终基于所提连锁故障时序事件搜索方法构建了可用于大停电风险可视化预警的智能预警系统。

基于台区时间差的计量终端掉电判断逻辑研究

为提高计量自动化终端掉电事件判断的准确性,提出一种计及台区时间差的计量终端掉电有效性判断逻辑。该方法对计量自动化系统各应用单元提出包括计量终端掉/上电事件判断限值和优先顺序设置,电能表上电启动工作响应等要求,搜集计量终端与同一台区电能表的掉电信息,根据该终端与同一台区电能表停电发生的时间差及其持续时间信息进行掉电事件有效性检验,并给出检验判据。最后以4类常见终端为例进行不同掉电情况的场景模拟测试。结果表明,该方法能准确识别出所模拟场景的掉电事件,满足现场应用需求。

大面积停电事件应急预案桌面推演优化与实践

依据《生产安全事故应急演练基本规范》有关要求,开展大面积停电事件应急预案桌面推演优化研究,结合福建省仙游县大面积停电事件应急体系建设,创新和优化了大面积停电事件桌面推演形式、内容和流程,提升和改善了预案的针对性和可操作性。

基于计量自动化系统中压停电事件的自动匹配

文中介绍了计量自动化系统和客户全方位系统中的停电信息集市。通过这两种系统的停电特点分析,并采用停电时间统计自适应匹配模型,实现客户停电时间的自动化统计,提高客户停电时间数据的准确性。且通过这两个系统数据的对比后,及时发现异常情况,对采购或管理规范方面进行优化,与传统停电管理系统相比,大大提升了客户停电管理工作的效率。

基于动态事件树的核电厂全厂断电事故分析

为解决传统事件树分析中缺少动态时间参数影响和较多依赖专家判断的不足,本研究使用动态事件树(DET)方法建立中国改进型三环路压水堆(CPR1000)核电厂全厂断电(SBO)事故响应模型。针对汽动辅助给水系统、交流电源恢复等分支节点建立时间相关分支,全面仿真事故分支结果,并计算分支概率与SBO事故下堆芯损伤的失效概率。计算结果表明,不同的汽动辅助给水系统运行时间与交流电源恢复时间对事故后果有明显影响,汽动辅助给水系统运行时间的增长可以延长电源恢复的时间窗口,但电源恢复时间存在上限,超过上限值则堆芯损伤不可避免。相比于传统事件树中计算得到的失效概率,动态事件树方法降低了失效概率值,挖掘出了潜在的安全裕度。