Risk-Balanced Routing Strategy for Service Function Chains of Cyber-Physical Power System Considering Cross-Space Cascading Failure

Cyber-physical power system(CPPS)has significantly improved the operational efficiency of power systems.However,cross-space cascading failures may occur due to the coupling characteristics,which poses a great threat to the safety and reliability of CPPS,and there is an acute need to reduce the probability of these failures.Towards this end,this paper first proposes a cascading failure index to identify and quantify the importance of different information in the same class of communication services.On this basis,a joint improved risk-balanced service function chain routing strategy(SFC-RS)is proposed,which is modeled as a robust optimization problem and solved by column-and-constraint generation(C-CG)algorithm.Compared with the traditional shortest-path routing algorithm,the superiority of SFC-RS is verified in the IEEE 30-bus system.The results demonstrate that SFC-RS effectively mitigates the risk associated with information transmission in the network,enhances information transmission accessibility,and effectively limits communication disruption from becoming the cause of cross-space cascading failures.

电力信息物理系统故障通信恢复策略

极端灾害将导致电力系统与通信系统同时发生大面积瘫痪,基于“保电救灾、通信先行”原则,优先恢复故障通信是支撑保障电力系统安全运行的关键。该文针对灾后电力通信高效恢复问题,提出了一种计及电力侧状态感知需求与运行调控能力保障的增广路径最大流电力通信网络恢复算法。首先考虑到电力通信系统与电力物理系统的紧耦合特性,设计了计及电力侧影响的状态感知与运行调控能力量化指标,辨识关键信息节点。然后,通过图论最大流理论,搜寻关键信息节点的增广路径集。在此基础上,引入恢复贡献度,从增广路径集中选择具有大容量、低延时以及少故障链路的通信路径进行优先重建,为灾后电力系统快速恢复过程提供可达、可靠的通信支撑。最后,以IEEE39标准系统作为仿真算例,验证了所提恢复策略下的通信系统具有更高的通信服务质量(quality of service,QoS),避免了在恢复过程中由于带宽容量不足而发生业务频繁掉线风险。

Research on large-scale cascading failure of power systems using synergistic effect

This paper discusses the primary causes from the point of synergistic effects to improve power system vulnerability in the power system planning and safety operation. Based on the vulnerability conception in the complex network theory the vulnerability of the power system can be evaluated by the minimum load loss rate when considering power supply ability.Consequently according to the synergistic effect theory the critical line of the power system is defined by its influence on failure set vulnerability in N-k contingencies.The cascading failure modes are proposed based on the criterion whether the acceptable load curtailment level is below a preset value.Significant conclusions are revealed by results of IEEE 39 case analysis weak points of power networks and heavy load condition are the main causes of large-scale cascading failures damaging synergistic effects can result in partial failure developed into large-scale cascading failures vulnerable lines of power systems can directly lead the partial failure to deteriorate into a large blackout while less vulnerable lines can cause a large-scale cascading failure.

无线供电MEC系统的计算能效最大化策略

为了解决无线供电移动边缘计算(MEC)系统的计算能效优化问题,提出一种基于非正交多址接入的无线供电MEC系统的资源分配策略。该策略将非线性能量收集模型应用到移动设备上,通过联合优化MEC服务器和移动设备的计算频率、执行时间、基站发射功率、设备发射功率、卸载时间和能量收集时间,比较充分地利用移动设备和MEC服务器的可用计算资源,提高设备的吞吐量和计算位数,进而最大限度地提升系统计算能效。将该联合优化问题转化为非凸分式规划问题,设计一种基于Dinkelbach的迭代算法来获得最优的资源分配方案。仿真实验表明:该资源分配策略所获得的系统计算能效更高,具有更好的性能增益。

基于用户最佳聚合模式的智能楼宇电能共享调度策略

针对拥有光伏装置的产消一体化智能楼宇,其多数时段处于供需不平衡的情况,存在“余电上网,缺电购买”等对电网依赖性较大的问题。为提升新能源的就地消纳率,降低用户用电成本,考虑不同用户用电行为的互补性,提出一种基于楼宇用户最佳聚合模式的电能共享调度策略。首先,建立了以非均衡蛛网定价模型驱动基于全景理论能量函数的聚合模型,寻求用户间电能共享效果最佳的聚合组合,以供需匹配度设置组合内部电能共享的套餐价格。接着,计及发电装置出力以及用户用电行为的不确定性,利用弱鲁棒优化理论求解所得聚合组合内部电能共享调度策略,通过算例仿真验证了所提模型的有效性。

Effect of surface crack on the bearing capacity of strip footing placed on rock mass

In hilly regions,the existence of surface cracks in rock mass induces a potential threat to structural stability.Thus,the present research aims to explore the impact of surface cracks on the loadbearing capacity of strip footing placed on the rock mass.By taking into account the various boundary constraints across the surface of crack edges,the study investigates the presence of two categories of surface cracks,namely(1)separated crack,and(2)fine crack.The lower bound limit analysis is employed in conjunction with the finite element method(LBFELA)to conduct the numerical analysis.In order to evaluate rock mass yielding,the power conic programming(PCP)method is utilized to implement the generalized Hoek-Brown(GHB)failure criterion.The stability of the strip footing is analyzed by determining the bearing capacity factor(Nσγ),which is presented in the form of design charts by varying the strength parameters of rock,including the Geological Strength Index(GSI),Hoek-Brown material parameter(mi),Disturbance factor(D),and Normalised Uniaxial Compressive Strength(σci/γB),whereγis the unit weight of rock mass,and B is the width of strip footing.The study also investigates the impact of cracks on strip footings,considering different positions of the crack(LC)and depths of the crack(DC).The results demonstrate that the influence of the fine crack is only noticeable until the LC/B ratio reaches 6.However,for the separated crack,its impact remains significant even when the LC/B ratio exceeds 16.The appearance of fine crack at the edge of the footing results in a decrease in the magnitude Nσγof up to 45%,indicating a substantial reduction in the stability of the footing.The failure patterns are presented and discussed in detail for various cases in this study to examine the effect of surface cracks on the strip footing and to address the extent of the plastic collapse.

基于结构功能和供电功能的电力系统震后功能损失评估研究

为探究电力系统的地震失效概率,提出了一种结合易损性分析方法和潮流分析法的功能损失评估方法。该方法首先从结构功能和供电功能两个维度定义了电力系统的功能函数,通过专家调查问卷,利用层次分析法确定了功能函数中各子系统的重要性系数以及各子系统中结构功能与供电功能的分项加权系数。然后以建筑场地设防烈度对应的峰值地震动加速度(PGA)替代了传统研究地震风险的概率分析方法,并应用《城市工程系统抗震韧性评价导则》中所提供的电力系统基础设施元件在4种极限损坏状态下的易损性曲线,对电力系统震后剩余功能进行了评估。最后考虑到电力系统前序元件的供电功能失效会影响后序元件的正常工作(级联故障),利用潮流分析方法和蒙特卡洛模拟方法,以带有7个负荷的小型电力系统为例,研究了其震后元件及系统的失效概率。结果表明:当PGA大于0.2 g(g为重力加速度)后,考虑电力系统元件间级联故障的潮流分析方法和利用易损性曲线估算方法的分析结果逐渐分离,前者失效概率更高,且剩余功能更少,因此在开展电力系统整体功能评估时,非常有必要考虑元件间的级联关系;结合易损性曲线方法和潮流分析法能够宏观评估复杂电力系统的失效概率,并且此方法可以很便利地应用到城市电力系统中,是研究电力系统韧性的一种有效方法。

高比例风电接入下电力系统连锁故障的关键传播模式辨识

高比例风电接入电网产生的强不确定性,使得电力系统发生连锁故障的场景更多、机理更复杂。辨识连锁故障的关键传播模式对于预防大停电事故具有重要意义。文章首先考虑风电出力不确定性、元件故障等因素,建立连锁故障动态分析模型,获取海量初始场景下故障传播路径数据;然后,建立描述连锁故障时序传播过程的影响关联图,结合概率-后果提出故障关键传播模式辨识方法,筛选高比例风电接入下连锁故障的高风险传播环节;最后,利用IEEE 118节点验证所提方法在关键传播模式辨识的有效性。

基于5G的电网通信电源故障检测与处理

对基于5G的电网通信电源故障进行检测,探讨了故障的类型、成因及其对电网运行的影响,并提出了相应的处理策略。通过故障检测与远程监控,结合5G的实时数据传输能力,能够快速响应和处理电源故障,从而提升电网的可靠性和安全性。不仅探讨了电网通信电源故障的检测与处理策略,还展示了5G在电力系统中的应用潜力,为未来电网的智能化管理提供了新的思路和解决方案。

大规模电力通信网链路故障保护算法设计

由于电力通信网链路数量庞大、状态变化频繁且故障类型多样化,易导致业务中断,影响电力通信网络运行的可靠性,为此,提出一种大规模电力通信网链路故障保护算法。采集电力通信网每一段链路的流量数据,利用K-Means算法批量聚类,检测并排除链路故障。引入人工蜂群算法,利用无故障链路重新组建最优通信保护路径,实现大规模电力通信网链路故障保护。测试结果表明,所提方法求出的链路保护方案的路径总长度更短,节点跳数仅为5跳,业务传递耗费总时间更短,由此说明所研究算法的性能更好。

左西孟旦联合无创呼吸机对急性左心衰竭患者心功能及血气指标的影响

目的:分析左西孟旦联合无创呼吸机对急性左心衰竭(ALHF)患者心功能及血气指标的影响。方法:回顾性选取2020年2月—2023年12月徐州市肿瘤医院收治的102例ALHF患者。根据不同的治疗方式将其分为联合组和常规组,各51例。常规组给予高流量鼻导管吸氧,联合组给予左西孟旦联合无创呼吸机治疗。比较两组临床疗效,治疗前、治疗7 d后心功能指标、血气指标。结果:联合组治疗7 d后的总有效率为92.16%,高于常规组的76.47%,差异有统计学意义(P<0.05)。治疗7 d后,两组N末端脑利钠肽前体(NT-proBNP)、左心室舒张末期内径(LVEDD)均降低,左心室射血分数(LVEF)升高,联合组NT-proBNP、LVEDD均低于常规组,LVEF高于常规组,差异有统计学意义(P<0.05)。治疗7 d后,两组动脉血二氧化碳分压(PaCO_(2))降低,而动脉氧分压(PaO_(2))、经皮血氧饱和度(SpO_(2))均升高,联合组PaO_(2)、SpO_(2)均高于常规组,PaCO_(2)低于常规组,差异有统计学意义(P<0.05)。结论:左西孟旦联合无创呼吸机治疗能有效改善ALHF患者的心脏射血功能,并优化血气指标。

反射片非接触式测量在核电测量中的应用

当代核电建设已经把保护职工生命和职业健康安全摆在首位,既要保证测量作业人员安全,又要保证测量精度与质量,更要不断提高测量作业效率。传统棱镜测量作业安全风险大、稳定性差,无棱镜测量易受作业环境、物体自身特性、距离与角度影响,其精度较低、容易出现粗差。为了实现安全、高效、精度稳定的施工测量方法,从反射片测量概念、原理、优势出发,通过实际案例分析反射片非接触式测量精度,并确定反射片非接触式测量在核电工程测量中的应用可行性、范围及注意事项。该测量方法具有作业安全风险低、质量稳定、人员与工具投入少和工作效率高等优点。

基于混合模型的非侵入式负荷监测数据的生成

非侵入式负荷监测(non-intrusive load monitoring,NILM)是一种无需进入每个用电器内部系统,仅在用户总线入口处安装监测设备的技术.在开展NILM技术研究时,往往需要收集大规模的用户负荷数据来证明所提出方法的普适性,此需求不可避免地带来了繁重的数据收集与整理负担.为克服该挑战,设计了一种结合周期信号频率不变变换(frequency invariant transformation for periodic signals,FIT-PS)原理与时间序列生成对抗网络(time series generative adversarial networks,TimeGAN)的混合模型,记为FIT-PSTimeGAN.针对全球家庭与工业瞬态能量数据集(worldwide household and industry transient energy dataset,WHITED)中的空调、微波炉、吸尘器、冰箱和热水壶5种电器,运用FIT-PS对负荷数据集进行切割和拼接,构建TimeGAN不同状态下的训练集和测试集.评估测试集的效果发现,生成的波形数据与真实数据表现出高度一致性.进一步采用FIT-PS对训练得到的生成数据进行截取和拼接,生成满足测试需求的完整的单负荷波形和多负荷波形.对这些生成的波形与相同状态下的真实数据进行对比,结果显示两者吻合度很高.与自回归模型和生成对抗网络(generative adversarial network,GAN)模型相比,FIT-PS-TimeGAN模型在生成数据的性能方面表现更优.研究结果表明,FIT-PS-TimeGAN混合模型能够有效生成符合标准电器运行规律的波形和场景数据.

基于STC32G单片机的电梯抱闸电源设计

针对电梯抱闸电源在模拟芯片控制下存在成本高、可控性差等不足,设计1种基于数字控制器的抱闸电源系统。以STC32G单片机为控制器,通过整流滤波电路将交流电压转换成直流电压,再通过Buck变换器进行降压处理对抱闸线圈供电;由STC32G自带的12位高精度模拟数字转换器(ADC)模块对电压电流进行采样,且实时调节电压反馈;以滑模控制理论为基础,对趋近律函数进行改进,设计新型非奇异终端滑模控制器,进一步提高抱闸电源的动态响应和抗干扰性能;最后,搭建基于Matlab/Simulink的仿真模型和STC32G的实验平台进行仿真和实验,验证设计电源的有效性。结果表明:相比于PI控制器,新型非奇异终端滑模控制器在参考电压改变和负载突变的情况下电压恢复时间分别提高了62.5%和66.7%以上,设计的抱闸电源系统具有较好的动稳态性能和抗干扰能力。

开关电源在安全级DCS中的应用失效研究

针对国产化安全级DCS平台的模拟量调理模块研制过程中,某型国产反激式开关电源曾多次偶发输入端短路失效问题。对该电源内部原理进行剖析,建立故障仿真模型。结合安全级DCS的实际应用场景,对该故障进行定位,明确国产某型反激式开关电源的失效机理,并给出对应的改进优化设计,有效提升国产化安全级DCS平台的可靠性及安全性。

Analysis of cascading failures of power cyber-physical systems considering false data injection attacks

This study considers the performance impacts of false data injection attacks on the cascading failures of a power cyber-physical system,and identifies vulnerable nodes.First,considering the monitoring and control functions of a cyber network and power flow characteristics of a power network,a power cyber-physical system model is established.Then,the influences of a false data attack on the decision-making and control processes of the cyber network communication processes are studied,and a cascading failure analysis process is proposed for the cyber-attack environment.In addition,a vulnerability evaluation index is defined from two perspectives,i.e.,the topology integrity and power network operation characteristics.Moreover,the effectiveness of a power flow betweenness assessment for vulnerable nodes in the cyberphysical environment is verified based on comparing the node power flow betweenness and vulnerability assessment index.Finally,an IEEE14-bus power network is selected for constructing a power cyber-physical system.Simulations show that both the uplink communication channel and downlink communication channel suffer from false data attacks,which affect the ability of the cyber network to suppress the propagation of cascading failures,and expand the scale of the cascading failures.The vulnerability evaluation index is calculated for each node,so as to verify the effectiveness of identifying vulnerable nodes based on the power flow betweenness.

Review on failure analysis of interconnections in power devices

Interconnections in microelectronic packaging are not only the physical carrier to realize the function of electronic circuits,but also the weak spots in reliability tests.Most of failures in power devices are caused by the malfunction of interconnections,including failure of bonding wire as well as cracks of solder layer.In fact,the interconnection failure of power devices is the result of a combination of factors such as electricity,temperature,and force.It is significant to investigate the failure mechanisms of various factors for the failure analysis of interconnections in power devices.This paper reviews the main failure modes of bonding wire and solder layer in the interconnection structure of power devices,and its failure mechanism.Then the reliability test method and failure analysis techniques of interconnection in power device are introduced.These methods are of great significance to the reliability analysis and life prediction of power devices.

Structural first failure times under non-Gaussian stochastic behavior

An analytical moment-based method for calculating structuralfirst failure times under non-Gaussian stochastic behavior is proposed. In the method, a power series that constants can be obtained from response moments （skewness, kurtosis, etc.） is used firstly to map a non-Gaussian structural response into a standard Gaussian process, then mean up-crossing rates, mean clump size and the initial passage probability of a critical barrier level by the original structural response are estimated, and finally, the formula for calculating first failure times is established on the assur^ption that corrected up-crossing rates are independent. An analysis of a nonlinear single-degree-of-freedom dynamical system excited by a Gaussian model of load not only demonstrates the usage of the proposed method but also shows the accuracy and efficiency of the proposed method by comparisons between the present method and other methods such as Monte Carlo simulation and the traditional Gaussian model.

Effects of low temperatures on strength and power input into rock failure

Study results of low temperature effects on the strength index and specific power input into rock failure are presented.It has been experimentally determined that within the range of-5 °С to-15 °С,there is a local minimum at which the compression strength and specific power input into failure of some rocks are 10%-50% lower than those at positive temperatures.

Effects of rh BNP after PCI on non-invasive hemodynamic in acute myocardial infarction patients with left heart failure

Objective: To investigate the effects of exogenous recombinant human brain natriuretic peptide(rh BNP) after primary percutaneous coronary intervention(PCI) on non-invasive hemodynamic in acute myocardial infarction patients with left ventricular failure. Methods: A number of 96 acute myocardial infarction patients accompanied with heart failure after PCI hospitalized in the People's Hospital of Sanya during February 2012 to October 2015 were selected. They were randomly divided into the therapy group(n = 50) and control group(n = 46). On the basis of routine treatment, patients in the therapy group were treated with intravenous rh BNP(1.5 μg/kg was intravenous injection with uniform speed of 3 min, followed by continuous infusion 0.007 5 μg/kg·min for 72 h), while the control group received conventional treatment. Bio Z-2011 non-invasive hemodynamic real-time monitoring system was used to monitor the hemodynamic parameters changes and the leves of plasma pro-BNP, serum creatinine, serum potassium, serum sodium and urine volume of each group before and after treating for 30 min, 1 h, 3 h, 6 h, 12 h, 24 h, 48 h, 72 h. Results: Patients in the therapy group showed no effect on heart rate, while after 30 min of intravenous injection of rh BNP, CO, CI, SV, and SI increased significantly and LVET and TFC reduced at the same time, which had certain effect on blood pressure(SBP/DBP). Compared with the control group, the therapy group showed a faster and more effective improvement on haemodynamics. Conclusions: Acute myocardial infarction patients complicated with left heart failure after primary PCI can significantly improve hemodynamics by treating with rh BNP.