Power management in co-phase traction power supply system with super capacitor energy storage for electrified railways

Increasing railway traffic and energy utilization issues prompt electrified railway systems to be more economical,efficient and sustainable.As regenerative braking energy in railway systems has huge potential for optimized utilization,a lot of research has been focusing on how to use the energy efficiently and gain sustainable benefits.The energy storage system is an alternative because it not only deals with regenerative braking energy but also smooths drastic fluctuation of load power profile and optimizes energy management.In this work,we propose a co-phase traction power supply system with super capacitor(CSS_SC)for the purpose of realizing the function of energy management and power quality management in electrified railways.Besides,the coordinated control strategy is presented to match four working modes,including traction,regenerative braking,peak shaving and valley filling.A corresponding simulation model is built in MATLAB/Simulink to verify the feasibility of the proposed system under dynamic working conditions.The results demonstrate that CSS_SC is flexible to deal with four different working conditions and can realize energy saving within the allowable voltage unbalance of 0.008%in simulation in contrast to 1.3%of the standard limit.With such a control strategy,the performance of super capacitor is controlled to comply with efficiency and safety constraints.Finally,a case study demonstrates the improvement in power fluctuation with the valley-to-peak ratio reduced by 20.3%and the daily load factor increased by 17.9%.

Research on Co-phase Power Supply Test System

Co-phase power supply system can solve the problems of power quality of heavy unbalanced three phase, large harmonics and reactive power and cancel neutral section in electric railway power supply system. In order to do further research, a co-phase power supply test system is proposed. By mean of analyzing on structures and principles of YNvd transformer, integrated power flow controller (IPFC) and simulation load, establishing control strategy on IPFC and simulation load, the system is simulated dynamically. The results illustrate that the scheme can well simulate co-phase system, and the negative sequence is eliminated, harmonic and reactive power are real-timely compensated in system.

A combined forecasting method for intermittent demand using the automotive aftermarket data

Intermittent demand forecasting is an important challenge in the process of smart supply chain transformation,and accurate demand forecasting can reduce costs and increase efficiency for enterprises.This study proposes an intermittent demand combination forecasting method based on internal and external data,builds intermittent demand feature engineering from the perspective of machine learning,predicts the occurrence of demand by classification model,and predicts non-zero demand quantity by regression model.Based on the strategy selection on the inventory side and the stocking needs on the replenishment side,this study focuses on the optimization of the classification problem,incorporates the internal and external data of the enterprise,and proposes two combination forecasting optimization methods on the basis of the best classification threshold searching and transfer learning,respectively.Based on the real data of auto after-sales business,these methods are evaluated and validated in multiple dimensions.Compared with other intermittent forecasting methods,the models proposed in this study have been improved significantly in terms of classification accuracy and forecasting precision,which validates the potential of combined forecasting framework for intermittent demand and provides an empirical study of the framework in industry practice.The results show that this research can further provide accurate upstream inputs for smart inventory and guarantee intelligent supply chain decision-making in terms of accuracy and efficiency.

Trend Analysis of Combined Drugs Creation （for Example Acetylsalicylic Acid）

The pharmaceutical market of Ukraine in January 2015 was registered 71 drug based acetylsalicylic acid （ASA）, for which 52% combined. The most common combinations of ASA with acetaminophen and caffeine （45.9%）, magnesium hydroxide （18.9%）, bisoprolol （10.8%）, ascorbic acid （8.1%）, clopidogrel （5.4%）. Comparing markets combined drugs ASA of Ukraine, the Russian Federation, 28 EU countries, Norway, Switzerland, India, Syria, Australia and the USA identified the active pharmaceutical ingredients, combined with ASA in a single dosage form. The analysis of questionnaires 40 pharmacists pharmacies Temopil, Khmelnytsky and Kyiv regions of Ukraine noted that the biggest demand is mono-drugs ASA, Citramon, Askofen and Cardiomagnyl Methods of pharmacoeconomic studies proved efficient use Upsaryn UPSA with vitamin C tabl. spike, tuba in box number 20 BMS （France）, Citramon tablets number 6 PJSC ＂Monfarm＂ （Ukraine） and Cardiomagnyl tabl. film-coated shell 75 mg in bottle number 100 Nycomed Austria （Austria）. On the basis of six State Forms of drugs in Ukraine （2009-2014） was found that the combination of drugs based on ASA is recommended to use of ascorbic acid （Aspiryn C, Asprovit C, Upsarin UPSA with vitamin C）, dipyridamole （Agrenox）, magnesium hydroxide （Cardiomagnyl, Cardiomagnyl Forte）. Some of the standard combination of ASA （combination of paracetamol and caffeine） are not in form. For optimize State Form of drugs by improving health system in Ukraine can be useful pharmacoeconomic analysis of combination therapies with the current official system to note the combination of ASA with statins, esomeprazole, isosorbide.

关于“理想电源连接”的理解及验证

提出了利用理想电源存在的条件来解释理想电源的连接问题.并用铜线连接电池的正、负极实验验证电压源被短路.利用电路仿真模拟电流源开路和电源串、并联验证上述结论.对于电路初学者正确理解理想电源的连接有一定帮助.

New generation traction power supply system and its key technologies for electrified railways

Unlike the traditional traction power supply system which enables the electrified railway traction sub- station to be connected to power grid in a way of phase rotation, a new generation traction power supply system without phase splits is proposed in this paper. Three key techniques used in this system have been discussed. First, a combined co-phase traction power supply system is applied at traction substations for compensating negative sequence current and eliminating phase splits at exits of substations; design method and procedure for this system are presented. Second, a new bilateral traction power supply technology is proposed to eliminate the phase split at section post and reduce the influence of equalizing current on the power grid. Meanwhile, power factor should be adjusted to ensure a proper voltage level of the traction network. Third, a seg- mental power supply technology of traction network is used to divide the power supply arms into several segments, and the synchronous measurement and control technology is applied to diagnose faults and their locations quickly and accurately. Thus, the fault impact can be limited to a min- imum degree. In addition, the economy and reliability of the new generation traction power supply system are analyzed.

跨境电商出口供应链风险体系构建与评估

跨境电子商务已成为数字经济时代国际贸易的新蓝海,是我国外贸增长的新业态、新引擎、新动能。与此同时,国际环境的深刻变化、国别政策环境的较大差异、跨境电商主体及业务模式的复杂性等,也使得跨境电商供应链管理面临众多的内生和外生风险。准确识别这些风险因素及其影响,成为促进跨境电商运行质量、提升企业竞争力的关键。本文借助文献计量分析、SCOR模型等,构建跨境电商出口供应链风险评价指标体系。在此基础上,运用层次分析法、熵权法对风险指标进行量化分析,并结合博弈论理论进行主客观组合赋权,以确定关键风险因素。最终,文章提出了针对性的对策建议,以期为提升企业风险抵御能力、促进跨境电商行业高质量发展提供有益参考。

未来气候情景下黑河中游灌溉缺水风险评估

【目的】评估未来气候情景下典型干旱区农业缺水风险,为研究区及类似区域未来灌溉水资源管理与农业可持续发展提供决策支持。【方法】对第六次国际耦合模式比较计划(CMIP6)中的3种共享社会经济路径情景(SSP126、SSP245和SSP585)进行降尺度处理以获取未来气象情景数据,结合BP神经网络、Hargreaves模型与作物系数法,预测黑河中游灌溉可用地表水与作物需水量的未来变化。应用Copula模型模拟灌溉供需水量的联合分布,分析水文情景组合概率,评估未来气候模式下的缺水风险。【结果】2024—2100年,SSP126、SSP245、SSP585情景下年平均灌溉需水量较2023年分别增长10.21%、11.73%、14.59%,年平均增长率分别为0.17%、0.16%、0.18%。各情景间最大与最小年径流量比值分别为1.21、1.27、1.34。SSP126情景下丰-枯与丰-丰概率增加,SSP245情景下丰-枯与平-平概率最高,SSP585情景下丰-枯概率降低,平-平概率上升。SSP126情景下大多数年份缺少风险率低于0.6,SSP245情景下部分年份低于0.6,而SSP585情景下所有年份缺水风险率均超过0.6。【结论】未来黑河上游径流量和中游作物灌溉需水量在不同SSP情景下均呈上升趋势。SSP126、SSP245、SSP585情景下缺水风险持续降低,其中SSP585情景下的缺水风险最高,SSP245情景次之,SSP126情景最低。

IMPROVE EFFICIENCY OF BIOGAS FEEDBACK SUPPLY CHAIN IN RURAL CHINA

Feedback supply chain is a key structure in the supply chain system, and the development of feedback supply chain for biogas biomass energy is one of the important ways of the rural ecological civilization construction. Presently, the efficiency problem of biogas supply chain in rural China has been restricting the development of biogas biomass energy business. This article, on the basis of combination of regulation parameters, describes the dynamic changes in the system, using differential equations integrated with simulation to reveal the rules of regulation parameters to investigate the efficiency problem in the biogas supply chain. First of all, on the basis of the actual situation, the flow level and flow rate system structure model and simulation equation set are established for the biogas energy feedback supply chain from a scale livestock farm to peasant households; On the basis of the differentiability of the simulation equation a third order inhomogeneous differential equation with constant coefficients containing regulative parameters is established for the quantity of biogas stored in the feedback supply chain. A theorem and its corollaries are established for the operating efficiency of supply chain to reveal the change law of the quantity of biogas, the quantity of biogas consumed daily by peasant households and its standard-reaching rate as well as other variables.

Supply chain coordination with CCPP for a short-life-cycle product

Supply chain coordination for short-life-cycle products with price-dependent demand is a focus in present operation management and management science fields. This paper considers the supply chain coordination problem for a single-cycle and two-selling-stage short-life-cycle product. Firstly, the inventory model of whole system is depicted with a stochastic dynamics programming. Then, a new combined contract CCPP （combined contract with pending prices） is developed to coordinate the decentralized system, and its validity for channel coordination is proved. Finally, the analysis on system performances is simulated with some examples.

考虑保供电需求的光储微电网优化配置及电能质量评估

针对用户日益迫切的保供电需求以及光伏出力与负荷用电的随机性、波动性引发的电能质量的问题,建立了考虑保供电需求的光储微电网双层优化模型,并对规划配置的微电网电能质量进行评估。该模型以等效净负荷标准差和弃光率最小为上层优化目标,以微电网有功功率损耗最小为下层优化目标,以储能满足保供电负荷的保供电需求作为附加约束条件,采用遗传算法求解。然后设计源、网、荷三类指标,采用组合赋权法确定各指标权重,实现对微电网电能质量的综合评估。最后以改进的IEEE-33系统验证了所提模型的有效性。结果表明考虑保供电需求后能够提高微电网电能质量,并在一定范围内保供电负荷越大时越能提高微电网电能质量和用户满意度。

基于在线评论的服装供应链的生产努力投入策略

考虑消费者购买意愿受在线评论与生产努力的共同影响,构建了由服装制造商、电商平台和消费者组成的服装供应链模型,重点探讨了集中决策模型和分散决策模型下在线评论和生产努力等因素对各参与方利润的影响,并引入“成本分担+收益共享”组合契约来实现供应链的协调。结果表明:集中决策和分散决策的最优解均与生产努力偏好系数呈正相关;受利益驱使,分散决策时的生产努力往往低于集中决策时的生产努力;组合契约模式下,契约参数的取值与批发价格的取值范围有关,在契约参数取值范围内,“成本分担+收益共享”组合契约能实现供应链的协调。研究结果为服装制造商和电商平台销售决策提供借鉴,可提高消费者满意度和市场竞争力。

基于预测负荷的暖通空调系统优化调度

随着我国“双碳”目标的提出,公共建筑能耗低碳化成为重点研究领域,其中基于冷热负荷预测结果优化供能系统调度策略是实现“按需供能”的有效技术手段。针对公共建筑,基于热阻法构建了冷热负荷预测模型,根据负荷预测结果,采用改进粒子群优化(PSO)算法对复合冷热源供能系统的负载、水网供回水温度和流量、阀门开度以及泵组启用台数进行迭代寻优,以供能系统运行成本、机组寿命和环保性为优化目标提出全工况最佳运行策略。基于研究成果对某公共建筑冬季供热系统进行节能改造,可在满足建筑热负荷、平衡水力工况和延长机组运行寿命的同时,分别实现降低泵组功耗10.66%、系统运行成本21.52%。结果符合理论实际,证明了所提方法的可行性与有效性,为公共建筑的按需供热、节能运行提供了有效参考。

虚实结合的供配电实训系统研究设计

供配电培训在提高电力行业运行人员专业技能、提升电气专业学生知识水平方面发挥着不可取代的作用.针对供配电试验安全风险大、培训效率低等问题,开发出虚实结合的供配电实训系统,实现在低电压工作环境下模拟供配电高压试验.该供配电虚实结合实训系统与实际运行状况相接近,可以快速、高效地进行专业人员的培训,具有高低压供配电实操、综合自动化系统实操、供配电系统虚实结合模拟操作等功能.该系统提高了培训效率,改善了培训质量,并在教学试验阶段得到了较好的效果,具有一定的推广价值.

计及热负荷柔性的户用氢能系统运行优化研究

针对风电/光伏出力的随机性和间歇性给户用氢能系统热电联供可靠性带来的挑战,提出基于热负荷柔性松弛运行约束的户用氢能系统热电联供优化策略。首先,搭建包含不同模块的户用氢能系统基础架构,并详细说明该系统的运行原理;其次,建立系统中关键环节的数学模型,确定电解槽平均氢/热比和燃料电池在不同温度下电/热比的范围;然后,为了兼顾用户的舒适度和热负荷的灵活性,根据热感觉平均标度预测指标对户用氢能系统的热负荷需求进行调整;最后,综合考虑储氢罐的容量限制、氢能设备的电/热功率和用户侧柔性热能需求等约束条件,以总投资成本最少和新能源弃电率最低为目标,建立户用氢能系统优化运行模型。仿真结果表明:引入柔性热负荷进行运行调节时,不仅增强了可再生能源的消纳能力,还显著降低了系统的运行成本。

政社互动视角下社区医养结合服务有效供给逻辑研究——基于广州实践的思考

目的:实现医养结合服务在社区中的有效供给对落实积极人口老龄化战略具有重要意义。本研究试图为三种典型社区医养结合服务模式的有效供给实践提供理论化阐释。方法:基于政社互动视角,采取案例研究法,以广州典型社区医养融合模式、医养嵌合模式以及医养合作模式为考察对象,从“资源整合有效”“需求回应有效”和“服务创新有效”展现社区医养结合服务“有效供给”的实践与行动逻辑。结果:“资源整合有效”遵从条块资源整合逻辑,实践表现为政策资源整合和区域资源整合;“需求回应有效”遵从分层满足需求逻辑,实践表现为专业服务回应规范性需求和精细服务回应个性化需求;“服务创新有效”遵从流程再造效率逻辑,实践表现为服务流程优化以及信息技术赋能。结论:社区医养结合服务“有效供给”透射出在以人民为中心的发展观下,政府与社会组织“利益共荣”的新型政社关系走向有助于社区医养结合服务有效供给形成。

考虑多热源协同互补的含先进绝热压缩空气储能系统容量配置方法

先进绝热压缩空气储能(advanced adiabatic compressed air energy storage,AA-CAES)具备天然的热电联供特性,能够有效缓解供热期出现的弃风问题。若能在规划阶段充分考虑运行需求,进而合理地配置储能容量,则能够在解决弃风问题的前提下,最大程度对燃煤机组进行清洁替代。为此,该文提出了多热源协同互补的AA-CAES系统容量配置模型。首先本模型在能量输入端引入电锅炉预热压缩机入口空气,以增大压缩机输气系数并提高机组产热量;其次在扩展热源端,通过太阳能反射镜场收集光热,以提高系统储热水平;并在计及储能系统各模块实际运行效率约束之余,以运行总成本最小为目标,计算储能容量配置最优解。再次,分析供热时长及环境温度等因素对投资成本回收年限的影响,并计算不同情况下本模型投资成本的回收年限,得出建设本模型可盈利的硬性条件;最后,基于东北某地区供热期及非供热期典型日负荷及气象数据在IEEE-39节点系统完成算例分析,验证所提模型有效性。

基于组合赋权-偏序集的应急供应链可靠性评价

为协调好应急供应链中物资的分配与使用,基于文献分析等方法提炼应急供应链可靠性评价指标,建立由组织保障可靠性、系统制度可靠性以及运作流程可靠性3个一级指标及其对应的17个二级指标组成的应急供应链可靠性评价指标体系;利用层次分析法(AHP)、熵权法(EWM)和三角模糊数计算指标权重,将蕴含权重信息的偏序关系引入评价研究中,构建组合赋权-偏序集模型评价应急供应链的可靠性,并应用该模型评价分析C市5个县级城市的应急供应链可靠性水平。结果表明:5个县级城市的应急供应链可靠性程度可分为4类,其中,地区03的可靠性水平高,地区04、02的可靠性水平较高,地区05的可靠性水平中等,而地区01的可靠性水平低;通过对比分析,获取各地区的优势环节和薄弱环节以及需改进的地方。该评价模型可有效评估应急供应链可靠性水平。

全渠道背景下生鲜农产品供应链风险评价与控制

将辽宁省作为研究区域选取算例,基于全渠道背景建立生鲜农产品供应链风险评估指标体系,该体系包括6个一级指标及相应的21个二级指标,运用博弈论组合赋权法确定各风险权重。通过模糊综合评判法,计算出全渠道下生鲜农产品供应链风险的综合评价得分。结果表明,全渠道模式下辽宁省生鲜农产品供应链风险趋近于较高风险;风险排序最高的是质量风险,最低的是环境风险;各指标层中的企业基因差异、冷链物流技术、信息安全保护、供应链服务质量等是引发全渠道生鲜农产品供应链高风险的因素。