巢湖发电厂单机运行及220kV线路跳闸时的安全性分析

华能巢湖电厂为新建电厂,一期工程安装2×600 MW超临界机组,220 kV配电装置采用单母线接线方案,并预留双母线位置,500 kV配电装置采用发变线组接线方案,采用220 kV和500 kV两级电压接入系统,各出线1回。在单机运行且220 kV线路跳闸时将全厂停电,如果此时不能保证保安电源及动力直流电源的可靠性,则可能引起设备烧损事故,文中对此进行了安全性分析。     

Efficient trip scheduling algorithms for groups

Given the source and destination locations of $n$ group members and a set of required point of interest (POI) types such as restaurants and shopping centers, a Group Trip Scheduling (GTS) query schedules $n$ individual trips such that each POI type is included in exactly one trip and an aggregate trip overhead distance for visiting the required POI types is minimized. Each trip starts at a member’s source location, goes through some POIs, and ends at the member’s destination location. The trip distance of a group member is the distance from her source to destination via the POIs that the group member visits, and the trip overhead distance of the group member is measured by subtracting the distance between her source and destination locations (without visiting any POI type) from her trip distance. The aggregate trip overhead distance is either the summation or the maximum of the trip overhead distances of the group members for visiting the POIs. A GTS query enables a group to schedule independent trips for its members in order to perform a set of tasks with the minimum travel cost. For example, family members normally have many outdoor tasks to perform within a short time for the proper management of home. The members may need to go to a bank to withdraw or deposit money, a pharmacy to buy medicine, or a supermarket to buy groceries. Similarly, organizers of an event may need to visit different POI types to perform many tasks. These scenarios motivate us to introduce a GTS query, a novel query type in spatial databases. We develop an efficient approach to process GTS queries and variants for the Euclidean space and road networks. By exploiting geometric properties, we refine the POI search space and prune POIs, which in turn reduce the query processing overhead significantly. In addition, we propose a dynamic programming technique to eliminate the trip combinations that cannot be part of the optimal query answer. We show that processing a GTS query is NP-hard and propose an approximation algorithm to further reduce the query processing overhead. We perform extensive experiments using real and synthetic datasets and show that our approach outperforms a straightforward approach with a large margin.     

面向出租车出行规律的预测式可视分析方法

针对传统交通数据可视分析方法缺乏预测分析能力的问题,提出了基于出租车出行数据的预测式可视分析方法,支持用户更有效地探索未来的交通状况.在可视分析模型中,提出了结合天气、星期几等多种非交通因素的预测模型,提高了预测的准确度;提出了基于预测数据和广义地点类型约束的路径规划方法,获得了更优的路径规划结果;以多种可视化手段分析和预测了出租车司机的运营状况,帮助司机进行运营决策.以温州市出租车数据进行的实验结果表明,与传统方法相比,文中方法能更准确地预测交通状况和运营状况,并获得更合理的路径规划结果.     

除氧器虚假水位引发机组跳闸的原因分析及防范措施

分析了600MW超临界机组除氧器虚假水位误发信号引发跳机事故的原因、处理过程及防范措施,为同行技术人员防范同类故障提供参考。     

远跳逻辑回路的浅析

文中以双母线接线以及3/2接线方式为例,初步分析了光纤纵差保护远跳逻辑回路从启动、传输到出口的全过程。     

线路雷击跳闸分析及防护措施

分析了雷击跳闸这个困扰安全供电的难题。通过对各种措施的综合运用,有效降低线路跳闸率,提高电网的安全可靠运行水平,确保城市工业农业以及生产生活用电。     

浅谈机械厂总降变电所变压器主保护的配置与整定

对机械厂35kV变压器主保护进行合理配置、整定,使电力系统运行更加安全、可靠。对主保护灵敏度不满足要求时如何处理进行了分析。     

300MW汽轮机危急跳闸保护系统的改进与实践

分析了贵溪发电公司300MW机组ETS保护系统设计存在的问题,提出了技术改造方案,该方案实施后取得了良好的改造效果,确保了机组安全稳定运行。     

110kV纵联备自投装置的应用及二次反措分析

备自投装置是为了提高电网的安全、可靠运行所采取的一种重要措施.本文阐述了目前广泛使用的110kV纵联备自投的基本原理,分析了110kV备自投装置断路器位置接点的引取问题及与保护装置二次回路的配合问题,探讨了110kV备自投应用中的危险点及防范措施.     

基于初始电压行波频域衰减速率的MMC-HVDC线路保护方案

针对目前基于模块化多电平换流器的高压直流(MMC-HVDC)电网的线路保护中存在的问题,提出了一种基于初始电压行波(IVTW)频域内衰减速率的MMC-HVDC线路单端量保护方案。首先,构建四端MMC-HVDC电网的等效模型,分别计算直流线路区内外故障下IVTW的频域表达式。由于输电线路两端限流电抗器的边界作用,区内外故障下IVTW随频率增大而衰减的速率具有不同的特点。以不同尺度的平稳小波变换(SWT)提取IVTW在不同频带下的细节系数,并用不同尺度下的小波变换模极大值(WTMM)的绝对值分别表征其在相应频带中的幅值,根据IVTW频域内等效衰减速率的平方构造了识别线路区内外故障的判据。最后,各种故障情况下的仿真结果验证了所提保护方案的有效性。