船舶直流电网短路故障限流保护方法

船舶直流电网短路下会导致电路中断,通过限流控制方法进行电网短路故障分析,提出一种基于LLC串联谐振保护控制的船舶直流电网短路故障限流保护方法。构建船舶直流电网短路故障下的耦合参数模型,测试电路的电流、电压和功率因素的参数,建立电网短路故障下的谐振参数分布矩阵,由此构造电网短路故障限流保护输出调节封闭方程组,调节输出线圈的次级侧绕组的自感,进行电流谐振控制,构建LLC串联等效电路模型,进行电网的连通性判别,计算电流超限阈值,实现船舶直流电网短路故障限流保护系统的硬件设计。测试表明,采用该方法进行电网的限流保护,能有效排除电网短路故障。     

熔丝型混合式直流限流开关的分析与设计

针对直流电网短路故障时迅速产生的短路电流,提出一种零电压型混合式直流短路电网限流开关拓扑结构,以超快速电磁斥力式机械开关为通流支路,用快速限流熔断器代替固态开关支路和能量吸收支路的功能.开发出额定功率为640 V/2 500 A的原理样机,实验结果表明,样机将预期峰值为100 kA,时间常数为4.17 ms的短路电流限制在10 kA以下,证明所设计限流开关工作的快速有效性.     

超快速开关在直流供电系统保护中的应用

直流电网发生短路故障时其短路电流巨大，可能超过现有保护设备分断能力，利用超快速开关技术，设计出一种新型的直流短路限流装置，阐述了其工作原理，研制出实验样机，完成了大电流分断实验，实验结果表明该型限流保护装置能有效抑制短路电流。     

熔丝型混合式直流限流开关的分析与设计

针对直流电网短路故障时迅速产生的短路电流，提出一种零电压型混合式直流短路电网限流开关拓扑结构，以超快速电磁斥力式机械开关为通流支路，用快速限流熔断器代替固态开关支路和能量吸收支路的功能。开发出额定功率为640V／2500A的原理样机，实验结果表明，样机将预期峰值为100kA，时间常数为4．17ms的短路电流限制在10kA以下，证明所设计限流开关工作的快速有效性。     

基于高速限流重合闸装置的舰船直流电网选择性保护方法

舰船电网电气传输距离短,短路电流沿线路衰减很小,高上升率的短路电流往往会使上下两级开关同时动作,导致选择性保护失效。本文在舰用300A和1000A塑壳开关电磁脱扣器特性曲线基础上,分析了舰船电网电流原则选择性保护失效的原因,提出了一种基于高速限流重合闸装置——HLB的选择性保护方法。故障时,通过HLB的快速限流,避免了上级开关动作,故障支路开关跳开后,HLB快速重合闸恢复对无故障支路的供电,实现系统的选择性保护。实验证明该方法可以将预期峰值100kA,时间常数为7ms的短路电流限流在15.4kA,故障切除后50ms内重合闸恢复对非故障支路的供电,实现电网的选择性保护。     

船舶直流电网模块化电力变换器短路保护研究

针对大功率电力变换器模块化设计带来的内部模块发生短路故障可能性增加的问题,提出模块短路时模块与整机之间的选择性保护方案.由于受限于采用固态断路器带来的尺寸和重量的显著增加,研究提出了利用模块化电力变换器与内部变换模块之间输入回路电流级差,在变换器以及内部模块输入回路串联不同限流熔断器的方案,仿真结果验证了该方案的可行性,并做了扩展讨论分析,结果表明该方案具有实现简单,可靠的特点,提高了船舶直流电网电力变换器的运行可靠性.     

大功率IGBT短路故障分析

IGBT模块正常条件下运转正常,但在低电感短路条件下时,却出现故障。通过对商用IGBT模块的主电流通路和栅极结构的内部电气通路进行分析,获取了部分电感的自感和互感。对部分电感应用PSPICE进行建模,经过仿真发现在短路试验时电流最高的通路与故障芯片的位置是一致的。同时还提出了一个相似的IGBT模块的布局方案。对IGBT模块的几何排布进行了建模仿真并给出了仿真结果。     

磁通流阻型高温超导限流器模型研究

磁通流阻型高温超导限流器利用磁通流动电阻来限制短路电流,具有失超恢复迅速的优点,能够满足电力系统重合闸要求.采用多根Bi2223超导管材设计了1台磁通流阻型高温超导限流器模型机,并对其进行了交流电力系统的正常运行和失超限流运行的动模实验.分析了在不同预期短路电流下,超导材料过流失超后的限流效果.给出了Bi2223管材串联后的磁通流阻特性曲线,分析了管材电阻率与短路电流的关系,并对超导管材的失超一致性进行了研究.     

相复励励磁方式下IGBT故障模式分析与保护措施

文章介绍了船用相复励励磁方式的原理和特点,分析了该励磁方式下IGBT可能遭遇的比较严重的故障模式.文章给出了发电机突然三相对称短路时冲击电流计算公式,计算了通过IGBT上的过电流和过电压,分析了此应力对IGBT的影响及其故障模式.并据此设计了IGBT限流封锁延时保护电路,通过对比试验验证了其保护效果的有效性.     

无速度反馈直流双闭环调速系统研究

在分析电压负反馈电流补偿直流调速系统的基础上,本文提出在主电路中增加了串联的取样电感,用来提取电枢自感电动势产生的压降。改进后的电流正反馈能补偿由电枢内阻和自感电动势产生的压降,提高了动态电流变化时电流补偿的精度。根据转速、电流双闭环调速系统的设计方法,用Simulink做了带电流补偿的电压负反馈直流调速系统仿真,仿真结果证明,增加取样电感后可以消除电流补偿的滞后,在忽略参数变化的影响下精确地补偿电枢压降,改进后的电压负反馈电流补偿能够获得跟转速负反馈同样的效果。     

Errata

正In the paper"Influence of Fouling Assemblage on the Corrosion Behaviour of Mild Steel in the Coastal Waters of The Gulf of Mannar,India"in Vol.12,No.4,Page:509,References were lost,and the two authors’biographies were identical.The correct text is shown below.We apologize to the authors and our readers for any inconvenience caused by the errors.     

Journal of Marine Science and Application 2014 Sum. Contents

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第34届海洋、离岸及极地工程国际会议(英文)

正St.John's,Newfoundland,Canada,May 31-June 5,2015 OMAE2015 is the ideal forum for researchers,engineers,managers,technicians and students from the scientific and industrial communities from around the world to: meet and present advances in technology and its scientific support;     

联合作战计划和执行系统

全球指挥控制系统(GCCS)实施当前美国海军网络中心战信息基础设施的联合计划网络。联合作战计划和执行系统(JOPES)支持GCCS实现联合计划。JOPES有两类计划：时间不限的精密预案计划生成作战计划、方案计划或职能计划；时间敏感的危机行动计划生成作战命令或战役方案。前者在和平时期创建的作战计划是后者的计划基础，加速应付危机的能力。     

Eastbound or westbound ?

In terms of equal sailing distances, where is the inflexion when ships depart from ports in the Asian Continent to New York via Suez and/or Panama？
The answer is China South Port Group （Hong Kong, Shenzhen and Guangzhou）.     

Recent progress on wave induced loading measurements in warships

Recent measurements of wave induced hull strain and flexure in RN warships are presented together with the derivation of the current design criteria for extreme hull girder bending loads. The history of the development of the shipboard instrumentation used is given and recent developments to improve the quality and ease of analysis of the data are described. An unexpectedly high transverse asymmetry in the longitudinal strains measured in destroyers is shown to be the result of a combination of vertical and lateral bending in oblique seas. Finally recent theoretical comparisons between the loading of Deep-Vee hulls and conventional UK rounded bilge hulls are presented which demonstrate the higher loading experienced by this type of hull form.     

桥梁防撞设施物理模型试验

物理模型试验是预报防撞设施所受撞击力及优化设计方案的主要方法之一。结合杭州湾大桥柔性防撞设施及东海大桥独立式防撞体设计方案,阐述了船—防撞体撞击试验的基本原理、方法、试验方案及相关试验结果。提出了柔性防撞系统的优化方案。试验结果表明,该方案经济有效,可供预报类似桥梁防撞设施撞击力时参考。     

印尼某电厂码头水工建筑物设计

印尼某电厂项目码头水工建筑物包括码头、防波堤和护岸等主要组成部分。在该项目水工建筑物的设计过程中,综合考虑当地的自然条件、施工能力和材料来源等因素,不断优化结构选型和结构断面。根据不同使用要求,护岸分别采用直立式和斜坡式2种结构型式,推荐的设计方案节省投资、施工方便,可供同类工程设计参考。     

Impact of regulation on the performances of long-distance transport services: A comparison of the different approaches in Sweden and Norway

Despite the many socio-economic similarities between Sweden and Norway, differences in jurisdiction, organisation, cooperation, and financing of long-distance passenger train and coach services have led to the development of four distinctively different ways of serving the markets. This paper describes how the train and coach markets have developed in the two countries, with emphasis on regulatory and industrial structure and a couple of performance variables.Looking at passenger rail, both countries separated infrastructure from operation over a decade ago. However, while Norwegian rail is characterised by an almost monopoly supplier, rail services in Sweden are partly decentralised to the responsibility of county authorities and are widely subjected to competitive tendering. The rest of the network is about to be opened up for on-the-track competition. Swedish Rail (SJ) has spent the last decades consolidating its core business (passenger rail) and sold out its other businesses. In contrast, the Norwegian state rail (NSB) has expanded its business to become a major bus operator and property owner, with extensions also into the Swedish market.The coach industry was more recently deregulated in both countries. The Swedish coach market is dominated by privately owned companies operating services to and from Stockholm. In Norway, state-owned NSB is a major coach operator on medium distance routes, and is also the largest partner of Nor-Way Bussekspress which totally dominates long-distance coach services. Further, the Norwegian coach market is characterised by cross-ownership and cooperation which has enabled an extensive route network which covers most of Norway.We find distinct differences in achievements in the two modes and in the two countries. Swedish rail services have succeeded in winning market shares and in renewing and developing both infrastructure and service levels to a greater extent than the Norwegian model. On the other hand, the Norwegian coach market seems to be more developed and efficient compared to its Swedish counterpart.The paper concludes with a discussion on the possible links between the different approaches and the performance observed, with the aim to stimulate further and more detailed research on some important issues.     

开放式数据挖掘系统模型

目前国内已经出现了少量的数据挖掘相关产品。国内数据挖掘软件无论从数量还是质量上比较，都与国外软件存在着较大的差距。随着数据仓库技术的普及，数据挖掘应用的需求越来越强烈，如何缩短这种差距，研发数据挖掘软件产品成为国内业界的一个重要问题。通过引用目前国际通用数据挖掘标准技术来构建开放式的数据挖掘系统模型，该系统模型从可扩展性、可重用性、易用性等方面得到了加强。