基于垂直中继的U型线圈切换系统设计与优化

与三线圈中继无线电能传输结构相比,两线圈结构具有更高的效率但传输距离较近,而三线圈结构多应用于中远距离无线电能传输,在近距离系统中效率偏低。对于电动汽车底盘距离不一导致充电效率低下的问题,本文给出一种基于垂直中继的U型线圈切换系统,该系统在适合的距离点切换,即在不同传输距离到达最优效率,可以解决间距变化导致效率低下的问题。本文对三线圈电路模型进行分析,对其线圈特性、负载特性和无线电能传输的距离特性进行分析及优化,推导出其效率影响因素,在此基础上进行系统仿真分析。仿真结果表明,与单一两线圈或三线圈结构模型相比,所设计的切换系统在较近和较远距离下无线电能传输效率都提升了58%;与普通三线圈结构相比,该系统无线电能传输效率最高提升了71%。     

继电保护电压切换回路的改进

实现保护装置所需交流电压的具有双电源切换作用的装置,就是现在继电保护广泛应用的交流电压切换装置,此种装置中大多采用了双线圈磁保持继电器作为电压切换的主要元器件,虽然这种继电器已经获得实践证明具有很好的可靠性,但在实际运行和设备检修改造过程中,却发现因为种种原因导致的继电器不能正常复位,而造成两条母线电压始终并列的异常现象。通过对此类异常情况的实际案例分析的基础上,找出采用此种类型继电器所存在的一些弊端,并从多方面提出相应改进措施的建议,消除其中的安全隐患。     

继电保护通道切换装置动模试验

建立了一次系统和保护通道的动模试验模型,设计了动模试验测试项目,针对各项目提出了具体的测试要求,并按照要求对继电保护的通道切换装置进行测试。测试结果表明,被测的继电保护通道切换装置基本满足技术要求,但是在给断电的切换装置重新上电后,或者备用通道延时增加、调整切换装置缓存后若立即发生区外故障,则保护容易发生误动。对误动的原因进行了分析,并提出了对应的解决方法。     

继电保护用开关电源的故障分析及改进

研究了实际运行中的继电保护用开关电源存在的几种问题.从开关电源工作原理入手,分析了两种故障现象:1)输入电源波动,导致开关电源停止工作;2)开关电源的启动电流过大,导致供电电源过载告警.通过试验分别重现了以上两种故障现象,分析了故障原因:1)由于设计时未考虑保护延时放电回路,输入电压快速通断导致电源欠压保护误动作;2)启动功率一定的情况下,启动门槛设置过低,导致启动电流过大.并把改进后的开关电源与改进前的开关电源进行了对比验证.     

基于开关网络的继电保护二次回路逻辑的模型与算法

继电保护二次回路的数学模型是进行继电保护系统评估和动态仿真的基础,本文引入开关网络的原理对继电保护二次回路的逻辑进行分析、建模,将二次回路描述成由逻辑对象组成的开关网络,有效地解决了对二次网络拓扑的自动跟踪和数学描述的维数灾问题.讨论了二次回路元件和拓扑的数据结构,分析了开关网络中元件的开关函数以进行二次回路逻辑的研究,最后应用模块间的消息传递提出了二次回路逻辑的计算机分析算法.     

基于开关网络的继电保护二次回路逻辑的模型与算法

继电保护二次回路的数学模型是进行继电保护系统评估和动态仿真的基础,本文引入开关网络的原理对继电保护二次回路的逻辑进行分析、建模,将二次回路描述成由逻辑对象组成的开关网络,有效地解决了对二次网络拓扑的自动跟踪和数学描述的维数灾问题。讨论了二次回路元件和拓扑的数据结构,分析了开关网络中元件的开关函数以进行二次回路逻辑的研究,最后应用模块间的消息传递提出了二次回路逻辑的计算机分析算法。     

继电保护仿真系统的研究

继电保护仿真系统是DTS中一个重要的组成部分.综合了逻辑判断仿真法和保护定值判断法的优点,提出了新的仿真方法,首先建立了各种保护类型的保护模型,基于广度优先搜索法提出了保护动作域的概念,在确定的保护动作域基础上进行定值判断,提高了仿真速度及逼真度.经过某实际电网中应用,取得较好的效果.     

Interactive relay controlled power system modeling

Four fundamental algorithms that make it possible to simulate numerous types of protective relay systems are identified. The characteristics of these fundamental modules necessary for building an embedded relay model within an EMTP (electromagnetic transient program) are discussed. A directional time overcurrent relay model is used to provide a detailed demonstration of relay model development and to illustrate the utilization of the fundamental modules. The results of using this relay model in a modeled power system reveal the power of this concept to enhance power systems education, applications engineering, and relay design procedures     

温度继电器温度特性检测系统

本文介绍了温度继电器自动测试系统的设计,此系统由温控箱、开关量检测电路、温度控制电路、接口电路及工控机等硬件组成.分析了信号测量、信号处理、温控箱的温度PID控制方法,介绍了动作温度、回复温度的测量结果,给出了系统的升温、降温过程的测试参数软件构成.最后讨论了本系统的误差来源.     

开关型限流装置接入线路对继电保护的影响

高压线路加装开关型限流装置是降低短路水平的有效措施,具有正常运行时不改变线路潮流的优点,但需要研究对线路继电保护装置的影响。通过330 kV安-迎线加装开关型限流装置进行人工短路保护动作行为试验,同时建立限流电抗器模型进行仿真计算,分析限流效果和对线路保护的影响,提出了加装限流装置后线路保护定值的运行策略。结果表明:限流装置效果明显,对线路主保护定值无影响,后备保护配合关系保持不变,仅需根据电抗器参数核算后备保护的灵敏度。     

360-Hz Complementary Impulse Commutated Inverter

A fixed-frequency 360-Hz SCR inverter operated with an inductive and three-phase motor load is described. Such an inverter could provide a solid-state motor control more compact and possibly at a lower cost for a given horsepower than a 60-Hz system. A McMurray-Bedford inverter circuit was used similar to that described by Bedford and Hoft in [1]. The inverter operation has been described in detail by an approximate equivalent circuit approach for which a digital computer simulation was devised. Computer plots of various waveforms and experimental results are included. This simulation gives a thorough prediction of the circuit behavior with inductive load. The circuit provides a reliable and efficient ac power source with a fixed frequency. An accurate prediction by the digital computer simulation enables one to choose most efficiently. circuit elements which would perform the function most efficiently.     

Some Improved Forced Commutated Cycloconverter Structures

Full automation in manufacturing processes has generated a considerable demand for ac motor drives and in particular static frequency changers (FC's). Forced commutated cycloconverters (FCC's) are frequency changers that can provide a wide output frequency range with minimum energy storage requirements. For this reason they can be manufactured in integrated form with significant savings in price, weight, and volume. These factors have generated considerable research activity toward the development of FCC structures that can compete with the typical rectifier-inverter structures. Some advanced FC cycloconverter structures with improved performance characteristics are considered. Areas of improvement include voltage utilization and generated harmonic distortion.     

基于DSP的智能化继电保护装置

介绍了一种基于DSP的继电保护装置。由于采用了高速、高性能DSP处理器 ,因而可以引入复杂的滤波和分析算法 ,且外围电路大为减少 ,具有监测精度高、动作速度快、体积小和抗干扰性强的特点 ;同时 ,丰富的片内资源使系统具备了面向继电保护网络化的二次开发能力     

全数字化继电保护测试系统设计

介绍了基于IEC61850规约的全数字化继电保护测试系统的设计思路和实现方案.该测试系统基于CPU+DSP模式的高速双处理器硬件平台,在硬实时多任务操作系统μC/OS的基础上,针对IEC61850通信及全数字化保护测试相关需求,通过合理分配任务优先级和任务间调度与通信,可很好地实现以太网链路层通信、模拟量电流和电压信号的采样与转换、符合IEC61850要求的采样值数据组帧与发送等强实时性功能.为了完成闭环试验,按照IEC61850的要求,该测试系统还具备接收、解析保护设备所发出的GOOSE跳闸信号,并将断路器位置接点信号编码、组帧、发送GOOSE开关量报文给全数字化继电保护装置等的功能.在上述基础上,通过人机接口软件配合,还可以实现全数字化保护的动态模拟试验、静态测试、暂态仿真闭环测试、定值校验等功能.     

便携式汽车继电器检测系统设计

本文介绍了一种采用单片机作为主控系统、便携的汽车继电器手动检测系统,通过对设计的分析,搭建了实验平台.使用这个平台对延迟时间、动作电压、释放电压和触点电压降进行了测试,并对实验结果做了分析.实验表明,该系统体积小、精度高,易于操作,有较好的实用价值.同时,针对实际的检测系统开发提供系统设计方案和对一些将要遇到的问题进行了分析,可以用作汽车继电器自动化生产线的辅助设备.     

Digital relay reports verify power system models

Digital relay event reports may come in a suitable form for verification of the fundamental frequency power system model that was used to determine the relay application and settings. Plotting the magnitude and angles of recorded phasors allows easy calculation of source impedances behind a relaying terminal     

Current-Source Double DC-Side Forced Commutated Inverter

DC-side commutated inverters are very attractive due to their simplicity and efficient use of the commutation circuit. A new current-source commutated inverter of this type equally applicable to both single and multiphase bridge configurations is considered. Simultaneous turn-off of all bridge thyristors allows ample possibilities for programming the commutation sequence. The behavior of a threephase bridge is analized, and the optimum values of the commutation components are obtained. Guidelines for analysis under any commutation condition, as well as general programming rules and suggestions for snubber design are given. Results obtained in a 8-kVA variable speed drive prototype are shown and discussed.     

HVDC滤波换相换流器的阻抗频率特性

高压直流输电(HVDC)换流器的阻抗频率特性是分析和解决谐波不稳定的一个重要因素,滤波换相换流器(filter commutated converter,FCC)是一种具有阀侧谐波抑制兼无功功率补偿功能的换流器,文章简要论述了FCC的接线方案和工作机理,并基于开关函数法对计及换流器换相过程影响下的FCC交、直流等值阻抗计算式进行了理论推导。以直流输电开发平台为例,对传统电网换相换流器(line commutated converter,LCC)与FCC的阻抗频率特性计算结果进行对比,仿真结果表明换流器的阻抗频率特性对交流系统的谐振频率有着不可忽略的作用,FCC在一定程度上提高了交流系统强度,改善了系统稳定性,有效降低了系统谐振频率下的交流等值阻抗,从而更好避免直流输电系统谐波不稳定现象的发生。     

光MOS继电器在正负高压电源极性切换中的应用

光MOS继电器是一种新型的固体继电器。讨论了应用光MOS继电器的开关特性,实现高压电源输出极性的快速切换,从而设计可靠的双极性小功率高压电源。介绍了光MOS继电器的结构、工作原理和作为高压开关应用的选型原则,讨论了光MOS继电器用于高压极性切换开关的两种实现方法,给出了在单逆变电路架构中应用光MOS继电器实现双极性高压输出的完善的应用电路。最后应用光MOS继电器、SG3525控制器等元件设计了一款应用于离子迁移谱仪器的双极性高压电源。     

Forced Commutated Cycloconverters for High-Frequency Link Applications

Forced commutated cycloconverters (FCC's) have been used successfully as static frequency changers for low-to-medium frequency applications. The use of FCC's for high-frequency applications and, in particular, in the role of high-frequency links (HFL's) is investigated. Such links are widely used as intermediate stage circuits to provide simultaneous power conditioning and ohmic isolation. The investigation shows that suitable HFL circuit topologies do exist for any combination of input-to-output number of phases. It also shows that, through the use of appropriate switching techniques, it is possible to obtain HFL output voltage and input current waveforms with low harmonic content and insignificant amplitude derating.