一种变电站自动化系统的构想

随着电力系统向大容量、高电压的方向发展,对变电站自动化系统的性能要求越来越高,现有的综合自动化系统也需要与时俱进。通过运行实践的总结,提出一种新的变电站自动化系统的模式构想,供参考。     

500kV开关防跳功能异常的分析及解决方案

通过对500kV香山变电站500kV开关防跳回路出现故障现象进行分析,阐述了开关本体防跳回路与操作箱控制回路配合的动作原理,揭示了开关本体防跳回路与操作箱控制回路之间存在的寄生回路问题,并提出解决技术方案。     

500kV线路光纤纵联保护应用的相关问题分析

光纤通道作为纵联保护的通信通道,具有传输速率高、抗干扰能力强、安全可靠性高、能长期保持不间断传输信号的特点,在500kV线路保护中得到广泛应用。文章介绍了光纤纵联保护的原理、光纤通道作为保护通道的特点和继电保护装置与光纤通道的几种连接方式及各自的时钟设置。根据光纤纵联保护在内蒙古500kV电网的应用,提出了在运行维护工作中应该注意的几个问题,以提高保护的正确动作率,确保电网安全运行。     

中继共享的高斯干扰信道可达和速率分析

为了研究2组用户共存时的高斯干扰信道问题,结合协同通信技术,在高斯干扰信道中引入共享中继,提出了2种基于中继共享的高斯干扰信道的通信系统模型. 分别从理论上推导了2种通信系统模型的可达和速率的上界和下界,并比较了中继处于不同位置时2种通信系统模型的性能. 仿真结果验证了理论分析,所提的2种中继共享通信系统模型的性能均优于无中继通信系统.     

IEC 61850数字化保护动模测试系统设计与实现

IEC 61850标准的应用给变电站自动化系统带来了重大变革。在此类变电站中,保护装置可以直接从电子式互感器处获取所需的电流、电压数字量信息,并向智能开关控制器发送数字化跳闸命令。这种数字化保护与传统的微机型保护在硬件结构和信号处理方面都存在差异,传统的保护测试方法将不再适用。文章分析了基于IEC 61850的数字化保护装置的测试要求,提出通过对传统的物理模拟系统进行升级改造,建立符合要求的测试系统。根据这一思路,该新型测试系统在山东大学电力系统动态模拟实验室的基础上开发而成。初步试验结果表明,测试平台能够提供所需要的二次接口特征和测试环境,可以对不同种类的IEC 61850保护装置进行动模测试。     

一起10kv短路引起的越级跳闸事故分析

以一起10 kV短路事故为例,分析了造成越级跳闸事故的具体原因,提出了可行的整改措施,指出了微机保护装置正确选型的重要性。     

邯钢继电保护管理问题探讨

继电保护是保障电力系统安全、稳定、可靠运行的第一道防线,在快速发展的电网中发挥着极其重要的作用。分析了目前邯钢电力系统在继电保护管理方面存在的问题,并针对问题提出了相应的解决方案。     

不同类型风电场对现有继电保护仿真对比分析

不同类型风电场接入电网系统表现出异于常规电源的故障特征,使得基于常规电源的继电保护应用存在适应性问题。针对不同类型风电场的故障特征,仿真分析风电场送出线路在不同故障、不同运行工况下各种继电保护元件(差动元件、方向元件、距离元件及选相元件等)的动作性能。分析结果表明,双馈风电场出现送出线路发生故障时系统表现出弱馈性和频偏性,对基于工频向量的保护元件产生严重影响;直驱风电场送出线路故障只对负序、零序方向元件及选相元件产生部分影响。     

Management optimisation based on dynamic SKU for RFID-enabled warehouse management in the steel supply chain

Radio-frequency identification (RFID) technology is one of the encouraging technologies to improve the productivity in warehouse management. However, the problem of how to explore the potential benefits of a RFID system and reduce the expenditure of RFID application are troubling many managers who are planning to, or have engaged in, the implementation. This paper enriches existing theory by introducing the useful and comprehensive warehouse management optimisation methods based on dynamic SKU (storage keeping unit) management in the design and development of a RFID-enabled warehouse. Based on the dynamic SKU management method proposed, cost optimisation methods are employed in the development of RFID-enabled warehouse. Furthermore, a storage area management optimisation for multi-size coils and a crane scheduling optimisation method is established for the purpose of enhancing the productivity of the warehouse. The optimisation methods are applied and verified in a coil warehouse and the result shows that the hardware investment is cut down by reducing the number of RFID cards used without any decrease in location accuracy and the warehouse productivity is improved significantly.     

An interference and latency aware uplink scheduling mechanism in IEEE 802.16j networks

IEEE 802.16j spreads out the coverage of WiMAX networks and strengthens wireless signal transmission using relay technology. To take advantage of relaying in IEEE 802.16j networks, an efficient scheduling schedule with quality of service (QoS) provision for multiple link transmissions is necessary, especially when link interference exists. In this paper, we propose an uplink scheduling mechanism in the transparent mode of IEEE 802.16j, which enables multiple devices to transmit without interference. The maximum latency of each connection has been considered in order to optimize the violation and transmission rate. An interference detection task is first carried out, and then a resource allocation algorithm and a dynamic frame adjustment method are developed. Two simulation experiments were conducted with different interference levels. The results demonstrate that under a fixed QoS type of connection, when the total number of connections goes up to 360 and 420 and the maximum latency violation rate approaches 20%, the average uplink transmission rate of the proposed mechanism can achieve 6.67 and 7.92 Mbps, which apparently outperform regular relay scheduling schemes with rate of 4 and 3.91 Mbps, respectively.