交直流电网故障暂态功率倒向解析

针对交直流电网出现的暂态功率倒向现象而导致继电保护误动的问题,从继电保护的视角出发,在电磁暂态时间框架下研究交直流系统相互影响机理和交流故障特征的变异机理,提出在换相失败电磁暂态过程的解析分析、特征变异对保护性能的影响评估方法和评价指标,进而给出了交直流混合电网界定暂态功率倒向的计算模型和方法。交直流系统相互作用而引发的暂态功率倒向是由交流故障和直流系统快速变化引起的2个不同扰动源同时作用于电网元件,且满足一定电气和时序条件下"竞争"的必然结果。仿真结果验证了所述模型和方法的正确性。     

多Agent技术在多端线路保护系统中的应用

针对传统的输电线路继电保护所存在的不足,提出了Agent技术在T接线路保护中的应用方案,阐述了该保护系统的结构和决策过程。Agent可以由一个人、一些软件或智能系统构成,具有自治、协调和分布等特性。仿真结果表明,与传统的距离保护和纵联保护相比,该保护系统具有能够实现全线速动和不需要专用通信通道的优点。     

基于光纤+SDH+IP技术的继电保护及故障信息传输系统

继电保护及故障信息传输系统是一个分布式管理系统。通过分析信息传输和信息流向,提出单子站和多主站的概念。结合电力系统数据网络现状,构建了一个基于光纤 SDH IP技术体制的网络化继电保护信息传输系统方案,并介绍了一个220kV变电所继电保护信息子站系统的结构和信息传输的技术方案及其设计经验。     

继电保护测试仪数据采集系统中的USB通信设计

介绍了通用串行总线(USB)的通信原理以及USB设备的开发方法,包括硬件、软件、firmware(固件)、驱动程序和应用程序的设计,并将其用于继电保护测试仪的数据采集系统中.在系统要求的数据传输速率下,分析了使用USB进行通信的必要性及其可行性,并对驱动程序和固件(下位机程序)进行逐次优化,使数据传输效率达到最优.实践证明,在继电保护测试仪的数据采集系统中用USB传输取代串口传输是势在必行的.     

变电站供电可靠性的定量评估

在综合考虑一次电气设备故障和备用设备影响以及继电保护配置和动作正确性影响的基础上,定量研究变电站供电可靠性评估问题,并研究了设备故障对整个变电站可靠性影响的灵敏度计算问题。其中,继电保护配置及动作正确性的影响主要包括变压器开关失灵保护是否投入、母线差动保护和线路保护误动等。由于变电站故障事件的持续时间在很大程度上取决于故障隔离时间和备用设备投入时间,因此为便于研究,把备用设备分为备用隔离开关型和非隔离开关型备用设备两个层次加以考虑。研究结果已形成软件包,已用于上海220kV变电站供电可靠性评估工程中。     

基于以太网的分布式发电厂电气监控系统实现

提出了一种基于以太网的分布式发电厂电气监控系统（ECS）,系统由间隔层、通信层、系统层组成。间隔层完成继电保护、模拟量和开关量的采集以及断路器的控制;通信层完成所有实时数据的分类转发,并实现与集散控制系统（DCS）的接口通信;系统层实现全厂电气系统信息的集中处理,提供各种站级应用功能。结合工程实践经验,阐述了一种典型的ECS组网方案,并指出了实践中的一些特殊问题及解决方案。     

End‐to‐end security‐reliability analysis of multi‐hop cognitive relaying protocol with TAS/SC‐based primary communication,total interference constraint and asymmetric fading channels

In this paper, we analyze the tradeoff between outage probability (OP) and intercept probability (IP) for a multi‐hop relaying scheme in cognitive radio (CR) networks. In the proposed protocol, a multi‐antenna primary transmitter (PT) communicates with a multi‐antenna primary receiver (PR), using transmit antenna selection (TAS) / selection combining (SC) technique, while a secondary source attempts to transmit its data to a secondary destination via a multi‐hop approach in presence of a secondary eavesdropper. The secondary transmitters such as source and relays have to adjust their transmit power to satisfy total interference constraint given by PR. We consider an asymmetric fading channel model, where the secondary channels are Rician fading, while the remaining ones experience the Rayleigh fading. Moreover, an optimal interference allocation method is proposed to minimize OP of the primary network. For the secondary network, we derive exact expressions of end‐to‐end OP and IP which are verified by Monte Carlo simulations.     

Capacity and outage analysis of a dual-hop decode-and-forward relay-aided NOMA scheme

Non-orthogonal multiple access (NOMA) is regarded as a candidate radio access technique for the next generation wireless networks because of its manifold spectral gains. A two-phase cooperative relaying strategy (CRS) is proposed in this paper by exploiting the concept of both downlink and uplink NOMA (termed as DU-CNOMA). In the proposed protocol, a transmitter considered as a source transmits a NOMA composite signal consisting of two symbols to the destination and relay during the first phase, following the principle of downlink NOMA. In the second phase, the relay forwards the symbol decoded by successive interference cancellation to the destination, whereas the source transmits a new symbol to the destination in parallel with the relay, following the principle of uplink NOMA. The ergodic sum capacity, outage probability, outage sum capacity, and energy efficiency are investigated comprehensively along with analytical derivations, under both perfect and imperfect successive interference cancellation. To inquire more insight into the system outage performance, diversity order for each symbol in the proposed DU-NOMA is also demonstrated. The performance improvement of the proposed DU-CNOMA over the conventional CRS using NOMA is proved through analysis and computer simulation. Furthermore, the correctness of the author's analysis is proved through a strong agreement between simulation and analytical results.     

基于FPGA的暂态信号可定制精细化实时时频关联分析算法

针对电力系统故障信号中暂态分量的精细化实时分析需求,提出一种不同于Mallat算法频域分段方式的时频关联分析算法。这一算法可以实时运行,既对频带进行了精细化的、可灵活设置的、有重点的划分,又实现了全频带的高时域分辨率,同时保持了输出数据的时频关联特性。基于现场可编程门阵列（field-programmable gate array,FPGA）设计了一个实现这一算法的范例模块,基于MATLAB建立了一个简化的分布式参数电网模型。在这一模型上以生成500 kHz的故障信号采样值序列作为输入范例模块的数据流,对范例模块进行仿真,初步验证了该算法的性能、实用性。就该算法在继电保护算法设计中的应用策略提出了建议,对该算法涉及的其他后续工作进行了展望。     

元件保护正确动作率长期偏低问题的我见

针对我国元件保护正确动作率长期偏低的现象,作者阐述了问题产生的主要根源,并结合国情讨论了如何改变元件保护落后面貌的意见和建议,与全国设计、制造、科研和运行管理部门的各位同仁共商。