防火墙集成系统设计

防火墙集成系统包括操作、集中管理控制、入侵检测三部分.其操作模块又含规则处理、规则库、智能分析、防火墙插件、决策、告警等模块.入侵检测模块则由发送、处理、检测器输送、检测器等规则模块组成.集中管理控制模块负责对防火墙操作、入侵检测模块进行图形界面管理,并对其配置、启动等方面加以控制.     

网中网理论在柔性制造系统中的应用

柔性制造系统的宏观模型,根据网中网理论并结合Renew构建,即将通用标记(网)用对象采替代.当变迁SupplyA激活后到达RobotSystem,通过共用库所与系统网发生交互.机械处理后到达装配缓冲区AssemblyBuffer,操作结束后标记到达装配系统对象网.此时另一标记SupplyB也参与到系统生产变迁,装配结束后到达处理缓冲库所,再经机器人控制系统及缓冲处理库所Deposit2,最终提交完成产品加工.     

基于J2EE的电力企业物资管理系统

基于J2EE的某电力企业物资管理系统,采用客户层、Web层、业务逻辑层及企业信息系统层四层结构.功能模块包括仓库管理、库存核算、合同管理、计划管理、统计报表及决策支持六部分.系统由IBM提供服务器平台,以创建EJB及Web组件、配置及部署J2EE应用完成其应用程序,最后通过报表打印及安全控制实现物资管理.     

电源系统的谐波干扰分析与抑制技术

谐波源分电流型和电压型2类.电流型的抑制采用滤波器分流,即通过滤波器电感和电容的谐振,形成低阻抗并为谐波电流提供通路,以降低进入电网中的谐波电流.而电压型谐波源的抑制则采用并联型滤波器分压,通过滤波器电感和电容的并联谐振,形成高阻抗,抑制降低电路中谐波电流在电网中所形成的谐波电压.2种谐波都可采用无源和有源滤波两种形式抑制.     

基于区间数学的系统稳定性分析

根据Routh判据,区间数学模型的线性系统稳定性的充要条件是第一列全部为正数,等价于其下界大于零.如果第一列区间数以零为下界,则特征方程有成对虚根,系统临界稳定.而Nyquist稳定判据则根据系统的开环频率特性判断闭环系统稳定性.由于参数可行域的引入,等价于给了系统一定的稳定裕度.     

电站设备评价认证系统数据库的设计研究

介绍了电站设备评价认证系统数据库设计研究的内容,讨论了数据库设计的过程,重点进行了数据库设计的需求分析。     

几种常用的成败型系统可靠性综合方法之比较

针对成败型复杂系统进行可靠性评估时综合方法易混淆使用造成评估结果错误的问题,提出了确定几种常用综合方法适用条件和范围的分析方法;首先通过对不同综合方法进行理论对比分析,再结合选取典型算例对分析结果进行验证;结果表明:该方法不仅有效地确定了几种常用的成败型串联综合评估方法的使用条件,而且确定了每种方法的优劣,为工程人员参考提供了应用.     

A stochastic methodology to adjust controllers based on moments Lyapunov exponents: Application to power systems

This paper presents a methodology, based on linear analysis, that uses stability indices based on the calculation of moments Lyapunov exponents to determine the optimum adjustment of controllers in linear stochastic systems. The purpose is to define what values the parameters must have so that the system, subjected to perturbations self-sustained over time, can maintain its stability during operation in permanent regime. The proposed development is applied to three test systems, including two electric power system.     

Mismatched disturbance attenuation control for static var compensator with uncertain parameters

The use of a static var compensator (SVC) as a component of flexible alternating current transmission system (FACTS) devices to control power systems has been investigated for decades. Its aim is to regulate the system voltage and improve the stability and loadability of power systems. A typical assumption in such a system is that the parameters of the controlled system are known accurately, which is rarely satisfied in practice. This paper explores the development of a simple but effective controller for a single-machine infinite-bus power system with SVC subjected to both matched and mismatched disturbances where the controller derivation is based on the assumption that all parameters used in the system modeling are unknown, but bounded in size. The research in this paper illustrates how an indirect robust control can be incorporated with a modified disturbance observer-based feedforward term to attenuate the influence of parameter variations and disturbances from the outputs of the system. Simulation results are presented to confirm the effectiveness of the proposed scheme.     

An Improved On-line Contingency Screening for Power System Transient Stability Assessment

This paper presents a contingency screening method and a framework for its on-line implementation. The proposed method carries out contingency screening and on-line stability assessment with respect to first-swing transient stability. For that purpose, it utilizes the single machine equivalent method and aims at improving the prior developed contingency screening approaches. In order to determine vulnerability of the system with respect to a particular contingency, only one time-domain simulation needs to be performed. An early stop criteria is proposed so that in a majority of the cases the simulation can be terminated after a few hundred milliseconds of simulated system response. The method’s outcome is an assessment of the system’s stability and a classification of each considered contingency. The contingencies are categorized by exploiting parameters of an equivalent one machine infinite bus system. A novel island detection approach, appropriate for an on-line application since it utilizes efficient algorithms from graph theory and enables stability assessment of individual islands, is also introduced. The New England and New York system as well as the large-scale model of the Continental-European interconnected system are used to test the proposed method with respect to assessment accuracy and computation time.