变电站自动化系统GPS对时技术分析

随着用电量不断增加,变电站承担的供电任务越来越重,传统的控制与管理系统已无法满足变电站的工作要求,因此,变电站也要向自动化方向转变。而在自动化系统中,GPS对时技术是确保整个系统同时动作的必要措施,其对变电站升级改造的重要性不言而喻。文章阐述了变电站自动化系统中时间同步的重要意义,分析了自动化系统中GPS对时技术及应用。

基于IEC61850通讯的发电厂时间同步方案设计及应用

本文从樟洋B厂自动化系统中目前的对时应用情况和实际需要,为解决6kV保护装置与电厂集散控制系统的时间同步问题,对比分析了电厂自动化系统常用的三种同步对时方法,采用基于IEC61850通信的网络SNTP同步对时技术。为提高对时网络的可靠性,两台交换机分别设置扩展对时装置,以防止某段网络故障或对时装置故障时对另一段保护装置的影响。

浅谈智能变电站对时技术

在电网运行和事故系统性分析的过程中,需要对断路器动作时序、电网暂态过程电流等各种事件发生的时间序列进行描述。而能否较好的进行这些序列的描述,将直接对电网运行和故障分析产生重要的影响。因此,基于这种认识,对智能变电站对时技术展开了探讨,从而为关注这一话题的人们提供参考。

基于智能变电站数字化保护的采样数据同步技术应用

智能变电站数字化保护是将变电站信息采集、传输、处理、输出过程全部数字化,通过分层、分布式通信网络传输,实现全站信息共享。由于超高压变电站动态电磁环境、温度等因素影响,采集电路易受干扰,严重影响采样过程和数据同步。解决这一难题,需要一次设备智能化,二次设备网络化,通过直接采样或网络采样方式,将电子式互感器、合并单元、智能终端、对时技术等有机结合,提高采样精度和信号传输的可靠性。

变电站电力系统的自动化智能控制技术探究

通过分析变电站电力系统自动化智能控制的必要性,能保证电能供应质量,降低人工成本,提高管理效率。变电站电力系统自动化智能控制系统主要由一次系统和二次系统构成。探讨变电站电力系统自动化智能控制体系结构及关键技术,其中体系结构主要由站控层、间隔层以及过程层构成,使用的关键技术有通信技术、电子式互感技术、对时同步技术以及在线监测技术等。

New criterion for delay-dependent absolute stability of Lurie system with interval time-varying delay

The delay-dependent absolute stability for a class of Lurie systems with interval time-varying delay is studied. By employing an augmented Lyapunov functional and combining a free-weighting matrix approach and the reciprocal convex technique, an improved stability condition is derived in terms of linear matrix inequalities （LMIs）. By retaining some useful terms that are usually ignored in the derivative of the Lyapunov function, the proposed sufficient condition depends not only on the lower and upper bounds of both the delay and its derivative, but it also depends on their differences, which has wider application fields than those of present results. Moreover, a new type of equality expression is developed to handle the sector bounds of the nonlinear function, which achieves fewer LMIs in the derived condition, compared with those based on the convex representation. Therefore, the proposed method is less conservative than the existing ones. Simulation examples are given to demonstrate the validity of the approach.

Review of Remotely Sensed Imagery Classification Patterns Based on Object-oriented Image Analysis

With the wide use of high-resolution remotely sensed imagery, the object-oriented remotely sensed informa- tion classification pattern has been intensively studied. Starting with the definition of object-oriented remotely sensed information classification pattern and a literature review of related research progress, this paper sums up 4 developing phases of object-oriented classification pattern during the past 20 years. Then, we discuss the three aspects of method- ology in detail, namely remotely sensed imagery segmentation, feature analysis and feature selection, and classification rule generation, through comparing them with remotely sensed information classification method based on per-pixel. At last, this paper presents several points that need to be paid attention to in the future studies on object-oriented RS in- formation classification pattern: 1) developing robust and highly effective image segmentation algorithm for multi-spectral RS imagery; 2) improving the feature-set including edge, spatial-adjacent and temporal characteristics; 3) discussing the classification rule generation classifier based on the decision tree; 4) presenting evaluation methods for classification result by object-oriented classification pattern.